[llvm] [InstCombine] Fix miscompilation caused by #90436 (PR #91133)
Yingwei Zheng via llvm-commits
llvm-commits at lists.llvm.org
Sun May 5 09:36:34 PDT 2024
https://github.com/dtcxzyw created https://github.com/llvm/llvm-project/pull/91133
Proof: https://alive2.llvm.org/ce/z/iRnJ4i
Fixes https://github.com/llvm/llvm-project/issues/91127.
>From 71c2249f077036c3f04424e715910b7d35031d33 Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Mon, 6 May 2024 00:22:21 +0800
Subject: [PATCH 1/2] [InstCombine] Add pre-commit tests for PR91127. NFC.
---
llvm/test/Transforms/InstCombine/pr91127.ll | 82 +++++++++++++++++++++
1 file changed, 82 insertions(+)
create mode 100644 llvm/test/Transforms/InstCombine/pr91127.ll
diff --git a/llvm/test/Transforms/InstCombine/pr91127.ll b/llvm/test/Transforms/InstCombine/pr91127.ll
new file mode 100644
index 00000000000000..3582841c0de79d
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/pr91127.ll
@@ -0,0 +1,82 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -S -passes=instcombine < %s | FileCheck %s
+
+define i1 @test_eq1(i32 %x, i16 %y) {
+; CHECK-LABEL: define i1 @test_eq1(
+; CHECK-SAME: i32 [[X:%.*]], i16 [[Y:%.*]]) {
+; CHECK-NEXT: [[TMP1:%.*]] = zext i16 [[Y]] to i32
+; CHECK-NEXT: [[COND:%.*]] = icmp eq i32 [[TMP1]], [[X]]
+; CHECK-NEXT: ret i1 [[COND]]
+;
+ %conv1 = trunc nsw i32 %x to i8
+ %conv2 = trunc nsw i16 %y to i8
+ %cond = icmp eq i8 %conv1, %conv2
+ ret i1 %cond
+}
+
+; FIXME: It is weird that we generate truncs for test_eq2, but not for test_eq1.
+
+define i1 @test_eq2(i32 %x, i16 %y) {
+; CHECK-LABEL: define i1 @test_eq2(
+; CHECK-SAME: i32 [[X:%.*]], i16 [[Y:%.*]]) {
+; CHECK-NEXT: [[TMP1:%.*]] = trunc i32 [[X]] to i16
+; CHECK-NEXT: [[COND:%.*]] = icmp eq i16 [[TMP1]], [[Y]]
+; CHECK-NEXT: ret i1 [[COND]]
+;
+ %conv1 = trunc nsw i32 %x to i8
+ %conv2 = trunc nsw i16 %y to i8
+ %cond = icmp eq i8 %conv2, %conv1
+ ret i1 %cond
+}
+
+define i1 @test_ult(i32 %x, i16 %y) {
+; CHECK-LABEL: define i1 @test_ult(
+; CHECK-SAME: i32 [[X:%.*]], i16 [[Y:%.*]]) {
+; CHECK-NEXT: [[TMP1:%.*]] = zext i16 [[Y]] to i32
+; CHECK-NEXT: [[COND:%.*]] = icmp ugt i32 [[TMP1]], [[X]]
+; CHECK-NEXT: ret i1 [[COND]]
+;
+ %conv1 = trunc nsw i32 %x to i8
+ %conv2 = trunc nsw i16 %y to i8
+ %cond = icmp ult i8 %conv1, %conv2
+ ret i1 %cond
+}
+
+define i1 @test_slt(i32 %x, i16 %y) {
+; CHECK-LABEL: define i1 @test_slt(
+; CHECK-SAME: i32 [[X:%.*]], i16 [[Y:%.*]]) {
+; CHECK-NEXT: [[TMP1:%.*]] = zext i16 [[Y]] to i32
+; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[TMP1]], [[X]]
+; CHECK-NEXT: ret i1 [[COND]]
+;
+ %conv1 = trunc nsw i32 %x to i8
+ %conv2 = trunc nsw i16 %y to i8
+ %cond = icmp slt i8 %conv1, %conv2
+ ret i1 %cond
+}
+
+define i1 @test_ult_nuw(i32 %x, i16 %y) {
+; CHECK-LABEL: define i1 @test_ult_nuw(
+; CHECK-SAME: i32 [[X:%.*]], i16 [[Y:%.*]]) {
