llvm/test/Transforms/SimplifyCFG/lifetime.ll
Rafael Espindola 7fef5a3d19 SimplifyCFG: Avoid miscompilations due to removed lifetime intrinsics.
The lifetime intrinsics need some work in order to make it clear which
optimizations are or are not valid.

For now dropping this optimization avoids a miscompilation.

Patch by Björn Steinbrink.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214336 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-30 21:04:00 +00:00

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LLVM

; RUN: opt < %s -simplifycfg -S | FileCheck %s
; Test that a lifetime intrinsic isn't removed because that would change semantics
; CHECK: foo
; CHECK: entry:
; CHECK: bb0:
; CHECK: bb1:
; CHECK: ret
define void @foo(i1 %x) {
entry:
%a = alloca i8
call void @llvm.lifetime.start(i64 -1, i8* %a) nounwind
br i1 %x, label %bb0, label %bb1
bb0:
call void @llvm.lifetime.end(i64 -1, i8* %a) nounwind
br label %bb1
bb1:
call void @f()
ret void
}
declare void @f()
declare void @llvm.lifetime.start(i64, i8* nocapture) nounwind
declare void @llvm.lifetime.end(i64, i8* nocapture) nounwind