RecursivelyDeleteTriviallyDeadInstructions() could remove

more than 1 instruction. The caller need to be aware of this
and adjust instruction iterators accordingly.

rdar://16679376

llvm-svn: 207302

1 files changed, 9 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyInstructions.cpp b/llvm/lib/Transforms/Utils/SimplifyInstructions.cpp
index c62aa663f6d..33b36378027 100644
--- a/llvm/lib/Transforms/Utils/SimplifyInstructions.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyInstructions.cpp
@@ -76,7 +76,15 @@ namespace {
                 ++NumSimplified;
                 Changed = true;
               }
-            Changed |= RecursivelyDeleteTriviallyDeadInstructions(I, TLI);
+            bool res = RecursivelyDeleteTriviallyDeadInstructions(I, TLI);
+            if (res)  {
+              // RecursivelyDeleteTriviallyDeadInstruction can remove
+              // more than one instruction, so simply incrementing the
+              // iterator does not work. When instructions get deleted
+              // re-iterate instead.
+              BI = BB->begin(); BE = BB->end();
+              Changed |= res;
+            }
           }
 
         // Place the list of instructions to simplify on the next loop iteration