[llvm] [InstCombine] optimize powi(X,Y) * X with Ofast (PR #69998)
via llvm-commits
llvm-commits at lists.llvm.org
Fri Mar 1 18:15:52 PST 2024
https://github.com/vfdff updated https://github.com/llvm/llvm-project/pull/69998
>From 0a480d454d2b2044b4626bcebfca3902f0c5c047 Mon Sep 17 00:00:00 2001
From: zhongyunde 00443407 <zhongyunde at huawei.com>
Date: Mon, 23 Oct 2023 09:19:54 -0400
Subject: [PATCH 1/2] [InstCombine] optimize powi(X,Y) * X with Ofast
Try to transform the powi(X, Y) * X into powi(X, Y+1) with Ofast
For this case, when the Y is 3, then powi(X, 4) is replaced by
X2 = X * X; X2 * X2 in the further step.
Similar to D109954, who requires reassoc.
Fixes https://github.com/llvm/llvm-project/issues/69862.
---
.../InstCombine/InstCombineMulDivRem.cpp | 12 +++++
llvm/test/Transforms/InstCombine/powi.ll | 49 +++++++++++++++++++
2 files changed, 61 insertions(+)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 0bd4b6d1a835af5..ae31e95220ce93d 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -683,6 +683,18 @@ Instruction *InstCombinerImpl::foldFMulReassoc(BinaryOperator &I) {
return replaceInstUsesWith(I, Pow);
}
+ // powi(X, Y) * X --> powi(X, Y+1)
+ // X * powi(X, Y) --> powi(X, Y+1)
+ if (match(&I, m_c_FMul(m_OneUse(m_Intrinsic<Intrinsic::powi>(m_Value(X),
+ m_Value(Y))),
+ m_Deferred(X))) &&
+ willNotOverflowSignedAdd(Y, ConstantInt::get(Y->getType(), 1), I)) {
+ auto *Y1 = Builder.CreateAdd(Y, ConstantInt::get(Y->getType(), 1));
+ auto *NewPow = Builder.CreateIntrinsic(
+ Intrinsic::powi, {X->getType(), Y1->getType()}, {X, Y1}, &I);
+ return replaceInstUsesWith(I, NewPow);
+ }
+
if (I.isOnlyUserOfAnyOperand()) {
// pow(X, Y) * pow(X, Z) -> pow(X, Y + Z)
if (match(Op0, m_Intrinsic<Intrinsic::pow>(m_Value(X), m_Value(Y))) &&
diff --git a/llvm/test/Transforms/InstCombine/powi.ll b/llvm/test/Transforms/InstCombine/powi.ll
index 89efbb6f4536113..95722d09a17ad32 100644
--- a/llvm/test/Transforms/InstCombine/powi.ll
+++ b/llvm/test/Transforms/InstCombine/powi.ll
@@ -341,3 +341,52 @@ define double @fdiv_pow_powi_negative_variable(double %x, i32 %y) {
%div = fdiv reassoc nnan double %p1, %x
ret double %div
}
+
+; powi(X, Y) * X --> powi(X, Y+1)
+define double @powi_fmul_powi_x(double noundef %x) {
+; CHECK-LABEL: @powi_fmul_powi_x(
+; CHECK-NEXT: [[MUL:%.*]] = call reassoc double @llvm.powi.f64.i32(double [[X:%.*]], i32 4)
+; CHECK-NEXT: ret double [[MUL]]
+;
+ %p1 = tail call double @llvm.powi.f64.i32(double %x, i32 3)
+ %mul = fmul reassoc double %p1, %x
+ ret double %mul
+}
+
+; Negative test: Multi-use
+define double @powi_fmul_powi_x_multi_use(double noundef %x) {
+; CHECK-LABEL: @powi_fmul_powi_x_multi_use(
+; CHECK-NEXT: [[P1:%.*]] = tail call double @llvm.powi.f64.i32(double [[X:%.*]], i32 3)
+; CHECK-NEXT: tail call void @use(double [[P1]])
+; CHECK-NEXT: [[MUL:%.*]] = fmul reassoc double [[P1]], [[X]]
+; CHECK-NEXT: ret double [[MUL]]
+;
+ %p1 = tail call double @llvm.powi.f64.i32(double %x, i32 3)
+ tail call void @use(double %p1)
+ %mul = fmul reassoc double %p1, %x
+ ret double %mul
+}
+
+; Negative test: Miss fmf flag
+define double @powi_fmul_powi_x_missing_reassoc(double noundef %x) {
+; CHECK-LABEL: @powi_fmul_powi_x_missing_reassoc(
+; CHECK-NEXT: [[P1:%.*]] = tail call double @llvm.powi.f64.i32(double [[X:%.*]], i32 3)
