[SimplifyCFG] Add a workaround to fix PR30188

We're sinking stores, which is a good thing, but in the process creating selects for the store address operand, which SROA/Mem2Reg can't look through, which caused serious regressions.

The real fix is in SROA, which I'll be looking into.

llvm-svn: 280219

1 files changed, 23 insertions, 0 deletions

diff --git a/llvm/test/Transforms/SimplifyCFG/sink-common-code.ll b/llvm/test/Transforms/SimplifyCFG/sink-common-code.ll
index 1a4884a6454..9f87d3bf3c5 100644
--- a/llvm/test/Transforms/SimplifyCFG/sink-common-code.ll
+++ b/llvm/test/Transforms/SimplifyCFG/sink-common-code.ll
@@ -537,6 +537,29 @@ if.end:
 ; CHECK-DAG: [ %cmp3, %if.then3 ]
 ; CHECK-NEXT: zext i1 %[[x]] to i8
 
+define i32 @test_pr30188(i1 zeroext %flag, i32 %x) {
+entry:
+  %y = alloca i32
+  %z = alloca i32
+  br i1 %flag, label %if.then, label %if.else
+
+if.then:
+  store i32 %x, i32* %y
+  br label %if.end
+
+if.else:
+  store i32 %x, i32* %z
+  br label %if.end
+
+if.end:
+  ret i32 1
+}
+
+; CHECK-LABEL: test_pr30188
+; CHECK-NOT: select
+; CHECK: store
+; CHECK: store
+
 ; CHECK: !0 = !{!1, !1, i64 0}
 ; CHECK: !1 = !{!"float", !2}
 ; CHECK: !2 = !{!"an example type tree"}