//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "deadargelim"
#include "llvm/Transforms/IPO.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
-#include "llvm/CallingConv.h"
-#include "llvm/Constant.h"
-#include "llvm/DIBuilder.h"
-#include "llvm/DebugInfo.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/Instructions.h"
-#include "llvm/IntrinsicInst.h"
-#include "llvm/LLVMContext.h"
-#include "llvm/Module.h"
+#include "llvm/IR/CallSite.h"
+#include "llvm/IR/CallingConv.h"
+#include "llvm/IR/Constant.h"
+#include "llvm/IR/DIBuilder.h"
+#include "llvm/IR/DebugInfo.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
-#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <map>
#include <set>
+#include <tuple>
using namespace llvm;
+#define DEBUG_TYPE "deadargelim"
+
STATISTIC(NumArgumentsEliminated, "Number of unread args removed");
STATISTIC(NumRetValsEliminated , "Number of unused return values removed");
STATISTIC(NumArgumentsReplacedWithUndef,
/// Make RetOrArg comparable, so we can put it into a map.
bool operator<(const RetOrArg &O) const {
- if (F != O.F)
- return F < O.F;
- else if (Idx != O.Idx)
- return Idx < O.Idx;
- else
- return IsArg < O.IsArg;
+ return std::tie(F, Idx, IsArg) < std::tie(O.F, O.Idx, O.IsArg);
}
/// Make RetOrArg comparable, so we can easily iterate the multimap.
// As the code generation for module is finished (and DIBuilder is
// finalized) we assume that subprogram descriptors won't be changed, and
// they are stored in map for short duration anyway.
- typedef DenseMap<Function*, DISubprogram> FunctionDIMap;
- FunctionDIMap FunctionDIs;
+ DenseMap<const Function *, DISubprogram> FunctionDIs;
protected:
// DAH uses this to specify a different ID.
initializeDAEPass(*PassRegistry::getPassRegistry());
}
- bool runOnModule(Module &M);
+ bool runOnModule(Module &M) override;
virtual bool ShouldHackArguments() const { return false; }
private:
Liveness MarkIfNotLive(RetOrArg Use, UseVector &MaybeLiveUses);
- Liveness SurveyUse(Value::const_use_iterator U, UseVector &MaybeLiveUses,
+ Liveness SurveyUse(const Use *U, UseVector &MaybeLiveUses,
unsigned RetValNum = 0);
Liveness SurveyUses(const Value *V, UseVector &MaybeLiveUses);
- void CollectFunctionDIs(Module &M);
void SurveyFunction(const Function &F);
void MarkValue(const RetOrArg &RA, Liveness L,
const UseVector &MaybeLiveUses);
static char ID;
DAH() : DAE(ID) {}
- virtual bool ShouldHackArguments() const { return true; }
+ bool ShouldHackArguments() const override { return true; }
};
}
ModulePass *llvm::createDeadArgEliminationPass() { return new DAE(); }
ModulePass *llvm::createDeadArgHackingPass() { return new DAH(); }
-/// CollectFunctionDIs - Map each function in the module to its debug info
-/// descriptor.
-void DAE::CollectFunctionDIs(Module &M) {
- FunctionDIs.clear();
-
- for (Module::named_metadata_iterator I = M.named_metadata_begin(),
- E = M.named_metadata_end(); I != E; ++I) {
- NamedMDNode &NMD = *I;
- for (unsigned MDIndex = 0, MDNum = NMD.getNumOperands();
- MDIndex < MDNum; ++MDIndex) {
- MDNode *Node = NMD.getOperand(MDIndex);
- if (!DIDescriptor(Node).isCompileUnit())
- continue;
- DICompileUnit CU(Node);
- const DIArray &SPs = CU.getSubprograms();
- for (unsigned SPIndex = 0, SPNum = SPs.getNumElements();
- SPIndex < SPNum; ++SPIndex) {
- DISubprogram SP(SPs.getElement(SPIndex));
- if (!SP.Verify())
- continue;
- if (Function *F = SP.getFunction())
- FunctionDIs[F] = SP;
- }
- }
- }
-}
-
/// DeleteDeadVarargs - If this is an function that takes a ... list, and if
/// llvm.vastart is never called, the varargs list is dead for the function.
bool DAE::DeleteDeadVarargs(Function &Fn) {
return false;
// Okay, we know we can transform this function if safe. Scan its body
- // looking for calls to llvm.vastart.
+ // looking for calls marked musttail or calls to llvm.vastart.
for (Function::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) {
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
- if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
+ CallInst *CI = dyn_cast<CallInst>(I);
+ if (!CI)
+ continue;
+ if (CI->isMustTailCall())
+ return false;
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI)) {
if (II->getIntrinsicID() == Intrinsic::vastart)
return false;
}
// 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::user_iterator I = Fn.user_begin(), E = Fn.user_end(); I != E; ) {
+ CallSite CS(*I++);
+ if (!CS)
+ continue;
Instruction *Call = CS.getInstruction();
// Pass all the same arguments.
