[llvm] [IR][PatternMatch] Only accept poison in getSplatValue() (PR #89159)

Nikita Popov via llvm-commits llvm-commits at lists.llvm.org
Wed Apr 17 17:21:40 PDT 2024


https://github.com/nikic created https://github.com/llvm/llvm-project/pull/89159

In #88217 a large set of matchers was changed to only accept poison values in splats, but not undef values. This is because we now use poison for non-demanded vector elements, and allowing undef can cause correctness issues.

This patch covers the remaining matchers by changing the AllowUndef parameter of getSplatValue() to AllowPoison instead. We also carry out corresponding renames in matchers.

As a followup, we may want to change the default for things like m_APInt to m_APIntAllowPoison (as this is much less risky when only allowing poison), but this change doesn't do that.

There is one caveat here: We have a single place (X86FixupVectorConstants) which does require handling of vector splats with undefs. This is because this works on backend constant pool entries, which currently still use undef instead of poison for non-demanded elements (because SDAG as a whole does not have an explicit poison representation). As it's just the single use, I've open-coded a getSplatValueAllowUndef() helper there, to discourage use in any other places.

>From 8dd1125186e0538f06b276d4cd93a4b7f1d07c59 Mon Sep 17 00:00:00 2001
From: Nikita Popov <npopov at redhat.com>
Date: Wed, 17 Apr 2024 18:48:52 +0900
Subject: [PATCH] [IR][PatternMatch] Only accept poison in getSplatValue()

In #88217 a large set of matchers was changed to only accept
poison values in splats, but not undef values. This is because we
now use poison for non-demanded vector elements, and allowing undef
can cause correctness issues.

This patch covers the remaining matchers by changing the
AllowUndef parameter of getSplatValue() to AllowPoison instead.
We also carry out corresponding renames in matchers.

As a followup, we may want to change the default for things like
m_APInt to m_APIntAllowPoison (as this is much less risky when
only allowing poison), but this change doesn't do that.

There is one caveat here: We have a single place
(X86FixupVectorConstants) which does require handling of vector
splats with undefs. This is because this works on backend constant
pool entries, which currently still use undef instead of poison
for non-demanded elements (because SDAG as a whole does not have
an explicit poison representation). As it's just the single use,
I've open-coded a getSplatValueAllowUndef() helper there, to
discourage use in any other places.
---
 llvm/include/llvm/IR/Constant.h               |  6 +-
 llvm/include/llvm/IR/Constants.h              |  6 +-
 llvm/include/llvm/IR/PatternMatch.h           | 66 +++++++-------
 llvm/lib/Analysis/CmpInstAnalysis.cpp         |  2 +-
 llvm/lib/Analysis/InstructionSimplify.cpp     | 14 +--
 llvm/lib/Analysis/ValueTracking.cpp           |  4 +-
 llvm/lib/IR/Constants.cpp                     | 14 +--
 llvm/lib/Target/AMDGPU/AMDGPULibCalls.cpp     |  6 +-
 .../Target/X86/X86FixupVectorConstants.cpp    | 19 ++++-
 .../InstCombine/InstCombineAddSub.cpp         |  4 +-
 .../InstCombine/InstCombineAndOrXor.cpp       | 22 ++---
 .../InstCombine/InstCombineCalls.cpp          |  8 +-
 .../InstCombine/InstCombineCasts.cpp          |  2 +-
 .../InstCombine/InstCombineCompares.cpp       | 37 ++++----
 .../InstCombine/InstCombineInternal.h         |  4 +-
 .../InstCombine/InstCombineMulDivRem.cpp      |  6 +-
 .../InstCombine/InstCombineNegator.cpp        |  2 +-
 .../InstCombine/InstCombineSelect.cpp         | 16 ++--
 .../InstCombine/InstCombineShifts.cpp         |  8 +-
 .../InstCombine/InstructionCombining.cpp      |  4 +-
 .../Transforms/Vectorize/VPlanPatternMatch.h  |  2 +-
 .../InstCombine/and-or-icmp-const-icmp.ll     | 14 +--
 .../Transforms/InstCombine/binop-itofp.ll     | 21 +++--
 .../test/Transforms/InstCombine/bswap-fold.ll |  8 +-
 llvm/test/Transforms/InstCombine/bswap.ll     | 46 +++++-----
 .../Transforms/InstCombine/compare-signs.ll   | 14 +--
 .../InstCombine/fcmp-range-check-idiom.ll     |  8 +-
 llvm/test/Transforms/InstCombine/icmp-fsh.ll  | 32 +++----
 .../icmp-power2-and-icmp-shifted-mask.ll      | 10 ++-
 .../InstCombine/icmp-vec-inseltpoison.ll      | 20 ++---
 llvm/test/Transforms/InstCombine/icmp-vec.ll  | 50 +++++------
 .../Transforms/InstCombine/low-bit-splat.ll   | 23 ++---
 .../lshr-trunc-sext-to-ashr-sext.ll           | 34 ++++----
 llvm/test/Transforms/InstCombine/select.ll    | 18 ++--
 .../InstCombine/signed-truncation-check.ll    | 74 ++++++++--------
 .../unsigned-add-lack-of-overflow-check.ll    |  2 +-
 llvm/test/Transforms/InstCombine/xor-ashr.ll  | 10 +--
 .../InstSimplify/cast-unsigned-icmp-cmp-0.ll  | 36 ++++----
 .../Transforms/InstSimplify/icmp-constant.ll  | 60 ++++++-------
 .../InstSimplify/maxmin_intrinsics.ll         | 52 ++++++------
 llvm/unittests/IR/InstructionsTest.cpp        | 23 +++--
 llvm/unittests/IR/PatternMatch.cpp            | 85 +++++++++++++------
 42 files changed, 479 insertions(+), 413 deletions(-)

diff --git a/llvm/include/llvm/IR/Constant.h b/llvm/include/llvm/IR/Constant.h
index 778764062227cb..d3171acf7b9ac2 100644
--- a/llvm/include/llvm/IR/Constant.h
+++ b/llvm/include/llvm/IR/Constant.h
@@ -146,9 +146,9 @@ class Constant : public User {
   Constant *getAggregateElement(Constant *Elt) const;
 
   /// If all elements of the vector constant have the same value, return that
-  /// value. Otherwise, return nullptr. Ignore undefined elements by setting
-  /// AllowUndefs to true.
-  Constant *getSplatValue(bool AllowUndefs = false) const;
+  /// value. Otherwise, return nullptr. Ignore poison elements by setting
+  /// AllowPoison to true.
+  Constant *getSplatValue(bool AllowPoison = false) const;
 
   /// If C is a constant integer then return its value, otherwise C must be a
   /// vector of constant integers, all equal, and the common value is returned.
diff --git a/llvm/include/llvm/IR/Constants.h b/llvm/include/llvm/IR/Constants.h
index 4290ef4486c6f4..9ec81903f09c96 100644
--- a/llvm/include/llvm/IR/Constants.h
+++ b/llvm/include/llvm/IR/Constants.h
@@ -532,9 +532,9 @@ class ConstantVector final : public ConstantAggregate {
   }
 
   /// If all elements of the vector constant have the same value, return that
-  /// value. Otherwise, return nullptr. Ignore undefined elements by setting
-  /// AllowUndefs to true.
-  Constant *getSplatValue(bool AllowUndefs = false) const;
+  /// value. Otherwise, return nullptr. Ignore poison elements by setting
+  /// AllowPoison to true.
+  Constant *getSplatValue(bool AllowPoison = false) const;
 
   /// Methods for support type inquiry through isa, cast, and dyn_cast:
   static bool classof(const Value *V) {
diff --git a/llvm/include/llvm/IR/PatternMatch.h b/llvm/include/llvm/IR/PatternMatch.h
index 98cc0e50376981..30e9c3900c8661 100644
--- a/llvm/include/llvm/IR/PatternMatch.h
+++ b/llvm/include/llvm/IR/PatternMatch.h
@@ -243,10 +243,10 @@ inline match_combine_and<LTy, RTy> m_CombineAnd(const LTy &L, const RTy &R) {
 
 struct apint_match {
   const APInt *&Res;
-  bool AllowUndef;
+  bool AllowPoison;
 
-  apint_match(const APInt *&Res, bool AllowUndef)
-      : Res(Res), AllowUndef(AllowUndef) {}
+  apint_match(const APInt *&Res, bool AllowPoison)
+      : Res(Res), AllowPoison(AllowPoison) {}
 
   template <typename ITy> bool match(ITy *V) {
     if (auto *CI = dyn_cast<ConstantInt>(V)) {
@@ -256,7 +256,7 @@ struct apint_match {
     if (V->getType()->isVectorTy())
       if (const auto *C = dyn_cast<Constant>(V))
         if (auto *CI =
-                dyn_cast_or_null<ConstantInt>(C->getSplatValue(AllowUndef))) {
+                dyn_cast_or_null<ConstantInt>(C->getSplatValue(AllowPoison))) {
           Res = &CI->getValue();
           return true;
         }
@@ -268,10 +268,10 @@ struct apint_match {
 // function for both apint/apfloat.
 struct apfloat_match {
   const APFloat *&Res;
-  bool AllowUndef;
+  bool AllowPoison;
 
-  apfloat_match(const APFloat *&Res, bool AllowUndef)
-      : Res(Res), AllowUndef(AllowUndef) {}
+  apfloat_match(const APFloat *&Res, bool AllowPoison)
+      : Res(Res), AllowPoison(AllowPoison) {}
 
   template <typename ITy> bool match(ITy *V) {
     if (auto *CI = dyn_cast<ConstantFP>(V)) {
@@ -281,7 +281,7 @@ struct apfloat_match {
     if (V->getType()->isVectorTy())
       if (const auto *C = dyn_cast<Constant>(V))
         if (auto *CI =
-                dyn_cast_or_null<ConstantFP>(C->getSplatValue(AllowUndef))) {
+                dyn_cast_or_null<ConstantFP>(C->getSplatValue(AllowPoison))) {
           Res = &CI->getValueAPF();
           return true;
         }
@@ -292,35 +292,35 @@ struct apfloat_match {
 /// Match a ConstantInt or splatted ConstantVector, binding the
 /// specified pointer to the contained APInt.
 inline apint_match m_APInt(const APInt *&Res) {
-  // Forbid undefs by default to maintain previous behavior.
-  return apint_match(Res, /* AllowUndef */ false);
+  // Forbid poison by default to maintain previous behavior.
+  return apint_match(Res, /* AllowPoison */ false);
 }
 
-/// Match APInt while allowing undefs in splat vector constants.
-inline apint_match m_APIntAllowUndef(const APInt *&Res) {
-  return apint_match(Res, /* AllowUndef */ true);
+/// Match APInt while allowing poison in splat vector constants.
+inline apint_match m_APIntAllowPoison(const APInt *&Res) {
+  return apint_match(Res, /* AllowPoison */ true);
 }
 
-/// Match APInt while forbidding undefs in splat vector constants.
-inline apint_match m_APIntForbidUndef(const APInt *&Res) {
-  return apint_match(Res, /* AllowUndef */ false);
+/// Match APInt while forbidding poison in splat vector constants.
+inline apint_match m_APIntForbidPoison(const APInt *&Res) {
+  return apint_match(Res, /* AllowPoison */ false);
 }
 
 /// Match a ConstantFP or splatted ConstantVector, binding the
 /// specified pointer to the contained APFloat.
 inline apfloat_match m_APFloat(const APFloat *&Res) {
   // Forbid undefs by default to maintain previous behavior.
-  return apfloat_match(Res, /* AllowUndef */ false);
+  return apfloat_match(Res, /* AllowPoison */ false);
 }
 
-/// Match APFloat while allowing undefs in splat vector constants.
-inline apfloat_match m_APFloatAllowUndef(const APFloat *&Res) {
-  return apfloat_match(Res, /* AllowUndef */ true);
+/// Match APFloat while allowing poison in splat vector constants.
+inline apfloat_match m_APFloatAllowPoison(const APFloat *&Res) {
+  return apfloat_match(Res, /* AllowPoison */ true);
 }
 
-/// Match APFloat while forbidding undefs in splat vector constants.
-inline apfloat_match m_APFloatForbidUndef(const APFloat *&Res) {
-  return apfloat_match(Res, /* AllowUndef */ false);
+/// Match APFloat while forbidding poison in splat vector constants.
+inline apfloat_match m_APFloatForbidPoison(const APFloat *&Res) {
+  return apfloat_match(Res, /* AllowPoison */ false);
 }
 
 template <int64_t Val> struct constantint_match {
@@ -418,7 +418,7 @@ template <typename Predicate> struct api_pred_ty : public Predicate {
 
 /// This helper class is used to match scalar and vector constants that
 /// satisfy a specified predicate, and bind them to an APFloat.
-/// Undefs are allowed in splat vector constants.
+/// Poison is allowed in splat vector constants.
 template <typename Predicate> struct apf_pred_ty : public Predicate {
   const APFloat *&Res;
 
@@ -433,7 +433,7 @@ template <typename Predicate> struct apf_pred_ty : public Predicate {
     if (V->getType()->isVectorTy())
       if (const auto *C = dyn_cast<Constant>(V))
         if (auto *CI = dyn_cast_or_null<ConstantFP>(
-                C->getSplatValue(/* AllowUndef */ true)))
+                C->getSplatValue(/* AllowPoison */ true)))
           if (this->isValue(CI->getValue())) {
             Res = &CI->getValue();
             return true;
@@ -883,7 +883,7 @@ struct bind_const_intval_ty {
 
 /// Match a specified integer value or vector of all elements of that
 /// value.
-template <bool AllowUndefs> struct specific_intval {
+template <bool AllowPoison> struct specific_intval {
   const APInt &Val;
 
   specific_intval(const APInt &V) : Val(V) {}
@@ -892,13 +892,13 @@ template <bool AllowUndefs> struct specific_intval {
     const auto *CI = dyn_cast<ConstantInt>(V);
     if (!CI && V->getType()->isVectorTy())
       if (const auto *C = dyn_cast<Constant>(V))
-        CI = dyn_cast_or_null<ConstantInt>(C->getSplatValue(AllowUndefs));
+        CI = dyn_cast_or_null<ConstantInt>(C->getSplatValue(AllowPoison));
 
     return CI && APInt::isSameValue(CI->getValue(), Val);
   }
 };
 
-template <bool AllowUndefs> struct specific_intval64 {
+template <bool AllowPoison> struct specific_intval64 {
   uint64_t Val;
 
   specific_intval64(uint64_t V) : Val(V) {}
@@ -907,7 +907,7 @@ template <bool AllowUndefs> struct specific_intval64 {
     const auto *CI = dyn_cast<ConstantInt>(V);
     if (!CI && V->getType()->isVectorTy())
       if (const auto *C = dyn_cast<Constant>(V))
-        CI = dyn_cast_or_null<ConstantInt>(C->getSplatValue(AllowUndefs));
+        CI = dyn_cast_or_null<ConstantInt>(C->getSplatValue(AllowPoison));
 
     return CI && CI->getValue() == Val;
   }
@@ -923,11 +923,11 @@ inline specific_intval64<false> m_SpecificInt(uint64_t V) {
   return specific_intval64<false>(V);
 }
 
-inline specific_intval<true> m_SpecificIntAllowUndef(const APInt &V) {
+inline specific_intval<true> m_SpecificIntAllowPoison(const APInt &V) {
   return specific_intval<true>(V);
 }
 
-inline specific_intval64<true> m_SpecificIntAllowUndef(uint64_t V) {
+inline specific_intval64<true> m_SpecificIntAllowPoison(uint64_t V) {
   return specific_intval64<true>(V);
 }
 
@@ -1699,9 +1699,9 @@ struct m_SpecificMask {
   bool match(ArrayRef<int> Mask) { return MaskRef == Mask; }
 };
 
-struct m_SplatOrUndefMask {
+struct m_SplatOrPoisonMask {
   int &SplatIndex;
-  m_SplatOrUndefMask(int &SplatIndex) : SplatIndex(SplatIndex) {}
+  m_SplatOrPoisonMask(int &SplatIndex) : SplatIndex(SplatIndex) {}
   bool match(ArrayRef<int> Mask) {
     const auto *First = find_if(Mask, [](int Elem) { return Elem != -1; });
     if (First == Mask.end())
diff --git a/llvm/lib/Analysis/CmpInstAnalysis.cpp b/llvm/lib/Analysis/CmpInstAnalysis.cpp
index d6407e8750737b..a1fa7857764d98 100644
--- a/llvm/lib/Analysis/CmpInstAnalysis.cpp
+++ b/llvm/lib/Analysis/CmpInstAnalysis.cpp
@@ -79,7 +79,7 @@ bool llvm::decomposeBitTestICmp(Value *LHS, Value *RHS,
   using namespace PatternMatch;
 
   const APInt *C;
-  if (!match(RHS, m_APIntAllowUndef(C)))
+  if (!match(RHS, m_APIntAllowPoison(C)))
     return false;
 
   switch (Pred) {
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 06ba5ca4c6b352..eb4e789b59b154 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -3023,7 +3023,7 @@ static Value *simplifyICmpWithConstant(CmpInst::Predicate Pred, Value *LHS,
 
   Value *X;
   const APInt *C;
-  if (!match(RHS, m_APIntAllowUndef(C)))
+  if (!match(RHS, m_APIntAllowPoison(C)))
     return nullptr;
 
   // Sign-bit checks can be optimized to true/false after unsigned
@@ -3056,9 +3056,9 @@ static Value *simplifyICmpWithConstant(CmpInst::Predicate Pred, Value *LHS,
   // (mul nuw/nsw X, MulC) == C --> false (if C is not a multiple of MulC)
   const APInt *MulC;
   if (IIQ.UseInstrInfo && ICmpInst::isEquality(Pred) &&
-      ((match(LHS, m_NUWMul(m_Value(), m_APIntAllowUndef(MulC))) &&
+      ((match(LHS, m_NUWMul(m_Value(), m_APIntAllowPoison(MulC))) &&
         *MulC != 0 && C->urem(*MulC) != 0) ||
-       (match(LHS, m_NSWMul(m_Value(), m_APIntAllowUndef(MulC))) &&
+       (match(LHS, m_NSWMul(m_Value(), m_APIntAllowPoison(MulC))) &&
         *MulC != 0 && C->srem(*MulC) != 0)))
     return ConstantInt::get(ITy, Pred == ICmpInst::ICMP_NE);
 
@@ -3203,7 +3203,7 @@ static Value *simplifyICmpWithBinOpOnLHS(CmpInst::Predicate Pred,
 
   // (sub C, X) == X, C is odd  --> false
   // (sub C, X) != X, C is odd  --> true
-  if (match(LBO, m_Sub(m_APIntAllowUndef(C), m_Specific(RHS))) &&
+  if (match(LBO, m_Sub(m_APIntAllowPoison(C), m_Specific(RHS))) &&
       (*C & 1) == 1 && ICmpInst::isEquality(Pred))
     return (Pred == ICmpInst::ICMP_EQ) ? getFalse(ITy) : getTrue(ITy);
 
@@ -3354,7 +3354,7 @@ static Value *simplifyICmpWithBinOp(CmpInst::Predicate Pred, Value *LHS,
   //   (C2 << X) != C --> true
   const APInt *C;
   if (match(LHS, m_Shl(m_Power2(), m_Value())) &&
-      match(RHS, m_APIntAllowUndef(C)) && !C->isPowerOf2()) {
+      match(RHS, m_APIntAllowPoison(C)) && !C->isPowerOf2()) {
     // C2 << X can equal zero in some circumstances.
     // This simplification might be unsafe if C is zero.
     //
@@ -4105,7 +4105,7 @@ static Value *simplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
   }
 
   const APFloat *C = nullptr;
-  match(RHS, m_APFloatAllowUndef(C));
+  match(RHS, m_APFloatAllowPoison(C));
   std::optional<KnownFPClass> FullKnownClassLHS;
 
   // Lazily compute the possible classes for LHS. Avoid computing it twice if
@@ -6459,7 +6459,7 @@ Value *llvm::simplifyBinaryIntrinsic(Intrinsic::ID IID, Type *ReturnType,
           ReturnType, MinMaxIntrinsic::getSaturationPoint(IID, BitWidth));
 
     const APInt *C;
-    if (match(Op1, m_APIntAllowUndef(C))) {
+    if (match(Op1, m_APIntAllowPoison(C))) {
       // Clamp to limit value. For example:
       // umax(i8 %x, i8 255) --> 255
       if (*C == MinMaxIntrinsic::getSaturationPoint(IID, BitWidth))
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index ab2f43e1033fa1..349077afef05c1 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4116,7 +4116,7 @@ std::pair<Value *, FPClassTest> llvm::fcmpToClassTest(FCmpInst::Predicate Pred,
                                                       Value *LHS, Value *RHS,
                                                       bool LookThroughSrc) {
   const APFloat *ConstRHS;
-  if (!match(RHS, m_APFloatAllowUndef(ConstRHS)))
+  if (!match(RHS, m_APFloatAllowPoison(ConstRHS)))
     return {nullptr, fcAllFlags};
 
   return fcmpToClassTest(Pred, F, LHS, ConstRHS, LookThroughSrc);
@@ -4517,7 +4517,7 @@ std::tuple<Value *, FPClassTest, FPClassTest>
 llvm::fcmpImpliesClass(CmpInst::Predicate Pred, const Function &F, Value *LHS,
                        Value *RHS, bool LookThroughSrc) {
   const APFloat *ConstRHS;
-  if (!match(RHS, m_APFloatAllowUndef(ConstRHS)))
+  if (!match(RHS, m_APFloatAllowPoison(ConstRHS)))
     return {nullptr, fcAllFlags, fcAllFlags};
 
