Extend the AliasAnalysis::pointsToConstantMemory interface to allow it
to optionally look for constant or local (alloca) memory.
Teach BasicAliasAnalysis::pointsToConstantMemory to look through Select
and Phi nodes, and to support looking for local memory.
Remove FunctionAttrs' PointsToLocalOrConstantMemory function, now that
AliasAnalysis knows all the tricks that it knew.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118412 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/FunctionAttrs.cpp b/lib/Transforms/IPO/FunctionAttrs.cpp
index 062e366..be5d827 100644
--- a/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -66,8 +66,6 @@
CallGraphSCCPass::getAnalysisUsage(AU);
}
- bool PointsToLocalOrConstantMemory(Value *V);
-
private:
AliasAnalysis *AA;
};
@@ -83,53 +81,6 @@
Pass *llvm::createFunctionAttrsPass() { return new FunctionAttrs(); }
-/// PointsToLocalOrConstantMemory - Returns whether the given pointer value
-/// points to memory that is local to the function, with global constants being
-/// considered local to all functions.
-bool FunctionAttrs::PointsToLocalOrConstantMemory(Value *V) {
- SmallVector<Value*, 16> Worklist;
- unsigned MaxLookup = 8;
-
- Worklist.push_back(V);
-
- do {
- V = Worklist.pop_back_val()->getUnderlyingObject();
-
- // An alloca instruction defines local memory.
- if (isa<AllocaInst>(V))
- continue;
-
- // A global constant counts as local memory for our purposes.
- if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
- if (!GV->isConstant())
- return false;
- continue;
- }
-
- // If both select values point to local memory, then so does the select.
- if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
- Worklist.push_back(SI->getTrueValue());
- Worklist.push_back(SI->getFalseValue());
- continue;
- }
-
- // If all values incoming to a phi node point to local memory, then so does
- // the phi.
- if (PHINode *PN = dyn_cast<PHINode>(V)) {
- // Don't bother inspecting phi nodes with many operands.
- if (PN->getNumIncomingValues() > MaxLookup)
- return false;
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
- Worklist.push_back(PN->getIncomingValue(i));
- continue;
- }
-
- return false;
- } while (!Worklist.empty() && --MaxLookup);
-
- return Worklist.empty();
-}
-
/// AddReadAttrs - Deduce readonly/readnone attributes for the SCC.
bool FunctionAttrs::AddReadAttrs(const CallGraphSCC &SCC) {
SmallPtrSet<Function*, 8> SCCNodes;
@@ -190,7 +141,7 @@
CI != CE; ++CI) {
Value *Arg = *CI;
if (Arg->getType()->isPointerTy() &&
- !PointsToLocalOrConstantMemory(Arg))
+ !AA->pointsToConstantMemory(Arg, /*OrLocal=*/true))
// Writes memory. Just give up.
return false;
}
@@ -203,12 +154,14 @@
} else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
// Ignore non-volatile loads from local memory.
if (!LI->isVolatile() &&
- PointsToLocalOrConstantMemory(LI->getPointerOperand()))
+ AA->pointsToConstantMemory(LI->getPointerOperand(),
+ /*OrLocal=*/true))
continue;
} else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
// Ignore non-volatile stores to local memory.
if (!SI->isVolatile() &&
- PointsToLocalOrConstantMemory(SI->getPointerOperand()))
+ AA->pointsToConstantMemory(SI->getPointerOperand(),
+ /*OrLocal=*/true))
continue;
}