[Simplify] Add testcase to show that merging conditional stores for triangles is sensitive to the order of the branch targets on the conditional branches. NFC

llvm-svn: 300915

test/Transforms/SimplifyCFG/merge-cond-stores.ll

@@ -36,6 +36,45 @@ end:
   ret void
 }
 
+; This is the same as test_simple, but the branch target order has been swapped
+; TODO: This test should succeed and end up if-converted.
+define void @test_simple_commuted(i32* %p, i32 %a, i32 %b) {
+; CHECK-LABEL: @test_simple_commuted(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[X1:%.*]] = icmp eq i32 [[A:%.*]], 0
+; CHECK-NEXT:    br i1 [[X1]], label [[YES1:%.*]], label [[FALLTHROUGH:%.*]]
+; CHECK:       yes1:
+; CHECK-NEXT:    store i32 0, i32* [[P:%.*]], align 4
+; CHECK-NEXT:    br label [[FALLTHROUGH]]
+; CHECK:       fallthrough:
+; CHECK-NEXT:    [[X2:%.*]] = icmp eq i32 [[B:%.*]], 0
+; CHECK-NEXT:    br i1 [[X2]], label [[YES2:%.*]], label [[END:%.*]]
+; CHECK:       yes2:
+; CHECK-NEXT:    store i32 1, i32* [[P]], align 4
+; CHECK-NEXT:    br label [[END]]
+; CHECK:       end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %x1 = icmp eq i32 %a, 0
+  br i1 %x1, label %yes1, label %fallthrough
+
+yes1:
+  store i32 0, i32* %p
+  br label %fallthrough
+
+fallthrough:
+  %x2 = icmp eq i32 %b, 0
+  br i1 %x2, label %yes2, label %end
+
+yes2:
+  store i32 1, i32* %p
+  br label %end
+
+end:
+  ret void
+}
+
 ; This test should entirely fold away, leaving one large basic block.
 define void @test_recursive(i32* %p, i32 %a, i32 %b, i32 %c, i32 %d) {
 ; CHECK-LABEL: @test_recursive(