llvm/test/Transforms/GVN/br-identical.ll
Peter Collingbourne 8d5e4e48bc GVN: If a branch has two identical successors, we cannot declare either dead.
This previously caused miscompilations as a result of phi nodes receiving
undef incoming values from blocks dominated by such successors.

Differential Revision: http://reviews.llvm.org/D10726

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240670 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-25 18:32:02 +00:00

39 lines
657 B
LLVM

; RUN: opt -gvn -S -o - %s | FileCheck %s
; If a branch has two identical successors, we cannot declare either dead.
define void @widget(i1 %p) {
entry:
br label %bb2
bb2:
%t1 = phi i64 [ 0, %entry ], [ %t5, %bb7 ]
%t2 = add i64 %t1, 1
%t3 = icmp ult i64 0, %t2
br i1 %t3, label %bb3, label %bb4
bb3:
%t4 = call i64 @f()
br label %bb4
bb4:
; CHECK-NOT: phi {{.*}} undef
%foo = phi i64 [ %t4, %bb3 ], [ 0, %bb2 ]
br i1 %p, label %bb5, label %bb6
bb5:
br i1 true, label %bb7, label %bb7
bb6:
br i1 true, label %bb7, label %bb7
bb7:
%t5 = add i64 %t1, 1
br i1 %p, label %bb2, label %bb8
bb8:
ret void
}
declare i64 @f()