   // TODO: Just call computeKnownFPClass for RHS to handle non-constants.
diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index 45b359a94b3ab7..5268eccf701442 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -1696,14 +1696,14 @@ void ConstantVector::destroyConstantImpl() {
   getType()->getContext().pImpl->VectorConstants.remove(this);
 }
 
-Constant *Constant::getSplatValue(bool AllowUndefs) const {
+Constant *Constant::getSplatValue(bool AllowPoison) const {
   assert(this->getType()->isVectorTy() && "Only valid for vectors!");
   if (isa<ConstantAggregateZero>(this))
     return getNullValue(cast<VectorType>(getType())->getElementType());
   if (const ConstantDataVector *CV = dyn_cast<ConstantDataVector>(this))
     return CV->getSplatValue();
   if (const ConstantVector *CV = dyn_cast<ConstantVector>(this))
-    return CV->getSplatValue(AllowUndefs);
+    return CV->getSplatValue(AllowPoison);
 
   // Check if this is a constant expression splat of the form returned by
   // ConstantVector::getSplat()
@@ -1728,7 +1728,7 @@ Constant *Constant::getSplatValue(bool AllowUndefs) const {
   return nullptr;
 }
 
-Constant *ConstantVector::getSplatValue(bool AllowUndefs) const {
+Constant *ConstantVector::getSplatValue(bool AllowPoison) const {
   // Check out first element.
   Constant *Elt = getOperand(0);
   // Then make sure all remaining elements point to the same value.
@@ -1738,15 +1738,15 @@ Constant *ConstantVector::getSplatValue(bool AllowUndefs) const {
       continue;
 
     // Strict mode: any mismatch is not a splat.
-    if (!AllowUndefs)
+    if (!AllowPoison)
       return nullptr;
 
-    // Allow undefs mode: ignore undefined elements.
-    if (isa<UndefValue>(OpC))
+    // Allow poison mode: ignore poison elements.
+    if (isa<PoisonValue>(OpC))
       continue;
 
     // If we do not have a defined element yet, use the current operand.
-    if (isa<UndefValue>(Elt))
+    if (isa<PoisonValue>(Elt))
       Elt = OpC;
 
     if (OpC != Elt)
diff --git a/llvm/lib/Target/AMDGPU/AMDGPULibCalls.cpp b/llvm/lib/Target/AMDGPU/AMDGPULibCalls.cpp
index 5aa35becd842c3..978a2d49b08bc2 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPULibCalls.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPULibCalls.cpp
@@ -906,8 +906,8 @@ bool AMDGPULibCalls::fold_pow(FPMathOperator *FPOp, IRBuilder<> &B,
 
   const APFloat *CF = nullptr;
   const APInt *CINT = nullptr;
-  if (!match(opr1, m_APFloatAllowUndef(CF)))
-    match(opr1, m_APIntAllowUndef(CINT));
+  if (!match(opr1, m_APFloatAllowPoison(CF)))
+    match(opr1, m_APIntAllowPoison(CINT));
 
   // 0x1111111 means that we don't do anything for this call.
   int ci_opr1 = (CINT ? (int)CINT->getSExtValue() : 0x1111111);
@@ -1039,7 +1039,7 @@ bool AMDGPULibCalls::fold_pow(FPMathOperator *FPOp, IRBuilder<> &B,
   Constant *cnval = nullptr;
   if (getVecSize(FInfo) == 1) {
     CF = nullptr;
-    match(opr0, m_APFloatAllowUndef(CF));
+    match(opr0, m_APFloatAllowPoison(CF));
 
     if (CF) {
       double V = (getArgType(FInfo) == AMDGPULibFunc::F32)
diff --git a/llvm/lib/Target/X86/X86FixupVectorConstants.cpp b/llvm/lib/Target/X86/X86FixupVectorConstants.cpp
index da7dcbb25a9577..c9f79e1645f58b 100644
--- a/llvm/lib/Target/X86/X86FixupVectorConstants.cpp
+++ b/llvm/lib/Target/X86/X86FixupVectorConstants.cpp
@@ -64,6 +64,23 @@ FunctionPass *llvm::createX86FixupVectorConstants() {
   return new X86FixupVectorConstantsPass();
 }
 
+/// Normally, we only allow poison in vector splats. However, as this is part
+/// of the backend, and working with the DAG representation, which currently
+/// only natively represents undef values, we need to accept undefs here.
+static Constant *getSplatValueAllowUndef(const ConstantVector *C) {
+  Constant *Res = nullptr;
+  for (Value *Op : C->operands()) {
+    Constant *OpC = cast<Constant>(Op);
+    if (isa<UndefValue>(OpC))
+      continue;
+    if (!Res)
+      Res = OpC;
+    else if (Res != OpC)
+      return nullptr;
+  }
+  return Res;
+}
+
 // Attempt to extract the full width of bits data from the constant.
 static std::optional<APInt> extractConstantBits(const Constant *C) {
   unsigned NumBits = C->getType()->getPrimitiveSizeInBits();
@@ -78,7 +95,7 @@ static std::optional<APInt> extractConstantBits(const Constant *C) {
     return CFP->getValue().bitcastToAPInt();
 
   if (auto *CV = dyn_cast<ConstantVector>(C)) {
-    if (auto *CVSplat = CV->getSplatValue(/*AllowUndefs*/ true)) {
+    if (auto *CVSplat = getSplatValueAllowUndef(CV)) {
       if (std::optional<APInt> Bits = extractConstantBits(CVSplat)) {
         assert((NumBits % Bits->getBitWidth()) == 0 && "Illegal splat");
         return APInt::getSplat(NumBits, *Bits);
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index c59b867b10e7d1..b853dc678877e0 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -896,7 +896,7 @@ Instruction *InstCombinerImpl::foldAddWithConstant(BinaryOperator &Add) {
   const APInt *C;
   unsigned BitWidth = Ty->getScalarSizeInBits();
   if (match(Op0, m_OneUse(m_AShr(m_Value(X),
-                                 m_SpecificIntAllowUndef(BitWidth - 1)))) &&
+                                 m_SpecificIntAllowPoison(BitWidth - 1)))) &&
       match(Op1, m_One()))
     return new ZExtInst(Builder.CreateIsNotNeg(X, "isnotneg"), Ty);
 
@@ -1656,7 +1656,7 @@ Instruction *InstCombinerImpl::visitAdd(BinaryOperator &I) {
   // (A s>> (BW - 1)) + (zext (A s> 0)) --> (A s>> (BW - 1)) | (zext (A != 0))
   ICmpInst::Predicate Pred;
   uint64_t BitWidth = Ty->getScalarSizeInBits();
-  if (match(LHS, m_AShr(m_Value(A), m_SpecificIntAllowUndef(BitWidth - 1))) &&
+  if (match(LHS, m_AShr(m_Value(A), m_SpecificIntAllowPoison(BitWidth - 1))) &&
       match(RHS, m_OneUse(m_ZExt(
                      m_OneUse(m_ICmp(Pred, m_Specific(A), m_ZeroInt()))))) &&
       Pred == CmpInst::ICMP_SGT) {
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 0f4fbf5bbfbbdc..bf7c0074a38f05 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -947,9 +947,9 @@ static Value *foldNegativePower2AndShiftedMask(
   // bits (0).
   auto isReducible = [](const Value *B, const Value *D, const Value *E) {
     const APInt *BCst, *DCst, *ECst;
-    return match(B, m_APIntAllowUndef(BCst)) && match(D, m_APInt(DCst)) &&
+    return match(B, m_APIntAllowPoison(BCst)) && match(D, m_APInt(DCst)) &&
            match(E, m_APInt(ECst)) && *DCst == *ECst &&
-           (isa<UndefValue>(B) ||
+           (isa<PoisonValue>(B) ||
             (BCst->countLeadingOnes() == DCst->countLeadingZeros()));
   };
 
@@ -1424,8 +1424,8 @@ Value *InstCombinerImpl::foldLogicOfFCmps(FCmpInst *LHS, FCmpInst *RHS,
   const APFloat *LHSC, *RHSC;
   if (LHS0 == RHS0 && LHS->hasOneUse() && RHS->hasOneUse() &&
       FCmpInst::getSwappedPredicate(PredL) == PredR &&
-      match(LHS1, m_APFloatAllowUndef(LHSC)) &&
-      match(RHS1, m_APFloatAllowUndef(RHSC)) &&
+      match(LHS1, m_APFloatAllowPoison(LHSC)) &&
+      match(RHS1, m_APFloatAllowPoison(RHSC)) &&
       LHSC->bitwiseIsEqual(neg(*RHSC))) {
     auto IsLessThanOrLessEqual = [](FCmpInst::Predicate Pred) {
       switch (Pred) {
@@ -2730,7 +2730,7 @@ Instruction *InstCombinerImpl::visitAnd(BinaryOperator &I) {
 
   // (iN X s>> (N-1)) & Y --> (X s< 0) ? Y : 0 -- with optional sext
   if (match(&I, m_c_And(m_OneUse(m_SExtOrSelf(
-                            m_AShr(m_Value(X), m_APIntAllowUndef(C)))),
+                            m_AShr(m_Value(X), m_APIntAllowPoison(C)))),
                         m_Value(Y))) &&
       *C == X->getType()->getScalarSizeInBits() - 1) {
     Value *IsNeg = Builder.CreateIsNeg(X, "isneg");
@@ -2739,7 +2739,7 @@ Instruction *InstCombinerImpl::visitAnd(BinaryOperator &I) {
   // If there's a 'not' of the shifted value, swap the select operands:
   // ~(iN X s>> (N-1)) & Y --> (X s< 0) ? 0 : Y -- with optional sext
   if (match(&I, m_c_And(m_OneUse(m_SExtOrSelf(
-                            m_Not(m_AShr(m_Value(X), m_APIntAllowUndef(C))))),
+                            m_Not(m_AShr(m_Value(X), m_APIntAllowPoison(C))))),
                         m_Value(Y))) &&
       *C == X->getType()->getScalarSizeInBits() - 1) {
     Value *IsNeg = Builder.CreateIsNeg(X, "isneg");
@@ -2840,7 +2840,7 @@ InstCombinerImpl::convertOrOfShiftsToFunnelShift(Instruction &Or) {
     auto matchShiftAmount = [&](Value *L, Value *R, unsigned Width) -> Value * {
       // Check for constant shift amounts that sum to the bitwidth.
       const APInt *LI, *RI;
-      if (match(L, m_APIntAllowUndef(LI)) && match(R, m_APIntAllowUndef(RI)))
+      if (match(L, m_APIntAllowPoison(LI)) && match(R, m_APIntAllowPoison(RI)))
         if (LI->ult(Width) && RI->ult(Width) && (*LI + *RI) == Width)
           return ConstantInt::get(L->getType(), *LI);
 
@@ -2850,7 +2850,7 @@ InstCombinerImpl::convertOrOfShiftsToFunnelShift(Instruction &Or) {
                 m_SpecificInt_ICMP(ICmpInst::ICMP_ULT, APInt(Width, Width))) &&
           match(R,
                 m_SpecificInt_ICMP(ICmpInst::ICMP_ULT, APInt(Width, Width))) &&
-          match(ConstantExpr::getAdd(LC, RC), m_SpecificIntAllowUndef(Width)))
+          match(ConstantExpr::getAdd(LC, RC), m_SpecificIntAllowPoison(Width)))
         return ConstantExpr::mergeUndefsWith(LC, RC);
 
       // (shl ShVal, X) | (lshr ShVal, (Width - x)) iff X < Width.
@@ -3195,14 +3195,14 @@ static Value *foldAndOrOfICmpEqConstantAndICmp(ICmpInst *LHS, ICmpInst *RHS,
 
   const APInt *CInt;
   if (LPred != ICmpInst::ICMP_EQ ||
-      !match(LHS->getOperand(1), m_APIntAllowUndef(CInt)) ||
+      !match(LHS->getOperand(1), m_APIntAllowPoison(CInt)) ||
       !LHS0->getType()->isIntOrIntVectorTy() ||
       !(LHS->hasOneUse() || RHS->hasOneUse()))
     return nullptr;
 
   auto MatchRHSOp = [LHS0, CInt](const Value *RHSOp) {
     return match(RHSOp,
-                 m_Add(m_Specific(LHS0), m_SpecificIntAllowUndef(-*CInt))) ||
+                 m_Add(m_Specific(LHS0), m_SpecificIntAllowPoison(-*CInt))) ||
            (CInt->isZero() && RHSOp == LHS0);
   };
 
@@ -4635,7 +4635,7 @@ Instruction *InstCombinerImpl::visitXor(BinaryOperator &I) {
     // constant depending on whether this input is less than 0.
     const APInt *CA;
     if (match(Op0, m_OneUse(m_TruncOrSelf(
-                       m_AShr(m_Value(X), m_APIntAllowUndef(CA))))) &&
+                       m_AShr(m_Value(X), m_APIntAllowPoison(CA))))) &&
         *CA == X->getType()->getScalarSizeInBits() - 1 &&
         !match(C1, m_AllOnes())) {
       assert(!C1->isZeroValue() && "Unexpected xor with 0");
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 60e4be883f513b..aa547565bd0859 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1821,7 +1821,7 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
        return NewMinMax;
 
     // Try to fold minmax with constant RHS based on range information
-    if (match(I1, m_APIntAllowUndef(RHSC))) {
+    if (match(I1, m_APIntAllowPoison(RHSC))) {
       ICmpInst::Predicate Pred =
           ICmpInst::getNonStrictPredicate(MinMaxIntrinsic::getPredicate(IID));
       bool IsSigned = MinMaxIntrinsic::isSigned(IID);
@@ -1865,12 +1865,8 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
     // bswap (lshr X, Y) --> shl (bswap X), Y
     Value *X, *Y;
     if (match(IIOperand, m_OneUse(m_LogicalShift(m_Value(X), m_Value(Y))))) {
-      // The transform allows undef vector elements, so try a constant match
-      // first. If knownbits can handle that case, that clause could be removed.
       unsigned BitWidth = IIOperand->getType()->getScalarSizeInBits();
-      const APInt *C;
-      if ((match(Y, m_APIntAllowUndef(C)) && (*C & 7) == 0) ||
-          MaskedValueIsZero(Y, APInt::getLowBitsSet(BitWidth, 3))) {
+      if (MaskedValueIsZero(Y, APInt::getLowBitsSet(BitWidth, 3))) {
         Value *NewSwap = Builder.CreateUnaryIntrinsic(Intrinsic::bswap, X);
         BinaryOperator::BinaryOps InverseShift =
             cast<BinaryOperator>(IIOperand)->getOpcode() == Instruction::Shl
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index d242d3f443def9..a4ddc3d24f59d5 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1481,7 +1481,7 @@ Instruction *InstCombinerImpl::visitSExt(SExtInst &Sext) {
     Value *Y;
     if (Src->hasOneUse() &&
         match(X, m_LShr(m_Value(Y),
-                        m_SpecificIntAllowUndef(XBitSize - SrcBitSize)))) {
+                        m_SpecificIntAllowPoison(XBitSize - SrcBitSize)))) {
       Value *Ashr = Builder.CreateAShr(Y, XBitSize - SrcBitSize);
       return CastInst::CreateIntegerCast(Ashr, DestTy, /* isSigned */ true);
     }
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index de909077017432..00fb1f7dd75b78 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3417,8 +3417,8 @@ Instruction *InstCombinerImpl::foldICmpInstWithConstant(ICmpInst &Cmp) {
       return new ICmpInst(Cmp.getPredicate(), X, Y);
   }
 
-  if (match(Cmp.getOperand(1), m_APIntAllowUndef(C)))
-    return foldICmpInstWithConstantAllowUndef(Cmp, *C);
+  if (match(Cmp.getOperand(1), m_APIntAllowPoison(C)))
+    return foldICmpInstWithConstantAllowPoison(Cmp, *C);
 
   return nullptr;
 }
@@ -3735,11 +3735,11 @@ foldICmpIntrinsicWithIntrinsic(ICmpInst &Cmp,
 }
 
 /// Try to fold integer comparisons with a constant operand: icmp Pred X, C
-/// where X is some kind of instruction and C is AllowUndef.
-/// TODO: Move more folds which allow undef to this function.
+/// where X is some kind of instruction and C is AllowPoison.
+/// TODO: Move more folds which allow poison to this function.
 Instruction *
-InstCombinerImpl::foldICmpInstWithConstantAllowUndef(ICmpInst &Cmp,
-                                                     const APInt &C) {
+InstCombinerImpl::foldICmpInstWithConstantAllowPoison(ICmpInst &Cmp,
+                                                      const APInt &C) {
   const ICmpInst::Predicate Pred = Cmp.getPredicate();
   if (auto *II = dyn_cast<IntrinsicInst>(Cmp.getOperand(0))) {
     switch (II->getIntrinsicID()) {
@@ -4844,7 +4844,7 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
     const APInt *C;
     if ((Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_UGE) &&
         match(Op0, m_And(m_BinOp(BO), m_LowBitMask(C))) &&
-        match(BO, m_Add(m_Specific(Op1), m_SpecificIntAllowUndef(*C)))) {
+        match(BO, m_Add(m_Specific(Op1), m_SpecificIntAllowPoison(*C)))) {
       CmpInst::Predicate NewPred =
           Pred == ICmpInst::ICMP_ULT ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ;
       Constant *Zero = ConstantInt::getNullValue(Op1->getType());
@@ -4853,7 +4853,7 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
 
     if ((Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_ULE) &&
         match(Op1, m_And(m_BinOp(BO), m_LowBitMask(C))) &&
-        match(BO, m_Add(m_Specific(Op0), m_SpecificIntAllowUndef(*C)))) {
+        match(BO, m_Add(m_Specific(Op0), m_SpecificIntAllowPoison(*C)))) {
       CmpInst::Predicate NewPred =
           Pred == ICmpInst::ICMP_UGT ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ;
       Constant *Zero = ConstantInt::getNullValue(Op1->getType());
@@ -5003,8 +5003,9 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
       (BO0->hasOneUse() || BO1->hasOneUse()) && !I.isUnsigned()) {
     const APInt *AP1, *AP2;
     // TODO: Support non-uniform vectors.
-    // TODO: Allow undef passthrough if B AND D's element is undef.
-    if (match(B, m_APIntAllowUndef(AP1)) && match(D, m_APIntAllowUndef(AP2)) &&
+    // TODO: Allow poison passthrough if B or D's element is poison.
+    if (match(B, m_APIntAllowPoison(AP1)) &&
+        match(D, m_APIntAllowPoison(AP2)) &&
         AP1->isNegative() == AP2->isNegative()) {
       APInt AP1Abs = AP1->abs();
       APInt AP2Abs = AP2->abs();
@@ -5575,10 +5576,10 @@ Instruction *InstCombinerImpl::foldICmpEquality(ICmpInst &I) {
   // (A >> C) == (B >> C) --> (A^B) u< (1 << C)
   // For lshr and ashr pairs.
   const APInt *AP1, *AP2;
-  if ((match(Op0, m_OneUse(m_LShr(m_Value(A), m_APIntAllowUndef(AP1)))) &&
-       match(Op1, m_OneUse(m_LShr(m_Value(B), m_APIntAllowUndef(AP2))))) ||
-      (match(Op0, m_OneUse(m_AShr(m_Value(A), m_APIntAllowUndef(AP1)))) &&
-       match(Op1, m_OneUse(m_AShr(m_Value(B), m_APIntAllowUndef(AP2)))))) {
+  if ((match(Op0, m_OneUse(m_LShr(m_Value(A), m_APIntAllowPoison(AP1)))) &&
+       match(Op1, m_OneUse(m_LShr(m_Value(B), m_APIntAllowPoison(AP2))))) ||
+      (match(Op0, m_OneUse(m_AShr(m_Value(A), m_APIntAllowPoison(AP1)))) &&
+       match(Op1, m_OneUse(m_AShr(m_Value(B), m_APIntAllowPoison(AP2)))))) {
     if (AP1 != AP2)
       return nullptr;
     unsigned TypeBits = AP1->getBitWidth();
@@ -6969,10 +6970,10 @@ static Instruction *foldVectorCmp(CmpInst &Cmp,
 
