Author: resistor
Date: Fri Jul 13 13:26:26 2007
New Revision: 39819
URL: http://llvm.org/viewvc/llvm-project?rev=39819&view=rev
Log:
Be more aggressive in removing dead stores, and in removing instructions
trivially dead after DSE.
This drastically improves the effect of FastDSE on kimwitu++.
Modified:
llvm/trunk/lib/Transforms/Scalar/FastDSE.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/FastDSE.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/FastDSE.cpp?rev=39819&r1=39818&r2=39819&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/FastDSE.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/FastDSE.cpp Fri Jul 13 13:26:26 2007
@@ -56,6 +56,14 @@
SetVector<Instruction*>& possiblyDead);
void DeleteDeadInstructionChains(Instruction *I,
SetVector<Instruction*> &DeadInsts);
+ void TranslatePointerBitCasts(Value*& v) {
+ assert(isa<PointerType>(v->getType()) && "Translating a non-pointer
type?");
+
+ // See through pointer-to-pointer bitcasts
+ while (BitCastInst* C = dyn_cast<BitCastInst>(v))
+ if (isa<PointerType>(C->getSrcTy()))
+ v = C->getOperand(0);
+ }
// getAnalysisUsage - We require post dominance frontiers (aka Control
// Dependence Graph)
@@ -93,6 +101,7 @@
pointer = S->getPointerOperand();
else if (FreeInst* F = dyn_cast<FreeInst>(BBI))
pointer = F->getPointerOperand();
+
assert(pointer && "Not a free or a store?");
StoreInst*& last = lastStore[pointer];
@@ -110,6 +119,8 @@
// DCE instructions only used to calculate that store
if (Instruction* D = dyn_cast<Instruction>(last->getOperand(0)))
possiblyDead.insert(D);
+ if (Instruction* D = dyn_cast<Instruction>(last->getOperand(1)))
+ possiblyDead.insert(D);
last->eraseFromParent();
NumFastStores++;
@@ -165,7 +176,7 @@
Value* depPointer = dependency->getPointerOperand();
unsigned depPointerSize =
TD.getTypeSize(dependency->getOperand(0)->getType());
-
+
// Check for aliasing
AliasAnalysis::AliasResult A = AA.alias(F->getPointerOperand(), ~0UL,
depPointer, depPointerSize);
@@ -177,6 +188,8 @@
// DCE instructions only used to calculate that store
if (Instruction* D = dyn_cast<Instruction>(dependency->getOperand(0)))
possiblyDead.insert(D);
+ if (Instruction* D = dyn_cast<Instruction>(dependency->getOperand(1)))
+ possiblyDead.insert(D);
dependency->eraseFromParent();
NumFastStores++;
@@ -216,23 +229,24 @@
// If we find a store whose pointer is dead...
if (StoreInst* S = dyn_cast<StoreInst>(BBI)) {
- if (deadPointers.count(S->getPointerOperand())){
+ Value* pointerOperand = S->getPointerOperand();
+ // See through pointer-to-pointer bitcasts
+ TranslatePointerBitCasts(pointerOperand);
+
+ if (deadPointers.count(pointerOperand)){
// Remove it!
MD.removeInstruction(S);
// DCE instructions only used to calculate that store
if (Instruction* D = dyn_cast<Instruction>(S->getOperand(0)))
possiblyDead.insert(D);
+ if (Instruction* D = dyn_cast<Instruction>(S->getOperand(1)))
+ possiblyDead.insert(D);
BBI++;
S->eraseFromParent();
NumFastStores++;
MadeChange = true;
-
- // If we can't trivially delete this store, consider it undead
- } else {
- killPointer = S->getPointerOperand();
- killPointerSize = TD.getTypeSize(S->getOperand(0)->getType());
}
// If we encounter a use of the pointer, it is no longer considered dead
@@ -261,7 +275,7 @@
// See if the call site touches it
AliasAnalysis::ModRefResult A = AA.getModRefInfo(CallSite::get(BBI),
*I, pointerSize);
- if (A != AliasAnalysis::NoModRef)
+ if (A == AliasAnalysis::ModRef || A == AliasAnalysis::Ref)
dead.push_back(*I);
}
@@ -315,6 +329,8 @@
// DCE instructions only used to calculate that store
if (Instruction* D = dyn_cast<Instruction>(S->getOperand(0)))
possiblyDead.insert(D);
+ if (Instruction* D = dyn_cast<Instruction>(S->getOperand(1)))
+ possiblyDead.insert(D);
BBI++;
S->eraseFromParent();
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