760dc9aba7
Summary: Solves PR 31990. The bad rewrite could replace a memcpy of one word with store i4 -1 while it should actually be store i8 -1 Hopefully opt and llc has improved enough so the original optimization done by the code isn't needed anymore. One already existing testcase is affected. It originally tested that the memcpy was replaced with load double but since we now remove that rewrite it will be load i64 instead. Patch suggestion by Eli Friedman. Reviewers: eli.friedman, majnemer, efriedma Reviewed By: efriedma Subscribers: efriedma, llvm-commits Differential Revision: https://reviews.llvm.org/D30254 llvm-svn: 296585
27 lines
739 B
LLVM
27 lines
739 B
LLVM
; RUN: opt -S -instcombine %s -o - | FileCheck %s
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; Regression test of PR31990. A memcpy of one byte, copying 0xff, was
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; replaced with a single store of an i4 0xf.
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@g = constant i8 -1
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define void @foo() {
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entry:
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%0 = alloca i8
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%1 = bitcast i8* %0 to i4*
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call void @bar(i4* %1)
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%2 = bitcast i4* %1 to i8*
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call void @llvm.memcpy.p0i8.p0i8.i32(i8* %2, i8* @g, i32 1, i32 1, i1 false)
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call void @gaz(i8* %2)
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ret void
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}
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declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture writeonly,
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i8* nocapture readonly, i32, i32, i1)
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declare void @bar(i4*)
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declare void @gaz(i8*)
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; The mempcy should be simplified to a single store of an i8, not i4
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; CHECK: store i8 -1
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; CHECK-NOT: store i4 -1
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