[llvm] [InstCombine] Fold negation of calls to `ucmp/scmp` by swapping its operands (PR #98360)
via llvm-commits
llvm-commits at lists.llvm.org
Wed Jul 10 11:51:24 PDT 2024
https://github.com/Poseydon42 updated https://github.com/llvm/llvm-project/pull/98360
>From 5f688810e86220ad4ee8eed3995868f07589311c Mon Sep 17 00:00:00 2001
From: Poseydon42 <vvmposeydon at gmail.com>
Date: Wed, 10 Jul 2024 18:52:46 +0100
Subject: [PATCH 1/3] [InstCombine] Add tests for folding -ucmp/scmp(x, y) =>
ucmp/scmp(y, x)
---
llvm/test/Transforms/InstCombine/scmp.ll | 13 +++++++++++++
llvm/test/Transforms/InstCombine/ucmp.ll | 13 +++++++++++++
2 files changed, 26 insertions(+)
diff --git a/llvm/test/Transforms/InstCombine/scmp.ll b/llvm/test/Transforms/InstCombine/scmp.ll
index 4f903a79afd5d..b2967d966ee99 100644
--- a/llvm/test/Transforms/InstCombine/scmp.ll
+++ b/llvm/test/Transforms/InstCombine/scmp.ll
@@ -154,3 +154,16 @@ define i1 @scmp_sle_neg_1(i32 %x, i32 %y) {
%2 = icmp sle i8 %1, -1
ret i1 %2
}
+
+; ========== Fold -scmp(x, y) => scmp(y, x) ==========
+define i8 @scmp_negated(i32 %x, i32 %y) {
+; CHECK-LABEL: define i8 @scmp_negated(
+; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
+; CHECK-NEXT: [[TMP1:%.*]] = call i8 @llvm.scmp.i8.i32(i32 [[X]], i32 [[Y]])
+; CHECK-NEXT: [[TMP2:%.*]] = sub nsw i8 0, [[TMP1]]
+; CHECK-NEXT: ret i8 [[TMP2]]
+;
+ %1 = call i8 @llvm.scmp(i32 %x, i32 %y)
+ %2 = sub i8 0, %1
+ ret i8 %2
+}
diff --git a/llvm/test/Transforms/InstCombine/ucmp.ll b/llvm/test/Transforms/InstCombine/ucmp.ll
index 9ab67560c9117..5e422042d65e8 100644
--- a/llvm/test/Transforms/InstCombine/ucmp.ll
+++ b/llvm/test/Transforms/InstCombine/ucmp.ll
@@ -154,3 +154,16 @@ define i1 @ucmp_sle_neg_1(i32 %x, i32 %y) {
%2 = icmp sle i8 %1, -1
ret i1 %2
}
+
+; ========== Fold -ucmp(x, y) => ucmp(y, x) ==========
+define i8 @ucmp_negated(i32 %x, i32 %y) {
+; CHECK-LABEL: define i8 @ucmp_negated(
+; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
+; CHECK-NEXT: [[TMP1:%.*]] = call i8 @llvm.ucmp.i8.i32(i32 [[X]], i32 [[Y]])
+; CHECK-NEXT: [[TMP2:%.*]] = sub nsw i8 0, [[TMP1]]
+; CHECK-NEXT: ret i8 [[TMP2]]
+;
+ %1 = call i8 @llvm.ucmp(i32 %x, i32 %y)
+ %2 = sub i8 0, %1
+ ret i8 %2
+}
>From de83a0b200d3e6169228928fd3d23525952e83a5 Mon Sep 17 00:00:00 2001
From: Poseydon42 <vvmposeydon at gmail.com>
Date: Wed, 10 Jul 2024 18:54:24 +0100
Subject: [PATCH 2/3] [InstCombine] Fold -ucmp/scmp(x, y) into ucmp/scmp(y, x)
---
llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp | 5 +++++
llvm/test/Transforms/InstCombine/scmp.ll | 3 +--
llvm/test/Transforms/InstCombine/ucmp.ll | 3 +--
3 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp b/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp
index b3426562a4d87..9ad594a6d7d61 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp
@@ -222,6 +222,11 @@ std::array<Value *, 2> Negator::getSortedOperandsOfBinOp(Instruction *I) {
}
break;
}
+ case Instruction::Call:
+ if (auto *CI = dyn_cast<CmpIntrinsic>(I))
+ return Builder.CreateIntrinsic(CI->getType(), CI->getIntrinsicID(),
+ {CI->getRHS(), CI->getLHS()});
+ break;
default:
break; // Other instructions require recursive reasoning.