+; CHECK-NEXT: [[MUL:%.*]] = fmul double [[P1]], [[X]]
+; CHECK-NEXT: ret double [[MUL]]
+;
+ %p1 = tail call double @llvm.powi.f64.i32(double %x, i32 3)
+ %mul = fmul double %p1, %x
+ ret double %mul
+}
+
+; Negative test: overflow
+define double @powi_fmul_powi_x_overflow(double noundef %x) {
+; CHECK-LABEL: @powi_fmul_powi_x_overflow(
+; CHECK-NEXT: [[P1:%.*]] = tail call double @llvm.powi.f64.i32(double [[X:%.*]], i32 2147483647)
+; CHECK-NEXT: [[MUL:%.*]] = fmul reassoc double [[P1]], [[X]]
+; CHECK-NEXT: ret double [[MUL]]
+;
+ %p1 = tail call double @llvm.powi.f64.i32(double %x, i32 2147483647) ; INT_MAX
+ %mul = fmul reassoc double %p1, %x
+ ret double %mul
+}
>From 322d458ff3540eb08654f9a9362939879dcb88f8 Mon Sep 17 00:00:00 2001
From: zhongyunde 00443407 <zhongyunde at huawei.com>
Date: Fri, 1 Mar 2024 20:33:54 -0500
Subject: [PATCH 2/2] [InstCombine] create a helper function createPowiExpr,
NFC
---
.../InstCombine/InstCombineMulDivRem.cpp | 32 ++++++++++++-------
1 file changed, 20 insertions(+), 12 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index ae31e95220ce93d..15d84cb934a8465 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -571,6 +571,22 @@ Instruction *InstCombinerImpl::foldFPSignBitOps(BinaryOperator &I) {
return nullptr;
}
+static Instruction *createPowiExpr(BinaryOperator &I, InstCombinerImpl &IC,
+ Value *X, Value *Y, Value *Z) {
+ Value *YZ;
+ InstCombiner::BuilderTy &Builder = IC.Builder;
+
+ if (auto *C = dyn_cast<ConstantInt>(Z)) {
+ if (C->isOne())
+ YZ = Builder.CreateAdd(Y, ConstantInt::get(Y->getType(), 1));
+ } else
+ YZ = Builder.CreateAdd(Y, Z);
+
+ auto *NewPow = Builder.CreateIntrinsic(
+ Intrinsic::powi, {X->getType(), YZ->getType()}, {X, YZ}, &I);
+ return IC.replaceInstUsesWith(I, NewPow);
+}
+
Instruction *InstCombinerImpl::foldFMulReassoc(BinaryOperator &I) {
Value *Op0 = I.getOperand(0);
Value *Op1 = I.getOperand(1);
@@ -688,12 +704,8 @@ Instruction *InstCombinerImpl::foldFMulReassoc(BinaryOperator &I) {
if (match(&I, m_c_FMul(m_OneUse(m_Intrinsic<Intrinsic::powi>(m_Value(X),
m_Value(Y))),
m_Deferred(X))) &&
- willNotOverflowSignedAdd(Y, ConstantInt::get(Y->getType(), 1), I)) {
- auto *Y1 = Builder.CreateAdd(Y, ConstantInt::get(Y->getType(), 1));
- auto *NewPow = Builder.CreateIntrinsic(
- Intrinsic::powi, {X->getType(), Y1->getType()}, {X, Y1}, &I);
- return replaceInstUsesWith(I, NewPow);
- }
+ willNotOverflowSignedAdd(Y, ConstantInt::get(Y->getType(), 1), I))
+ return createPowiExpr(I, *this, X, Y, ConstantInt::get(Y->getType(), 1));
if (I.isOnlyUserOfAnyOperand()) {
// pow(X, Y) * pow(X, Z) -> pow(X, Y + Z)
@@ -714,12 +726,8 @@ Instruction *InstCombinerImpl::foldFMulReassoc(BinaryOperator &I) {
// powi(x, y) * powi(x, z) -> powi(x, y + z)
if (match(Op0, m_Intrinsic<Intrinsic::powi>(m_Value(X), m_Value(Y))) &&
match(Op1, m_Intrinsic<Intrinsic::powi>(m_Specific(X), m_Value(Z))) &&
- Y->getType() == Z->getType()) {
- auto *YZ = Builder.CreateAdd(Y, Z);
- auto *NewPow = Builder.CreateIntrinsic(
- Intrinsic::powi, {X->getType(), YZ->getType()}, {X, YZ}, &I);
- return replaceInstUsesWith(I, NewPow);
- }
+ Y->getType() == Z->getType())
+ return createPowiExpr(I, *this, X, Y, Z);
// exp(X) * exp(Y) -> exp(X + Y)
if (match(Op0, m_Intrinsic<Intrinsic::exp>(m_Value(X))) &&
More information about the llvm-commits
mailing list