//===- GlobalsModRef.cpp - Simple Mod/Ref Analysis for Globals ------------===//
-//
+//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
-//
+//
//===----------------------------------------------------------------------===//
//
// This simple pass provides alias and mod/ref information for global values
return I->second;
return 0;
}
-
+
/// FunctionEffect - Capture whether or not this function reads or writes to
/// ANY memory. If not, we can do a lot of aggressive analysis on it.
unsigned FunctionEffect;
//------------------------------------------------
// Implement the AliasAnalysis API
- //
+ //
AliasResult alias(const Value *V1, unsigned V1Size,
const Value *V2, unsigned V2Size);
ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
if (FunctionRecord *FR = getFunctionInfo(F))
if (FR->FunctionEffect == 0)
return DoesNotAccessMemory;
- else if ((FR->FunctionEffect & Mod) == 0)
- return OnlyReadsMemory;
- return AliasAnalysis::getModRefBehavior(F, CS, Info);
+ else if ((FR->FunctionEffect & Mod) == 0)
+ return OnlyReadsMemory;
+ return AliasAnalysis::getModRefBehavior(F, CS, Info);
}
virtual void deleteValue(Value *V);
bool AnalyzeUsesOfGlobal(Value *V, std::vector<Function*> &Readers,
std::vector<Function*> &Writers);
};
-
+
RegisterOpt<GlobalsModRef> X("globalsmodref-aa",
"Simple mod/ref analysis for globals");
RegisterAnalysisGroup<AliasAnalysis, GlobalsModRef> Y;
Readers.clear(); Writers.clear();
}
- for (Module::global_iterator I = M.global_begin(), E = M.global_end(); I != E; ++I)
+ for (Module::global_iterator I = M.global_begin(), E = M.global_end();
+ I != E; ++I)
if (I->hasInternalLinkage()) {
if (!AnalyzeUsesOfGlobal(I, Readers, Writers)) {
// Remember that we are tracking this global, and the mod/ref fns
return true;
} else {
return true;
- }
+ }
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(*UI)) {
if (AnalyzeUsesOfGlobal(GV, Readers, Writers)) return true;
} else {
/// AnalyzeCallGraph - At this point, we know the functions where globals are
/// immediately stored to and read from. Propagate this information up the call
/// graph to all callers and compute the mod/ref info for all memory for each
-/// function.
+/// function.
void GlobalsModRef::AnalyzeCallGraph(CallGraph &CG, Module &M) {
// We do a bottom-up SCC traversal of the call graph. In other words, we
// visit all callees before callers (leaf-first).
for (unsigned i = 0, e = SCC.size(); i != e && !CallsExternal; ++i)
for (CallGraphNode::iterator CI = SCC[i]->begin(), E = SCC[i]->end();
CI != E; ++CI)
- if (Function *Callee = (*CI)->getFunction()) {
+ if (Function *Callee = CI->second->getFunction()) {
if (FunctionRecord *CalleeFR = getFunctionInfo(Callee)) {
// Propagate function effect up.
FunctionEffect |= CalleeFR->FunctionEffect;
ModRefBehavior MRB =
AliasAnalysis::getModRefBehavior(Callee, CallSite());
if (MRB != DoesNotAccessMemory) {
- if (MRB == OnlyReadsMemory) {
- // This reads memory, but we don't know what, just say that it
- // reads all globals.
- for (std::map<GlobalValue*, unsigned>::iterator
- GI = CalleeFR->GlobalInfo.begin(),
- E = CalleeFR->GlobalInfo.end();
- GI != E; ++GI)
- FR.GlobalInfo[GI->first] |= Ref;
-
- } else {
- CallsExternal = true;
- break;
- }
+ // FIXME: could make this more aggressive for functions that just
+ // read memory. We should just say they read all globals.
+ CallsExternal = true;
+ break;
}
}
} else {
FunctionInfo.erase(SCC[i]->getFunction());
return;
}
-
+
// Otherwise, unless we already know that this function mod/refs memory, scan
// the function bodies to see if there are any explicit loads or stores.
if (FunctionEffect != ModRef) {
for (unsigned i = 0, e = SCC.size(); i != e && FunctionEffect != ModRef;++i)
for (inst_iterator II = inst_begin(SCC[i]->getFunction()),
- E = inst_end(SCC[i]->getFunction());
+ E = inst_end(SCC[i]->getFunction());
II != E && FunctionEffect != ModRef; ++II)
if (isa<LoadInst>(*II))
FunctionEffect |= Ref;
else if (isa<StoreInst>(*II))
FunctionEffect |= Mod;
+ else if (isa<MallocInst>(*II) || isa<FreeInst>(*II))
+ FunctionEffect |= ModRef;
}
if ((FunctionEffect & Mod) == 0)
// If we are at some type of object... return it.
if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) return GV;
-
+
// Traverse through different addressing mechanisms...
if (const Instruction *I = dyn_cast<Instruction>(V)) {
if (isa<CastInst>(I) || isa<GetElementPtrInst>(I))