[llvm] [InstCombine] Extend `foldICmpAddConstant` to disjoint `or`. (PR #75899)
Mikhail Gudim via llvm-commits
llvm-commits at lists.llvm.org
Mon Dec 18 23:06:54 PST 2023
https://github.com/mgudim updated https://github.com/llvm/llvm-project/pull/75899
>From f601b61c686e8c1890dbd421f59930551aff0216 Mon Sep 17 00:00:00 2001
From: Mikhail Gudim <mgudim at gmail.com>
Date: Tue, 19 Dec 2023 01:58:12 -0500
Subject: [PATCH] [InstCombine] Extend `foldICmpAddConstant` to disjoint `or`.
---
.../InstCombine/InstCombineCompares.cpp | 40 ++++++++++---------
.../InstCombine/InstCombineInternal.h | 4 +-
.../InstCombine/InstCombineSelect.cpp | 2 +-
llvm/test/Transforms/InstCombine/icmp.ll | 10 +++++
4 files changed, 34 insertions(+), 22 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 289976718e52f3..0ba3e90efead2e 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -2918,19 +2918,21 @@ static Value *createLogicFromTable(const std::bitset<4> &Table, Value *Op0,
}
/// Fold icmp (add X, Y), C.
-Instruction *InstCombinerImpl::foldICmpAddConstant(ICmpInst &Cmp,
- BinaryOperator *Add,
- const APInt &C) {
- Value *Y = Add->getOperand(1);
- Value *X = Add->getOperand(0);
+Instruction *InstCombinerImpl::foldICmpAddLikeConstant(ICmpInst &Cmp,
+ BinaryOperator *AddLike,
+ const APInt &C) {
+ Value *X = nullptr;
+ Value *Y = nullptr;
+ if (!match(AddLike, m_AddLike(m_Value(X), m_Value(Y))))
+ return nullptr;
Value *Op0, *Op1;
Instruction *Ext0, *Ext1;
const CmpInst::Predicate Pred = Cmp.getPredicate();
- if (match(Add,
- m_Add(m_CombineAnd(m_Instruction(Ext0), m_ZExtOrSExt(m_Value(Op0))),
- m_CombineAnd(m_Instruction(Ext1),
- m_ZExtOrSExt(m_Value(Op1))))) &&
+ if (match(AddLike, m_AddLike(m_CombineAnd(m_Instruction(Ext0),
+ m_ZExtOrSExt(m_Value(Op0))),
+ m_CombineAnd(m_Instruction(Ext1),
+ m_ZExtOrSExt(m_Value(Op1))))) &&
Op0->getType()->isIntOrIntVectorTy(1) &&
Op1->getType()->isIntOrIntVectorTy(1)) {
unsigned BW = C.getBitWidth();
@@ -2948,8 +2950,8 @@ Instruction *InstCombinerImpl::foldICmpAddConstant(ICmpInst &Cmp,
Table[1] = ComputeTable(false, true);
Table[2] = ComputeTable(true, false);
Table[3] = ComputeTable(true, true);
- if (auto *Cond =
- createLogicFromTable(Table, Op0, Op1, Builder, Add->hasOneUse()))
+ if (auto *Cond = createLogicFromTable(Table, Op0, Op1, Builder,
+ AddLike->hasOneUse()))
return replaceInstUsesWith(Cmp, Cond);
}
const APInt *C2;
@@ -2957,14 +2959,15 @@ Instruction *InstCombinerImpl::foldICmpAddConstant(ICmpInst &Cmp,
return nullptr;
// Fold icmp pred (add X, C2), C.
- Type *Ty = Add->getType();
+ Type *Ty = AddLike->getType();
// If the add does not wrap, we can always adjust the compare by subtracting
// the constants. Equality comparisons are handled elsewhere. SGE/SLE/UGE/ULE
// are canonicalized to SGT/SLT/UGT/ULT.
