1881711fbb
This removes memset with undef char. We already do this for stores of undef value. This comes with the caveat that this optimization is not, strictly speaking, legal for undef values, because we might be overwriting a poison value. However, our entire load/store model currently still operates on undef values, so we need to support undef here as well for internal consistency. Once https://github.com/llvm/llvm-project/issues/52930 is resolved, these and related folds can be limited to poison -- I've added FIXMEs to that effect. Differential Revision: https://reviews.llvm.org/D124173
73 lines
2.6 KiB
LLVM
73 lines
2.6 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -passes=instcombine -S | FileCheck %s
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define i32 @test([1024 x i8]* %target) {
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; CHECK-LABEL: @test(
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; CHECK-NEXT: [[TMP1:%.*]] = getelementptr [1024 x i8], [1024 x i8]* [[TARGET:%.*]], i64 0, i64 0
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; CHECK-NEXT: store i8 1, i8* [[TMP1]], align 1
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; CHECK-NEXT: [[TMP2:%.*]] = bitcast [1024 x i8]* [[TARGET]] to i16*
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; CHECK-NEXT: store i16 257, i16* [[TMP2]], align 2
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; CHECK-NEXT: [[TMP3:%.*]] = bitcast [1024 x i8]* [[TARGET]] to i32*
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; CHECK-NEXT: store i32 16843009, i32* [[TMP3]], align 4
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; CHECK-NEXT: [[TMP4:%.*]] = bitcast [1024 x i8]* [[TARGET]] to i64*
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; CHECK-NEXT: store i64 72340172838076673, i64* [[TMP4]], align 8
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; CHECK-NEXT: ret i32 0
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;
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%target_p = getelementptr [1024 x i8], [1024 x i8]* %target, i32 0, i32 0
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call void @llvm.memset.p0i8.i32(i8* %target_p, i8 1, i32 0, i1 false)
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call void @llvm.memset.p0i8.i32(i8* %target_p, i8 1, i32 1, i1 false)
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call void @llvm.memset.p0i8.i32(i8* align 2 %target_p, i8 1, i32 2, i1 false)
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call void @llvm.memset.p0i8.i32(i8* align 4 %target_p, i8 1, i32 4, i1 false)
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call void @llvm.memset.p0i8.i32(i8* align 8 %target_p, i8 1, i32 8, i1 false)
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ret i32 0
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}
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@Unknown = external constant i128
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define void @memset_to_constant() {
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; CHECK-LABEL: @memset_to_constant(
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; CHECK-NEXT: ret void
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;
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%p = bitcast i128* @Unknown to i8*
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call void @llvm.memset.p0i8.i32(i8* %p, i8 0, i32 16, i1 false)
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ret void
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}
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; FIXME: This is technically incorrect because it might overwrite a poison
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; value. Stop folding it once #52930 is resolved.
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define void @memset_undef(i8* %p) {
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; CHECK-LABEL: @memset_undef(
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; CHECK-NEXT: ret void
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;
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call void @llvm.memset.p0i8.i32(i8* %p, i8 undef, i32 8, i1 false)
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ret void
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}
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define void @memset_undef_volatile(i8* %p) {
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; CHECK-LABEL: @memset_undef_volatile(
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; CHECK-NEXT: call void @llvm.memset.p0i8.i32(i8* [[P:%.*]], i8 undef, i32 8, i1 true)
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; CHECK-NEXT: ret void
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;
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call void @llvm.memset.p0i8.i32(i8* %p, i8 undef, i32 8, i1 true)
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ret void
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}
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define void @memset_poison(i8* %p) {
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; CHECK-LABEL: @memset_poison(
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; CHECK-NEXT: ret void
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;
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call void @llvm.memset.p0i8.i32(i8* %p, i8 poison, i32 8, i1 false)
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ret void
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}
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define void @memset_poison_volatile(i8* %p) {
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; CHECK-LABEL: @memset_poison_volatile(
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; CHECK-NEXT: call void @llvm.memset.p0i8.i32(i8* [[P:%.*]], i8 poison, i32 8, i1 true)
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; CHECK-NEXT: ret void
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;
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call void @llvm.memset.p0i8.i32(i8* %p, i8 poison, i32 8, i1 true)
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ret void
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}
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declare void @llvm.memset.p0i8.i32(i8* nocapture writeonly, i8, i32, i1) argmemonly nounwind
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