for (unsigned SPIndex = 0, SPNum = SPs.getNumElements();
SPIndex < SPNum; ++SPIndex) {
DISubprogram SP(SPs.getElement(SPIndex));
- if (!SP.Verify())
+ assert((!SP || SP.isSubprogram()) &&
+ "A MDNode in subprograms of a CU should be null or a DISubprogram.");
+ if (!SP)
continue;
if (Function *F = SP.getFunction())
FunctionDIs[F] = SP;
// to pass in a smaller number of arguments into the new function.
//
std::vector<Value*> Args;
- while (!Fn.use_empty()) {
- CallSite CS(Fn.use_back());
+ for (Value::use_iterator I = Fn.use_begin(), E = Fn.use_end(); I != E; ) {
+ CallSite CS(*I++);
+ if (!CS)
+ continue;
Instruction *Call = CS.getInstruction();
// Pass all the same arguments.
if (DI != FunctionDIs.end())
DI->second.replaceFunction(NF);
+ // Fix up any BlockAddresses that refer to the function.
+ Fn.replaceAllUsesWith(ConstantExpr::getBitCast(NF, Fn.getType()));
+ // Delete the bitcast that we just created, so that NF does not
+ // appear to be address-taken.
+ NF->removeDeadConstantUsers();
// Finally, nuke the old function.
Fn.eraseFromParent();
return true;
if (Fn.isDeclaration() || Fn.mayBeOverridden())
return false;
- // Functions with local linkage should already have been handled.
- if (Fn.hasLocalLinkage())
+ // Functions with local linkage should already have been handled, except the
+ // fragile (variadic) ones which we can improve here.
+ if (Fn.hasLocalLinkage() && !Fn.getFunctionType()->isVarArg())
return false;
if (Fn.use_empty())
UseVector MaybeLiveArgUses;
for (Function::const_arg_iterator AI = F.arg_begin(),
E = F.arg_end(); AI != E; ++AI, ++i) {
- // See what the effect of this use is (recording any uses that cause
- // MaybeLive in MaybeLiveArgUses).
- Liveness Result = SurveyUses(AI, MaybeLiveArgUses);
+ Liveness Result;
+ if (F.getFunctionType()->isVarArg()) {
+ // Variadic functions will already have a va_arg function expanded inside
+ // them, making them potentially very sensitive to ABI changes resulting
+ // from removing arguments entirely, so don't. For example AArch64 handles
+ // register and stack HFAs very differently, and this is reflected in the
+ // IR which has already been generated.
+ Result = Live;
+ } else {
+ // See what the effect of this use is (recording any uses that cause
+ // MaybeLive in MaybeLiveArgUses).
+ Result = SurveyUses(AI, MaybeLiveArgUses);
+ }
+
// Mark the result.
MarkValue(CreateArg(&F, i), Result, MaybeLiveArgUses);
// Clear the vector again for the next iteration.
FunctionType *FTy = F->getFunctionType();
std::vector<Type*> Params;
+ // Keep track of if we have a live 'returned' argument
+ bool HasLiveReturnedArg = false;
+
// Set up to build a new list of parameter attributes.
SmallVector<AttributeSet, 8> AttributesVec;
const AttributeSet &PAL = F->getAttributes();
+ // Remember which arguments are still alive.
+ SmallVector<bool, 10> ArgAlive(FTy->getNumParams(), false);
+ // Construct the new parameter list from non-dead arguments. Also construct
+ // a new set of parameter attributes to correspond. Skip the first parameter
+ // attribute, since that belongs to the return value.
+ unsigned i = 0;
+ for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end();
+ I != E; ++I, ++i) {
+ RetOrArg Arg = CreateArg(F, i);
+ if (LiveValues.erase(Arg)) {
+ Params.push_back(I->getType());
+ ArgAlive[i] = true;
+
+ // Get the original parameter attributes (skipping the first one, that is
+ // for the return value.
