[llvm-commits] [llvm] r122787 - in /llvm/trunk/lib: Analysis/IPA/GlobalsModRef.cpp Analysis/NoAliasAnalysis.cpp Transforms/Scalar/GVN.cpp

[Owen Anderson]

Author: resistor
Date: Mon Jan  3 17:51:43 2011
New Revision: 122787

URL: http://llvm.org/viewvc/llvm-project?rev=122787&view=rev
Log:
Use the new addEscapingValue callback to update GlobalsModRef when GVN adds PHIs of GEPs. For the moment,
have GlobalsModRef handle this conservatively by simply removing the value from its maps.

Modified:
    llvm/trunk/lib/Analysis/IPA/GlobalsModRef.cpp
    llvm/trunk/lib/Analysis/NoAliasAnalysis.cpp
    llvm/trunk/lib/Transforms/Scalar/GVN.cpp

Modified: llvm/trunk/lib/Analysis/IPA/GlobalsModRef.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/IPA/GlobalsModRef.cpp?rev=122787&r1=122786&r2=122787&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/IPA/GlobalsModRef.cpp (original)
+++ llvm/trunk/lib/Analysis/IPA/GlobalsModRef.cpp Mon Jan  3 17:51:43 2011
@@ -152,6 +152,7 @@
 
     virtual void deleteValue(Value *V);
     virtual void copyValue(Value *From, Value *To);
+    virtual void addEscapingUse(Use &U);
 
     /// getAdjustedAnalysisPointer - This method is used when a pass implements
     /// an analysis interface through multiple inheritance.  If needed, it
@@ -596,3 +597,13 @@
 void GlobalsModRef::copyValue(Value *From, Value *To) {
   AliasAnalysis::copyValue(From, To);
 }
+
+void GlobalsModRef::addEscapingUse(Use &U) {
+  // For the purposes of this analysis, it is conservatively correct to treat
+  // a newly escaping value equivalently to a deleted one.  We could perhaps
+  // be more precise by processing the new use and attempting to update our
+  // saved analysis results to accomodate it.
+  deleteValue(U);
+  
+  AliasAnalysis::addEscapingUse(U);
+}

Modified: llvm/trunk/lib/Analysis/NoAliasAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/NoAliasAnalysis.cpp?rev=122787&r1=122786&r2=122787&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/NoAliasAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/NoAliasAnalysis.cpp Mon Jan  3 17:51:43 2011
@@ -65,6 +65,7 @@
 
     virtual void deleteValue(Value *V) {}
     virtual void copyValue(Value *From, Value *To) {}
+    virtual void addEscapingUse(Use &U) {}
     
     /// getAdjustedAnalysisPointer - This method is used when a pass implements
     /// an analysis interface through multiple inheritance.  If needed, it

Modified: llvm/trunk/lib/Transforms/Scalar/GVN.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/GVN.cpp?rev=122787&r1=122786&r2=122787&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/GVN.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/GVN.cpp Mon Jan  3 17:51:43 2011
@@ -1063,6 +1063,15 @@
   if (V->getType()->isPointerTy())
     for (unsigned i = 0, e = NewPHIs.size(); i != e; ++i)
       AA->copyValue(LI, NewPHIs[i]);
+    
+    // Now that we've copied information to the new PHIs, scan through
+    // them again and inform alias analysis that we've added potentially
+    // escaping uses to any values that are operands to these PHIs.
+    for (unsigned i = 0, e = NewPHIs.size(); i != e; ++i) {
+      PHINode *P = NewPHIs[i];
+      for (unsigned ii = 0, ee = P->getNumIncomingValues(); ii != ee; ++ii)
+        AA->addEscapingUse(P->getOperandUse(2*ii));
+    }
 
   return V;
 }
@@ -1957,8 +1966,16 @@
       insert_table(ValNo, Phi, CurrentBlock);
 
       CurInst->replaceAllUsesWith(Phi);
-      if (MD && Phi->getType()->isPointerTy())
-        MD->invalidateCachedPointerInfo(Phi);
+      if (Phi->getType()->isPointerTy()) {
+        // Because we have added a PHI-use of the pointer value, it has now
+        // "escaped" from alias analysis' perspective.  We need to inform
+        // AA of this.
+        for (unsigned ii = 0, ee = Phi->getNumIncomingValues(); ii != ee; ++ii)
+          VN.getAliasAnalysis()->addEscapingUse(Phi->getOperandUse(2*ii));
+        
+        if (MD)
+          MD->invalidateCachedPointerInfo(Phi);
+      }
       VN.erase(CurInst);
       erase_table(ValNo, CurInst, CurrentBlock);