llvm/test/Transforms/ScalarRepl/2008-09-22-vector-gep.ll
Matthijs Kooijman 5fac55fafb Allow scalarrepl to treat an all-zero GEP just as bitcast.
This includes not marking a GEP involving a vector as unsafe, but only when it
has all zero indices. This allows scalarrepl to work in a few more cases.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57177 91177308-0d34-0410-b5e6-96231b3b80d8
2008-10-06 16:23:31 +00:00

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LLVM

; This test checks to see if scalarrepl also works when a gep with all zeroes is
; used instead of a bitcast to prepare a memmove pointer argument. Previously,
; this would not work when there was a vector involved in the struct, preventing
; scalarrepl from removing the alloca below.
; RUN: llvm-as < %s | opt -scalarrepl | llvm-dis > %t
; RUN: cat %t | not grep alloca
%struct.two = type <{ < 2 x i8 >, i16 }>
define void @main(%struct.two* %D, i16 %V) {
entry:
%S = alloca %struct.two
%S.2 = getelementptr %struct.two* %S, i32 0, i32 1
store i16 %V, i16* %S.2
; This gep is effectively a bitcast to i8*, but is sometimes generated
; because the type of the first element in %struct.two is i8.
%tmpS = getelementptr %struct.two* %S, i32 0, i32 0, i32 0
%tmpD = bitcast %struct.two* %D to i8*
call void @llvm.memmove.i32(i8* %tmpD, i8* %tmpS, i32 4, i32 1)
ret void
}
declare void @llvm.memmove.i32(i8*, i8*, i32, i32) nounwind