[llvm] 94eebf7 - InstSimplify: support floating-point equivalences (#115152)

via llvm-commits llvm-commits at lists.llvm.org
Fri Nov 15 12:06:15 PST 2024


Author: Ramkumar Ramachandra
Date: 2024-11-15T20:06:11Z
New Revision: 94eebf721a2f8630412730f51d5071816a686ea0

URL: https://github.com/llvm/llvm-project/commit/94eebf721a2f8630412730f51d5071816a686ea0
DIFF: https://github.com/llvm/llvm-project/commit/94eebf721a2f8630412730f51d5071816a686ea0.diff

LOG: InstSimplify: support floating-point equivalences (#115152)

Since cd16b07 (IR: introduce CmpInst::isEquivalence), there is now an
isEquivalence routine in CmpInst that we can use to determine
equivalence in simplifySelectWithICmpEq. Implement this, extending the
code from integer-equalities to integer and floating-point equivalences.

Added: 
    llvm/test/Transforms/InstSimplify/select-equivalence-fp.ll

Modified: 
    llvm/lib/Analysis/InstructionSimplify.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index ccb7fd39ba969d..93b601b22c3a39 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -4466,13 +4466,15 @@ static Value *simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
       } else
         return nullptr;
     }
-    Constant *Res = ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI);
+    Constant *Res = ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI,
+                                             /*AllowNonDeterministic=*/false);
     if (DropFlags && Res && I->hasPoisonGeneratingAnnotations())
       DropFlags->push_back(I);
     return Res;
   }
 
-  return ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI);
+  return ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI,
+                                  /*AllowNonDeterministic=*/false);
 }
 
 Value *llvm::simplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
@@ -4616,11 +4618,11 @@ static Value *simplifySelectWithFakeICmpEq(Value *CmpLHS, Value *CmpRHS,
 }
 
 /// Try to simplify a select instruction when its condition operand is an
-/// integer equality comparison.
-static Value *simplifySelectWithICmpEq(Value *CmpLHS, Value *CmpRHS,
-                                       Value *TrueVal, Value *FalseVal,
-                                       const SimplifyQuery &Q,
-                                       unsigned MaxRecurse) {
+/// integer equality or floating-point equivalence comparison.
+static Value *simplifySelectWithEquivalence(Value *CmpLHS, Value *CmpRHS,
+                                            Value *TrueVal, Value *FalseVal,
+                                            const SimplifyQuery &Q,
+                                            unsigned MaxRecurse) {
   if (simplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q.getWithoutUndef(),
                              /* AllowRefinement */ false,
                              /* DropFlags */ nullptr, MaxRecurse) == TrueVal)
@@ -4721,11 +4723,11 @@ static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal,
   // the arms of the select. See if substituting this value into the arm and
   // simplifying the result yields the same value as the other arm.
   if (Pred == ICmpInst::ICMP_EQ) {
-    if (Value *V = simplifySelectWithICmpEq(CmpLHS, CmpRHS, TrueVal, FalseVal,
-                                            Q, MaxRecurse))
+    if (Value *V = simplifySelectWithEquivalence(CmpLHS, CmpRHS, TrueVal,
+                                                 FalseVal, Q, MaxRecurse))
       return V;
-    if (Value *V = simplifySelectWithICmpEq(CmpRHS, CmpLHS, TrueVal, FalseVal,
-                                            Q, MaxRecurse))
+    if (Value *V = simplifySelectWithEquivalence(CmpRHS, CmpLHS, TrueVal,
+                                                 FalseVal, Q, MaxRecurse))
       return V;
 
     Value *X;
@@ -4734,11 +4736,11 @@ static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal,
     if (match(CmpLHS, m_Or(m_Value(X), m_Value(Y))) &&
         match(CmpRHS, m_Zero())) {
       // (X | Y) == 0 implies X == 0 and Y == 0.
-      if (Value *V = simplifySelectWithICmpEq(X, CmpRHS, TrueVal, FalseVal, Q,
-                                              MaxRecurse))
+      if (Value *V = simplifySelectWithEquivalence(X, CmpRHS, TrueVal, FalseVal,
+                                                   Q, MaxRecurse))
         return V;
-      if (Value *V = simplifySelectWithICmpEq(Y, CmpRHS, TrueVal, FalseVal, Q,
-                                              MaxRecurse))
+      if (Value *V = simplifySelectWithEquivalence(Y, CmpRHS, TrueVal, FalseVal,
+                                                   Q, MaxRecurse))
         return V;
     }
 
