[llvm] [CVP] Simplify minmax at use (PR #125341)
Yingwei Zheng via llvm-commits
llvm-commits at lists.llvm.org
Sat Feb 1 00:55:15 PST 2025
https://github.com/dtcxzyw created https://github.com/llvm/llvm-project/pull/125341
Address a regression caused by https://github.com/llvm/llvm-project/pull/121958.
>From bac08403c5aafd7f68899ecd0f60df7506887719 Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Sat, 1 Feb 2025 16:45:00 +0800
Subject: [PATCH 1/2] [CVP] Add pre-commit tests. NFC.
---
.../CorrelatedValuePropagation/min-max.ll | 25 +++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/min-max.ll b/llvm/test/Transforms/CorrelatedValuePropagation/min-max.ll
index c9ee233b5a4612..601cdc65367f69 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/min-max.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/min-max.ll
@@ -355,3 +355,28 @@ define i8 @test_umax_nneg(i8 %a, i8 %b) {
%ret = call i8 @llvm.umax.i8(i8 %nneg_a, i8 %nneg_b)
ret i8 %ret
}
+
+define i64 @test_at_use2(i32 %x) {
+; CHECK-LABEL: @test_at_use2(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[COND:%.*]] = icmp slt i32 [[X:%.*]], 0
+; CHECK-NEXT: [[SMAX:%.*]] = call i32 @llvm.smax.i32(i32 [[X]], i32 -1)
+; CHECK-NEXT: br i1 [[COND]], label [[IF_END:%.*]], label [[IF_THEN:%.*]]
+; CHECK: if.then:
+; CHECK-NEXT: [[EXT:%.*]] = zext nneg i32 [[SMAX]] to i64
+; CHECK-NEXT: ret i64 [[EXT]]
+; CHECK: if.end:
+; CHECK-NEXT: ret i64 0
+;
+entry:
+ %cond = icmp slt i32 %x, 0
+ %smax = call i32 @llvm.smax.i32(i32 %x, i32 -1)
+ br i1 %cond, label %if.end, label %if.then
+
+if.then:
+ %ext = zext nneg i32 %smax to i64
+ ret i64 %ext
+
+if.end:
+ ret i64 0
+}
>From d5d2f34faeb7045c0cceecfc9af3c291e8af7d75 Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Sat, 1 Feb 2025 16:52:56 +0800
Subject: [PATCH 2/2] [CVP] Simplify minmax at use
---
.../Scalar/CorrelatedValuePropagation.cpp | 73 +++++++++++++------
.../CorrelatedValuePropagation/min-max.ll | 3 +-
2 files changed, 50 insertions(+), 26 deletions(-)
diff --git a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index 8e74b8645fad9a..c6faabda0e9231 100644
--- a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -579,38 +579,63 @@ static bool processCmpIntrinsic(CmpIntrinsic *CI, LazyValueInfo *LVI) {
// See if this min/max intrinsic always picks it's one specific operand.
