[llvm-commits] [llvm] r133035 - /llvm/trunk/lib/Transforms/Scalar/MemCpyOptimizer.cpp

[Eli Friedman]

Author: efriedma
Date: Tue Jun 14 20:25:56 2011
New Revision: 133035

URL: http://llvm.org/viewvc/llvm-project?rev=133035&view=rev
Log:
Stop using memdep for a check that didn't really make sense with memdep. In terms of specific issues, using memdep here checks irrelevant instructions and won't work properly once we start returning "unknown" more aggressively from memdep.


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

Modified: llvm/trunk/lib/Transforms/Scalar/MemCpyOptimizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/MemCpyOptimizer.cpp?rev=133035&r1=133034&r2=133035&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/MemCpyOptimizer.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/MemCpyOptimizer.cpp Tue Jun 14 20:25:56 2011
@@ -487,7 +487,8 @@
   // happen to be using a load-store pair to implement it, rather than
   // a memcpy.
   if (LoadInst *LI = dyn_cast<LoadInst>(SI->getOperand(0))) {
-    if (!LI->isVolatile() && LI->hasOneUse()) {
+    if (!LI->isVolatile() && LI->hasOneUse() &&
+        LI->getParent() == SI->getParent()) {
       MemDepResult ldep = MD->getDependency(LI);
       CallInst *C = 0;
       if (ldep.isClobber() && !isa<MemCpyInst>(ldep.getInst()))
@@ -496,17 +497,14 @@
       if (C) {
         // Check that nothing touches the dest of the "copy" between
         // the call and the store.
-        MemDepResult sdep = MD->getDependency(SI);
-        if (!sdep.isNonLocal() && !sdep.isUnknown()) {
-          bool FoundCall = false;
-          for (BasicBlock::iterator I = SI, E = sdep.getInst(); I != E; --I) {
-            if (&*I == C) {
-              FoundCall = true;
-              break;
-            }
-          }
-          if (!FoundCall)
+        AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
+        AliasAnalysis::Location StoreLoc = AA.getLocation(SI);
+        for (BasicBlock::iterator I = --BasicBlock::iterator(SI),
+                                  E = C; I != E; --I) {
+          if (AA.getModRefInfo(&*I, StoreLoc) != AliasAnalysis::NoModRef) {
             C = 0;
+            break;
+          }
         }
       }