   // Length-changing splats are ok, so adjust the constants as needed:
   // cmp (shuffle V1, M), C --> shuffle (cmp V1, C'), M
-  Constant *ScalarC = C->getSplatValue(/* AllowUndefs */ true);
+  Constant *ScalarC = C->getSplatValue(/* AllowPoison */ true);
   int MaskSplatIndex;
-  if (ScalarC && match(M, m_SplatOrUndefMask(MaskSplatIndex))) {
-    // We allow undefs in matching, but this transform removes those for safety.
+  if (ScalarC && match(M, m_SplatOrPoisonMask(MaskSplatIndex))) {
+    // We allow poison in matching, but this transform removes it for safety.
     // Demanded elements analysis should be able to recover some/all of that.
     C = ConstantVector::getSplat(cast<VectorType>(V1Ty)->getElementCount(),
                                  ScalarC);
@@ -7444,7 +7445,7 @@ Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I) {
       unsigned OpWidth = Op0->getType()->getScalarSizeInBits();
       Instruction *ShiftI;
       if (match(Op0, m_CombineAnd(m_Instruction(ShiftI),
-                                  m_Shr(m_Value(X), m_SpecificIntAllowUndef(
+                                  m_Shr(m_Value(X), m_SpecificIntAllowPoison(
                                                         OpWidth - 1))))) {
         unsigned ExtOpc = ExtI->getOpcode();
         unsigned ShiftOpc = ShiftI->getOpcode();
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index b9ad3a74007929..f4d559036b31fd 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -661,8 +661,8 @@ class LLVM_LIBRARY_VISIBILITY InstCombinerImpl final
   Instruction *foldICmpUsingBoolRange(ICmpInst &I);
   Instruction *foldICmpInstWithConstant(ICmpInst &Cmp);
   Instruction *foldICmpInstWithConstantNotInt(ICmpInst &Cmp);
-  Instruction *foldICmpInstWithConstantAllowUndef(ICmpInst &Cmp,
-                                                  const APInt &C);
+  Instruction *foldICmpInstWithConstantAllowPoison(ICmpInst &Cmp,
+                                                   const APInt &C);
   Instruction *foldICmpBinOp(ICmpInst &Cmp, const SimplifyQuery &SQ);
   Instruction *foldICmpWithMinMax(Instruction &I, MinMaxIntrinsic *MinMax,
                                   Value *Z, ICmpInst::Predicate Pred);
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 7b86fcde8937ba..53478e07394b2c 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -276,7 +276,7 @@ Instruction *InstCombinerImpl::visitMul(BinaryOperator &I) {
     const APInt *NegPow2C;
     Value *X;
     if (match(Op0, m_ZExtOrSExt(m_Value(X))) &&
-        match(Op1, m_APIntAllowUndef(NegPow2C))) {
+        match(Op1, m_APIntAllowPoison(NegPow2C))) {
       unsigned SrcWidth = X->getType()->getScalarSizeInBits();
       unsigned ShiftAmt = NegPow2C->countr_zero();
       if (ShiftAmt >= BitWidth - SrcWidth) {
@@ -485,7 +485,7 @@ Instruction *InstCombinerImpl::visitMul(BinaryOperator &I) {
   // ((ashr X, 31) | 1) * X --> abs(X)
   // X * ((ashr X, 31) | 1) --> abs(X)
   if (match(&I, m_c_BinOp(m_Or(m_AShr(m_Value(X),
-                                      m_SpecificIntAllowUndef(BitWidth - 1)),
+                                      m_SpecificIntAllowPoison(BitWidth - 1)),
                                m_One()),
                           m_Deferred(X)))) {
     Value *Abs = Builder.CreateBinaryIntrinsic(
@@ -836,7 +836,7 @@ Instruction *InstCombinerImpl::visitFMul(BinaryOperator &I) {
   // X * 0.0 --> copysign(0.0, X)
   // X * -0.0 --> copysign(0.0, -X)
   const APFloat *FPC;
-  if (match(Op1, m_APFloatAllowUndef(FPC)) && FPC->isZero() &&
+  if (match(Op1, m_APFloatAllowPoison(FPC)) && FPC->isZero() &&
       ((I.hasNoInfs() &&
         isKnownNeverNaN(Op0, /*Depth=*/0, SQ.getWithInstruction(&I))) ||
        isKnownNeverNaN(&I, /*Depth=*/0, SQ.getWithInstruction(&I)))) {
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp b/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp
index cd8e47e1b39113..d697f361dec023 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp
@@ -249,7 +249,7 @@ std::array<Value *, 2> Negator::getSortedOperandsOfBinOp(Instruction *I) {
     unsigned SrcWidth = SrcOp->getType()->getScalarSizeInBits();
     const APInt &FullShift = APInt(SrcWidth, SrcWidth - 1);
     if (IsTrulyNegation &&
-        match(SrcOp, m_LShr(m_Value(X), m_SpecificIntAllowUndef(FullShift)))) {
+        match(SrcOp, m_LShr(m_Value(X), m_SpecificIntAllowPoison(FullShift)))) {
       Value *Ashr = Builder.CreateAShr(X, FullShift);
       return Builder.CreateSExt(Ashr, I->getType());
     }
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 2d78fcee1152d7..0952160b96dd08 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -1621,7 +1621,7 @@ static Instruction *foldSelectZeroOrOnes(ICmpInst *Cmp, Value *TVal,
     return nullptr;
 
   const APInt *CmpC;
-  if (!match(Cmp->getOperand(1), m_APIntAllowUndef(CmpC)))
+  if (!match(Cmp->getOperand(1), m_APIntAllowPoison(CmpC)))
     return nullptr;
 
   // (X u< 2) ? -X : -1 --> sext (X != 0)
@@ -2489,8 +2489,8 @@ static Instruction *foldSelectToCopysign(SelectInst &Sel,
   // Match select ?, TC, FC where the constants are equal but negated.
   // TODO: Generalize to handle a negated variable operand?
   const APFloat *TC, *FC;
-  if (!match(TVal, m_APFloatAllowUndef(TC)) ||
-      !match(FVal, m_APFloatAllowUndef(FC)) ||
+  if (!match(TVal, m_APFloatAllowPoison(TC)) ||
+      !match(FVal, m_APFloatAllowPoison(FC)) ||
       !abs(*TC).bitwiseIsEqual(abs(*FC)))
     return nullptr;
 
@@ -2939,17 +2939,17 @@ foldRoundUpIntegerWithPow2Alignment(SelectInst &SI,
   // FIXME: we could support non non-splats here.
 
   const APInt *LowBitMaskCst;
-  if (!match(XLowBits, m_And(m_Specific(X), m_APIntAllowUndef(LowBitMaskCst))))
+  if (!match(XLowBits, m_And(m_Specific(X), m_APIntAllowPoison(LowBitMaskCst))))
     return nullptr;
 
   // Match even if the AND and ADD are swapped.
   const APInt *BiasCst, *HighBitMaskCst;
   if (!match(XBiasedHighBits,
-             m_And(m_Add(m_Specific(X), m_APIntAllowUndef(BiasCst)),
-                   m_APIntAllowUndef(HighBitMaskCst))) &&
+             m_And(m_Add(m_Specific(X), m_APIntAllowPoison(BiasCst)),
+                   m_APIntAllowPoison(HighBitMaskCst))) &&
       !match(XBiasedHighBits,
-             m_Add(m_And(m_Specific(X), m_APIntAllowUndef(HighBitMaskCst)),
-                   m_APIntAllowUndef(BiasCst))))
+             m_Add(m_And(m_Specific(X), m_APIntAllowPoison(HighBitMaskCst)),
+                   m_APIntAllowPoison(BiasCst))))
     return nullptr;
 
   if (!LowBitMaskCst->isMask())
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
index 95aa2119e2d88b..244f03a1bc2b4c 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
@@ -778,7 +778,7 @@ Instruction *InstCombinerImpl::FoldShiftByConstant(Value *Op0, Constant *C1,
   // (X / +DivC) >> (Width - 1) --> ext (X <= -DivC)
   // (X / -DivC) >> (Width - 1) --> ext (X >= +DivC)
   const APInt *DivC;
-  if (!IsLeftShift && match(C1, m_SpecificIntAllowUndef(TypeBits - 1)) &&
+  if (!IsLeftShift && match(C1, m_SpecificIntAllowPoison(TypeBits - 1)) &&
       match(Op0, m_SDiv(m_Value(X), m_APInt(DivC))) && !DivC->isZero() &&
       !DivC->isMinSignedValue()) {
     Constant *NegDivC = ConstantInt::get(Ty, -(*DivC));
@@ -1264,7 +1264,7 @@ Instruction *InstCombinerImpl::visitLShr(BinaryOperator &I) {
 
   // (iN (~X) u>> (N - 1)) --> zext (X > -1)
   if (match(Op0, m_OneUse(m_Not(m_Value(X)))) &&
-      match(Op1, m_SpecificIntAllowUndef(BitWidth - 1)))
+      match(Op1, m_SpecificIntAllowPoison(BitWidth - 1)))
     return new ZExtInst(Builder.CreateIsNotNeg(X, "isnotneg"), Ty);
 
   if (match(Op1, m_APInt(C))) {
@@ -1666,9 +1666,9 @@ Instruction *InstCombinerImpl::visitAShr(BinaryOperator &I) {
   // as the pattern to splat the lowest bit.
   // FIXME: iff X is already masked, we don't need the one-use check.
   Value *X;
-  if (match(Op1, m_SpecificIntAllowUndef(BitWidth - 1)) &&
+  if (match(Op1, m_SpecificIntAllowPoison(BitWidth - 1)) &&
       match(Op0, m_OneUse(m_Shl(m_Value(X),
-                                m_SpecificIntAllowUndef(BitWidth - 1))))) {
+                                m_SpecificIntAllowPoison(BitWidth - 1))))) {
     Constant *Mask = ConstantInt::get(Ty, 1);
     // Retain the knowledge about the ignored lanes.
     Mask = Constant::mergeUndefsWith(
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 5a144cc7378962..ae422f3ac9f681 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2190,7 +2190,7 @@ Instruction *InstCombinerImpl::foldVectorBinop(BinaryOperator &Inst) {
     Value *Y, *OtherOp;
     if (!match(LHS,
                m_OneUse(m_Shuffle(m_Value(X), m_Undef(), m_Mask(MaskC)))) ||
-        !match(MaskC, m_SplatOrUndefMask(SplatIndex)) ||
+        !match(MaskC, m_SplatOrPoisonMask(SplatIndex)) ||
         X->getType() != Inst.getType() ||
         !match(RHS, m_OneUse(m_BinOp(Opcode, m_Value(Y), m_Value(OtherOp)))))
       return nullptr;
@@ -3740,7 +3740,7 @@ InstCombinerImpl::foldExtractOfOverflowIntrinsic(ExtractValueInst &EV) {
 
   Intrinsic::ID OvID = WO->getIntrinsicID();
   const APInt *C = nullptr;
-  if (match(WO->getRHS(), m_APIntAllowUndef(C))) {
+  if (match(WO->getRHS(), m_APIntAllowPoison(C))) {
     if (*EV.idx_begin() == 0 && (OvID == Intrinsic::smul_with_overflow ||
                                  OvID == Intrinsic::umul_with_overflow)) {
       // extractvalue (any_mul_with_overflow X, -1), 0 --> -X
diff --git a/llvm/lib/Transforms/Vectorize/VPlanPatternMatch.h b/llvm/lib/Transforms/Vectorize/VPlanPatternMatch.h
index a03a408686ef13..ae7717eb7cc97f 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanPatternMatch.h
+++ b/llvm/lib/Transforms/Vectorize/VPlanPatternMatch.h
@@ -65,7 +65,7 @@ struct specific_intval {
     if (!CI && V->getType()->isVectorTy())
       if (const auto *C = dyn_cast<Constant>(V))
         CI = dyn_cast_or_null<ConstantInt>(
-            C->getSplatValue(/*UndefsAllowed=*/false));
+            C->getSplatValue(/*AllowPoison=*/false));
 
     return CI && APInt::isSameValue(CI->getValue(), Val);
   }
diff --git a/llvm/test/Transforms/InstCombine/and-or-icmp-const-icmp.ll b/llvm/test/Transforms/InstCombine/and-or-icmp-const-icmp.ll
index 8531c7db1ee3fd..9143a2d0ccda24 100644
--- a/llvm/test/Transforms/InstCombine/and-or-icmp-const-icmp.ll
+++ b/llvm/test/Transforms/InstCombine/and-or-icmp-const-icmp.ll
@@ -223,30 +223,30 @@ define <2 x i1> @ne_vector_unequal2(<2 x i8> %x, <2 x i8> %y) {
 }
 
 ; ==============================================================================
-; Tests with undef
+; Tests with poison
 ; ==============================================================================
-define <2 x i1> @eq_vector_undef_icmp(<2 x i8> %x, <2 x i8> %y) {
-; CHECK-LABEL: define <2 x i1> @eq_vector_undef_icmp
+define <2 x i1> @eq_vector_poison_icmp(<2 x i8> %x, <2 x i8> %y) {
+; CHECK-LABEL: define <2 x i1> @eq_vector_poison_icmp
 ; CHECK-SAME: (<2 x i8> [[X:%.*]], <2 x i8> [[Y:%.*]]) {
 ; CHECK-NEXT:    [[TMP1:%.*]] = add <2 x i8> [[X]], <i8 -6, i8 -6>
 ; CHECK-NEXT:    [[OR:%.*]] = icmp uge <2 x i8> [[TMP1]], [[Y]]
 ; CHECK-NEXT:    ret <2 x i1> [[OR]]
 ;
   %sub = add <2 x i8> %x, <i8 -5, i8 -5>
-  %c1 = icmp eq <2 x i8> %x, <i8 5, i8 undef>
+  %c1 = icmp eq <2 x i8> %x, <i8 5, i8 poison>
   %c2 = icmp ugt <2 x i8> %sub, %y
   %or = or <2 x i1> %c1, %c2
   ret <2 x i1> %or
 }
 
-define <2 x i1> @eq_vector_undef_add(<2 x i8> %x, <2 x i8> %y) {
-; CHECK-LABEL: define <2 x i1> @eq_vector_undef_add
+define <2 x i1> @eq_vector_poison_add(<2 x i8> %x, <2 x i8> %y) {
+; CHECK-LABEL: define <2 x i1> @eq_vector_poison_add
 ; CHECK-SAME: (<2 x i8> [[X:%.*]], <2 x i8> [[Y:%.*]]) {
 ; CHECK-NEXT:    [[TMP1:%.*]] = add <2 x i8> [[X]], <i8 -6, i8 -6>
 ; CHECK-NEXT:    [[OR:%.*]] = icmp uge <2 x i8> [[TMP1]], [[Y]]
 ; CHECK-NEXT:    ret <2 x i1> [[OR]]
 ;
-  %sub = add <2 x i8> %x, <i8 -5, i8 undef>
+  %sub = add <2 x i8> %x, <i8 -5, i8 poison>
   %c1 = icmp eq <2 x i8> %x, <i8 5, i8 5>
   %c2 = icmp ugt <2 x i8> %sub, %y
   %or = or <2 x i1> %c1, %c2
diff --git a/llvm/test/Transforms/InstCombine/binop-itofp.ll b/llvm/test/Transforms/InstCombine/binop-itofp.ll
index 097a8196af80f8..19f7ca9282f291 100644
--- a/llvm/test/Transforms/InstCombine/binop-itofp.ll
+++ b/llvm/test/Transforms/InstCombine/binop-itofp.ll
@@ -1063,8 +1063,8 @@ define float @negzero_check_on_constant_for_si_fmul(i1 %c, i1 %.b, ptr %g_2345)
   ret float %mul3.i.i
 }
 
-define <2 x float> @nonzero_check_on_constant_for_si_fmul_vec_w_undef(i1 %c, i1 %.b, ptr %g_2345) {
-; CHECK-LABEL: @nonzero_check_on_constant_for_si_fmul_vec_w_undef(
+define <2 x float> @nonzero_check_on_constant_for_si_fmul_vec_w_poison(i1 %c, i1 %.b, ptr %g_2345) {
+; CHECK-LABEL: @nonzero_check_on_constant_for_si_fmul_vec_w_poison(
 ; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[C:%.*]], i32 65529, i32 53264
 ; CHECK-NEXT:    [[CONV_I_S:%.*]] = trunc nuw i32 [[SEL]] to i16
 ; CHECK-NEXT:    [[CONV_I_V:%.*]] = insertelement <2 x i16> poison, i16 [[CONV_I_S]], i64 0
@@ -1079,34 +1079,33 @@ define <2 x float> @nonzero_check_on_constant_for_si_fmul_vec_w_undef(i1 %c, i1
   %conv.i.v = insertelement <2 x i16> poison, i16 %conv.i.s, i64 0
   %conv.i = insertelement <2 x i16> %conv.i.v, i16 %conv.i.s, i64 1
   %conv1.i = sitofp <2 x i16> %conv.i to <2 x float>
-  %mul3.i.i = fmul <2 x float> %conv1.i, <float undef, float 0.000000e+00>
+  %mul3.i.i = fmul <2 x float> %conv1.i, <float poison, float 0.000000e+00>
   store i32 %sel, ptr %g_2345, align 4
   ret <2 x float> %mul3.i.i
 }
 
-define <2 x float> @nonzero_check_on_constant_for_si_fmul_nz_vec_w_undef(i1 %c, i1 %.b, ptr %g_2345) {
-; CHECK-LABEL: @nonzero_check_on_constant_for_si_fmul_nz_vec_w_undef(
+define <2 x float> @nonzero_check_on_constant_for_si_fmul_nz_vec_w_poison(i1 %c, i1 %.b, ptr %g_2345) {
+; CHECK-LABEL: @nonzero_check_on_constant_for_si_fmul_nz_vec_w_poison(
 ; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[C:%.*]], i32 65529, i32 53264
 ; CHECK-NEXT:    [[CONV_I_S:%.*]] = trunc nuw i32 [[SEL]] to i16
 ; CHECK-NEXT:    [[CONV_I_V:%.*]] = insertelement <2 x i16> poison, i16 [[CONV_I_S]], i64 0
 ; CHECK-NEXT:    [[CONV_I:%.*]] = shufflevector <2 x i16> [[CONV_I_V]], <2 x i16> poison, <2 x i32> zeroinitializer
 ; CHECK-NEXT:    [[CONV1_I:%.*]] = sitofp <2 x i16> [[CONV_I]] to <2 x float>
-; CHECK-NEXT:    [[MUL3_I_I:%.*]] = fmul <2 x float> [[CONV1_I]], <float undef, float 1.000000e+00>
 ; CHECK-NEXT:    store i32 [[SEL]], ptr [[G_2345:%.*]], align 4
-; CHECK-NEXT:    ret <2 x float> [[MUL3_I_I]]
+; CHECK-NEXT:    ret <2 x float> [[CONV1_I]]
 ;
   %sel = select i1 %c, i32 65529, i32 53264
   %conv.i.s = trunc i32 %sel to i16
   %conv.i.v = insertelement <2 x i16> poison, i16 %conv.i.s, i64 0
   %conv.i = insertelement <2 x i16> %conv.i.v, i16 %conv.i.s, i64 1
   %conv1.i = sitofp <2 x i16> %conv.i to <2 x float>
-  %mul3.i.i = fmul <2 x float> %conv1.i, <float undef, float 1.000000e+00>
+  %mul3.i.i = fmul <2 x float> %conv1.i, <float poison, float 1.000000e+00>
   store i32 %sel, ptr %g_2345, align 4
   ret <2 x float> %mul3.i.i
 }
 
-define <2 x float> @nonzero_check_on_constant_for_si_fmul_negz_vec_w_undef(i1 %c, i1 %.b, ptr %g_2345) {
-; CHECK-LABEL: @nonzero_check_on_constant_for_si_fmul_negz_vec_w_undef(
+define <2 x float> @nonzero_check_on_constant_for_si_fmul_negz_vec_w_poison(i1 %c, i1 %.b, ptr %g_2345) {
+; CHECK-LABEL: @nonzero_check_on_constant_for_si_fmul_negz_vec_w_poison(
 ; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[C:%.*]], i32 65529, i32 53264
 ; CHECK-NEXT:    [[CONV_I_S:%.*]] = trunc nuw i32 [[SEL]] to i16
 ; CHECK-NEXT:    [[CONV_I_V:%.*]] = insertelement <2 x i16> poison, i16 [[CONV_I_S]], i64 0
@@ -1122,7 +1121,7 @@ define <2 x float> @nonzero_check_on_constant_for_si_fmul_negz_vec_w_undef(i1 %c
   %conv.i.v = insertelement <2 x i16> poison, i16 %conv.i.s, i64 0
   %conv.i = insertelement <2 x i16> %conv.i.v, i16 %conv.i.s, i64 1
   %conv1.i = sitofp <2 x i16> %conv.i to <2 x float>
-  %mul3.i.i = fmul <2 x float> %conv1.i, <float undef, float -0.000000e+00>
+  %mul3.i.i = fmul <2 x float> %conv1.i, <float poison, float -0.000000e+00>
   store i32 %sel, ptr %g_2345, align 4
   ret <2 x float> %mul3.i.i
 }
diff --git a/llvm/test/Transforms/InstCombine/bswap-fold.ll b/llvm/test/Transforms/InstCombine/bswap-fold.ll
index 19522168beaf5e..91674c6017a9e5 100644
--- a/llvm/test/Transforms/InstCombine/bswap-fold.ll
+++ b/llvm/test/Transforms/InstCombine/bswap-fold.ll
@@ -870,13 +870,13 @@ define <2 x i64> @bs_active_high_different_negative(<2 x i64> %0) {
 }
 
 ; TODO: This should fold to 'and'.
-define <2 x i64> @bs_active_high_undef(<2 x i64> %0) {
-; CHECK-LABEL: @bs_active_high_undef(
+define <2 x i64> @bs_active_high_poison(<2 x i64> %0) {
+; CHECK-LABEL: @bs_active_high_poison(
 ; CHECK-NEXT:    [[TMP2:%.*]] = call <2 x i64> @llvm.bswap.v2i64(<2 x i64> [[TMP0:%.*]])
-; CHECK-NEXT:    [[TMP3:%.*]] = lshr <2 x i64> [[TMP2]], <i64 56, i64 undef>
+; CHECK-NEXT:    [[TMP3:%.*]] = lshr <2 x i64> [[TMP2]], <i64 56, i64 poison>
 ; CHECK-NEXT:    ret <2 x i64> [[TMP3]]
 ;
-  %2 = shl <2 x i64> %0, <i64 56, i64 undef>
+  %2 = shl <2 x i64> %0, <i64 56, i64 poison>
   %3 = call <2 x i64> @llvm.bswap.v2i64(<2 x i64> %2)
   ret <2 x i64> %3
 }
diff --git a/llvm/test/Transforms/InstCombine/bswap.ll b/llvm/test/Transforms/InstCombine/bswap.ll
index d42583bb5699b7..fa61bc841f0199 100644
--- a/llvm/test/Transforms/InstCombine/bswap.ll
+++ b/llvm/test/Transforms/InstCombine/bswap.ll
@@ -107,27 +107,27 @@ define <2 x i32> @test2_vector(<2 x i32> %arg) {
   ret <2 x i32> %t14
 }
 
