Fix 12513: Loop unrolling breaks with indirect branches.

Take this opportunity to generalize the indirectbr bailout logic for
loop transformations. CFG transformations will never get indirectbr
right, and there's no point trying.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154386 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 0 deletions

diff --git a/lib/Analysis/LoopInfo.cpp b/lib/Analysis/LoopInfo.cpp
index 858cc642f4..f7a60a1737 100644
--- a/lib/Analysis/LoopInfo.cpp
+++ b/lib/Analysis/LoopInfo.cpp
@@ -205,6 +205,17 @@ bool Loop::isLoopSimplifyForm() const {
   return getLoopPreheader() && getLoopLatch() && hasDedicatedExits();
 }
 
+/// isSafeToClone - Return true if the loop body is safe to clone in practice.
+/// Routines that reform the loop CFG and split edges often fail on indirectbr.
+bool Loop::isSafeToClone() const {
+  // Return false if any loop blocks contain indirectbrs.
+  for (Loop::block_iterator I = block_begin(), E = block_end(); I != E; ++I) {
+    if (isa<IndirectBrInst>((*I)->getTerminator()))
+      return false;
+  }
+  return true;
+}
+
 /// hasDedicatedExits - Return true if no exit block for the loop
 /// has a predecessor that is outside the loop.
 bool Loop::hasDedicatedExits() const {