| ; RUN: opt < %s -basicaa -gvn -instcombine -S | grep {ret i32 0} | |
| @flag0 = internal global i32 zeroinitializer | |
| @turn = internal global i32 zeroinitializer | |
| define i32 @main() { | |
| %a = load i32* @flag0 | |
| %b = tail call i32 @llvm.atomic.swap.i32.p0i32(i32* @turn, i32 1) | |
| %c = load i32* @flag0 | |
| %d = sub i32 %a, %c | |
| ret i32 %d | |
| } | |
| declare i32 @llvm.atomic.swap.i32.p0i32(i32*, i32) nounwind |