@@ -4746,11 +4748,11 @@ static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal,
     if (match(CmpLHS, m_And(m_Value(X), m_Value(Y))) &&
         match(CmpRHS, m_AllOnes())) {
       // (X & Y) == -1 implies X == -1 and Y == -1.
-      if (Value *V = simplifySelectWithICmpEq(X, CmpRHS, TrueVal, FalseVal, Q,
-                                              MaxRecurse))
+      if (Value *V = simplifySelectWithEquivalence(X, CmpRHS, TrueVal, FalseVal,
+                                                   Q, MaxRecurse))
         return V;
-      if (Value *V = simplifySelectWithICmpEq(Y, CmpRHS, TrueVal, FalseVal, Q,
-                                              MaxRecurse))
+      if (Value *V = simplifySelectWithEquivalence(Y, CmpRHS, TrueVal, FalseVal,
+                                                   Q, MaxRecurse))
         return V;
     }
   }
@@ -4761,27 +4763,46 @@ static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal,
 /// Try to simplify a select instruction when its condition operand is a
 /// floating-point comparison.
 static Value *simplifySelectWithFCmp(Value *Cond, Value *T, Value *F,
-                                     const SimplifyQuery &Q) {
+                                     const SimplifyQuery &Q,
+                                     unsigned MaxRecurse) {
   FCmpInst::Predicate Pred;
-  if (!match(Cond, m_FCmp(Pred, m_Specific(T), m_Specific(F))) &&
-      !match(Cond, m_FCmp(Pred, m_Specific(F), m_Specific(T))))
+  Value *CmpLHS, *CmpRHS;
+  if (!match(Cond, m_FCmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS))))
+    return nullptr;
+  FCmpInst *I = cast<FCmpInst>(Cond);
+
+  bool IsEquiv = I->isEquivalence();
+  if (I->isEquivalence(/*Invert=*/true)) {
+    std::swap(T, F);
+    Pred = FCmpInst::getInversePredicate(Pred);
+    IsEquiv = true;
+  }
+
+  // This transforms is safe if at least one operand is known to not be zero.
+  // Otherwise, the select can change the sign of a zero operand.
+  if (IsEquiv) {
+    if (Value *V =
+            simplifySelectWithEquivalence(CmpLHS, CmpRHS, T, F, Q, MaxRecurse))
+      return V;
+    if (Value *V =
+            simplifySelectWithEquivalence(CmpRHS, CmpLHS, T, F, Q, MaxRecurse))
+      return V;
+  }
+
+  // Canonicalize CmpLHS to be T, and CmpRHS to be F, if they're swapped.
+  if (CmpLHS == F && CmpRHS == T)
+    std::swap(CmpLHS, CmpRHS);
+
+  if (CmpLHS != T || CmpRHS != F)
     return nullptr;
 
-  // This transform is safe if we do not have (do not care about) -0.0 or if
-  // at least one operand is known to not be -0.0. Otherwise, the select can
-  // change the sign of a zero operand.
-  bool HasNoSignedZeros =
-      Q.CxtI && isa<FPMathOperator>(Q.CxtI) && Q.CxtI->hasNoSignedZeros();
-  const APFloat *C;
-  if (HasNoSignedZeros || (match(T, m_APFloat(C)) && C->isNonZero()) ||
-      (match(F, m_APFloat(C)) && C->isNonZero())) {
+  // This transform is also safe if we do not have (do not care about) -0.0.
+  if (Q.CxtI && isa<FPMathOperator>(Q.CxtI) && Q.CxtI->hasNoSignedZeros()) {
     // (T == F) ? T : F --> F
-    // (F == T) ? T : F --> F
     if (Pred == FCmpInst::FCMP_OEQ)
       return F;
 
     // (T != F) ? T : F --> T
-    // (F != T) ? T : F --> T
     if (Pred == FCmpInst::FCMP_UNE)
       return T;
   }
@@ -4955,7 +4976,7 @@ static Value *simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
           simplifySelectWithICmpCond(Cond, TrueVal, FalseVal, Q, MaxRecurse))
     return V;
 