-define <2 x i32> @test2_vector_undef(<2 x i32> %arg) {
-; CHECK-LABEL: @test2_vector_undef(
-; CHECK-NEXT:    [[T2:%.*]] = shl <2 x i32> [[ARG:%.*]], <i32 24, i32 undef>
+define <2 x i32> @test2_vector_poison(<2 x i32> %arg) {
+; CHECK-LABEL: @test2_vector_poison(
+; CHECK-NEXT:    [[T2:%.*]] = shl <2 x i32> [[ARG:%.*]], <i32 24, i32 poison>
 ; CHECK-NEXT:    [[T4:%.*]] = shl <2 x i32> [[ARG]], <i32 8, i32 8>
-; CHECK-NEXT:    [[T5:%.*]] = and <2 x i32> [[T4]], <i32 16711680, i32 undef>
-; CHECK-NEXT:    [[T6:%.*]] = or <2 x i32> [[T2]], [[T5]]
+; CHECK-NEXT:    [[T5:%.*]] = and <2 x i32> [[T4]], <i32 16711680, i32 poison>
+; CHECK-NEXT:    [[T6:%.*]] = or disjoint <2 x i32> [[T2]], [[T5]]
 ; CHECK-NEXT:    [[T8:%.*]] = lshr <2 x i32> [[ARG]], <i32 8, i32 8>
-; CHECK-NEXT:    [[T9:%.*]] = and <2 x i32> [[T8]], <i32 65280, i32 undef>
-; CHECK-NEXT:    [[T10:%.*]] = or <2 x i32> [[T6]], [[T9]]
-; CHECK-NEXT:    [[T12:%.*]] = lshr <2 x i32> [[ARG]], <i32 24, i32 undef>
-; CHECK-NEXT:    [[T14:%.*]] = or <2 x i32> [[T10]], [[T12]]
+; CHECK-NEXT:    [[T9:%.*]] = and <2 x i32> [[T8]], <i32 65280, i32 poison>
+; CHECK-NEXT:    [[T10:%.*]] = or disjoint <2 x i32> [[T6]], [[T9]]
+; CHECK-NEXT:    [[T12:%.*]] = lshr <2 x i32> [[ARG]], <i32 24, i32 poison>
+; CHECK-NEXT:    [[T14:%.*]] = or disjoint <2 x i32> [[T10]], [[T12]]
 ; CHECK-NEXT:    ret <2 x i32> [[T14]]
 ;
-  %t2 = shl <2 x i32> %arg, <i32 24, i32 undef>
+  %t2 = shl <2 x i32> %arg, <i32 24, i32 poison>
   %t4 = shl <2 x i32> %arg, <i32 8, i32 8>
-  %t5 = and <2 x i32> %t4, <i32 16711680, i32 undef>
+  %t5 = and <2 x i32> %t4, <i32 16711680, i32 poison>
   %t6 = or <2 x i32> %t2, %t5
   %t8 = lshr <2 x i32> %arg, <i32 8, i32 8>
-  %t9 = and <2 x i32> %t8, <i32 65280, i32 undef>
+  %t9 = and <2 x i32> %t8, <i32 65280, i32 poison>
   %t10 = or <2 x i32> %t6, %t9
-  %t12 = lshr <2 x i32> %arg, <i32 24, i32 undef>
+  %t12 = lshr <2 x i32> %arg, <i32 24, i32 poison>
   %t14 = or <2 x i32> %t10, %t12
   ret <2 x i32> %t14
 }
@@ -154,13 +154,13 @@ define <2 x i16> @test3_vector(<2 x i16> %s) {
   ret <2 x i16> %t5
 }
 
-define <2 x i16> @test3_vector_undef(<2 x i16> %s) {
-; CHECK-LABEL: @test3_vector_undef(
+define <2 x i16> @test3_vector_poison(<2 x i16> %s) {
+; CHECK-LABEL: @test3_vector_poison(
 ; CHECK-NEXT:    [[T5:%.*]] = call <2 x i16> @llvm.bswap.v2i16(<2 x i16> [[S:%.*]])
 ; CHECK-NEXT:    ret <2 x i16> [[T5]]
 ;
-  %t2 = lshr <2 x i16> %s, <i16 undef, i16 8>
-  %t4 = shl <2 x i16> %s, <i16 8, i16 undef>
+  %t2 = lshr <2 x i16> %s, <i16 poison, i16 8>
+  %t4 = shl <2 x i16> %s, <i16 8, i16 poison>
   %t5 = or <2 x i16> %t2, %t4
   ret <2 x i16> %t5
 }
@@ -657,7 +657,7 @@ define i32 @shuf_4bytes(<4 x i8> %x) {
 ; CHECK-NEXT:    [[CAST:%.*]] = call i32 @llvm.bswap.i32(i32 [[TMP1]])
 ; CHECK-NEXT:    ret i32 [[CAST]]
 ;
-  %bswap = shufflevector <4 x i8> %x, <4 x i8> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+  %bswap = shufflevector <4 x i8> %x, <4 x i8> poison, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
   %cast = bitcast <4 x i8> %bswap to i32
   ret i32 %cast
 }
@@ -669,7 +669,7 @@ define i32 @shuf_load_4bytes(ptr %p) {
 ; CHECK-NEXT:    ret i32 [[CAST]]
 ;
   %x = load <4 x i8>, ptr %p
-  %bswap = shufflevector <4 x i8> %x, <4 x i8> undef, <4 x i32> <i32 3, i32 2, i32 undef, i32 0>
+  %bswap = shufflevector <4 x i8> %x, <4 x i8> poison, <4 x i32> <i32 3, i32 2, i32 poison, i32 0>
   %cast = bitcast <4 x i8> %bswap to i32
   ret i32 %cast
 }
@@ -680,7 +680,7 @@ define i32 @shuf_bitcast_twice_4bytes(i32 %x) {
 ; CHECK-NEXT:    ret i32 [[CAST2]]
 ;
   %cast1 = bitcast i32 %x to <4 x i8>
-  %bswap = shufflevector <4 x i8> %cast1, <4 x i8> undef, <4 x i32> <i32 undef, i32 2, i32 1, i32 0>
+  %bswap = shufflevector <4 x i8> %cast1, <4 x i8> poison, <4 x i32> <i32 poison, i32 2, i32 1, i32 0>
   %cast2 = bitcast <4 x i8> %bswap to i32
   ret i32 %cast2
 }
@@ -695,7 +695,7 @@ define i32 @shuf_4bytes_extra_use(<4 x i8> %x) {
 ; CHECK-NEXT:    [[CAST:%.*]] = bitcast <4 x i8> [[BSWAP]] to i32
 ; CHECK-NEXT:    ret i32 [[CAST]]
 ;
-  %bswap = shufflevector <4 x i8> %x, <4 x i8> undef, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+  %bswap = shufflevector <4 x i8> %x, <4 x i8> poison, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
   call void @use(<4 x i8> %bswap)
   %cast = bitcast <4 x i8> %bswap to i32
   ret i32 %cast
@@ -709,7 +709,7 @@ define i128 @shuf_16bytes(<16 x i8> %x) {
 ; CHECK-NEXT:    [[CAST:%.*]] = bitcast <16 x i8> [[BSWAP]] to i128
 ; CHECK-NEXT:    ret i128 [[CAST]]
 ;
-  %bswap = shufflevector <16 x i8> %x, <16 x i8> undef, <16 x i32> <i32 15, i32 14, i32 13, i32 12, i32 11, i32 10, i32 9, i32 8, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
+  %bswap = shufflevector <16 x i8> %x, <16 x i8> poison, <16 x i32> <i32 15, i32 14, i32 13, i32 12, i32 11, i32 10, i32 9, i32 8, i32 7, i32 6, i32 5, i32 4, i32 3, i32 2, i32 1, i32 0>
   %cast = bitcast <16 x i8> %bswap to i128
   ret i128 %cast
 }
@@ -722,7 +722,7 @@ define i32 @shuf_2bytes_widening(<2 x i8> %x) {
 ; CHECK-NEXT:    [[CAST:%.*]] = bitcast <4 x i8> [[BSWAP]] to i32
 ; CHECK-NEXT:    ret i32 [[CAST]]
 ;
-  %bswap = shufflevector <2 x i8> %x, <2 x i8> undef, <4 x i32> <i32 1, i32 0, i32 undef, i32 undef>
+  %bswap = shufflevector <2 x i8> %x, <2 x i8> poison, <4 x i32> <i32 1, i32 0, i32 poison, i32 poison>
   %cast = bitcast <4 x i8> %bswap to i32
   ret i32 %cast
 }
diff --git a/llvm/test/Transforms/InstCombine/compare-signs.ll b/llvm/test/Transforms/InstCombine/compare-signs.ll
index 3730d46d5f0f4b..ede652869212c1 100644
--- a/llvm/test/Transforms/InstCombine/compare-signs.ll
+++ b/llvm/test/Transforms/InstCombine/compare-signs.ll
@@ -61,29 +61,29 @@ define <2 x i32> @test3vec(<2 x i32> %a, <2 x i32> %b) nounwind readnone {
   ret <2 x i32> %t3
 }
 
-define <2 x i32> @test3vec_undef1(<2 x i32> %a, <2 x i32> %b) nounwind readnone {
-; CHECK-LABEL: @test3vec_undef1(
+define <2 x i32> @test3vec_poison1(<2 x i32> %a, <2 x i32> %b) nounwind readnone {
+; CHECK-LABEL: @test3vec_poison1(
 ; CHECK-NEXT:    [[T2_UNSHIFTED:%.*]] = xor <2 x i32> [[A:%.*]], [[B:%.*]]
 ; CHECK-NEXT:    [[T2:%.*]] = icmp ult <2 x i32> [[T2_UNSHIFTED]], <i32 16777216, i32 16777216>
 ; CHECK-NEXT:    [[T3:%.*]] = zext <2 x i1> [[T2]] to <2 x i32>
 ; CHECK-NEXT:    ret <2 x i32> [[T3]]
 ;
-  %t0 = lshr <2 x i32> %a, <i32 24, i32 undef>
+  %t0 = lshr <2 x i32> %a, <i32 24, i32 poison>
   %t1 = lshr <2 x i32> %b, <i32 24, i32 24>
   %t2 = icmp eq <2 x i32> %t0, %t1
   %t3 = zext <2 x i1> %t2 to <2 x i32>
   ret <2 x i32> %t3
 }
 
-define <2 x i32> @test3vec_undef2(<2 x i32> %a, <2 x i32> %b) nounwind readnone {
-; CHECK-LABEL: @test3vec_undef2(
+define <2 x i32> @test3vec_poison2(<2 x i32> %a, <2 x i32> %b) nounwind readnone {
+; CHECK-LABEL: @test3vec_poison2(
 ; CHECK-NEXT:    [[T2_UNSHIFTED:%.*]] = xor <2 x i32> [[A:%.*]], [[B:%.*]]
 ; CHECK-NEXT:    [[T2:%.*]] = icmp ult <2 x i32> [[T2_UNSHIFTED]], <i32 131072, i32 131072>
 ; CHECK-NEXT:    [[T3:%.*]] = zext <2 x i1> [[T2]] to <2 x i32>
 ; CHECK-NEXT:    ret <2 x i32> [[T3]]
 ;
-  %t0 = lshr <2 x i32> %a, <i32 undef, i32 17>
-  %t1 = lshr <2 x i32> %b, <i32 undef, i32 17>
+  %t0 = lshr <2 x i32> %a, <i32 poison, i32 17>
+  %t1 = lshr <2 x i32> %b, <i32 poison, i32 17>
   %t2 = icmp eq <2 x i32> %t0, %t1
   %t3 = zext <2 x i1> %t2 to <2 x i32>
   ret <2 x i32> %t3
diff --git a/llvm/test/Transforms/InstCombine/fcmp-range-check-idiom.ll b/llvm/test/Transforms/InstCombine/fcmp-range-check-idiom.ll
index 0893b27f5cf49f..10a3ccf3cdb48a 100644
--- a/llvm/test/Transforms/InstCombine/fcmp-range-check-idiom.ll
+++ b/llvm/test/Transforms/InstCombine/fcmp-range-check-idiom.ll
@@ -182,15 +182,15 @@ define i1 @test_and_olt_logical(float %x) {
   ret i1 %cond
 }
 
-define <2 x i1> @test_and_olt_undef(<2 x float> %x) {
-; CHECK-LABEL: define <2 x i1> @test_and_olt_undef(
+define <2 x i1> @test_and_olt_poison(<2 x float> %x) {
+; CHECK-LABEL: define <2 x i1> @test_and_olt_poison(
 ; CHECK-SAME: <2 x float> [[X:%.*]]) {
 ; CHECK-NEXT:    [[TMP1:%.*]] = call <2 x float> @llvm.fabs.v2f32(<2 x float> [[X]])
 ; CHECK-NEXT:    [[COND:%.*]] = fcmp olt <2 x float> [[TMP1]], <float 0x3C00000000000000, float 0x3C00000000000000>
 ; CHECK-NEXT:    ret <2 x i1> [[COND]]
 ;
-  %cmp1 = fcmp olt <2 x float> %x, <float 0x3C00000000000000, float undef>
-  %cmp2 = fcmp ogt <2 x float> %x, <float 0xBC00000000000000, float undef>
+  %cmp1 = fcmp olt <2 x float> %x, <float 0x3C00000000000000, float poison>
+  %cmp2 = fcmp ogt <2 x float> %x, <float 0xBC00000000000000, float poison>
   %cond = and <2 x i1> %cmp1, %cmp2
   ret <2 x i1> %cond
 }
diff --git a/llvm/test/Transforms/InstCombine/icmp-fsh.ll b/llvm/test/Transforms/InstCombine/icmp-fsh.ll
index 8fad3f94df13f6..8154f312dc5d40 100644
--- a/llvm/test/Transforms/InstCombine/icmp-fsh.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-fsh.ll
@@ -53,49 +53,49 @@ define <2 x i1> @rotl_ne_n1(<2 x i5> %x, <2 x i5> %y) {
   ret <2 x i1> %r
 }
 
-define <2 x i1> @rotl_ne_n1_undef(<2 x i5> %x, <2 x i5> %y) {
-; CHECK-LABEL: @rotl_ne_n1_undef(
-; CHECK-NEXT:    [[R:%.*]] = icmp ne <2 x i5> [[X:%.*]], <i5 -1, i5 undef>
+define <2 x i1> @rotl_ne_n1_poison(<2 x i5> %x, <2 x i5> %y) {
+; CHECK-LABEL: @rotl_ne_n1_poison(
+; CHECK-NEXT:    [[R:%.*]] = icmp ne <2 x i5> [[X:%.*]], <i5 -1, i5 poison>
 ; CHECK-NEXT:    ret <2 x i1> [[R]]
 ;
   %rot = tail call <2 x i5> @llvm.fshl.v2i5(<2 x i5>%x, <2 x i5> %x, <2 x i5> %y)
-  %r = icmp ne <2 x i5> %rot, <i5 -1, i5 undef>
+  %r = icmp ne <2 x i5> %rot, <i5 -1, i5 poison>
   ret <2 x i1> %r
 }
 
-define <2 x i1> @rotl_eq_0_undef(<2 x i5> %x, <2 x i5> %y) {
-; CHECK-LABEL: @rotl_eq_0_undef(
-; CHECK-NEXT:    [[R:%.*]] = icmp eq <2 x i5> [[X:%.*]], <i5 0, i5 undef>
+define <2 x i1> @rotl_eq_0_poison(<2 x i5> %x, <2 x i5> %y) {
+; CHECK-LABEL: @rotl_eq_0_poison(
+; CHECK-NEXT:    [[R:%.*]] = icmp eq <2 x i5> [[X:%.*]], <i5 0, i5 poison>
 ; CHECK-NEXT:    ret <2 x i1> [[R]]
 ;
   %rot = tail call <2 x i5> @llvm.fshl.v2i5(<2 x i5>%x, <2 x i5> %x, <2 x i5> %y)
-  %r = icmp eq <2 x i5> %rot, <i5 0, i5 undef>
+  %r = icmp eq <2 x i5> %rot, <i5 0, i5 poison>
   ret <2 x i1> %r
 }
 
 ; negative test - wrong constant value
 
-define <2 x i1> @rotl_eq_1_undef(<2 x i5> %x, <2 x i5> %y) {
-; CHECK-LABEL: @rotl_eq_1_undef(
+define <2 x i1> @rotl_eq_1_poison(<2 x i5> %x, <2 x i5> %y) {
+; CHECK-LABEL: @rotl_eq_1_poison(
 ; CHECK-NEXT:    [[ROT:%.*]] = tail call <2 x i5> @llvm.fshl.v2i5(<2 x i5> [[X:%.*]], <2 x i5> [[X]], <2 x i5> [[Y:%.*]])
-; CHECK-NEXT:    [[R:%.*]] = icmp eq <2 x i5> [[ROT]], <i5 undef, i5 1>
+; CHECK-NEXT:    [[R:%.*]] = icmp eq <2 x i5> [[ROT]], <i5 poison, i5 1>
 ; CHECK-NEXT:    ret <2 x i1> [[R]]
 ;
   %rot = tail call <2 x i5> @llvm.fshl.v2i5(<2 x i5>%x, <2 x i5> %x, <2 x i5> %y)
-  %r = icmp eq <2 x i5> %rot, <i5 undef, i5 1>
+  %r = icmp eq <2 x i5> %rot, <i5 poison, i5 1>
   ret <2 x i1> %r
 }
 
 ; negative test - wrong predicate
 
-define <2 x i1> @rotl_sgt_0_undef(<2 x i5> %x, <2 x i5> %y) {
-; CHECK-LABEL: @rotl_sgt_0_undef(
+define <2 x i1> @rotl_sgt_0_poison(<2 x i5> %x, <2 x i5> %y) {
+; CHECK-LABEL: @rotl_sgt_0_poison(
 ; CHECK-NEXT:    [[ROT:%.*]] = tail call <2 x i5> @llvm.fshl.v2i5(<2 x i5> [[X:%.*]], <2 x i5> [[X]], <2 x i5> [[Y:%.*]])
-; CHECK-NEXT:    [[R:%.*]] = icmp sgt <2 x i5> [[ROT]], <i5 0, i5 undef>
+; CHECK-NEXT:    [[R:%.*]] = icmp sgt <2 x i5> [[ROT]], <i5 0, i5 poison>
 ; CHECK-NEXT:    ret <2 x i1> [[R]]
 ;
   %rot = tail call <2 x i5> @llvm.fshl.v2i5(<2 x i5>%x, <2 x i5> %x, <2 x i5> %y)
-  %r = icmp sgt <2 x i5> %rot, <i5 0, i5 undef>
+  %r = icmp sgt <2 x i5> %rot, <i5 0, i5 poison>
   ret <2 x i1> %r
 }
 
diff --git a/llvm/test/Transforms/InstCombine/icmp-power2-and-icmp-shifted-mask.ll b/llvm/test/Transforms/InstCombine/icmp-power2-and-icmp-shifted-mask.ll
index 82fcca07a00ac6..a151fd96ef4981 100644
--- a/llvm/test/Transforms/InstCombine/icmp-power2-and-icmp-shifted-mask.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-power2-and-icmp-shifted-mask.ll
@@ -448,7 +448,10 @@ define <2 x i1> @icmp_power2_and_icmp_shifted_mask_vector_swapped_splat_poison_2
 ; Vector of 2 reduction with splat containing undef
 define <2 x i1> @icmp_power2_and_icmp_shifted_mask_vector_splat_undef_2147483648_1610612736_2147483647(<2 x i32> %x) {
 ; CHECK-LABEL: @icmp_power2_and_icmp_shifted_mask_vector_splat_undef_2147483648_1610612736_2147483647(
-; CHECK-NEXT:    [[T4:%.*]] = icmp ult <2 x i32> [[X:%.*]], <i32 1610612736, i32 2147483647>
+; CHECK-NEXT:    [[T1:%.*]] = icmp ult <2 x i32> [[X:%.*]], <i32 -2147483648, i32 undef>
+; CHECK-NEXT:    [[T2:%.*]] = and <2 x i32> [[X]], <i32 1610612736, i32 2147483647>
+; CHECK-NEXT:    [[T3:%.*]] = icmp ne <2 x i32> [[T2]], <i32 1610612736, i32 2147483647>
+; CHECK-NEXT:    [[T4:%.*]] = and <2 x i1> [[T1]], [[T3]]
 ; CHECK-NEXT:    ret <2 x i1> [[T4]]
 ;
   %t1 = icmp ult <2 x i32> %x, <i32 2147483648, i32 undef>
@@ -460,7 +463,10 @@ define <2 x i1> @icmp_power2_and_icmp_shifted_mask_vector_splat_undef_2147483648
 
 define <2 x i1> @icmp_power2_and_icmp_shifted_mask_vector_swapped_splat_undef_2147483648_1610612736_2147483647(<2 x i32> %x) {
 ; CHECK-LABEL: @icmp_power2_and_icmp_shifted_mask_vector_swapped_splat_undef_2147483648_1610612736_2147483647(
-; CHECK-NEXT:    [[T4:%.*]] = icmp ult <2 x i32> [[X:%.*]], <i32 1610612736, i32 2147483647>
+; CHECK-NEXT:    [[T1:%.*]] = icmp ult <2 x i32> [[X:%.*]], <i32 -2147483648, i32 undef>
+; CHECK-NEXT:    [[T2:%.*]] = and <2 x i32> [[X]], <i32 1610612736, i32 2147483647>
+; CHECK-NEXT:    [[T3:%.*]] = icmp ne <2 x i32> [[T2]], <i32 1610612736, i32 2147483647>
+; CHECK-NEXT:    [[T4:%.*]] = and <2 x i1> [[T3]], [[T1]]
 ; CHECK-NEXT:    ret <2 x i1> [[T4]]
 ;
   %t1 = icmp ult <2 x i32> %x, <i32 2147483648, i32 undef>
diff --git a/llvm/test/Transforms/InstCombine/icmp-vec-inseltpoison.ll b/llvm/test/Transforms/InstCombine/icmp-vec-inseltpoison.ll
index 04d8d294c31935..677655a0a99ab6 100644
--- a/llvm/test/Transforms/InstCombine/icmp-vec-inseltpoison.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-vec-inseltpoison.ll
@@ -184,7 +184,7 @@ define <3 x i1> @PR27756_2(<3 x i8> %a) {
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp slt <3 x i8> [[A:%.*]], <i8 43, i8 43, i8 1>
 ; CHECK-NEXT:    ret <3 x i1> [[CMP]]
 ;
-  %cmp = icmp sle <3 x i8> %a, <i8 42, i8 undef, i8 0>
+  %cmp = icmp sle <3 x i8> %a, <i8 42, i8 poison, i8 0>
   ret <3 x i1> %cmp
 }
 
