Strip metadata when speculatively hoisting instructions

[oota-llvm.git] / lib / Transforms / Scalar / LICM.cpp

diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index 342ea6c8fff3729498b79b87da3b5a1d9c6f57fd..6d70cdc3ade2d1a81cc54f0beef1c07882745f2b 100644 (file)
--- a/lib/Transforms/Scalar/LICM.cpp
+++ b/lib/Transforms/Scalar/LICM.cpp
@@ -471,6 +471,17 @@ bool canSinkOrHoistInst(Instruction &I, AliasAnalysis *AA, DominatorTree *DT,
     if (Behavior == FMRB_DoesNotAccessMemory)
       return true;
     if (AliasAnalysis::onlyReadsMemory(Behavior)) {
+      // A readonly argmemonly function only reads from memory pointed to by
+      // it's arguments with arbitrary offsets.  If we can prove there are no
+      // writes to this memory in the loop, we can hoist or sink.
+      if (AliasAnalysis::onlyAccessesArgPointees(Behavior)) {
+        for (Value *Op : CI->arg_operands())
+          if (Op->getType()->isPointerTy() &&
+              pointerInvalidatedByLoop(Op, MemoryLocation::UnknownSize,
+                                       AAMDNodes(), CurAST))
+            return false;
+        return true;
+      }
       // If this call only reads from memory and there are no writes to memory
       // in the loop, we can hoist or sink the call as appropriate.
       bool FoundMod = false;
@@ -576,7 +587,7 @@ static Instruction *CloneInstructionInExitBlock(const Instruction &I,
         if (!OLoop->contains(&PN)) {
           PHINode *OpPN =
               PHINode::Create(OInst->getType(), PN.getNumIncomingValues(),
-                              OInst->getName() + ".lcssa", ExitBlock.begin());
+                              OInst->getName() + ".lcssa", &ExitBlock.front());
           for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
             OpPN->addIncoming(OInst, PN.getIncomingBlock(i));
           *OI = OpPN;
@@ -661,6 +672,10 @@ static bool hoist(Instruction &I, BasicBlock *Preheader) {
   // Move the new node to the Preheader, before its terminator.
   I.moveBefore(Preheader->getTerminator());
 
+  // Metadata can be dependent on the condition we are hoisting above.
+  // Conservatively strip all metadata on the instruction.
+  I.dropUnknownNonDebugMetadata();
+
   if (isa<LoadInst>(I)) ++NumMovedLoads;
   else if (isa<CallInst>(I)) ++NumMovedCalls;
   ++NumHoisted;
@@ -740,9 +755,9 @@ namespace {
           if (!L->contains(BB)) {
             // We need to create an LCSSA PHI node for the incoming value and
             // store that.
-            PHINode *PN = PHINode::Create(
-                I->getType(), PredCache.size(BB),
-                I->getName() + ".lcssa", BB->begin());
+            PHINode *PN =
+                PHINode::Create(I->getType(), PredCache.size(BB),
+                                I->getName() + ".lcssa", &BB->front());
             for (BasicBlock *Pred : PredCache.get(BB))
               PN->addIncoming(I, Pred);
             return PN;
@@ -952,7 +967,7 @@ bool llvm::promoteLoopAccessesToScalars(AliasSet &AS,
     CurLoop->getUniqueExitBlocks(ExitBlocks);
     InsertPts.resize(ExitBlocks.size());
     for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
-      InsertPts[i] = ExitBlocks[i]->getFirstInsertionPt();
+      InsertPts[i] = &*ExitBlocks[i]->getFirstInsertionPt();
   }
 
   // We use the SSAUpdater interface to insert phi nodes as required.