[llvm-commits] [llvm] r140193 - /llvm/trunk/lib/Transforms/IPO/LoopExtractor.cpp

[Bill Wendling]

Author: void
Date: Tue Sep 20 17:23:09 2011
New Revision: 140193

URL: http://llvm.org/viewvc/llvm-project?rev=140193&view=rev
Log:
Omit extracting a loop if one of the exits is a landing pad.

The landing pad must accompany the invoke when it's extracted. However, if it
does, then the loop isn't properly extracted. I.e., the resulting extraction has
a loop in it. The extracted function is then extracted, etc. resulting in an
infinite loop.

Modified:
    llvm/trunk/lib/Transforms/IPO/LoopExtractor.cpp

Modified: llvm/trunk/lib/Transforms/IPO/LoopExtractor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/LoopExtractor.cpp?rev=140193&r1=140192&r2=140193&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/LoopExtractor.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/LoopExtractor.cpp Tue Sep 20 17:23:09 2011
@@ -101,18 +101,24 @@
     L->getHeader()->getParent()->getEntryBlock().getTerminator();
   if (!isa<BranchInst>(EntryTI) ||
       !cast<BranchInst>(EntryTI)->isUnconditional() ||
-      EntryTI->getSuccessor(0) != L->getHeader())
+      EntryTI->getSuccessor(0) != L->getHeader()) {
     ShouldExtractLoop = true;
-  else {
+  } else {
     // Check to see if any exits from the loop are more than just return
-    // blocks.
+    // blocks. We also must omit landing pads. Landing pads must accompany the
+    // invoke instruction. But this would result in a loop in the extracted
+    // function. An infinite cycle occurs when it tries to extract that loop as
+    // well.
     SmallVector<BasicBlock*, 8> ExitBlocks;
     L->getExitBlocks(ExitBlocks);
-    for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
-      if (!isa<ReturnInst>(ExitBlocks[i]->getTerminator())) {
+    for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
+      if (!isa<ReturnInst>(ExitBlocks[i]->getTerminator()))
         ShouldExtractLoop = true;
+      if (ExitBlocks[i]->isLandingPad()) {
+        ShouldExtractLoop = false;
         break;
       }
+    }
   }
   if (ShouldExtractLoop) {
     if (NumLoops == 0) return Changed;