@@ -193,7 +193,7 @@ define <3 x i1> @PR27756_3(<3 x i8> %a) {
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <3 x i8> [[A:%.*]], <i8 0, i8 0, i8 41>
 ; CHECK-NEXT:    ret <3 x i1> [[CMP]]
 ;
-  %cmp = icmp sge <3 x i8> %a, <i8 undef, i8 1, i8 42>
+  %cmp = icmp sge <3 x i8> %a, <i8 poison, i8 1, i8 42>
   ret <3 x i1> %cmp
 }
 
@@ -300,14 +300,14 @@ define <4 x i1> @splat_icmp(<4 x i8> %x) {
   ret <4 x i1> %cmp
 }
 
-define <4 x i1> @splat_icmp_undef(<4 x i8> %x) {
-; CHECK-LABEL: @splat_icmp_undef(
+define <4 x i1> @splat_icmp_poison(<4 x i8> %x) {
+; CHECK-LABEL: @splat_icmp_poison(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp ult <4 x i8> [[X:%.*]], <i8 42, i8 42, i8 42, i8 42>
 ; CHECK-NEXT:    [[CMP:%.*]] = shufflevector <4 x i1> [[TMP1]], <4 x i1> poison, <4 x i32> <i32 2, i32 2, i32 2, i32 2>
 ; CHECK-NEXT:    ret <4 x i1> [[CMP]]
 ;
-  %splatx = shufflevector <4 x i8> %x, <4 x i8> poison, <4 x i32> <i32 2, i32 undef, i32 undef, i32 2>
-  %cmp = icmp ult <4 x i8> %splatx, <i8 undef, i8 42, i8 undef, i8 42>
+  %splatx = shufflevector <4 x i8> %x, <4 x i8> poison, <4 x i32> <i32 2, i32 poison, i32 poison, i32 2>
+  %cmp = icmp ult <4 x i8> %splatx, <i8 poison, i8 42, i8 poison, i8 42>
   ret <4 x i1> %cmp
 }
 
@@ -317,8 +317,8 @@ define <4 x i1> @splat_icmp_larger_size(<2 x i8> %x) {
 ; CHECK-NEXT:    [[CMP:%.*]] = shufflevector <2 x i1> [[TMP1]], <2 x i1> poison, <4 x i32> <i32 1, i32 1, i32 1, i32 1>
 ; CHECK-NEXT:    ret <4 x i1> [[CMP]]
 ;
-  %splatx = shufflevector <2 x i8> %x, <2 x i8> poison, <4 x i32> <i32 1, i32 undef, i32 1, i32 undef>
-  %cmp = icmp eq <4 x i8> %splatx, <i8 42, i8 42, i8 undef, i8 42>
+  %splatx = shufflevector <2 x i8> %x, <2 x i8> poison, <4 x i32> <i32 1, i32 poison, i32 1, i32 poison>
+  %cmp = icmp eq <4 x i8> %splatx, <i8 42, i8 42, i8 poison, i8 42>
   ret <4 x i1> %cmp
 }
 
@@ -328,8 +328,8 @@ define <4 x i1> @splat_fcmp_smaller_size(<5 x float> %x) {
 ; CHECK-NEXT:    [[CMP:%.*]] = shufflevector <5 x i1> [[TMP1]], <5 x i1> poison, <4 x i32> <i32 1, i32 1, i32 1, i32 1>
 ; CHECK-NEXT:    ret <4 x i1> [[CMP]]
 ;
-  %splatx = shufflevector <5 x float> %x, <5 x float> poison, <4 x i32> <i32 1, i32 undef, i32 1, i32 undef>
-  %cmp = fcmp oeq <4 x float> %splatx, <float 42.0, float 42.0, float undef, float 42.0>
+  %splatx = shufflevector <5 x float> %x, <5 x float> poison, <4 x i32> <i32 1, i32 poison, i32 1, i32 poison>
+  %cmp = fcmp oeq <4 x float> %splatx, <float 42.0, float 42.0, float poison, float 42.0>
   ret <4 x i1> %cmp
 }
 
diff --git a/llvm/test/Transforms/InstCombine/icmp-vec.ll b/llvm/test/Transforms/InstCombine/icmp-vec.ll
index 63dd535c527ef9..1e392635936b7e 100644
--- a/llvm/test/Transforms/InstCombine/icmp-vec.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-vec.ll
@@ -186,7 +186,7 @@ define <3 x i1> @PR27756_2(<3 x i8> %a) {
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp slt <3 x i8> [[A:%.*]], <i8 43, i8 43, i8 1>
 ; CHECK-NEXT:    ret <3 x i1> [[CMP]]
 ;
-  %cmp = icmp sle <3 x i8> %a, <i8 42, i8 undef, i8 0>
+  %cmp = icmp sle <3 x i8> %a, <i8 42, i8 poison, i8 0>
   ret <3 x i1> %cmp
 }
 
@@ -195,7 +195,7 @@ define <3 x i1> @PR27756_3(<3 x i8> %a) {
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <3 x i8> [[A:%.*]], <i8 0, i8 0, i8 41>
 ; CHECK-NEXT:    ret <3 x i1> [[CMP]]
 ;
-  %cmp = icmp sge <3 x i8> %a, <i8 undef, i8 1, i8 42>
+  %cmp = icmp sge <3 x i8> %a, <i8 poison, i8 1, i8 42>
   ret <3 x i1> %cmp
 }
 
@@ -218,8 +218,8 @@ define <4 x i1> @same_shuffle_inputs_icmp(<4 x i8> %x, <4 x i8> %y) {
 ; CHECK-NEXT:    [[CMP:%.*]] = shufflevector <4 x i1> [[TMP1]], <4 x i1> poison, <4 x i32> <i32 3, i32 3, i32 2, i32 0>
 ; CHECK-NEXT:    ret <4 x i1> [[CMP]]
 ;
-  %shufx = shufflevector <4 x i8> %x, <4 x i8> undef, <4 x i32> < i32 3, i32 3, i32 2, i32 0 >
-  %shufy = shufflevector <4 x i8> %y, <4 x i8> undef, <4 x i32> < i32 3, i32 3, i32 2, i32 0 >
+  %shufx = shufflevector <4 x i8> %x, <4 x i8> poison, <4 x i32> < i32 3, i32 3, i32 2, i32 0 >
+  %shufy = shufflevector <4 x i8> %y, <4 x i8> poison, <4 x i32> < i32 3, i32 3, i32 2, i32 0 >
   %cmp = icmp sgt <4 x i8> %shufx, %shufy
   ret <4 x i1> %cmp
 }
@@ -232,8 +232,8 @@ define <5 x i1> @same_shuffle_inputs_fcmp(<4 x float> %x, <4 x float> %y) {
 ; CHECK-NEXT:    [[CMP:%.*]] = shufflevector <4 x i1> [[TMP1]], <4 x i1> poison, <5 x i32> <i32 0, i32 1, i32 3, i32 2, i32 0>
 ; CHECK-NEXT:    ret <5 x i1> [[CMP]]
 ;
-  %shufx = shufflevector <4 x float> %x, <4 x float> undef, <5 x i32> < i32 0, i32 1, i32 3, i32 2, i32 0 >
-  %shufy = shufflevector <4 x float> %y, <4 x float> undef, <5 x i32> < i32 0, i32 1, i32 3, i32 2, i32 0 >
+  %shufx = shufflevector <4 x float> %x, <4 x float> poison, <5 x i32> < i32 0, i32 1, i32 3, i32 2, i32 0 >
+  %shufy = shufflevector <4 x float> %y, <4 x float> poison, <5 x i32> < i32 0, i32 1, i32 3, i32 2, i32 0 >
   %cmp = fcmp oeq <5 x float> %shufx, %shufy
   ret <5 x i1> %cmp
 }
@@ -248,8 +248,8 @@ define <4 x i1> @same_shuffle_inputs_icmp_extra_use1(<4 x i8> %x, <4 x i8> %y) {
 ; CHECK-NEXT:    call void @use_v4i8(<4 x i8> [[SHUFX]])
 ; CHECK-NEXT:    ret <4 x i1> [[CMP]]
 ;
-  %shufx = shufflevector <4 x i8> %x, <4 x i8> undef, <4 x i32> < i32 3, i32 3, i32 3, i32 3 >
-  %shufy = shufflevector <4 x i8> %y, <4 x i8> undef, <4 x i32> < i32 3, i32 3, i32 3, i32 3 >
+  %shufx = shufflevector <4 x i8> %x, <4 x i8> poison, <4 x i32> < i32 3, i32 3, i32 3, i32 3 >
+  %shufy = shufflevector <4 x i8> %y, <4 x i8> poison, <4 x i32> < i32 3, i32 3, i32 3, i32 3 >
   %cmp = icmp ugt <4 x i8> %shufx, %shufy
   call void @use_v4i8(<4 x i8> %shufx)
   ret <4 x i1> %cmp
@@ -265,8 +265,8 @@ define <2 x i1> @same_shuffle_inputs_icmp_extra_use2(<4 x i8> %x, <4 x i8> %y) {
 ; CHECK-NEXT:    call void @use_v2i8(<2 x i8> [[SHUFY]])
 ; CHECK-NEXT:    ret <2 x i1> [[CMP]]
 ;
-  %shufx = shufflevector <4 x i8> %x, <4 x i8> undef, <2 x i32> < i32 3, i32 2 >
-  %shufy = shufflevector <4 x i8> %y, <4 x i8> undef, <2 x i32> < i32 3, i32 2 >
+  %shufx = shufflevector <4 x i8> %x, <4 x i8> poison, <2 x i32> < i32 3, i32 2 >
+  %shufy = shufflevector <4 x i8> %y, <4 x i8> poison, <2 x i32> < i32 3, i32 2 >
   %cmp = icmp eq <2 x i8> %shufx, %shufy
   call void @use_v2i8(<2 x i8> %shufy)
   ret <2 x i1> %cmp
@@ -283,8 +283,8 @@ define <2 x i1> @same_shuffle_inputs_icmp_extra_use3(<4 x i8> %x, <4 x i8> %y) {
 ; CHECK-NEXT:    call void @use_v2i8(<2 x i8> [[SHUFY]])
 ; CHECK-NEXT:    ret <2 x i1> [[CMP]]
 ;
-  %shufx = shufflevector <4 x i8> %x, <4 x i8> undef, <2 x i32> < i32 0, i32 0 >
-  %shufy = shufflevector <4 x i8> %y, <4 x i8> undef, <2 x i32> < i32 0, i32 0 >
+  %shufx = shufflevector <4 x i8> %x, <4 x i8> poison, <2 x i32> < i32 0, i32 0 >
+  %shufy = shufflevector <4 x i8> %y, <4 x i8> poison, <2 x i32> < i32 0, i32 0 >
   %cmp = icmp eq <2 x i8> %shufx, %shufy
   call void @use_v2i8(<2 x i8> %shufx)
   call void @use_v2i8(<2 x i8> %shufy)
@@ -297,19 +297,19 @@ define <4 x i1> @splat_icmp(<4 x i8> %x) {
 ; CHECK-NEXT:    [[CMP:%.*]] = shufflevector <4 x i1> [[TMP1]], <4 x i1> poison, <4 x i32> <i32 3, i32 3, i32 3, i32 3>
 ; CHECK-NEXT:    ret <4 x i1> [[CMP]]
 ;
-  %splatx = shufflevector <4 x i8> %x, <4 x i8> undef, <4 x i32> <i32 3, i32 3, i32 3, i32 3>
+  %splatx = shufflevector <4 x i8> %x, <4 x i8> poison, <4 x i32> <i32 3, i32 3, i32 3, i32 3>
   %cmp = icmp sgt <4 x i8> %splatx, <i8 42, i8 42, i8 42, i8 42>
   ret <4 x i1> %cmp
 }
 
-define <4 x i1> @splat_icmp_undef(<4 x i8> %x) {
-; CHECK-LABEL: @splat_icmp_undef(
+define <4 x i1> @splat_icmp_poison(<4 x i8> %x) {
+; CHECK-LABEL: @splat_icmp_poison(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp ult <4 x i8> [[X:%.*]], <i8 42, i8 42, i8 42, i8 42>
 ; CHECK-NEXT:    [[CMP:%.*]] = shufflevector <4 x i1> [[TMP1]], <4 x i1> poison, <4 x i32> <i32 2, i32 2, i32 2, i32 2>
 ; CHECK-NEXT:    ret <4 x i1> [[CMP]]
 ;
-  %splatx = shufflevector <4 x i8> %x, <4 x i8> undef, <4 x i32> <i32 2, i32 undef, i32 undef, i32 2>
-  %cmp = icmp ult <4 x i8> %splatx, <i8 undef, i8 42, i8 undef, i8 42>
+  %splatx = shufflevector <4 x i8> %x, <4 x i8> poison, <4 x i32> <i32 2, i32 poison, i32 poison, i32 2>
+  %cmp = icmp ult <4 x i8> %splatx, <i8 poison, i8 42, i8 poison, i8 42>
   ret <4 x i1> %cmp
 }
 
@@ -319,8 +319,8 @@ define <4 x i1> @splat_icmp_larger_size(<2 x i8> %x) {
 ; CHECK-NEXT:    [[CMP:%.*]] = shufflevector <2 x i1> [[TMP1]], <2 x i1> poison, <4 x i32> <i32 1, i32 1, i32 1, i32 1>
 ; CHECK-NEXT:    ret <4 x i1> [[CMP]]
 ;
-  %splatx = shufflevector <2 x i8> %x, <2 x i8> undef, <4 x i32> <i32 1, i32 undef, i32 1, i32 undef>
-  %cmp = icmp eq <4 x i8> %splatx, <i8 42, i8 42, i8 undef, i8 42>
+  %splatx = shufflevector <2 x i8> %x, <2 x i8> poison, <4 x i32> <i32 1, i32 poison, i32 1, i32 poison>
+  %cmp = icmp eq <4 x i8> %splatx, <i8 42, i8 42, i8 poison, i8 42>
   ret <4 x i1> %cmp
 }
 
@@ -330,8 +330,8 @@ define <4 x i1> @splat_fcmp_smaller_size(<5 x float> %x) {
 ; CHECK-NEXT:    [[CMP:%.*]] = shufflevector <5 x i1> [[TMP1]], <5 x i1> poison, <4 x i32> <i32 1, i32 1, i32 1, i32 1>
 ; CHECK-NEXT:    ret <4 x i1> [[CMP]]
 ;
-  %splatx = shufflevector <5 x float> %x, <5 x float> undef, <4 x i32> <i32 1, i32 undef, i32 1, i32 undef>
-  %cmp = fcmp oeq <4 x float> %splatx, <float 42.0, float 42.0, float undef, float 42.0>
+  %splatx = shufflevector <5 x float> %x, <5 x float> poison, <4 x i32> <i32 1, i32 poison, i32 1, i32 poison>
+  %cmp = fcmp oeq <4 x float> %splatx, <float 42.0, float 42.0, float poison, float 42.0>
   ret <4 x i1> %cmp
 }
 
@@ -344,7 +344,7 @@ define <4 x i1> @splat_icmp_extra_use(<4 x i8> %x) {
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <4 x i8> [[SPLATX]], <i8 42, i8 42, i8 42, i8 42>
 ; CHECK-NEXT:    ret <4 x i1> [[CMP]]
 ;
-  %splatx = shufflevector <4 x i8> %x, <4 x i8> undef, <4 x i32> <i32 3, i32 3, i32 3, i32 3>
+  %splatx = shufflevector <4 x i8> %x, <4 x i8> poison, <4 x i32> <i32 3, i32 3, i32 3, i32 3>
   call void @use_v4i8(<4 x i8> %splatx)
   %cmp = icmp sgt <4 x i8> %splatx, <i8 42, i8 42, i8 42, i8 42>
   ret <4 x i1> %cmp
@@ -358,7 +358,7 @@ define <4 x i1> @not_splat_icmp(<4 x i8> %x) {
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <4 x i8> [[SPLATX]], <i8 42, i8 42, i8 42, i8 42>
 ; CHECK-NEXT:    ret <4 x i1> [[CMP]]
 ;
-  %splatx = shufflevector <4 x i8> %x, <4 x i8> undef, <4 x i32> <i32 3, i32 2, i32 3, i32 3>
+  %splatx = shufflevector <4 x i8> %x, <4 x i8> poison, <4 x i32> <i32 3, i32 2, i32 3, i32 3>
   %cmp = icmp sgt <4 x i8> %splatx, <i8 42, i8 42, i8 42, i8 42>
   ret <4 x i1> %cmp
 }
@@ -371,7 +371,7 @@ define <4 x i1> @not_splat_icmp2(<4 x i8> %x) {
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <4 x i8> [[SPLATX]], <i8 43, i8 42, i8 42, i8 42>
 ; CHECK-NEXT:    ret <4 x i1> [[CMP]]
 ;
-  %splatx = shufflevector <4 x i8> %x, <4 x i8> undef, <4 x i32> <i32 2, i32 2, i32 2, i32 2>
+  %splatx = shufflevector <4 x i8> %x, <4 x i8> poison, <4 x i32> <i32 2, i32 2, i32 2, i32 2>
   %cmp = icmp sgt <4 x i8> %splatx, <i8 43, i8 42, i8 42, i8 42>
   ret <4 x i1> %cmp
 }
@@ -385,7 +385,7 @@ define <2 x i1> @icmp_logical_or_vec(<2 x i64> %x, <2 x i64> %y, <2 x i1> %false
 ; CHECK-NEXT:    ret <2 x i1> [[SEL]]
 ;
   %cmp.ne = icmp ne <2 x i64> %x, zeroinitializer
-  %sel = select <2 x i1> %cmp.ne, <2 x i1> shufflevector (<2 x i1> insertelement (<2 x i1> undef, i1 true, i32 0), <2 x i1> undef, <2 x i32> zeroinitializer), <2 x i1> %falseval
+  %sel = select <2 x i1> %cmp.ne, <2 x i1> shufflevector (<2 x i1> insertelement (<2 x i1> poison, i1 true, i32 0), <2 x i1> poison, <2 x i32> zeroinitializer), <2 x i1> %falseval
   ret <2 x i1> %sel
 }
 
diff --git a/llvm/test/Transforms/InstCombine/low-bit-splat.ll b/llvm/test/Transforms/InstCombine/low-bit-splat.ll
index 5a4b00a6f17e73..a86ab0359afd78 100644
--- a/llvm/test/Transforms/InstCombine/low-bit-splat.ll
+++ b/llvm/test/Transforms/InstCombine/low-bit-splat.ll
@@ -39,34 +39,37 @@ define <2 x i8> @t2_vec(<2 x i8> %x) {
   %r = ashr <2 x i8> %i0, <i8 7, i8 7>
   ret <2 x i8> %r
 }
-define <3 x i8> @t3_vec_undef0(<3 x i8> %x) {
-; CHECK-LABEL: @t3_vec_undef0(
+
+; TODO: The result constants should contain poison instead of undef.
+
+define <3 x i8> @t3_vec_poison0(<3 x i8> %x) {
+; CHECK-LABEL: @t3_vec_poison0(
 ; CHECK-NEXT:    [[TMP1:%.*]] = and <3 x i8> [[X:%.*]], <i8 1, i8 undef, i8 1>
 ; CHECK-NEXT:    [[R:%.*]] = sub <3 x i8> zeroinitializer, [[TMP1]]
 ; CHECK-NEXT:    ret <3 x i8> [[R]]
 ;
-  %i0 = shl <3 x i8> %x, <i8 7, i8 undef, i8 7>
+  %i0 = shl <3 x i8> %x, <i8 7, i8 poison, i8 7>
   %r = ashr <3 x i8> %i0, <i8 7, i8 7, i8 7>
   ret <3 x i8> %r
 }
-define <3 x i8> @t4_vec_undef1(<3 x i8> %x) {
-; CHECK-LABEL: @t4_vec_undef1(
+define <3 x i8> @t4_vec_poison1(<3 x i8> %x) {
+; CHECK-LABEL: @t4_vec_poison1(
 ; CHECK-NEXT:    [[TMP1:%.*]] = and <3 x i8> [[X:%.*]], <i8 1, i8 undef, i8 1>
 ; CHECK-NEXT:    [[R:%.*]] = sub <3 x i8> zeroinitializer, [[TMP1]]
 ; CHECK-NEXT:    ret <3 x i8> [[R]]
 ;
   %i0 = shl <3 x i8> %x, <i8 7, i8 7, i8 7>
-  %r = ashr <3 x i8> %i0, <i8 7, i8 undef, i8 7>
+  %r = ashr <3 x i8> %i0, <i8 7, i8 poison, i8 7>
   ret <3 x i8> %r
 }
-define <3 x i8> @t5_vec_undef2(<3 x i8> %x) {
-; CHECK-LABEL: @t5_vec_undef2(
+define <3 x i8> @t5_vec_poison2(<3 x i8> %x) {
+; CHECK-LABEL: @t5_vec_poison2(
 ; CHECK-NEXT:    [[TMP1:%.*]] = and <3 x i8> [[X:%.*]], <i8 1, i8 undef, i8 1>
 ; CHECK-NEXT:    [[R:%.*]] = sub <3 x i8> zeroinitializer, [[TMP1]]
 ; CHECK-NEXT:    ret <3 x i8> [[R]]
 ;
-  %i0 = shl <3 x i8> %x, <i8 7, i8 undef, i8 7>
-  %r = ashr <3 x i8> %i0, <i8 7, i8 undef, i8 7>
+  %i0 = shl <3 x i8> %x, <i8 7, i8 poison, i8 7>
+  %r = ashr <3 x i8> %i0, <i8 7, i8 poison, i8 7>
   ret <3 x i8> %r
 }
 
diff --git a/llvm/test/Transforms/InstCombine/lshr-trunc-sext-to-ashr-sext.ll b/llvm/test/Transforms/InstCombine/lshr-trunc-sext-to-ashr-sext.ll
index 8e7491ee403701..a77ad3a7ea74ee 100644
--- a/llvm/test/Transforms/InstCombine/lshr-trunc-sext-to-ashr-sext.ll
+++ b/llvm/test/Transforms/InstCombine/lshr-trunc-sext-to-ashr-sext.ll
@@ -74,13 +74,13 @@ define <2 x i16> @t4_vec_splat(<2 x i8> %x) {
   ret <2 x i16> %c
 }
 
