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0760338efa
MemorySSA currently treats lifetime.end intrinsics as not aliasing anything. This breaks MemorySSA-based MemCpyOpt, because we'll happily move a read of a pointer below a lifetime.end intrinsic, as no clobber is reported. I think the MemorySSA modelling here isn't correct: lifetime.end(p) has approximately the same effect as doing a memcpy(p, undef), and should be treated as a clobber. This patch removes the special handling of lifetime.end, leaving alias analysis to handle it appropriately. Differential Revision: https://reviews.llvm.org/D95763
30 lines
1.2 KiB
LLVM
30 lines
1.2 KiB
LLVM
; RUN: opt -basic-aa -print-memoryssa -verify-memoryssa -enable-new-pm=0 -analyze < %s 2>&1 | FileCheck %s
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; RUN: opt -aa-pipeline=basic-aa -passes='print<memoryssa>,verify<memoryssa>' -disable-output < %s 2>&1 | FileCheck %s
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; This test checks that lifetime markers are considered clobbers of %P,
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; and due to lack of noalias information, of %Q as well.
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define i8 @test(i8* %P, i8* %Q) {
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entry:
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; CHECK: 1 = MemoryDef(liveOnEntry)
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; CHECK-NEXT: call void @llvm.lifetime.start.p0i8(i64 32, i8* %P)
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call void @llvm.lifetime.start.p0i8(i64 32, i8* %P)
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; CHECK: MemoryUse(1)
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; CHECK-NEXT: %0 = load i8, i8* %P
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%0 = load i8, i8* %P
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; CHECK: 2 = MemoryDef(1)
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; CHECK-NEXT: store i8 1, i8* %P
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store i8 1, i8* %P
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; CHECK: 3 = MemoryDef(2)
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; CHECK-NEXT: call void @llvm.lifetime.end.p0i8(i64 32, i8* %P)
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call void @llvm.lifetime.end.p0i8(i64 32, i8* %P)
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; CHECK: MemoryUse(3)
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; CHECK-NEXT: %1 = load i8, i8* %P
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%1 = load i8, i8* %P
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; CHECK: MemoryUse(3)
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; CHECK-NEXT: %2 = load i8, i8* %Q
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%2 = load i8, i8* %Q
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ret i8 %1
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}
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declare void @llvm.lifetime.start.p0i8(i64 %S, i8* nocapture %P) readonly
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declare void @llvm.lifetime.end.p0i8(i64 %S, i8* nocapture %P)
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