[llvm-commits] [llvm] r40933 - /llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp

[Owen Anderson]

Author: resistor
Date: Wed Aug  8 12:58:56 2007
New Revision: 40933

URL: http://llvm.org/viewvc/llvm-project?rev=40933&view=rev
Log:
Small improvement: if a function doesn't access memory, we don't need to scan
it for potentially undeading pointers.

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

Modified: llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp?rev=40933&r1=40932&r2=40933&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp Wed Aug  8 12:58:56 2007
@@ -287,6 +287,13 @@
       deadPointers.erase(A);
       continue;
     } else if (CallSite::get(BBI).getInstruction() != 0) {
+      // If this call does not access memory, it can't
+      // be undeadifying any of our pointers.
+      CallSite CS = CallSite::get(BBI);
+      if (CS.getCalledFunction() &&
+          AA.doesNotAccessMemory(CS.getCalledFunction()))
+        continue;
+      
       // Remove any pointers made undead by the call from the dead set
       std::vector<Instruction*> dead;
       for (SmallPtrSet<AllocaInst*, 64>::iterator I = deadPointers.begin(),
@@ -298,8 +305,7 @@
                         TD.getTypeSize((*I)->getAllocatedType());     
         
         // See if the call site touches it
-        AliasAnalysis::ModRefResult A = AA.getModRefInfo(CallSite::get(BBI),
-                                                         *I, pointerSize);
+        AliasAnalysis::ModRefResult A = AA.getModRefInfo(CS, *I, pointerSize);
         if (A == AliasAnalysis::ModRef || A == AliasAnalysis::Ref)
           dead.push_back(*I);
       }