-define <2 x i16> @t5_vec_undef(<2 x i8> %x) {
-; CHECK-LABEL: @t5_vec_undef(
+define <2 x i16> @t5_vec_poison(<2 x i8> %x) {
+; CHECK-LABEL: @t5_vec_poison(
 ; CHECK-NEXT:    [[TMP1:%.*]] = ashr <2 x i8> [[X:%.*]], <i8 4, i8 4>
 ; CHECK-NEXT:    [[C:%.*]] = sext <2 x i8> [[TMP1]] to <2 x i16>
 ; CHECK-NEXT:    ret <2 x i16> [[C]]
 ;
-  %a = lshr <2 x i8> %x, <i8 4, i8 undef>
+  %a = lshr <2 x i8> %x, <i8 4, i8 poison>
   %b = trunc <2 x i8> %a to <2 x i4>
   %c = sext <2 x i4> %b to <2 x i16>
   ret <2 x i16> %c
@@ -105,15 +105,15 @@ define i16 @t6_extrause0(i8 %x) {
 
 ; TODO: We could convert %a to ashr and eliminate 2nd use of %b.
 
-define <2 x i16> @t7_extrause0_vec_undef(<2 x i8> %x) {
-; CHECK-LABEL: @t7_extrause0_vec_undef(
-; CHECK-NEXT:    [[A:%.*]] = lshr <2 x i8> [[X:%.*]], <i8 4, i8 undef>
-; CHECK-NEXT:    [[B:%.*]] = trunc <2 x i8> [[A]] to <2 x i4>
+define <2 x i16> @t7_extrause0_vec_poison(<2 x i8> %x) {
+; CHECK-LABEL: @t7_extrause0_vec_poison(
+; CHECK-NEXT:    [[A:%.*]] = lshr <2 x i8> [[X:%.*]], <i8 4, i8 poison>
+; CHECK-NEXT:    [[B:%.*]] = trunc nuw <2 x i8> [[A]] to <2 x i4>
 ; CHECK-NEXT:    call void @usevec4(<2 x i4> [[B]])
 ; CHECK-NEXT:    [[C:%.*]] = sext <2 x i4> [[B]] to <2 x i16>
 ; CHECK-NEXT:    ret <2 x i16> [[C]]
 ;
-  %a = lshr <2 x i8> %x, <i8 4, i8 undef>
+  %a = lshr <2 x i8> %x, <i8 4, i8 poison>
   %b = trunc <2 x i8> %a to <2 x i4>
   call void @usevec4(<2 x i4> %b)
   %c = sext <2 x i4> %b to <2 x i16>
@@ -139,15 +139,15 @@ define i16 @t8_extrause1(i8 %x) {
 
 ; TODO: We could convert %a to ashr + mask (and) and eliminate %b.
 
-define <2 x i16> @t9_extrause1_vec_undef(<2 x i8> %x) {
-; CHECK-LABEL: @t9_extrause1_vec_undef(
-; CHECK-NEXT:    [[A:%.*]] = lshr <2 x i8> [[X:%.*]], <i8 4, i8 undef>
+define <2 x i16> @t9_extrause1_vec_poison(<2 x i8> %x) {
+; CHECK-LABEL: @t9_extrause1_vec_poison(
+; CHECK-NEXT:    [[A:%.*]] = lshr <2 x i8> [[X:%.*]], <i8 4, i8 poison>
 ; CHECK-NEXT:    call void @usevec8(<2 x i8> [[A]])
 ; CHECK-NEXT:    [[TMP1:%.*]] = ashr <2 x i8> [[X]], <i8 4, i8 4>
 ; CHECK-NEXT:    [[C:%.*]] = sext <2 x i8> [[TMP1]] to <2 x i16>
 ; CHECK-NEXT:    ret <2 x i16> [[C]]
 ;
-  %a = lshr <2 x i8> %x, <i8 4, i8 undef>
+  %a = lshr <2 x i8> %x, <i8 4, i8 poison>
   call void @usevec8(<2 x i8> %a)
   %b = trunc <2 x i8> %a to <2 x i4>
   %c = sext <2 x i4> %b to <2 x i16>
@@ -169,16 +169,16 @@ define i16 @t10_extrause2(i8 %x) {
   %c = sext i4 %b to i16
   ret i16 %c
 }
-define <2 x i16> @t11_extrause2_vec_undef(<2 x i8> %x) {
-; CHECK-LABEL: @t11_extrause2_vec_undef(
-; CHECK-NEXT:    [[A:%.*]] = lshr <2 x i8> [[X:%.*]], <i8 4, i8 undef>
+define <2 x i16> @t11_extrause2_vec_poison(<2 x i8> %x) {
+; CHECK-LABEL: @t11_extrause2_vec_poison(
+; CHECK-NEXT:    [[A:%.*]] = lshr <2 x i8> [[X:%.*]], <i8 4, i8 poison>
 ; CHECK-NEXT:    call void @usevec8(<2 x i8> [[A]])
-; CHECK-NEXT:    [[B:%.*]] = trunc <2 x i8> [[A]] to <2 x i4>
+; CHECK-NEXT:    [[B:%.*]] = trunc nuw <2 x i8> [[A]] to <2 x i4>
 ; CHECK-NEXT:    call void @usevec4(<2 x i4> [[B]])
 ; CHECK-NEXT:    [[C:%.*]] = sext <2 x i4> [[B]] to <2 x i16>
 ; CHECK-NEXT:    ret <2 x i16> [[C]]
 ;
-  %a = lshr <2 x i8> %x, <i8 4, i8 undef>
+  %a = lshr <2 x i8> %x, <i8 4, i8 poison>
   call void @usevec8(<2 x i8> %a)
   %b = trunc <2 x i8> %a to <2 x i4>
   call void @usevec4(<2 x i4> %b)
diff --git a/llvm/test/Transforms/InstCombine/select.ll b/llvm/test/Transforms/InstCombine/select.ll
index 8654691c6f875f..8776ec6a29b43a 100644
--- a/llvm/test/Transforms/InstCombine/select.ll
+++ b/llvm/test/Transforms/InstCombine/select.ll
@@ -1665,37 +1665,37 @@ define float @copysign3(float %x) {
   ret float %r
 }
 
-define <2 x float> @copysign_vec_undef(<2 x float> %x) {
-; CHECK-LABEL: @copysign_vec_undef(
+define <2 x float> @copysign_vec_poison(<2 x float> %x) {
+; CHECK-LABEL: @copysign_vec_poison(
 ; CHECK-NEXT:    [[TMP1:%.*]] = fneg <2 x float> [[X:%.*]]
 ; CHECK-NEXT:    [[R:%.*]] = call <2 x float> @llvm.copysign.v2f32(<2 x float> <float 4.200000e+01, float 4.200000e+01>, <2 x float> [[TMP1]])
 ; CHECK-NEXT:    ret <2 x float> [[R]]
 ;
   %i = bitcast <2 x float> %x to <2 x i32>
   %isneg = icmp ugt <2 x i32> %i, <i32 2147483647, i32 2147483647>
-  %r = select arcp nnan <2 x i1> %isneg, <2 x float> <float 42.0, float undef>, <2 x float> <float -42.0, float -42.0>
+  %r = select arcp nnan <2 x i1> %isneg, <2 x float> <float 42.0, float poison>, <2 x float> <float -42.0, float -42.0>
   ret <2 x float> %r
 }
 
-define <2 x float> @copysign_vec_undef1(<2 x float> %x) {
-; CHECK-LABEL: @copysign_vec_undef1(
+define <2 x float> @copysign_vec_poison1(<2 x float> %x) {
+; CHECK-LABEL: @copysign_vec_poison1(
 ; CHECK-NEXT:    [[R:%.*]] = call <2 x float> @llvm.copysign.v2f32(<2 x float> <float 4.200000e+01, float 4.200000e+01>, <2 x float> [[X:%.*]])
 ; CHECK-NEXT:    ret <2 x float> [[R]]
 ;
   %i = bitcast <2 x float> %x to <2 x i32>
   %isneg = icmp ult <2 x i32> %i, <i32 2147483648, i32 2147483648>
-  %r = select arcp nnan <2 x i1> %isneg, <2 x float> <float 42.0, float 42.0>, <2 x float> <float undef, float -42.0>
+  %r = select arcp nnan <2 x i1> %isneg, <2 x float> <float 42.0, float 42.0>, <2 x float> <float poison, float -42.0>
   ret <2 x float> %r
 }
 
-define <2 x float> @copysign_vec_undef3(<2 x float> %x) {
-; CHECK-LABEL: @copysign_vec_undef3(
+define <2 x float> @copysign_vec_poison3(<2 x float> %x) {
+; CHECK-LABEL: @copysign_vec_poison3(
 ; CHECK-NEXT:    [[R:%.*]] = call <2 x float> @llvm.copysign.v2f32(<2 x float> <float 4.200000e+01, float 4.200000e+01>, <2 x float> [[X:%.*]])
 ; CHECK-NEXT:    ret <2 x float> [[R]]
 ;
   %i = bitcast <2 x float> %x to <2 x i32>
   %isneg = icmp ugt <2 x i32> %i, <i32 2147483647, i32 2147483647>
-  %r = select arcp nnan <2 x i1> %isneg, <2 x float> <float -42.0, float undef>, <2 x float> <float +42.0, float undef>
+  %r = select arcp nnan <2 x i1> %isneg, <2 x float> <float -42.0, float poison>, <2 x float> <float +42.0, float poison>
   ret <2 x float> %r
 }
 
diff --git a/llvm/test/Transforms/InstCombine/signed-truncation-check.ll b/llvm/test/Transforms/InstCombine/signed-truncation-check.ll
index 208e166b2c8760..17cd536de91f4d 100644
--- a/llvm/test/Transforms/InstCombine/signed-truncation-check.ll
+++ b/llvm/test/Transforms/InstCombine/signed-truncation-check.ll
@@ -198,104 +198,104 @@ define <2 x i1> @positive_vec_nonsplat(<2 x i32> %arg) {
   ret <2 x i1> %t4
 }
 
-define <3 x i1> @positive_vec_undef0(<3 x i32> %arg) {
-; CHECK-LABEL: @positive_vec_undef0(
+define <3 x i1> @positive_vec_poison0(<3 x i32> %arg) {
+; CHECK-LABEL: @positive_vec_poison0(
 ; CHECK-NEXT:    [[T4_SIMPLIFIED:%.*]] = icmp ult <3 x i32> [[ARG:%.*]], <i32 128, i32 128, i32 128>
 ; CHECK-NEXT:    ret <3 x i1> [[T4_SIMPLIFIED]]
 ;
-  %t1 = icmp sgt <3 x i32> %arg, <i32 -1, i32 undef, i32 -1>
+  %t1 = icmp sgt <3 x i32> %arg, <i32 -1, i32 poison, i32 -1>
   %t2 = add <3 x i32> %arg, <i32 128, i32 128, i32 128>
   %t3 = icmp ult <3 x i32> %t2, <i32 256, i32 256, i32 256>
   %t4 = and <3 x i1> %t1, %t3
   ret <3 x i1> %t4
 }
 
-define <3 x i1> @positive_vec_undef1(<3 x i32> %arg) {
-; CHECK-LABEL: @positive_vec_undef1(
+define <3 x i1> @positive_vec_poison1(<3 x i32> %arg) {
+; CHECK-LABEL: @positive_vec_poison1(
 ; CHECK-NEXT:    [[T1:%.*]] = icmp sgt <3 x i32> [[ARG:%.*]], <i32 -1, i32 -1, i32 -1>
-; CHECK-NEXT:    [[T2:%.*]] = add <3 x i32> [[ARG]], <i32 128, i32 undef, i32 128>
+; CHECK-NEXT:    [[T2:%.*]] = add <3 x i32> [[ARG]], <i32 128, i32 poison, i32 128>
 ; CHECK-NEXT:    [[T3:%.*]] = icmp ult <3 x i32> [[T2]], <i32 256, i32 256, i32 256>
 ; CHECK-NEXT:    [[T4:%.*]] = and <3 x i1> [[T1]], [[T3]]
 ; CHECK-NEXT:    ret <3 x i1> [[T4]]
 ;
   %t1 = icmp sgt <3 x i32> %arg, <i32 -1, i32 -1, i32 -1>
-  %t2 = add <3 x i32> %arg, <i32 128, i32 undef, i32 128>
+  %t2 = add <3 x i32> %arg, <i32 128, i32 poison, i32 128>
   %t3 = icmp ult <3 x i32> %t2, <i32 256, i32 256, i32 256>
   %t4 = and <3 x i1> %t1, %t3
   ret <3 x i1> %t4
 }
 
-define <3 x i1> @positive_vec_undef2(<3 x i32> %arg) {
-; CHECK-LABEL: @positive_vec_undef2(
+define <3 x i1> @positive_vec_poison2(<3 x i32> %arg) {
+; CHECK-LABEL: @positive_vec_poison2(
 ; CHECK-NEXT:    [[T1:%.*]] = icmp sgt <3 x i32> [[ARG:%.*]], <i32 -1, i32 -1, i32 -1>
 ; CHECK-NEXT:    [[T2:%.*]] = add <3 x i32> [[ARG]], <i32 128, i32 128, i32 128>
-; CHECK-NEXT:    [[T3:%.*]] = icmp ult <3 x i32> [[T2]], <i32 256, i32 undef, i32 256>
+; CHECK-NEXT:    [[T3:%.*]] = icmp ult <3 x i32> [[T2]], <i32 256, i32 poison, i32 256>
 ; CHECK-NEXT:    [[T4:%.*]] = and <3 x i1> [[T1]], [[T3]]
 ; CHECK-NEXT:    ret <3 x i1> [[T4]]
 ;
   %t1 = icmp sgt <3 x i32> %arg, <i32 -1, i32 -1, i32 -1>
   %t2 = add <3 x i32> %arg, <i32 128, i32 128, i32 128>
-  %t3 = icmp ult <3 x i32> %t2, <i32 256, i32 undef, i32 256>
+  %t3 = icmp ult <3 x i32> %t2, <i32 256, i32 poison, i32 256>
   %t4 = and <3 x i1> %t1, %t3
   ret <3 x i1> %t4
 }
 
-define <3 x i1> @positive_vec_undef3(<3 x i32> %arg) {
-; CHECK-LABEL: @positive_vec_undef3(
-; CHECK-NEXT:    [[T1:%.*]] = icmp sgt <3 x i32> [[ARG:%.*]], <i32 -1, i32 undef, i32 -1>
-; CHECK-NEXT:    [[T2:%.*]] = add <3 x i32> [[ARG]], <i32 128, i32 undef, i32 128>
+define <3 x i1> @positive_vec_poison3(<3 x i32> %arg) {
+; CHECK-LABEL: @positive_vec_poison3(
+; CHECK-NEXT:    [[T1:%.*]] = icmp sgt <3 x i32> [[ARG:%.*]], <i32 -1, i32 poison, i32 -1>
+; CHECK-NEXT:    [[T2:%.*]] = add <3 x i32> [[ARG]], <i32 128, i32 poison, i32 128>
 ; CHECK-NEXT:    [[T3:%.*]] = icmp ult <3 x i32> [[T2]], <i32 256, i32 256, i32 256>
 ; CHECK-NEXT:    [[T4:%.*]] = and <3 x i1> [[T1]], [[T3]]
 ; CHECK-NEXT:    ret <3 x i1> [[T4]]
 ;
-  %t1 = icmp sgt <3 x i32> %arg, <i32 -1, i32 undef, i32 -1>
-  %t2 = add <3 x i32> %arg, <i32 128, i32 undef, i32 128>
+  %t1 = icmp sgt <3 x i32> %arg, <i32 -1, i32 poison, i32 -1>
+  %t2 = add <3 x i32> %arg, <i32 128, i32 poison, i32 128>
   %t3 = icmp ult <3 x i32> %t2, <i32 256, i32 256, i32 256>
   %t4 = and <3 x i1> %t1, %t3
   ret <3 x i1> %t4
 }
 
-define <3 x i1> @positive_vec_undef4(<3 x i32> %arg) {
-; CHECK-LABEL: @positive_vec_undef4(
-; CHECK-NEXT:    [[T1:%.*]] = icmp sgt <3 x i32> [[ARG:%.*]], <i32 -1, i32 undef, i32 -1>
+define <3 x i1> @positive_vec_poison4(<3 x i32> %arg) {
+; CHECK-LABEL: @positive_vec_poison4(
+; CHECK-NEXT:    [[T1:%.*]] = icmp sgt <3 x i32> [[ARG:%.*]], <i32 -1, i32 poison, i32 -1>
 ; CHECK-NEXT:    [[T2:%.*]] = add <3 x i32> [[ARG]], <i32 128, i32 128, i32 128>
-; CHECK-NEXT:    [[T3:%.*]] = icmp ult <3 x i32> [[T2]], <i32 256, i32 undef, i32 256>
+; CHECK-NEXT:    [[T3:%.*]] = icmp ult <3 x i32> [[T2]], <i32 256, i32 poison, i32 256>
 ; CHECK-NEXT:    [[T4:%.*]] = and <3 x i1> [[T1]], [[T3]]
 ; CHECK-NEXT:    ret <3 x i1> [[T4]]
 ;
-  %t1 = icmp sgt <3 x i32> %arg, <i32 -1, i32 undef, i32 -1>
+  %t1 = icmp sgt <3 x i32> %arg, <i32 -1, i32 poison, i32 -1>
   %t2 = add <3 x i32> %arg, <i32 128, i32 128, i32 128>
-  %t3 = icmp ult <3 x i32> %t2, <i32 256, i32 undef, i32 256>
+  %t3 = icmp ult <3 x i32> %t2, <i32 256, i32 poison, i32 256>
   %t4 = and <3 x i1> %t1, %t3
   ret <3 x i1> %t4
 }
 
-define <3 x i1> @positive_vec_undef5(<3 x i32> %arg) {
-; CHECK-LABEL: @positive_vec_undef5(
+define <3 x i1> @positive_vec_poison5(<3 x i32> %arg) {
+; CHECK-LABEL: @positive_vec_poison5(
 ; CHECK-NEXT:    [[T1:%.*]] = icmp sgt <3 x i32> [[ARG:%.*]], <i32 -1, i32 -1, i32 -1>
-; CHECK-NEXT:    [[T2:%.*]] = add <3 x i32> [[ARG]], <i32 128, i32 undef, i32 128>
-; CHECK-NEXT:    [[T3:%.*]] = icmp ult <3 x i32> [[T2]], <i32 256, i32 undef, i32 256>
+; CHECK-NEXT:    [[T2:%.*]] = add <3 x i32> [[ARG]], <i32 128, i32 poison, i32 128>
+; CHECK-NEXT:    [[T3:%.*]] = icmp ult <3 x i32> [[T2]], <i32 256, i32 poison, i32 256>
 ; CHECK-NEXT:    [[T4:%.*]] = and <3 x i1> [[T1]], [[T3]]
 ; CHECK-NEXT:    ret <3 x i1> [[T4]]
 ;
   %t1 = icmp sgt <3 x i32> %arg, <i32 -1, i32 -1, i32 -1>
-  %t2 = add <3 x i32> %arg, <i32 128, i32 undef, i32 128>
-  %t3 = icmp ult <3 x i32> %t2, <i32 256, i32 undef, i32 256>
+  %t2 = add <3 x i32> %arg, <i32 128, i32 poison, i32 128>
+  %t3 = icmp ult <3 x i32> %t2, <i32 256, i32 poison, i32 256>
   %t4 = and <3 x i1> %t1, %t3
   ret <3 x i1> %t4
 }
 