-  if (Value *V = simplifySelectWithFCmp(Cond, TrueVal, FalseVal, Q))
+  if (Value *V = simplifySelectWithFCmp(Cond, TrueVal, FalseVal, Q, MaxRecurse))
     return V;
 
   if (Value *V = foldSelectWithBinaryOp(Cond, TrueVal, FalseVal))

diff  --git a/llvm/test/Transforms/InstSimplify/select-equivalence-fp.ll b/llvm/test/Transforms/InstSimplify/select-equivalence-fp.ll
new file mode 100644
index 00000000000000..8af751d0a4246d
--- /dev/null
+++ b/llvm/test/Transforms/InstSimplify/select-equivalence-fp.ll
@@ -0,0 +1,250 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=instsimplify -S | FileCheck %s
+
+define float @select_fcmp_fsub_oeq(float %x) {
+; CHECK-LABEL: @select_fcmp_fsub_oeq(
+; CHECK-NEXT:    ret float 0.000000e+00
+;
+  %fcmp = fcmp oeq float %x, 2.0
+  %fadd = fsub float %x, 2.0
+  %sel = select i1 %fcmp, float %fadd, float 0.0
+  ret float %sel
+}
+
+define float @select_fcmp_fsub_oeq_zero(float %x) {
+; CHECK-LABEL: @select_fcmp_fsub_oeq_zero(
+; CHECK-NEXT:    [[FCMP:%.*]] = fcmp oeq float [[X:%.*]], 0.000000e+00
+; CHECK-NEXT:    [[FADD:%.*]] = fsub float [[X]], 2.000000e+00
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[FCMP]], float [[FADD]], float 2.000000e+00
+; CHECK-NEXT:    ret float [[SEL]]
+;
+  %fcmp = fcmp oeq float %x, 0.0
+  %fadd = fsub float %x, 2.0
+  %sel = select i1 %fcmp, float %fadd, float 2.0
+  ret float %sel
+}
+
+define float @select_fcmp_fsub_ueq(float %x) {
+; CHECK-LABEL: @select_fcmp_fsub_ueq(
+; CHECK-NEXT:    [[FCMP:%.*]] = fcmp ueq float [[X:%.*]], 2.000000e+00
+; CHECK-NEXT:    [[FADD:%.*]] = fsub float [[X]], 2.000000e+00
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[FCMP]], float [[FADD]], float 0.000000e+00
+; CHECK-NEXT:    ret float [[SEL]]
+;
+  %fcmp = fcmp ueq float %x, 2.0
+  %fadd = fsub float %x, 2.0
+  %sel = select i1 %fcmp, float %fadd, float 0.0
+  ret float %sel
+}
+
+define float @select_fcmp_fsub_ueq_nnan(float %x) {
+; CHECK-LABEL: @select_fcmp_fsub_ueq_nnan(
+; CHECK-NEXT:    ret float 0.000000e+00
+;
+  %fcmp = fcmp nnan ueq float %x, 2.0
+  %fadd = fsub float %x, 2.0
+  %sel = select i1 %fcmp, float %fadd, float 0.0
+  ret float %sel
+}
+
+define float @select_fcmp_fsub_une(float %x) {
+; CHECK-LABEL: @select_fcmp_fsub_une(
+; CHECK-NEXT:    ret float 0.000000e+00
+;
+  %fcmp = fcmp une float %x, 2.0
+  %fadd = fsub float %x, 2.0
+  %sel = select i1 %fcmp, float 0.0, float %fadd
+  ret float %sel
+}
+
+define float @select_fcmp_fsub_une_zero(float %x) {
+; CHECK-LABEL: @select_fcmp_fsub_une_zero(
+; CHECK-NEXT:    [[FCMP:%.*]] = fcmp une float [[X:%.*]], 0.000000e+00
+; CHECK-NEXT:    [[FADD:%.*]] = fsub float [[X]], 2.000000e+00
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[FCMP]], float 2.000000e+00, float [[FADD]]
+; CHECK-NEXT:    ret float [[SEL]]
+;
+  %fcmp = fcmp une float %x, 0.0
+  %fadd = fsub float %x, 2.0
+  %sel = select i1 %fcmp, float 2.0, float %fadd
+  ret float %sel
+}
+
+define float @select_fcmp_fsub_one(float %x) {
+; CHECK-LABEL: @select_fcmp_fsub_one(
+; CHECK-NEXT:    [[FCMP:%.*]] = fcmp one float [[X:%.*]], 2.000000e+00
