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llvm-mirror/test/Analysis/BasicAA/2008-12-09-GEP-IndicesAlias.ll
Chris Lattner e2b5854e41 Allow basicaa to walk through geps with identical indices in
parallel, allowing it to decide that P/Q must alias if A/B
must alias in things like:
 P = gep A, 0, i, 1
 Q = gep B, 0, i, 1

This allows GVN to delete 62 more instructions out of 403.gcc.

llvm-svn: 60820
2008-12-10 01:04:47 +00:00

17 lines
449 B
LLVM

; RUN: llvm-as < %s | opt -aa-eval -print-all-alias-modref-info -disable-output |& grep {MustAlias:.*%R,.*%r}
; Make sure that basicaa thinks R and r are must aliases.
define i32 @test(i8 * %P) {
entry:
%Q = bitcast i8* %P to {i32, i32}*
%R = getelementptr {i32, i32}* %Q, i32 0, i32 1
%S = load i32* %R
%q = bitcast i8* %P to {i32, i32}*
%r = getelementptr {i32, i32}* %q, i32 0, i32 1
%s = load i32* %r
%t = sub i32 %S, %s
ret i32 %t
}