[llvm-commits] [llvm] r138890 - /llvm/trunk/lib/Transforms/Scalar/SCCP.cpp

[Bill Wendling]

Author: void
Date: Wed Aug 31 15:55:20 2011
New Revision: 138890

URL: http://llvm.org/viewvc/llvm-project?rev=138890&view=rev
Log:
Make sure we aren't deleting the landingpad instruction.

The landingpad instruction is required in the landing pad block. Because we're
not deleting terminating instructions, the invoke may still jump to here (see
Transforms/SCCP/2004-11-16-DeadInvoke.ll). Remove all uses of the landingpad
instruction, but keep it around until code-gen can remove the basic block.

Modified:
    llvm/trunk/lib/Transforms/Scalar/SCCP.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SCCP.cpp?rev=138890&r1=138889&r2=138890&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SCCP.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SCCP.cpp Wed Aug 31 15:55:20 2011
@@ -1681,15 +1681,31 @@
 static void DeleteInstructionInBlock(BasicBlock *BB) {
   DEBUG(dbgs() << "  BasicBlock Dead:" << *BB);
   ++NumDeadBlocks;
-  
+
+  // Check to see if there are non-terminating instructions to delete.
+  if (isa<TerminatorInst>(BB->begin()))
+    return;
+
   // Delete the instructions backwards, as it has a reduced likelihood of
   // having to update as many def-use and use-def chains.
-  while (!isa<TerminatorInst>(BB->begin())) {
-    Instruction *I = --BasicBlock::iterator(BB->getTerminator());
-    
+  std::vector<Instruction*> WorkList;
+  WorkList.reserve(BB->size());
+  BasicBlock::iterator I = --BasicBlock::iterator(BB->getTerminator());
+
+  while (true) {
     if (!I->use_empty())
       I->replaceAllUsesWith(UndefValue::get(I->getType()));
-    BB->getInstList().erase(I);
+    WorkList.push_back(I);
+    if (I == BB->begin())
+      break;
+    --I;
+  }
+
+  for (std::vector<Instruction*>::iterator
+         II = WorkList.begin(), IE = WorkList.end(); II != IE; ++II) {
+    if (isa<LandingPadInst>(*II))
+      continue;
+    BB->getInstList().erase(*II);
     ++NumInstRemoved;
   }
 }