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
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);
+}
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
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;
}
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);