+ if (PAL.hasAttributes(i + 1)) {
+ AttrBuilder B(PAL, i + 1);
+ if (B.contains(Attribute::Returned))
+ HasLiveReturnedArg = true;
+ AttributesVec.
+ push_back(AttributeSet::get(F->getContext(), Params.size(), B));
+ }
+ } else {
+ ++NumArgumentsEliminated;
+ DEBUG(dbgs() << "DAE - Removing argument " << i << " (" << I->getName()
+ << ") from " << F->getName() << "\n");
+ }
+ }
+
// Find out the new return value.
Type *RetTy = FTy->getReturnType();
Type *NRetTy = NULL;
// -1 means unused, other numbers are the new index
SmallVector<int, 5> NewRetIdxs(RetCount, -1);
std::vector<Type*> RetTypes;
- if (RetTy->isVoidTy()) {
+
+ // If there is a function with a live 'returned' argument but a dead return
+ // value, then there are two possible actions:
+ // 1) Eliminate the return value and take off the 'returned' attribute on the
+ // argument.
+ // 2) Retain the 'returned' attribute and treat the return value (but not the
+ // entire function) as live so that it is not eliminated.
+ //
+ // It's not clear in the general case which option is more profitable because,
+ // even in the absence of explicit uses of the return value, code generation
+ // is free to use the 'returned' attribute to do things like eliding
+ // save/restores of registers across calls. Whether or not this happens is
+ // target and ABI-specific as well as depending on the amount of register
+ // pressure, so there's no good way for an IR-level pass to figure this out.
+ //
+ // Fortunately, the only places where 'returned' is currently generated by
+ // the FE are places where 'returned' is basically free and almost always a
+ // performance win, so the second option can just be used always for now.
+ //
+ // This should be revisited if 'returned' is ever applied more liberally.
+ if (RetTy->isVoidTy() || HasLiveReturnedArg) {
NRetTy = RetTy;
} else {
StructType *STy = dyn_cast<StructType>(RetTy);
if (RAttrs.hasAttributes(AttributeSet::ReturnIndex))
AttributesVec.push_back(AttributeSet::get(NRetTy->getContext(), RAttrs));
- // Remember which arguments are still alive.
- SmallVector<bool, 10> ArgAlive(FTy->getNumParams(), false);
- // Construct the new parameter list from non-dead arguments. Also construct
- // a new set of parameter attributes to correspond. Skip the first parameter
- // attribute, since that belongs to the return value.
- unsigned i = 0;
- for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end();
- I != E; ++I, ++i) {
- RetOrArg Arg = CreateArg(F, i);
- if (LiveValues.erase(Arg)) {
- Params.push_back(I->getType());
- ArgAlive[i] = true;
-
- // Get the original parameter attributes (skipping the first one, that is
- // for the return value.
- if (PAL.hasAttributes(i + 1)) {
- AttrBuilder B(PAL, i + 1);
- AttributesVec.
- push_back(AttributeSet::get(F->getContext(), Params.size(), B));
- }
- } else {
- ++NumArgumentsEliminated;
- DEBUG(dbgs() << "DAE - Removing argument " << i << " (" << I->getName()
- << ") from " << F->getName() << "\n");
- }
- }
-
if (PAL.hasAttributes(AttributeSet::FunctionIndex))
AttributesVec.push_back(AttributeSet::get(F->getContext(),
PAL.getFnAttributes()));
// Get original parameter attributes, but skip return attributes.
if (CallPAL.hasAttributes(i + 1)) {
AttrBuilder B(CallPAL, i + 1);
+ // If the return type has changed, then get rid of 'returned' on the
+ // call site. The alternative is to make all 'returned' attributes on
+ // call sites keep the return value alive just like 'returned'
+ // attributes on function declaration but it's less clearly a win
+ // and this is not an expected case anyway
+ if (NRetTy != RetTy && B.contains(Attribute::Returned))
+ B.removeAttribute(Attribute::Returned);
AttributesVec.
push_back(AttributeSet::get(F->getContext(), Args.size(), B));
}
projects / oota-llvm.git / blobdiff