LowerSwitch: Fix producing invalid IR on unreachable code
If a switch was in an unreachable block that branched
to a block with a phi, it would leave phis with missing
predecessors.
llvm-svn: 301064
diff --git a/llvm/test/Transforms/LowerSwitch/phi-in-dead-block.ll b/llvm/test/Transforms/LowerSwitch/phi-in-dead-block.ll
new file mode 100644
index 0000000..a632584
--- /dev/null
+++ b/llvm/test/Transforms/LowerSwitch/phi-in-dead-block.ll
@@ -0,0 +1,40 @@
+; RUN: opt -S -lowerswitch %s | FileCheck %s
+
+; CHECK-LABEL: @phi_in_dead_block(
+; CHECK-NOT: switch
+define void @phi_in_dead_block() {
+bb:
+ br i1 undef, label %bb2, label %bb3
+
+bb1: ; No predecessors!
+ switch i32 undef, label %bb2 [
+ i32 9, label %bb3
+ ]
+
+bb2: ; preds = %bb1, %bb
+ %tmp = phi i64 [ undef, %bb1 ], [ undef, %bb ]
+ unreachable
+
+bb3: ; preds = %bb1, %bb
+ unreachable
+}
+
+; CHECK-LABEL: @phi_in_dead_block_br_to_self(
+; CHECK-NOT: switch
+define void @phi_in_dead_block_br_to_self() {
+bb:
+ br i1 undef, label %bb2, label %bb3
+
+bb1: ; No predecessors!
+ switch i32 undef, label %bb2 [
+ i32 9, label %bb3
+ i32 10, label %bb1
+ ]
+
+bb2: ; preds = %bb1, %bb
+ %tmp = phi i64 [ undef, %bb1 ], [ undef, %bb ]
+ unreachable
+
+bb3: ; preds = %bb1, %bb
+ unreachable
+}