-define <3 x i1> @positive_vec_undef6(<3 x i32> %arg) {
-; CHECK-LABEL: @positive_vec_undef6(
-; CHECK-NEXT:    [[T1:%.*]] = icmp sgt <3 x i32> [[ARG:%.*]], <i32 -1, i32 undef, i32 -1>
-; CHECK-NEXT:    [[T2:%.*]] = add <3 x i32> [[ARG]], <i32 128, i32 undef, i32 128>
-; CHECK-NEXT:    [[T3:%.*]] = icmp ult <3 x i32> [[T2]], <i32 256, i32 undef, i32 256>
+define <3 x i1> @positive_vec_poison6(<3 x i32> %arg) {
+; CHECK-LABEL: @positive_vec_poison6(
+; CHECK-NEXT:    [[T1:%.*]] = icmp sgt <3 x i32> [[ARG:%.*]], <i32 -1, i32 poison, i32 -1>
+; CHECK-NEXT:    [[T2:%.*]] = add <3 x i32> [[ARG]], <i32 128, i32 poison, i32 128>
+; CHECK-NEXT:    [[T3:%.*]] = icmp ult <3 x i32> [[T2]], <i32 256, i32 poison, i32 256>
 ; CHECK-NEXT:    [[T4:%.*]] = and <3 x i1> [[T1]], [[T3]]
 ; CHECK-NEXT:    ret <3 x i1> [[T4]]
 ;
-  %t1 = icmp sgt <3 x i32> %arg, <i32 -1, i32 undef, i32 -1>
-  %t2 = add <3 x i32> %arg, <i32 128, i32 undef, i32 128>
-  %t3 = icmp ult <3 x i32> %t2, <i32 256, i32 undef, i32 256>
+  %t1 = icmp sgt <3 x i32> %arg, <i32 -1, i32 poison, i32 -1>
+  %t2 = add <3 x i32> %arg, <i32 128, i32 poison, i32 128>
+  %t3 = icmp ult <3 x i32> %t2, <i32 256, i32 poison, i32 256>
   %t4 = and <3 x i1> %t1, %t3
   ret <3 x i1> %t4
 }
diff --git a/llvm/test/Transforms/InstCombine/unsigned-add-lack-of-overflow-check.ll b/llvm/test/Transforms/InstCombine/unsigned-add-lack-of-overflow-check.ll
index 6dde54b17c9edd..e7120a7d01cfaa 100644
--- a/llvm/test/Transforms/InstCombine/unsigned-add-lack-of-overflow-check.ll
+++ b/llvm/test/Transforms/InstCombine/unsigned-add-lack-of-overflow-check.ll
@@ -214,7 +214,7 @@ define <2 x i1> @low_bitmask_uge(<2 x i8> %x) {
 ; CHECK-NEXT:    [[R:%.*]] = icmp eq <2 x i8> [[X:%.*]], zeroinitializer
 ; CHECK-NEXT:    ret <2 x i1> [[R]]
 ;
-  %a = add <2 x i8> %x, <i8 15, i8 undef>
+  %a = add <2 x i8> %x, <i8 15, i8 poison>
   %m = and <2 x i8> %a, <i8 15, i8 15>
   %r = icmp uge <2 x i8> %m, %x
   ret <2 x i1> %r
diff --git a/llvm/test/Transforms/InstCombine/xor-ashr.ll b/llvm/test/Transforms/InstCombine/xor-ashr.ll
index 097e04b3b9cb56..6f501184b63574 100644
--- a/llvm/test/Transforms/InstCombine/xor-ashr.ll
+++ b/llvm/test/Transforms/InstCombine/xor-ashr.ll
@@ -63,15 +63,15 @@ define <4 x i8> @testv4i16i8(<4 x i16> %add) {
   ret <4 x i8> %x
 }
 
-define <4 x i8> @testv4i16i8_undef(<4 x i16> %add) {
-; CHECK-LABEL: @testv4i16i8_undef(
+define <4 x i8> @testv4i16i8_poison(<4 x i16> %add) {
+; CHECK-LABEL: @testv4i16i8_poison(
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp sgt <4 x i16> [[ADD:%.*]], <i16 -1, i16 -1, i16 -1, i16 -1>
-; CHECK-NEXT:    [[X:%.*]] = select <4 x i1> [[TMP1]], <4 x i8> <i8 27, i8 27, i8 undef, i8 27>, <4 x i8> <i8 -28, i8 -28, i8 undef, i8 -28>
+; CHECK-NEXT:    [[X:%.*]] = select <4 x i1> [[TMP1]], <4 x i8> <i8 27, i8 27, i8 poison, i8 27>, <4 x i8> <i8 -28, i8 -28, i8 poison, i8 -28>
 ; CHECK-NEXT:    ret <4 x i8> [[X]]
 ;
-  %sh = ashr <4 x i16> %add, <i16 15, i16 undef, i16 15, i16 15>
+  %sh = ashr <4 x i16> %add, <i16 15, i16 poison, i16 15, i16 15>
   %t = trunc <4 x i16> %sh to <4 x i8>
-  %x = xor <4 x i8> %t, <i8 27, i8 27, i8 undef, i8 27>
+  %x = xor <4 x i8> %t, <i8 27, i8 27, i8 poison, i8 27>
   ret <4 x i8> %x
 }
 
diff --git a/llvm/test/Transforms/InstSimplify/cast-unsigned-icmp-cmp-0.ll b/llvm/test/Transforms/InstSimplify/cast-unsigned-icmp-cmp-0.ll
index 5a61a060785ff4..8f9c75bae1097d 100644
--- a/llvm/test/Transforms/InstSimplify/cast-unsigned-icmp-cmp-0.ll
+++ b/llvm/test/Transforms/InstSimplify/cast-unsigned-icmp-cmp-0.ll
@@ -27,13 +27,13 @@ define <2 x i1> @i32_cast_cmp_slt_int_0_uitofp_float_vec(<2 x i32> %i) {
   ret <2 x i1> %cmp
 }
 
-define <3 x i1> @i32_cast_cmp_slt_int_0_uitofp_float_vec_undef(<3 x i32> %i) {
-; CHECK-LABEL: @i32_cast_cmp_slt_int_0_uitofp_float_vec_undef(
+define <3 x i1> @i32_cast_cmp_slt_int_0_uitofp_float_vec_poison(<3 x i32> %i) {
+; CHECK-LABEL: @i32_cast_cmp_slt_int_0_uitofp_float_vec_poison(
 ; CHECK-NEXT:    ret <3 x i1> zeroinitializer
 ;
   %f = uitofp <3 x i32> %i to <3 x float>
   %b = bitcast <3 x float> %f to <3 x i32>
-  %cmp = icmp slt <3 x i32> %b, <i32 0, i32 undef, i32 0>
+  %cmp = icmp slt <3 x i32> %b, <i32 0, i32 poison, i32 0>
   ret <3 x i1> %cmp
 }
 
@@ -70,13 +70,13 @@ define i1 @i32_cast_cmp_sgt_int_m1_uitofp_float_vec_mismatch(<2 x i32> %i) {
   ret i1 %cmp
 }
 
-define <3 x i1> @i32_cast_cmp_sgt_int_m1_uitofp_float_vec_undef(<3 x i32> %i) {
-; CHECK-LABEL: @i32_cast_cmp_sgt_int_m1_uitofp_float_vec_undef(
+define <3 x i1> @i32_cast_cmp_sgt_int_m1_uitofp_float_vec_poison(<3 x i32> %i) {
+; CHECK-LABEL: @i32_cast_cmp_sgt_int_m1_uitofp_float_vec_poison(
 ; CHECK-NEXT:    ret <3 x i1> <i1 true, i1 true, i1 true>
 ;
   %f = uitofp <3 x i32> %i to <3 x float>
   %b = bitcast <3 x float> %f to <3 x i32>
-  %cmp = icmp sgt <3 x i32> %b, <i32 -1, i32 undef, i32 -1>
+  %cmp = icmp sgt <3 x i32> %b, <i32 -1, i32 poison, i32 -1>
   ret <3 x i1> %cmp
 }
 
@@ -100,13 +100,13 @@ define <2 x i1> @i32_cast_cmp_slt_int_0_uitofp_double_vec(<2 x i32> %i) {
   ret <2 x i1> %cmp
 }
 
-define <3 x i1> @i32_cast_cmp_slt_int_0_uitofp_double_vec_undef(<3 x i32> %i) {
-; CHECK-LABEL: @i32_cast_cmp_slt_int_0_uitofp_double_vec_undef(
+define <3 x i1> @i32_cast_cmp_slt_int_0_uitofp_double_vec_poison(<3 x i32> %i) {
+; CHECK-LABEL: @i32_cast_cmp_slt_int_0_uitofp_double_vec_poison(
 ; CHECK-NEXT:    ret <3 x i1> zeroinitializer
 ;
   %f = uitofp <3 x i32> %i to <3 x double>
   %b = bitcast <3 x double> %f to <3 x i64>
-  %cmp = icmp slt <3 x i64> %b, <i64 0, i64 undef, i64 0>
+  %cmp = icmp slt <3 x i64> %b, <i64 0, i64 poison, i64 0>
   ret <3 x i1> %cmp
 }
 
@@ -130,13 +130,13 @@ define <2 x i1> @i32_cast_cmp_sgt_int_m1_uitofp_double_vec(<2 x i32> %i) {
   ret <2 x i1> %cmp
 }
 
-define <3 x i1> @i32_cast_cmp_sgt_int_m1_uitofp_double_vec_undef(<3 x i32> %i) {
-; CHECK-LABEL: @i32_cast_cmp_sgt_int_m1_uitofp_double_vec_undef(
+define <3 x i1> @i32_cast_cmp_sgt_int_m1_uitofp_double_vec_poison(<3 x i32> %i) {
+; CHECK-LABEL: @i32_cast_cmp_sgt_int_m1_uitofp_double_vec_poison(
 ; CHECK-NEXT:    ret <3 x i1> <i1 true, i1 true, i1 true>
 ;
   %f = uitofp <3 x i32> %i to <3 x double>
   %b = bitcast <3 x double> %f to <3 x i64>
-  %cmp = icmp sgt <3 x i64> %b, <i64 -1, i64 undef, i64 -1>
+  %cmp = icmp sgt <3 x i64> %b, <i64 -1, i64 poison, i64 -1>
   ret <3 x i1> %cmp
 }
 
@@ -160,13 +160,13 @@ define <2 x i1> @i32_cast_cmp_slt_int_0_uitofp_half_vec(<2 x i32> %i) {
   ret <2 x i1> %cmp
 }
 
-define <3 x i1> @i32_cast_cmp_slt_int_0_uitofp_half_vec_undef(<3 x i32> %i) {
-; CHECK-LABEL: @i32_cast_cmp_slt_int_0_uitofp_half_vec_undef(
+define <3 x i1> @i32_cast_cmp_slt_int_0_uitofp_half_vec_poison(<3 x i32> %i) {
+; CHECK-LABEL: @i32_cast_cmp_slt_int_0_uitofp_half_vec_poison(
 ; CHECK-NEXT:    ret <3 x i1> zeroinitializer
 ;
   %f = uitofp <3 x i32> %i to <3 x half>
   %b = bitcast <3 x half> %f to <3 x i16>
-  %cmp = icmp slt <3 x i16> %b, <i16 0, i16 undef, i16 0>
+  %cmp = icmp slt <3 x i16> %b, <i16 0, i16 poison, i16 0>
   ret <3 x i1> %cmp
 }
 
@@ -190,12 +190,12 @@ define <2 x i1> @i32_cast_cmp_sgt_int_m1_uitofp_half_vec(<2 x i32> %i) {
   ret <2 x i1> %cmp
 }
 
-define <3 x i1> @i32_cast_cmp_sgt_int_m1_uitofp_half_vec_undef(<3 x i32> %i) {
-; CHECK-LABEL: @i32_cast_cmp_sgt_int_m1_uitofp_half_vec_undef(
+define <3 x i1> @i32_cast_cmp_sgt_int_m1_uitofp_half_vec_poison(<3 x i32> %i) {
+; CHECK-LABEL: @i32_cast_cmp_sgt_int_m1_uitofp_half_vec_poison(
 ; CHECK-NEXT:    ret <3 x i1> <i1 true, i1 true, i1 true>
 ;
   %f = uitofp <3 x i32> %i to <3 x half>
   %b = bitcast <3 x half> %f to <3 x i16>
-  %cmp = icmp sgt <3 x i16> %b, <i16 -1, i16 undef, i16 -1>
+  %cmp = icmp sgt <3 x i16> %b, <i16 -1, i16 poison, i16 -1>
   ret <3 x i1> %cmp
 }
diff --git a/llvm/test/Transforms/InstSimplify/icmp-constant.ll b/llvm/test/Transforms/InstSimplify/icmp-constant.ll
index 99bf11bd4e8c47..4f3a5d3dba3b5c 100644
--- a/llvm/test/Transforms/InstSimplify/icmp-constant.ll
+++ b/llvm/test/Transforms/InstSimplify/icmp-constant.ll
@@ -19,11 +19,11 @@ define <2 x i1> @tautological_ule_vec(<2 x i8> %x) {
   ret <2 x i1> %cmp
 }
 
-define <2 x i1> @tautological_ule_vec_partial_undef(<2 x i8> %x) {
-; CHECK-LABEL: @tautological_ule_vec_partial_undef(
+define <2 x i1> @tautological_ule_vec_partial_poison(<2 x i8> %x) {
+; CHECK-LABEL: @tautological_ule_vec_partial_poison(
 ; CHECK-NEXT:    ret <2 x i1> <i1 true, i1 true>
 ;
-  %cmp = icmp ule <2 x i8> %x, <i8 255, i8 undef>
+  %cmp = icmp ule <2 x i8> %x, <i8 255, i8 poison>
   ret <2 x i1> %cmp
 }
 
@@ -43,11 +43,11 @@ define <2 x i1> @tautological_ugt_vec(<2 x i8> %x) {
   ret <2 x i1> %cmp
 }
 
-define <2 x i1> @tautological_ugt_vec_partial_undef(<2 x i8> %x) {
-; CHECK-LABEL: @tautological_ugt_vec_partial_undef(
+define <2 x i1> @tautological_ugt_vec_partial_poison(<2 x i8> %x) {
+; CHECK-LABEL: @tautological_ugt_vec_partial_poison(
 ; CHECK-NEXT:    ret <2 x i1> zeroinitializer
 ;
-  %cmp = icmp ugt <2 x i8> %x, <i8 undef, i8 255>
+  %cmp = icmp ugt <2 x i8> %x, <i8 poison, i8 255>
   ret <2 x i1> %cmp
 }
 
@@ -70,12 +70,12 @@ define <2 x i1> @urem3_vec(<2 x i32> %X) {
   ret <2 x i1> %B
 }
 
-define <2 x i1> @urem3_vec_partial_undef(<2 x i32> %X) {
-; CHECK-LABEL: @urem3_vec_partial_undef(
+define <2 x i1> @urem3_vec_partial_poison(<2 x i32> %X) {
+; CHECK-LABEL: @urem3_vec_partial_poison(
 ; CHECK-NEXT:    ret <2 x i1> <i1 true, i1 true>
 ;
   %A = urem <2 x i32> %X, <i32 10, i32 10>
-  %B = icmp ult <2 x i32> %A, <i32 undef, i32 15>
+  %B = icmp ult <2 x i32> %A, <i32 poison, i32 15>
   ret <2 x i1> %B
 }
 
@@ -98,12 +98,12 @@ define <2 x i1> @srem1_vec(<2 x i32> %X) {
   ret <2 x i1> %B
 }
 
-define <2 x i1> @srem1_vec_partial_undef(<2 x i32> %X) {
-; CHECK-LABEL: @srem1_vec_partial_undef(
+define <2 x i1> @srem1_vec_partial_poison(<2 x i32> %X) {
+; CHECK-LABEL: @srem1_vec_partial_poison(
 ; CHECK-NEXT:    ret <2 x i1> zeroinitializer
 ;
   %A = srem <2 x i32> %X, <i32 -5, i32 -5>
-  %B = icmp sgt <2 x i32> %A, <i32 5, i32 undef>
+  %B = icmp sgt <2 x i32> %A, <i32 5, i32 poison>
   ret <2 x i1> %B
 }
 
@@ -203,12 +203,12 @@ define <2 x i1> @shl5_vec(<2 x i32> %X) {
   ret <2 x i1> %cmp
 }
 
-define <2 x i1> @shl5_vec_partial_undef(<2 x i32> %X) {
-; CHECK-LABEL: @shl5_vec_partial_undef(
+define <2 x i1> @shl5_vec_partial_poison(<2 x i32> %X) {
+; CHECK-LABEL: @shl5_vec_partial_poison(
 ; CHECK-NEXT:    ret <2 x i1> <i1 true, i1 true>
 ;
   %sub = shl nuw <2 x i32> <i32 4, i32 4>, %X
-  %cmp = icmp ugt <2 x i32> %sub, <i32 undef, i32 3>
+  %cmp = icmp ugt <2 x i32> %sub, <i32 poison, i32 3>
   ret <2 x i1> %cmp
 }
 
@@ -421,12 +421,12 @@ define <2 x i1> @or1_vec(<2 x i32> %X) {
   ret <2 x i1> %B
 }
 
-define <2 x i1> @or1_vec_partial_undef(<2 x i32> %X) {
-; CHECK-LABEL: @or1_vec_partial_undef(
+define <2 x i1> @or1_vec_partial_poison(<2 x i32> %X) {
+; CHECK-LABEL: @or1_vec_partial_poison(
 ; CHECK-NEXT:    ret <2 x i1> zeroinitializer
 ;
   %A = or <2 x i32> %X, <i32 62, i32 62>
-  %B = icmp ult <2 x i32> %A, <i32 undef, i32 50>
+  %B = icmp ult <2 x i32> %A, <i32 poison, i32 50>
   ret <2 x i1> %B
 }
 
@@ -900,22 +900,22 @@ define <2 x i1> @mul_nuw_urem_cmp_constant_vec_splat(<2 x i8> %x) {
 
 ; Undefs in vector constants are ok.
 
-define <2 x i1> @mul_nuw_urem_cmp_constant_vec_splat_undef1(<2 x i8> %x) {
-; CHECK-LABEL: @mul_nuw_urem_cmp_constant_vec_splat_undef1(
+define <2 x i1> @mul_nuw_urem_cmp_constant_vec_splat_poison1(<2 x i8> %x) {
+; CHECK-LABEL: @mul_nuw_urem_cmp_constant_vec_splat_poison1(
 ; CHECK-NEXT:    ret <2 x i1> <i1 true, i1 true>
 ;
   %m = mul nuw <2 x i8> %x, <i8 45, i8 45>
-  %r = icmp ne <2 x i8> %m, <i8 15, i8 undef>
+  %r = icmp ne <2 x i8> %m, <i8 15, i8 poison>
   ret <2 x i1> %r
 }
 
 ; Undefs in vector constants are ok.
 
-define <2 x i1> @mul_nuw_urem_cmp_constant_vec_splat_undef2(<2 x i8> %x) {
-; CHECK-LABEL: @mul_nuw_urem_cmp_constant_vec_splat_undef2(
+define <2 x i1> @mul_nuw_urem_cmp_constant_vec_splat_poison2(<2 x i8> %x) {
+; CHECK-LABEL: @mul_nuw_urem_cmp_constant_vec_splat_poison2(
 ; CHECK-NEXT:    ret <2 x i1> <i1 true, i1 true>
 ;
-  %m = mul nuw <2 x i8> %x, <i8 undef, i8 45>
+  %m = mul nuw <2 x i8> %x, <i8 poison, i8 45>
   %r = icmp ne <2 x i8> %m, <i8 15, i8 15>
   ret <2 x i1> %r
 }
@@ -1007,22 +1007,22 @@ define <2 x i1> @mul_nsw_srem_cmp_constant_vec_splat(<2 x i8> %x) {
 
 ; Undefs in vector constants are ok.
 
-define <2 x i1> @mul_nsw_srem_cmp_constant_vec_splat_undef1(<2 x i8> %x) {
-; CHECK-LABEL: @mul_nsw_srem_cmp_constant_vec_splat_undef1(
+define <2 x i1> @mul_nsw_srem_cmp_constant_vec_splat_poison1(<2 x i8> %x) {
+; CHECK-LABEL: @mul_nsw_srem_cmp_constant_vec_splat_poison1(
 ; CHECK-NEXT:    ret <2 x i1> <i1 true, i1 true>
 ;
   %m = mul nsw <2 x i8> %x, <i8 45, i8 45>
-  %r = icmp ne <2 x i8> %m, <i8 15, i8 undef>
+  %r = icmp ne <2 x i8> %m, <i8 15, i8 poison>
   ret <2 x i1> %r
 }
 
 ; Undefs in vector constants are ok.
 
