PR9446: RecursivelyDeleteTriviallyDeadInstructions can delete the instruction

after the given instruction; make sure to handle that case correctly.
(It's difficult to trigger; the included testcase involves a dead 
block, but I don't think that's a requirement.) 

While I'm here, get rid of the unnecessary warning about
SimplifyInstructionsInBlock, since it should work correctly as far as I know.

llvm-svn: 128782

1 files changed, 32 insertions, 0 deletions

diff --git a/llvm/test/Transforms/JumpThreading/2011-04-02-SimplifyDeadBlock.ll b/llvm/test/Transforms/JumpThreading/2011-04-02-SimplifyDeadBlock.ll
new file mode 100644
index 00000000000..76dd2d12bde
--- /dev/null
+++ b/llvm/test/Transforms/JumpThreading/2011-04-02-SimplifyDeadBlock.ll
@@ -0,0 +1,32 @@
+; RUN: opt < %s -jump-threading
+; PR9446
+; Just check that it doesn't crash
+
+define void @int327() nounwind {
+entry:
+  unreachable
+
+for.cond:                                         ; preds = %for.cond4
+  %tobool3 = icmp eq i8 undef, 0
+  br i1 %tobool3, label %for.cond23, label %for.cond4
+
+for.cond4:                                        ; preds = %for.cond
+  br label %for.cond
+
+for.cond23:                                       ; preds = %for.body28, %for.cond23, %for.cond
+  %conv321 = phi i32 [ %conv32, %for.body28 ], [ 0, %for.cond ], [ %conv321, %for.cond23 ]
+  %l_266.0 = phi i32 [ %phitmp, %for.body28 ], [ 0, %for.cond ], [ 0, %for.cond23 ]
+  %cmp26 = icmp eq i32 %l_266.0, 0
+  br i1 %cmp26, label %for.body28, label %for.cond23
+
+for.body28:                                       ; preds = %for.cond23
+  %and = and i32 %conv321, 1
+  %conv32 = zext i8 undef to i32
+  %add = add nsw i32 %l_266.0, 1
+  %phitmp = and i32 %add, 255
+  br label %for.cond23
+
+if.end43:                                         ; No predecessors!
+  ret void
+}
+