TRE: Just erase dead BBs and tweak the iteration loop not to increment the deleted BB iterator.

Leaving empty blocks around just opens up a can of bugs like PR22704. Deleting
them early also slightly simplifies code.

Thanks to Sanjay for the IR test case.

llvm-svn: 230856

1 files changed, 21 insertions, 0 deletions

diff --git a/llvm/test/Transforms/TailCallElim/inf-recursion.ll b/llvm/test/Transforms/TailCallElim/inf-recursion.ll
index 157226f93d3..c121c25aee9 100644
--- a/llvm/test/Transforms/TailCallElim/inf-recursion.ll
+++ b/llvm/test/Transforms/TailCallElim/inf-recursion.ll
@@ -31,3 +31,24 @@ define float @fabsf(float %f) {
 }
 
 declare x86_fp80 @fabsl(x86_fp80 %f)
+
+; Don't crash while transforming a function with infinite recursion.
+define i32 @PR22704(i1 %bool) {
+entry:
+  br i1 %bool, label %t, label %f
+
+t:
+  %call1 = call i32 @PR22704(i1 1)
+  br label %return
+
+f:
+  %call = call i32 @PR22704(i1 1)
+  br label %return
+
+return:
+  ret i32 0
+
+; CHECK-LABEL: @PR22704(
+; CHECK:       %bool.tr = phi i1 [ %bool, %entry ], [ true, %t ], [ true, %f ]
+; CHECK:       br i1 %bool.tr, label %t, label %f
+}