-define <2 x i1> @mul_nsw_srem_cmp_constant_vec_splat_undef2(<2 x i8> %x) {
-; CHECK-LABEL: @mul_nsw_srem_cmp_constant_vec_splat_undef2(
+define <2 x i1> @mul_nsw_srem_cmp_constant_vec_splat_poison2(<2 x i8> %x) {
+; CHECK-LABEL: @mul_nsw_srem_cmp_constant_vec_splat_poison2(
 ; CHECK-NEXT:    ret <2 x i1> <i1 true, i1 true>
 ;
-  %m = mul nsw <2 x i8> %x, <i8 undef, i8 45>
+  %m = mul nsw <2 x i8> %x, <i8 poison, i8 45>
   %r = icmp ne <2 x i8> %m, <i8 15, i8 15>
   ret <2 x i1> %r
 }
diff --git a/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll b/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
index 17f39a23d4f7a4..5c659a1e7086a6 100644
--- a/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
+++ b/llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
@@ -257,67 +257,67 @@ define <2 x i8> @umin_maxval_commute(<2 x i8> %x) {
   ret <2 x i8> %r
 }
 
-define <2 x i8> @smax_maxval_partial_undef(<2 x i8> %x) {
-; CHECK-LABEL: @smax_maxval_partial_undef(
+define <2 x i8> @smax_maxval_partial_poison(<2 x i8> %x) {
+; CHECK-LABEL: @smax_maxval_partial_poison(
 ; CHECK-NEXT:    ret <2 x i8> <i8 127, i8 127>
 ;
-  %r = call <2 x i8> @llvm.smax.v2i8(<2 x i8> <i8 undef, i8 127>, <2 x i8> %x)
+  %r = call <2 x i8> @llvm.smax.v2i8(<2 x i8> <i8 poison, i8 127>, <2 x i8> %x)
   ret <2 x i8> %r
 }
 
-define <2 x i8> @smin_minval_partial_undef(<2 x i8> %x) {
-; CHECK-LABEL: @smin_minval_partial_undef(
+define <2 x i8> @smin_minval_partial_poison(<2 x i8> %x) {
+; CHECK-LABEL: @smin_minval_partial_poison(
 ; CHECK-NEXT:    ret <2 x i8> <i8 -128, i8 -128>
 ;
-  %r = call <2 x i8> @llvm.smin.v2i8(<2 x i8> %x, <2 x i8> <i8 -128, i8 undef>)
+  %r = call <2 x i8> @llvm.smin.v2i8(<2 x i8> %x, <2 x i8> <i8 -128, i8 poison>)
   ret <2 x i8> %r
 }
 
-define <2 x i8> @umax_maxval_partial_undef(<2 x i8> %x) {
-; CHECK-LABEL: @umax_maxval_partial_undef(
+define <2 x i8> @umax_maxval_partial_poison(<2 x i8> %x) {
+; CHECK-LABEL: @umax_maxval_partial_poison(
 ; CHECK-NEXT:    ret <2 x i8> <i8 -1, i8 -1>
 ;
-  %r = call <2 x i8> @llvm.umax.v2i8(<2 x i8> <i8 255, i8 undef>, <2 x i8> %x)
+  %r = call <2 x i8> @llvm.umax.v2i8(<2 x i8> <i8 255, i8 poison>, <2 x i8> %x)
   ret <2 x i8> %r
 }
 
-define <2 x i8> @umin_minval_partial_undef(<2 x i8> %x) {
-; CHECK-LABEL: @umin_minval_partial_undef(
+define <2 x i8> @umin_minval_partial_poison(<2 x i8> %x) {
+; CHECK-LABEL: @umin_minval_partial_poison(
 ; CHECK-NEXT:    ret <2 x i8> zeroinitializer
 ;
-  %r = call <2 x i8> @llvm.umin.v2i8(<2 x i8> %x, <2 x i8> <i8 undef, i8 0>)
+  %r = call <2 x i8> @llvm.umin.v2i8(<2 x i8> %x, <2 x i8> <i8 poison, i8 0>)
   ret <2 x i8> %r
 }
 
-define <2 x i8> @smax_minval_partial_undef(<2 x i8> %x) {
-; CHECK-LABEL: @smax_minval_partial_undef(
+define <2 x i8> @smax_minval_partial_poison(<2 x i8> %x) {
+; CHECK-LABEL: @smax_minval_partial_poison(
 ; CHECK-NEXT:    ret <2 x i8> [[X:%.*]]
 ;
-  %r = call <2 x i8> @llvm.smax.v2i8(<2 x i8> <i8 undef, i8 -128>, <2 x i8> %x)
+  %r = call <2 x i8> @llvm.smax.v2i8(<2 x i8> <i8 poison, i8 -128>, <2 x i8> %x)
   ret <2 x i8> %r
 }
 
-define <2 x i8> @smin_maxval_partial_undef(<2 x i8> %x) {
-; CHECK-LABEL: @smin_maxval_partial_undef(
+define <2 x i8> @smin_maxval_partial_poison(<2 x i8> %x) {
+; CHECK-LABEL: @smin_maxval_partial_poison(
 ; CHECK-NEXT:    ret <2 x i8> [[X:%.*]]
 ;
-  %r = call <2 x i8> @llvm.smin.v2i8(<2 x i8> %x, <2 x i8> <i8 undef, i8 127>)
+  %r = call <2 x i8> @llvm.smin.v2i8(<2 x i8> %x, <2 x i8> <i8 poison, i8 127>)
   ret <2 x i8> %r
 }
 
-define <2 x i8> @umax_minval_partial_undef(<2 x i8> %x) {
-; CHECK-LABEL: @umax_minval_partial_undef(
+define <2 x i8> @umax_minval_partial_poison(<2 x i8> %x) {
+; CHECK-LABEL: @umax_minval_partial_poison(
 ; CHECK-NEXT:    ret <2 x i8> [[X:%.*]]
 ;
-  %r = call <2 x i8> @llvm.umax.v2i8(<2 x i8> <i8 0, i8 undef>, <2 x i8> %x)
+  %r = call <2 x i8> @llvm.umax.v2i8(<2 x i8> <i8 0, i8 poison>, <2 x i8> %x)
   ret <2 x i8> %r
 }
 
-define <2 x i8> @umin_maxval_partial_undef(<2 x i8> %x) {
-; CHECK-LABEL: @umin_maxval_partial_undef(
+define <2 x i8> @umin_maxval_partial_poison(<2 x i8> %x) {
+; CHECK-LABEL: @umin_maxval_partial_poison(
 ; CHECK-NEXT:    ret <2 x i8> [[X:%.*]]
 ;
-  %r = call <2 x i8> @llvm.umin.v2i8(<2 x i8> %x, <2 x i8> <i8 255, i8 undef>)
+  %r = call <2 x i8> @llvm.umin.v2i8(<2 x i8> %x, <2 x i8> <i8 255, i8 poison>)
   ret <2 x i8> %r
 }
 
@@ -743,7 +743,7 @@ define <2 x i8> @umin_umin_constants_commute2(<2 x i8> %x) {
 ; CHECK-NEXT:    ret <2 x i8> [[M]]
 ;
   %m = call <2 x i8> @llvm.umin.v2i8(<2 x i8> %x, <2 x i8> <i8 127, i8 127>)
-  %m2 = call <2 x i8> @llvm.umin.v2i8(<2 x i8> %m, <2 x i8> <i8 200, i8 undef>)
+  %m2 = call <2 x i8> @llvm.umin.v2i8(<2 x i8> %m, <2 x i8> <i8 200, i8 poison>)
   ret <2 x i8> %m2
 }
 
@@ -803,7 +803,7 @@ define <2 x i8> @smin_smin_constants(<2 x i8> %x) {
 ; CHECK-NEXT:    ret <2 x i8> [[M]]
 ;
   %m = call <2 x i8> @llvm.smin.v2i8(<2 x i8> %x, <2 x i8> <i8 7, i8 7>)
-  %m2 = call <2 x i8> @llvm.smin.v2i8(<2 x i8> <i8 undef, i8 9>, <2 x i8> %m)
+  %m2 = call <2 x i8> @llvm.smin.v2i8(<2 x i8> <i8 poison, i8 9>, <2 x i8> %m)
   ret <2 x i8> %m2
 }
 
diff --git a/llvm/unittests/IR/InstructionsTest.cpp b/llvm/unittests/IR/InstructionsTest.cpp
index a48a51b1bf474c..b47c73f0b329ae 100644
--- a/llvm/unittests/IR/InstructionsTest.cpp
+++ b/llvm/unittests/IR/InstructionsTest.cpp
@@ -1410,6 +1410,7 @@ TEST(InstructionsTest, GetSplat) {
   LLVMContext Ctx;
   Type *Int32Ty = Type::getInt32Ty(Ctx);
   Constant *CU = UndefValue::get(Int32Ty);
+  Constant *CP = PoisonValue::get(Int32Ty);
   Constant *C0 = ConstantInt::get(Int32Ty, 0);
   Constant *C1 = ConstantInt::get(Int32Ty, 1);
 
@@ -1419,30 +1420,42 @@ TEST(InstructionsTest, GetSplat) {
   Constant *Splat1Undef = ConstantVector::get({CU, CU, C1, CU});
   Constant *NotSplat = ConstantVector::get({C1, C1, C0, C1 ,C1});
   Constant *NotSplatUndef = ConstantVector::get({CU, C1, CU, CU ,C0});
+  Constant *Splat0Poison = ConstantVector::get({C0, CP, C0, CP});
+  Constant *Splat1Poison = ConstantVector::get({CP, CP, C1, CP});
+  Constant *NotSplatPoison = ConstantVector::get({CP, C1, CP, CP, C0});
 
-  // Default - undefs are not allowed.
+  // Default - undef/poison is not allowed.
   EXPECT_EQ(Splat0->getSplatValue(), C0);
   EXPECT_EQ(Splat1->getSplatValue(), C1);
   EXPECT_EQ(Splat0Undef->getSplatValue(), nullptr);
   EXPECT_EQ(Splat1Undef->getSplatValue(), nullptr);
+  EXPECT_EQ(Splat0Poison->getSplatValue(), nullptr);
+  EXPECT_EQ(Splat1Poison->getSplatValue(), nullptr);
   EXPECT_EQ(NotSplat->getSplatValue(), nullptr);
   EXPECT_EQ(NotSplatUndef->getSplatValue(), nullptr);
+  EXPECT_EQ(NotSplatPoison->getSplatValue(), nullptr);
 
-  // Disallow undefs explicitly.
+  // Disallow poison explicitly.
   EXPECT_EQ(Splat0->getSplatValue(false), C0);
   EXPECT_EQ(Splat1->getSplatValue(false), C1);
   EXPECT_EQ(Splat0Undef->getSplatValue(false), nullptr);
   EXPECT_EQ(Splat1Undef->getSplatValue(false), nullptr);
+  EXPECT_EQ(Splat0Poison->getSplatValue(false), nullptr);
+  EXPECT_EQ(Splat1Poison->getSplatValue(false), nullptr);
   EXPECT_EQ(NotSplat->getSplatValue(false), nullptr);
   EXPECT_EQ(NotSplatUndef->getSplatValue(false), nullptr);
+  EXPECT_EQ(NotSplatPoison->getSplatValue(false), nullptr);
 
-  // Allow undefs.
+  // Allow poison but not undef.
   EXPECT_EQ(Splat0->getSplatValue(true), C0);
   EXPECT_EQ(Splat1->getSplatValue(true), C1);
-  EXPECT_EQ(Splat0Undef->getSplatValue(true), C0);
-  EXPECT_EQ(Splat1Undef->getSplatValue(true), C1);
+  EXPECT_EQ(Splat0Undef->getSplatValue(true), nullptr);
+  EXPECT_EQ(Splat1Undef->getSplatValue(true), nullptr);
+  EXPECT_EQ(Splat0Poison->getSplatValue(true), C0);
+  EXPECT_EQ(Splat1Poison->getSplatValue(true), C1);
   EXPECT_EQ(NotSplat->getSplatValue(true), nullptr);
   EXPECT_EQ(NotSplatUndef->getSplatValue(true), nullptr);
+  EXPECT_EQ(NotSplatPoison->getSplatValue(true), nullptr);
 }
 
 TEST(InstructionsTest, SkipDebug) {
diff --git a/llvm/unittests/IR/PatternMatch.cpp b/llvm/unittests/IR/PatternMatch.cpp
index 133012684d16d8..f0377eae9989fd 100644
--- a/llvm/unittests/IR/PatternMatch.cpp
+++ b/llvm/unittests/IR/PatternMatch.cpp
@@ -1222,40 +1222,51 @@ TEST_F(PatternMatchTest, VectorUndefInt) {
   EXPECT_TRUE(match(VectorZeroPoison, m_Zero()));
 
   const APInt *C;
-  // Regardless of whether undefs are allowed,
-  // a fully undef constant does not match.
+  // Regardless of whether poison is allowed,
+  // a fully undef/poison constant does not match.
   EXPECT_FALSE(match(ScalarUndef, m_APInt(C)));
-  EXPECT_FALSE(match(ScalarUndef, m_APIntForbidUndef(C)));
-  EXPECT_FALSE(match(ScalarUndef, m_APIntAllowUndef(C)));
+  EXPECT_FALSE(match(ScalarUndef, m_APIntForbidPoison(C)));
+  EXPECT_FALSE(match(ScalarUndef, m_APIntAllowPoison(C)));
   EXPECT_FALSE(match(VectorUndef, m_APInt(C)));
-  EXPECT_FALSE(match(VectorUndef, m_APIntForbidUndef(C)));
-  EXPECT_FALSE(match(VectorUndef, m_APIntAllowUndef(C)));
+  EXPECT_FALSE(match(VectorUndef, m_APIntForbidPoison(C)));
+  EXPECT_FALSE(match(VectorUndef, m_APIntAllowPoison(C)));
+  EXPECT_FALSE(match(ScalarPoison, m_APInt(C)));
+  EXPECT_FALSE(match(ScalarPoison, m_APIntForbidPoison(C)));
+  EXPECT_FALSE(match(ScalarPoison, m_APIntAllowPoison(C)));
+  EXPECT_FALSE(match(VectorPoison, m_APInt(C)));
+  EXPECT_FALSE(match(VectorPoison, m_APIntForbidPoison(C)));
+  EXPECT_FALSE(match(VectorPoison, m_APIntAllowPoison(C)));
 
   // We can always match simple constants and simple splats.
   C = nullptr;
   EXPECT_TRUE(match(ScalarZero, m_APInt(C)));
   EXPECT_TRUE(C->isZero());
   C = nullptr;
-  EXPECT_TRUE(match(ScalarZero, m_APIntForbidUndef(C)));
+  EXPECT_TRUE(match(ScalarZero, m_APIntForbidPoison(C)));
   EXPECT_TRUE(C->isZero());
   C = nullptr;
-  EXPECT_TRUE(match(ScalarZero, m_APIntAllowUndef(C)));
+  EXPECT_TRUE(match(ScalarZero, m_APIntAllowPoison(C)));
   EXPECT_TRUE(C->isZero());
   C = nullptr;
   EXPECT_TRUE(match(VectorZero, m_APInt(C)));
   EXPECT_TRUE(C->isZero());
   C = nullptr;
-  EXPECT_TRUE(match(VectorZero, m_APIntForbidUndef(C)));
+  EXPECT_TRUE(match(VectorZero, m_APIntForbidPoison(C)));
   EXPECT_TRUE(C->isZero());
   C = nullptr;
-  EXPECT_TRUE(match(VectorZero, m_APIntAllowUndef(C)));
+  EXPECT_TRUE(match(VectorZero, m_APIntAllowPoison(C)));
   EXPECT_TRUE(C->isZero());
 
-  // Whether splats with undef can be matched depends on the matcher.
+  // Splats with undef are never allowed.
+  // Whether splats with poison can be matched depends on the matcher.
   EXPECT_FALSE(match(VectorZeroUndef, m_APInt(C)));
-  EXPECT_FALSE(match(VectorZeroUndef, m_APIntForbidUndef(C)));
+  EXPECT_FALSE(match(VectorZeroUndef, m_APIntForbidPoison(C)));
+  EXPECT_FALSE(match(VectorZeroUndef, m_APIntAllowPoison(C)));
+
+  EXPECT_FALSE(match(VectorZeroPoison, m_APInt(C)));
+  EXPECT_FALSE(match(VectorZeroPoison, m_APIntForbidPoison(C)));
   C = nullptr;
-  EXPECT_TRUE(match(VectorZeroUndef, m_APIntAllowUndef(C)));
+  EXPECT_TRUE(match(VectorZeroPoison, m_APIntAllowPoison(C)));
   EXPECT_TRUE(C->isZero());
 }
 
@@ -1387,43 +1398,63 @@ TEST_F(PatternMatchTest, VectorUndefFloat) {
   EXPECT_FALSE(match(VectorNaNPoison, m_Finite()));
 
   const APFloat *C;
-  // Regardless of whether undefs are allowed,
-  // a fully undef constant does not match.
+  // Regardless of whether poison is allowed,
+  // a fully undef/poison constant does not match.
   EXPECT_FALSE(match(ScalarUndef, m_APFloat(C)));
-  EXPECT_FALSE(match(ScalarUndef, m_APFloatForbidUndef(C)));
-  EXPECT_FALSE(match(ScalarUndef, m_APFloatAllowUndef(C)));
+  EXPECT_FALSE(match(ScalarUndef, m_APFloatForbidPoison(C)));
+  EXPECT_FALSE(match(ScalarUndef, m_APFloatAllowPoison(C)));
   EXPECT_FALSE(match(VectorUndef, m_APFloat(C)));
-  EXPECT_FALSE(match(VectorUndef, m_APFloatForbidUndef(C)));
-  EXPECT_FALSE(match(VectorUndef, m_APFloatAllowUndef(C)));
+  EXPECT_FALSE(match(VectorUndef, m_APFloatForbidPoison(C)));
+  EXPECT_FALSE(match(VectorUndef, m_APFloatAllowPoison(C)));
+  EXPECT_FALSE(match(ScalarPoison, m_APFloat(C)));
+  EXPECT_FALSE(match(ScalarPoison, m_APFloatForbidPoison(C)));
+  EXPECT_FALSE(match(ScalarPoison, m_APFloatAllowPoison(C)));
+  EXPECT_FALSE(match(VectorPoison, m_APFloat(C)));
+  EXPECT_FALSE(match(VectorPoison, m_APFloatForbidPoison(C)));
+  EXPECT_FALSE(match(VectorPoison, m_APFloatAllowPoison(C)));
 
   // We can always match simple constants and simple splats.
   C = nullptr;
   EXPECT_TRUE(match(ScalarZero, m_APFloat(C)));
   EXPECT_TRUE(C->isZero());
   C = nullptr;
-  EXPECT_TRUE(match(ScalarZero, m_APFloatForbidUndef(C)));
+  EXPECT_TRUE(match(ScalarZero, m_APFloatForbidPoison(C)));
   EXPECT_TRUE(C->isZero());
   C = nullptr;
-  EXPECT_TRUE(match(ScalarZero, m_APFloatAllowUndef(C)));
+  EXPECT_TRUE(match(ScalarZero, m_APFloatAllowPoison(C)));
   EXPECT_TRUE(C->isZero());
   C = nullptr;
   EXPECT_TRUE(match(VectorZero, m_APFloat(C)));
   EXPECT_TRUE(C->isZero());
   C = nullptr;
-  EXPECT_TRUE(match(VectorZero, m_APFloatForbidUndef(C)));
+  EXPECT_TRUE(match(VectorZero, m_APFloatForbidPoison(C)));
   EXPECT_TRUE(C->isZero());
   C = nullptr;
-  EXPECT_TRUE(match(VectorZero, m_APFloatAllowUndef(C)));
+  EXPECT_TRUE(match(VectorZero, m_APFloatAllowPoison(C)));
   EXPECT_TRUE(C->isZero());
 
-  // Whether splats with undef can be matched depends on the matcher.
+  // Splats with undef are never allowed.
+  // Whether splats with poison can be matched depends on the matcher.
   EXPECT_FALSE(match(VectorZeroUndef, m_APFloat(C)));
-  EXPECT_FALSE(match(VectorZeroUndef, m_APFloatForbidUndef(C)));
+  EXPECT_FALSE(match(VectorZeroUndef, m_APFloatForbidPoison(C)));
+  EXPECT_FALSE(match(VectorZeroUndef, m_APFloatAllowPoison(C)));
+  EXPECT_FALSE(match(VectorZeroUndef, m_Finite(C)));
+
+  EXPECT_FALSE(match(VectorZeroPoison, m_APFloat(C)));
+  EXPECT_FALSE(match(VectorZeroPoison, m_APFloatForbidPoison(C)));
+  C = nullptr;
+  EXPECT_TRUE(match(VectorZeroPoison, m_APFloatAllowPoison(C)));
+  EXPECT_TRUE(C->isZero());
+  C = nullptr;
+  EXPECT_TRUE(match(VectorZeroPoison, m_Finite(C)));
+  EXPECT_TRUE(C->isZero());
+  EXPECT_FALSE(match(VectorZeroPoison, m_APFloat(C)));
+  EXPECT_FALSE(match(VectorZeroPoison, m_APFloatForbidPoison(C)));
   C = nullptr;
-  EXPECT_TRUE(match(VectorZeroUndef, m_APFloatAllowUndef(C)));
+  EXPECT_TRUE(match(VectorZeroPoison, m_APFloatAllowPoison(C)));
   EXPECT_TRUE(C->isZero());
   C = nullptr;
-  EXPECT_TRUE(match(VectorZeroUndef, m_Finite(C)));
+  EXPECT_TRUE(match(VectorZeroPoison, m_Finite(C)));
   EXPECT_TRUE(C->isZero());
 }
 



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