[llvm-commits] [llvm] r94433 - in /llvm/trunk: include/llvm/Value.h lib/Transforms/Scalar/ScalarReplAggregates.cpp lib/VMCore/Value.cpp

[Bob Wilson]

Author: bwilson
Date: Mon Jan 25 12:26:54 2010
New Revision: 94433

URL: http://llvm.org/viewvc/llvm-project?rev=94433&view=rev
Log:
Change Value::getUnderlyingObject to have the MaxLookup value specified as a
parameter with a default value, instead of just hardcoding it in the
implementation.  The limit of MaxLookup = 6 was introduced in r69151 to fix
a performance problem with O(n^2) behavior in instcombine, but the scalarrepl
pass is relying on getUnderlyingObject to go all the way back to an AllocaInst.
Making the limit part of the method signature makes it clear that by default
the result is limited and should help avoid similar problems in the future.
This fixes pr6126.

Modified:
    llvm/trunk/include/llvm/Value.h
    llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp
    llvm/trunk/lib/VMCore/Value.cpp

Modified: llvm/trunk/include/llvm/Value.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Value.h?rev=94433&r1=94432&r2=94433&view=diff

==============================================================================
--- llvm/trunk/include/llvm/Value.h (original)
+++ llvm/trunk/include/llvm/Value.h Mon Jan 25 12:26:54 2010
@@ -285,10 +285,11 @@
   /// getUnderlyingObject - This method strips off any GEP address adjustments
   /// and pointer casts from the specified value, returning the original object
   /// being addressed.  Note that the returned value has pointer type if the
-  /// specified value does.
-  Value *getUnderlyingObject();
-  const Value *getUnderlyingObject() const {
-    return const_cast<Value*>(this)->getUnderlyingObject();
+  /// specified value does.  If the MaxLookup value is non-zero, it limits the
+  /// number of instructions to be stripped off.
+  Value *getUnderlyingObject(unsigned MaxLookup = 6);
+  const Value *getUnderlyingObject(unsigned MaxLookup = 6) const {
+    return const_cast<Value*>(this)->getUnderlyingObject(MaxLookup);
   }
   
   /// DoPHITranslation - If this value is a PHI node with CurBB as its parent,

Modified: llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp?rev=94433&r1=94432&r2=94433&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/ScalarReplAggregates.cpp Mon Jan 25 12:26:54 2010
@@ -1384,9 +1384,9 @@
       // If the source and destination are both to the same alloca, then this is
       // a noop copy-to-self, just delete it.  Otherwise, emit a load and store
       // as appropriate.
-      AllocaInst *OrigAI = cast<AllocaInst>(Ptr->getUnderlyingObject());
+      AllocaInst *OrigAI = cast<AllocaInst>(Ptr->getUnderlyingObject(0));
       
-      if (MTI->getSource()->getUnderlyingObject() != OrigAI) {
+      if (MTI->getSource()->getUnderlyingObject(0) != OrigAI) {
         // Dest must be OrigAI, change this to be a load from the original
         // pointer (bitcasted), then a store to our new alloca.
         assert(MTI->getRawDest() == Ptr && "Neither use is of pointer?");
@@ -1396,7 +1396,7 @@
         LoadInst *SrcVal = Builder.CreateLoad(SrcPtr, "srcval");
         SrcVal->setAlignment(MTI->getAlignment());
         Builder.CreateStore(SrcVal, NewAI);
-      } else if (MTI->getDest()->getUnderlyingObject() != OrigAI) {
+      } else if (MTI->getDest()->getUnderlyingObject(0) != OrigAI) {
         // Src must be OrigAI, change this to be a load from NewAI then a store
         // through the original dest pointer (bitcasted).
         assert(MTI->getRawSource() == Ptr && "Neither use is of pointer?");

Modified: llvm/trunk/lib/VMCore/Value.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/VMCore/Value.cpp?rev=94433&r1=94432&r2=94433&view=diff

==============================================================================
--- llvm/trunk/lib/VMCore/Value.cpp (original)
+++ llvm/trunk/lib/VMCore/Value.cpp Mon Jan 25 12:26:54 2010
@@ -341,12 +341,11 @@
   } while (1);
 }
 
-Value *Value::getUnderlyingObject() {
+Value *Value::getUnderlyingObject(unsigned MaxLookup) {
   if (!isa<PointerType>(getType()))
     return this;
   Value *V = this;
-  unsigned MaxLookup = 6;
-  do {
+  for (unsigned Count = 0; MaxLookup == 0 || Count < MaxLookup; ++Count) {
     if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
       V = GEP->getPointerOperand();
     } else if (Operator::getOpcode(V) == Instruction::BitCast) {
@@ -359,7 +358,7 @@
       return V;
     }
     assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
-  } while (--MaxLookup);
+  }
   return V;
 }