}
diff --git a/llvm/test/Transforms/InstCombine/scmp.ll b/llvm/test/Transforms/InstCombine/scmp.ll
index b2967d966ee99..80b32e73a757d 100644
--- a/llvm/test/Transforms/InstCombine/scmp.ll
+++ b/llvm/test/Transforms/InstCombine/scmp.ll
@@ -159,8 +159,7 @@ define i1 @scmp_sle_neg_1(i32 %x, i32 %y) {
define i8 @scmp_negated(i32 %x, i32 %y) {
; CHECK-LABEL: define i8 @scmp_negated(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
-; CHECK-NEXT: [[TMP1:%.*]] = call i8 @llvm.scmp.i8.i32(i32 [[X]], i32 [[Y]])
-; CHECK-NEXT: [[TMP2:%.*]] = sub nsw i8 0, [[TMP1]]
+; CHECK-NEXT: [[TMP2:%.*]] = call i8 @llvm.scmp.i8.i32(i32 [[Y]], i32 [[X]])
; CHECK-NEXT: ret i8 [[TMP2]]
;
%1 = call i8 @llvm.scmp(i32 %x, i32 %y)
diff --git a/llvm/test/Transforms/InstCombine/ucmp.ll b/llvm/test/Transforms/InstCombine/ucmp.ll
index 5e422042d65e8..74313403d7c0c 100644
--- a/llvm/test/Transforms/InstCombine/ucmp.ll
+++ b/llvm/test/Transforms/InstCombine/ucmp.ll
@@ -159,8 +159,7 @@ define i1 @ucmp_sle_neg_1(i32 %x, i32 %y) {
define i8 @ucmp_negated(i32 %x, i32 %y) {
; CHECK-LABEL: define i8 @ucmp_negated(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
-; CHECK-NEXT: [[TMP1:%.*]] = call i8 @llvm.ucmp.i8.i32(i32 [[X]], i32 [[Y]])
-; CHECK-NEXT: [[TMP2:%.*]] = sub nsw i8 0, [[TMP1]]
+; CHECK-NEXT: [[TMP2:%.*]] = call i8 @llvm.ucmp.i8.i32(i32 [[Y]], i32 [[X]])
; CHECK-NEXT: ret i8 [[TMP2]]
;
%1 = call i8 @llvm.ucmp(i32 %x, i32 %y)
>From 6c68deb005af476aee496da1d593335a4c99cb33 Mon Sep 17 00:00:00 2001
From: Poseydon42 <vvmposeydon at gmail.com>
Date: Wed, 10 Jul 2024 19:50:56 +0100
Subject: [PATCH 3/3] Do not fold when the original result is used more than
once
---
.../InstCombine/InstCombineNegator.cpp | 2 +-
llvm/test/Transforms/InstCombine/scmp.ll | 17 +++++++++++++++++
llvm/test/Transforms/InstCombine/ucmp.ll | 17 +++++++++++++++++
3 files changed, 35 insertions(+), 1 deletion(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp b/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp
index 9ad594a6d7d61..e4895b59f4b4a 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineNegator.cpp
@@ -223,7 +223,7 @@ std::array<Value *, 2> Negator::getSortedOperandsOfBinOp(Instruction *I) {
break;
}
case Instruction::Call:
- if (auto *CI = dyn_cast<CmpIntrinsic>(I))
+ if (auto *CI = dyn_cast<CmpIntrinsic>(I); CI && CI->hasOneUse())
return Builder.CreateIntrinsic(CI->getType(), CI->getIntrinsicID(),
{CI->getRHS(), CI->getLHS()});
break;
diff --git a/llvm/test/Transforms/InstCombine/scmp.ll b/llvm/test/Transforms/InstCombine/scmp.ll
index 80b32e73a757d..2523872562cad 100644
--- a/llvm/test/Transforms/InstCombine/scmp.ll
+++ b/llvm/test/Transforms/InstCombine/scmp.ll
@@ -1,6 +1,8 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+declare void @use(i8 %value)
+
define i1 @scmp_eq_0(i32 %x, i32 %y) {
; CHECK-LABEL: define i1 @scmp_eq_0(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
@@ -166,3 +168,18 @@ define i8 @scmp_negated(i32 %x, i32 %y) {
%2 = sub i8 0, %1
ret i8 %2
}
+
+; Negative test: do not fold if the original scmp result is already used
+define i8 @scmp_negated_multiuse(i32 %x, i32 %y) {
+; CHECK-LABEL: define i8 @scmp_negated_multiuse(
+; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
+; CHECK-NEXT: [[TMP1:%.*]] = call i8 @llvm.scmp.i8.i32(i32 [[X]], i32 [[Y]])
+; CHECK-NEXT: call void @use(i8 [[TMP1]])
+; CHECK-NEXT: [[TMP2:%.*]] = sub nsw i8 0, [[TMP1]]
+; CHECK-NEXT: ret i8 [[TMP2]]
+;
+ %1 = call i8 @llvm.scmp(i32 %x, i32 %y)
+ call void @use(i8 %1)
+ %2 = sub i8 0, %1
+ ret i8 %2
+}
diff --git a/llvm/test/Transforms/InstCombine/ucmp.ll b/llvm/test/Transforms/InstCombine/ucmp.ll
index 74313403d7c0c..7210455094baa 100644
--- a/llvm/test/Transforms/InstCombine/ucmp.ll
+++ b/llvm/test/Transforms/InstCombine/ucmp.ll
@@ -1,6 +1,8 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+declare void @use(i8 %value)
+
define i1 @ucmp_eq_0(i32 %x, i32 %y) {
; CHECK-LABEL: define i1 @ucmp_eq_0(
; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
@@ -166,3 +168,18 @@ define i8 @ucmp_negated(i32 %x, i32 %y) {
%2 = sub i8 0, %1
ret i8 %2
}
+
+; Negative test: do not fold if the original ucmp result is already used
+define i8 @ucmp_negated_multiuse(i32 %x, i32 %y) {
+; CHECK-LABEL: define i8 @ucmp_negated_multiuse(
+; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
+; CHECK-NEXT: [[TMP1:%.*]] = call i8 @llvm.ucmp.i8.i32(i32 [[X]], i32 [[Y]])
+; CHECK-NEXT: call void @use(i8 [[TMP1]])
+; CHECK-NEXT: [[TMP2:%.*]] = sub nsw i8 0, [[TMP1]]
+; CHECK-NEXT: ret i8 [[TMP2]]
+;
+ %1 = call i8 @llvm.ucmp(i32 %x, i32 %y)
+ call void @use(i8 %1)
+ %2 = sub i8 0, %1
+ ret i8 %2
+}
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