- if ((Add->hasNoSignedWrap() &&
+ if (AddLike->getOpcode() == Instruction::Or ||
+ (AddLike->hasNoSignedWrap() &&
(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SLT)) ||
- (Add->hasNoUnsignedWrap() &&
+ (AddLike->hasNoUnsignedWrap() &&
(Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_ULT))) {
bool Overflow;
APInt NewC =
@@ -3021,7 +3024,7 @@ Instruction *InstCombinerImpl::foldICmpAddConstant(ICmpInst &Cmp,
return new ICmpInst(ICmpInst::ICMP_ULE, X, ConstantInt::get(Ty, C));
}
- if (!Add->hasOneUse())
+ if (!AddLike->hasOneUse())
return nullptr;
// X+C <u C2 -> (X & -C2) == C
@@ -3674,6 +3677,9 @@ InstCombinerImpl::foldICmpInstWithConstantAllowUndef(ICmpInst &Cmp,
Instruction *InstCombinerImpl::foldICmpBinOpWithConstant(ICmpInst &Cmp,
BinaryOperator *BO,
const APInt &C) {
+ if (Instruction *I = foldICmpAddLikeConstant(Cmp, BO, C))
+ return I;
+
switch (BO->getOpcode()) {
case Instruction::Xor:
if (Instruction *I = foldICmpXorConstant(Cmp, BO, C))
@@ -3716,10 +3722,6 @@ Instruction *InstCombinerImpl::foldICmpBinOpWithConstant(ICmpInst &Cmp,
if (Instruction *I = foldICmpSubConstant(Cmp, BO, C))
return I;
break;
- case Instruction::Add:
- if (Instruction *I = foldICmpAddConstant(Cmp, BO, C))
- return I;
- break;
default:
break;
}
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index f86db698ef8f12..475c250600ee11 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -671,8 +671,8 @@ class LLVM_LIBRARY_VISIBILITY InstCombinerImpl final
const APInt &C);
Instruction *foldICmpSubConstant(ICmpInst &Cmp, BinaryOperator *Sub,
const APInt &C);
- Instruction *foldICmpAddConstant(ICmpInst &Cmp, BinaryOperator *Add,
- const APInt &C);
+ Instruction *foldICmpAddLikeConstant(ICmpInst &Cmp, BinaryOperator *AddLike,
+ const APInt &C);
Instruction *foldICmpAndConstConst(ICmpInst &Cmp, BinaryOperator *And,
const APInt &C1);
Instruction *foldICmpAndShift(ICmpInst &Cmp, BinaryOperator *And,
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 20bf00344b144b..f5a91f5a84f012 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -1550,7 +1550,7 @@ tryToReuseConstantFromSelectInComparison(SelectInst &Sel, ICmpInst &Cmp,
if (C0->getType() != Sel.getType())
return nullptr;
- // ULT with 'add' of a constant is canonical. See foldICmpAddConstant().
+ // ULT with 'add' of a constant is canonical. See foldICmpAddLikeConstant().
// FIXME: Are there more magic icmp predicate+constant pairs we must avoid?
// Or should we just abandon this transform entirely?
if (Pred == CmpInst::ICMP_ULT && match(X, m_Add(m_Value(), m_Constant())))
diff --git a/llvm/test/Transforms/InstCombine/icmp.ll b/llvm/test/Transforms/InstCombine/icmp.ll
index 1c7bb36f0d34c0..33d09bfad856a7 100644
--- a/llvm/test/Transforms/InstCombine/icmp.ll
+++ b/llvm/test/Transforms/InstCombine/icmp.ll
@@ -4912,3 +4912,13 @@ define i1 @or_positive_sgt_zero_multi_use(i8 %a) {
%cmp = icmp sgt i8 %b, 0
ret i1 %cmp
}
+
+define i1 @icmp_disjoint_or(i32 %x) {
+; CHECK-LABEL: @icmp_disjoint_or(
+; CHECK-NEXT: [[C:%.*]] = icmp sgt i32 [[X:%.*]], 35
+; CHECK-NEXT: ret i1 [[C]]
+;
+ %or_ = or disjoint i32 %x, 6
+ %C = icmp sgt i32 %or_, 41
+ ret i1 %C
+}
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