31 lines
1.5 KiB
LLVM
31 lines
1.5 KiB
LLVM
; RUN: opt < %s -S -basicaa -memcpyopt | FileCheck %s
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target datalayout = "e-i64:64-f80:128-n8:16:32:64-S128"
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declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture readonly, i64, i32, i1) unnamed_addr nounwind
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declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1) nounwind
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; all bytes of %dst that are touch by the memset are dereferenceable
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define void @must_remove_memcpy(i8* noalias nocapture dereferenceable(4096) %dst) {
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; CHECK-LABEL: @must_remove_memcpy(
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; CHECK: call void @llvm.memset.p0i8.i64
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; CHECK-NOT: call void @llvm.memcpy.p0i8.p0i8.i64
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%src = alloca [4096 x i8], align 1
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%p = getelementptr inbounds [4096 x i8], [4096 x i8]* %src, i64 0, i64 0
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call void @llvm.memset.p0i8.i64(i8* %p, i8 0, i64 4096, i32 1, i1 false)
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call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %p, i64 4096, i32 1, i1 false) #2
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ret void
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}
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; memset touch more bytes than those guaranteed to be dereferenceable
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; We can't remove the memcpy, but we can turn it into an independent memset.
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define void @must_not_remove_memcpy(i8* noalias nocapture dereferenceable(1024) %dst) {
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; CHECK-LABEL: @must_not_remove_memcpy(
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; CHECK: call void @llvm.memset.p0i8.i64
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; CHECK: call void @llvm.memset.p0i8.i64
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%src = alloca [4096 x i8], align 1
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%p = getelementptr inbounds [4096 x i8], [4096 x i8]* %src, i64 0, i64 0
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call void @llvm.memset.p0i8.i64(i8* %p, i8 0, i64 4096, i32 1, i1 false)
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call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %p, i64 4096, i32 1, i1 false) #2
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ret void
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}
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