+; CHECK-NEXT:    [[FADD:%.*]] = fsub float [[X]], 2.000000e+00
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[FCMP]], float 0.000000e+00, float [[FADD]]
+; CHECK-NEXT:    ret float [[SEL]]
+;
+  %fcmp = fcmp one float %x, 2.0
+  %fadd = fsub float %x, 2.0
+  %sel = select i1 %fcmp, float 0.0, float %fadd
+  ret float %sel
+}
+
+define float @select_fcmp_fsub_one_nnan(float %x) {
+; CHECK-LABEL: @select_fcmp_fsub_one_nnan(
+; CHECK-NEXT:    ret float 0.000000e+00
+;
+  %fcmp = fcmp nnan one float %x, 2.0
+  %fadd = fsub float %x, 2.0
+  %sel = select i1 %fcmp, float 0.0, float %fadd
+  ret float %sel
+}
+
+define float @select_fcmp_fadd(float %x) {
+; CHECK-LABEL: @select_fcmp_fadd(
+; CHECK-NEXT:    ret float 4.000000e+00
+;
+  %fcmp = fcmp oeq float %x, 2.0
+  %fadd = fadd float %x, 2.0
+  %sel = select i1 %fcmp, float %fadd, float 4.0
+  ret float %sel
+}
+
+define <2 x float> @select_fcmp_fadd_vec(<2 x float> %x) {
+; CHECK-LABEL: @select_fcmp_fadd_vec(
+; CHECK-NEXT:    ret <2 x float> splat (float 4.000000e+00)
+;
+  %fcmp = fcmp oeq <2 x float> %x, <float 2.0, float 2.0>
+  %fadd = fadd <2 x float> %x, <float 2.0, float 2.0>
+  %sel = select <2 x i1> %fcmp, <2 x float> %fadd, <2 x float> <float 4.0, float 4.0>
+  ret <2 x float> %sel
+}
+
+
+define float @select_fcmp_fmul_nonrefinement(float %x, float %y) {
+; CHECK-LABEL: @select_fcmp_fmul_nonrefinement(
+; CHECK-NEXT:    [[FMUL:%.*]] = fmul float [[Y:%.*]], [[X:%.*]]
+; CHECK-NEXT:    ret float [[FMUL]]
+;
+  %fcmp = fcmp oeq float %x, 1.0
+  %fmul = fmul float %y, %x
+  %sel = select i1 %fcmp, float %y, float %fmul
+  ret float %sel
+}
+
+define float @select_fcmp_fmul(float %x) {
+; CHECK-LABEL: @select_fcmp_fmul(
+; CHECK-NEXT:    ret float 4.000000e+00
+;
+  %fcmp = fcmp oeq float %x, 2.0
+  %fmul = fmul float %x, 2.0
+  %sel = select i1 %fcmp, float %fmul, float 4.0
+  ret float %sel
+}
+
+define float @select_fcmp_fdiv_nonrefinement(float %x, float %y) {
+; CHECK-LABEL: @select_fcmp_fdiv_nonrefinement(
+; CHECK-NEXT:    [[FDIV:%.*]] = fdiv float [[Y:%.*]], [[X:%.*]]
+; CHECK-NEXT:    ret float [[FDIV]]
+;
+  %fcmp = fcmp oeq float %x, 1.0
+  %fdiv = fdiv float %y, %x
+  %sel = select i1 %fcmp, float %y, float %fdiv
+  ret float %sel
+}
+
+define float @select_fcmp_fdiv(float %x) {
+; CHECK-LABEL: @select_fcmp_fdiv(
+; CHECK-NEXT:    ret float 1.000000e+00
+;
+  %fcmp = fcmp oeq float %x, 2.0
+  %fdiv = fdiv float %x, 2.0
+  %sel = select i1 %fcmp, float %fdiv, float 1.0
+  ret float %sel
+}
+
+define float @select_fcmp_frem(float %x) {
+; CHECK-LABEL: @select_fcmp_frem(
+; CHECK-NEXT:    ret float 1.000000e+00
+;
+  %fcmp = fcmp oeq float %x, 3.0
+  %frem = frem float %x, 2.0
+  %sel = select i1 %fcmp, float %frem, float 1.0
+  ret float %sel
+}
+
+define <2 x float> @select_fcmp_insertelement(<2 x float> %x) {
+; CHECK-LABEL: @select_fcmp_insertelement(
+; CHECK-NEXT:    ret <2 x float> <float 4.000000e+00, float 2.000000e+00>
+;
+  %fcmp = fcmp oeq <2 x float> %x, <float 2.0, float 2.0>
+  %insert = insertelement <2 x float> %x, float 4.0, i64 0