+; CHECK-NEXT: [[TMP1:%.*]] = zext i16 [[Y]] to i32
+; CHECK-NEXT: [[COND:%.*]] = icmp ugt i32 [[TMP1]], [[X]]
+; CHECK-NEXT: ret i1 [[COND]]
+;
+ %conv1 = trunc nuw nsw i32 %x to i8
+ %conv2 = trunc nuw nsw i16 %y to i8
+ %cond = icmp ult i8 %conv1, %conv2
+ ret i1 %cond
+}
+
+define i1 @test_slt_nuw(i32 %x, i16 %y) {
+; CHECK-LABEL: define i1 @test_slt_nuw(
+; CHECK-SAME: i32 [[X:%.*]], i16 [[Y:%.*]]) {
+; CHECK-NEXT: [[TMP1:%.*]] = zext i16 [[Y]] to i32
+; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[TMP1]], [[X]]
+; CHECK-NEXT: ret i1 [[COND]]
+;
+ %conv1 = trunc nuw nsw i32 %x to i8
+ %conv2 = trunc nuw nsw i16 %y to i8
+ %cond = icmp slt i8 %conv1, %conv2
+ ret i1 %cond
+}
>From 3465baef1793fa11c51ad5f8ba95724c4063221c Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Mon, 6 May 2024 00:23:44 +0800
Subject: [PATCH 2/2] [InstCombine] Fix miscompilation caused by PR90436
---
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp | 1 +
llvm/test/Transforms/InstCombine/pr91127.ll | 6 +++---
2 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index c60a290ce72e06..7092fb5e509bb1 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1510,6 +1510,7 @@ InstCombinerImpl::foldICmpTruncWithTruncOrExt(ICmpInst &Cmp,
std::swap(X, Y);
Pred = Cmp.getSwappedPredicate(Pred);
}
+ YIsSExt = !(NoWrapFlags & TruncInst::NoUnsignedWrap);
}
// Try to match icmp (trunc nuw X), (zext Y)
else if (!Cmp.isSigned() &&
diff --git a/llvm/test/Transforms/InstCombine/pr91127.ll b/llvm/test/Transforms/InstCombine/pr91127.ll
index 3582841c0de79d..43d431486d2d1b 100644
--- a/llvm/test/Transforms/InstCombine/pr91127.ll
+++ b/llvm/test/Transforms/InstCombine/pr91127.ll
@@ -4,7 +4,7 @@
define i1 @test_eq1(i32 %x, i16 %y) {
; CHECK-LABEL: define i1 @test_eq1(
; CHECK-SAME: i32 [[X:%.*]], i16 [[Y:%.*]]) {
-; CHECK-NEXT: [[TMP1:%.*]] = zext i16 [[Y]] to i32
+; CHECK-NEXT: [[TMP1:%.*]] = sext i16 [[Y]] to i32
; CHECK-NEXT: [[COND:%.*]] = icmp eq i32 [[TMP1]], [[X]]
; CHECK-NEXT: ret i1 [[COND]]
;
@@ -32,7 +32,7 @@ define i1 @test_eq2(i32 %x, i16 %y) {
define i1 @test_ult(i32 %x, i16 %y) {
; CHECK-LABEL: define i1 @test_ult(
; CHECK-SAME: i32 [[X:%.*]], i16 [[Y:%.*]]) {
-; CHECK-NEXT: [[TMP1:%.*]] = zext i16 [[Y]] to i32
+; CHECK-NEXT: [[TMP1:%.*]] = sext i16 [[Y]] to i32
; CHECK-NEXT: [[COND:%.*]] = icmp ugt i32 [[TMP1]], [[X]]
; CHECK-NEXT: ret i1 [[COND]]
;
@@ -45,7 +45,7 @@ define i1 @test_ult(i32 %x, i16 %y) {
define i1 @test_slt(i32 %x, i16 %y) {
; CHECK-LABEL: define i1 @test_slt(
; CHECK-SAME: i32 [[X:%.*]], i16 [[Y:%.*]]) {
-; CHECK-NEXT: [[TMP1:%.*]] = zext i16 [[Y]] to i32
+; CHECK-NEXT: [[TMP1:%.*]] = sext i16 [[Y]] to i32
; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[TMP1]], [[X]]
; CHECK-NEXT: ret i1 [[COND]]
;
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