// If not, check whether we can canonicalize signed minmax into unsigned version
static bool processMinMaxIntrinsic(MinMaxIntrinsic *MM, LazyValueInfo *LVI) {
+ bool Changed = false;
CmpInst::Predicate Pred = CmpInst::getNonStrictPredicate(MM->getPredicate());
- ConstantRange LHS_CR = LVI->getConstantRangeAtUse(MM->getOperandUse(0),
- /*UndefAllowed*/ false);
- ConstantRange RHS_CR = LVI->getConstantRangeAtUse(MM->getOperandUse(1),
- /*UndefAllowed*/ false);
- if (LHS_CR.icmp(Pred, RHS_CR)) {
- ++NumMinMax;
- MM->replaceAllUsesWith(MM->getLHS());
- MM->eraseFromParent();
- return true;
+ for (Use &U : make_early_inc_range(MM->uses())) {
+ ConstantRange LHS_CR =
+ ConstantRange::getEmpty(MM->getType()->getScalarSizeInBits());
+ ConstantRange RHS_CR = LHS_CR;
+ auto *CxtI = cast<Instruction>(U.getUser());
+ if (auto *PN = dyn_cast<PHINode>(CxtI)) {
+ BasicBlock *FromBB = PN->getIncomingBlock(U);
+ LHS_CR = LVI->getConstantRangeOnEdge(MM->getOperand(0), FromBB,
+ CxtI->getParent(), CxtI);
+ RHS_CR = LVI->getConstantRangeOnEdge(MM->getOperand(1), FromBB,
+ CxtI->getParent(), CxtI);
+ } else {
+ LHS_CR = LVI->getConstantRange(MM->getOperand(0), CxtI,
+ /*UndefAllowed=*/false);
+ RHS_CR = LVI->getConstantRange(MM->getOperand(1), CxtI,
+ /*UndefAllowed=*/false);
+ }
+ if (LHS_CR.icmp(Pred, RHS_CR)) {
+ Changed = true;
+ ++NumMinMax;
+ U.set(MM->getLHS());
+ continue;
+ }
+ if (RHS_CR.icmp(Pred, LHS_CR)) {
+ Changed = true;
+ ++NumMinMax;
+ U.set(MM->getRHS());
+ continue;
+ }
}
- if (RHS_CR.icmp(Pred, LHS_CR)) {
- ++NumMinMax;
- MM->replaceAllUsesWith(MM->getRHS());
+
+ if (MM->use_empty()) {
MM->eraseFromParent();
return true;
}
- if (MM->isSigned() &&
- ConstantRange::areInsensitiveToSignednessOfICmpPredicate(LHS_CR,
- RHS_CR)) {
- ++NumSMinMax;
- IRBuilder<> B(MM);
- MM->replaceAllUsesWith(B.CreateBinaryIntrinsic(
- MM->getIntrinsicID() == Intrinsic::smin ? Intrinsic::umin
- : Intrinsic::umax,
- MM->getLHS(), MM->getRHS()));
- MM->eraseFromParent();
- return true;
+ if (MM->isSigned()) {
+ ConstantRange LHS_CR = LVI->getConstantRangeAtUse(MM->getOperandUse(0),
+ /*UndefAllowed=*/false);
+ ConstantRange RHS_CR = LVI->getConstantRangeAtUse(MM->getOperandUse(1),
+ /*UndefAllowed=*/false);
+ if (ConstantRange::areInsensitiveToSignednessOfICmpPredicate(LHS_CR,
+ RHS_CR)) {
+ ++NumSMinMax;
+ IRBuilder<> B(MM);
+ MM->replaceAllUsesWith(B.CreateBinaryIntrinsic(
+ MM->getIntrinsicID() == Intrinsic::smin ? Intrinsic::umin
+ : Intrinsic::umax,
+ MM->getLHS(), MM->getRHS()));
+ MM->eraseFromParent();
+ return true;
+ }
}
- return false;
+ return Changed;
}
// Rewrite this with.overflow intrinsic as non-overflowing.
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/min-max.ll b/llvm/test/Transforms/CorrelatedValuePropagation/min-max.ll
index 601cdc65367f69..563c813336705b 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/min-max.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/min-max.ll
@@ -360,10 +360,9 @@ define i64 @test_at_use2(i32 %x) {
; CHECK-LABEL: @test_at_use2(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[COND:%.*]] = icmp slt i32 [[X:%.*]], 0
-; CHECK-NEXT: [[SMAX:%.*]] = call i32 @llvm.smax.i32(i32 [[X]], i32 -1)
; CHECK-NEXT: br i1 [[COND]], label [[IF_END:%.*]], label [[IF_THEN:%.*]]
; CHECK: if.then:
-; CHECK-NEXT: [[EXT:%.*]] = zext nneg i32 [[SMAX]] to i64
+; CHECK-NEXT: [[EXT:%.*]] = zext nneg i32 [[X]] to i64
; CHECK-NEXT: ret i64 [[EXT]]
; CHECK: if.end:
; CHECK-NEXT: ret i64 0
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