+  %sel = select <2 x i1> %fcmp, <2 x float> %insert, <2 x float> <float 4.0, float 2.0>
+  ret <2 x float> %sel
+}
+
+define <4 x float> @select_fcmp_shufflevector_select(<4 x float> %x) {
+; CHECK-LABEL: @select_fcmp_shufflevector_select(
+; CHECK-NEXT:    ret <4 x float> <float poison, float 2.000000e+00, float poison, float 2.000000e+00>
+;
+  %fcmp = fcmp oeq <4 x float> %x, <float 2.0, float 2.0, float 2.0, float 2.0>
+  %shuffle = shufflevector <4 x float> %x, <4 x float> poison, <4 x i32> <i32 4, i32 1, i32 6, i32 3>
+  %sel = select <4 x i1> %fcmp, <4 x float> %shuffle, <4 x float> <float poison, float 2.0, float poison, float 2.0>
+  ret <4 x float> %sel
+}
+
+; The hexfloat constant is PI / 2.
+define float @select_fcmp_sin_nonrefinement(float %x) {
+; CHECK-LABEL: @select_fcmp_sin_nonrefinement(
+; CHECK-NEXT:    [[FCMP:%.*]] = fcmp oeq float [[X:%.*]], 0x3FF921FB60000000
+; CHECK-NEXT:    [[SIN:%.*]] = call float @llvm.sin.f32(float [[X]])
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[FCMP]], float 1.000000e+00, float [[SIN]]
+; CHECK-NEXT:    ret float [[SEL]]
+;
+  %fcmp = fcmp oeq float %x, 0x3FF921FB60000000
+  %sin = call float @llvm.sin.f32(float %x)
+  %sel = select i1 %fcmp, float 1.0, float %sin
+  ret float %sel
+}
+
+; The hexfloat constant is PI / 2.
+define float @select_fcmp_sin(float %x) {
+; CHECK-LABEL: @select_fcmp_sin(
+; CHECK-NEXT:    ret float 1.000000e+00
+;
+  %fcmp = fcmp oeq float %x, 0x3FF921FB60000000
+  %sin = call float @llvm.sin.f32(float %x)
+  %sel = select i1 %fcmp, float %sin, float 1.0
+  ret float %sel
+}
+
+; The hexfloat constant is PI.
+define float @select_fcmp_cos_nonrefinement(float %x) {
+; CHECK-LABEL: @select_fcmp_cos_nonrefinement(
+; CHECK-NEXT:    [[FCMP:%.*]] = fcmp oeq float [[X:%.*]], 0x400921FB60000000
+; CHECK-NEXT:    [[COS:%.*]] = call float @llvm.cos.f32(float [[X]])
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[FCMP]], float -1.000000e+00, float [[COS]]
+; CHECK-NEXT:    ret float [[SEL]]
+;
+  %fcmp = fcmp oeq float %x, 0x400921FB60000000
+  %cos = call float @llvm.cos.f32(float %x)
+  %sel = select i1 %fcmp, float -1.0, float %cos
+  ret float %sel
+}
+
+; The hexfloat constant is PI.
+define float @select_fcmp_cos(float %x) {
+; CHECK-LABEL: @select_fcmp_cos(
+; CHECK-NEXT:    ret float -1.000000e+00
+;
+  %fcmp = fcmp oeq float %x, 0x400921FB60000000
+  %cos = call float @llvm.cos.f32(float %x)
+  %sel = select i1 %fcmp, float %cos, float -1.0
+  ret float %sel
+}
+
+define i32 @select_fcmp_lrint(float %x) {
+; CHECK-LABEL: @select_fcmp_lrint(
+; CHECK-NEXT:    [[FCMP:%.*]] = fcmp oeq float [[X:%.*]], 1.000000e+00
+; CHECK-NEXT:    [[LRINT:%.*]] = call i32 @llvm.lrint.i32.f32(float [[X]])
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[FCMP]], i32 [[LRINT]], i32 1
+; CHECK-NEXT:    ret i32 [[SEL]]
+;
+  %fcmp = fcmp oeq float %x, 1.0
+  %lrint = call i32 @llvm.lrint.i32.f32(float %x)
+  %sel = select i1 %fcmp, i32 %lrint, i32 1
+  ret i32 %sel
+}


        


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