// Drop any attributes that were on the vararg arguments.
AttributeSet PAL = CS.getAttributes();
- if (!PAL.isEmpty() && PAL.getSlot(PAL.getNumSlots() - 1).Index > NumArgs) {
- SmallVector<AttributeWithIndex, 8> AttributesVec;
- for (unsigned i = 0; PAL.getSlot(i).Index <= NumArgs; ++i)
- AttributesVec.push_back(PAL.getSlot(i));
- Attributes FnAttrs = PAL.getFnAttributes();
- if (FnAttrs.hasAttributes())
- AttributesVec.push_back(AttributeWithIndex::get(AttributeSet::FunctionIndex,
- FnAttrs));
+ if (!PAL.isEmpty() && PAL.getSlotIndex(PAL.getNumSlots() - 1) > NumArgs) {
+ SmallVector<AttributeSet, 8> AttributesVec;
+ for (unsigned i = 0; PAL.getSlotIndex(i) <= NumArgs; ++i)
+ AttributesVec.push_back(PAL.getSlotAttributes(i));
+ if (PAL.hasAttributes(AttributeSet::FunctionIndex))
+ AttributesVec.push_back(AttributeSet::get(Fn.getContext(),
+ PAL.getFnAttributes()));
PAL = AttributeSet::get(Fn.getContext(), AttributesVec);
}
}
// Patch the pointer to LLVM function in debug info descriptor.
- FunctionDIMap::iterator DI = FunctionDIs.find(&Fn);
- if (DI != FunctionDIs.end())
- DI->second.replaceFunction(NF);
+ auto DI = FunctionDIs.find(&Fn);
+ if (DI != FunctionDIs.end()) {
+ DISubprogram SP = DI->second;
+ SP.replaceFunction(NF);
+ // Ensure the map is updated so it can be reused on non-varargs argument
+ // eliminations of the same function.
+ FunctionDIs.erase(DI);
+ FunctionDIs[NF] = SP;
+ }
+ // 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 a function seen at compile time is not necessarily the one linked to
+ // the binary being built, it is illegal to change the actual arguments
+ // passed to it. These functions can be captured by isWeakForLinker().
+ // *NOTE* that mayBeOverridden() is insufficient for this purpose as it
+ // doesn't include linkage types like AvailableExternallyLinkage and
+ // LinkOnceODRLinkage. Take link_odr* as an example, it indicates a set of
+ // *EQUIVALENT* globals that can be merged at link-time. However, the
+ // semantic of *EQUIVALENT*-functions includes parameters. Changing
+ // parameters breaks this assumption.
+ //
+ if (Fn.isWeakForLinker())
return false;
if (Fn.use_empty())
return false;
- llvm::SmallVector<unsigned, 8> UnusedArgs;
+ SmallVector<unsigned, 8> UnusedArgs;
for (Function::arg_iterator I = Fn.arg_begin(), E = Fn.arg_end();
I != E; ++I) {
Argument *Arg = I;
- if (Arg->use_empty() && !Arg->hasByValAttr())
+ if (Arg->use_empty() && !Arg->hasByValOrInAllocaAttr())
UnusedArgs.push_back(Arg->getArgNo());
}
bool Changed = false;
- for (Function::use_iterator I = Fn.use_begin(), E = Fn.use_end();
- I != E; ++I) {
- CallSite CS(*I);
- if (!CS || !CS.isCallee(I))
+ for (Use &U : Fn.uses()) {
+ CallSite CS(U.getUser());
+ if (!CS || !CS.isCallee(&U))
continue;
// Now go through all unused args and replace them with "undef".
/// for void functions and 1 for functions not returning a struct. It returns
/// the number of struct elements for functions returning a struct.
static unsigned NumRetVals(const Function *F) {
- if (F->getReturnType()->isVoidTy())
+ Type *RetTy = F->getReturnType();
+ if (RetTy->isVoidTy())
return 0;
- else if (StructType *STy = dyn_cast<StructType>(F->getReturnType()))
+ else if (StructType *STy = dyn_cast<StructType>(RetTy))
return STy->getNumElements();
+ else if (ArrayType *ATy = dyn_cast<ArrayType>(RetTy))
+ return ATy->getNumElements();
else
return 1;
}
+/// Returns the sub-type a function will return at a given Idx. Should
+/// correspond to the result type of an ExtractValue instruction executed with
+/// just that one Idx (i.e. only top-level structure is considered).
+static Type *getRetComponentType(const Function *F, unsigned Idx) {
+ Type *RetTy = F->getReturnType();
+ assert(!RetTy->isVoidTy() && "void type has no subtype");
+
+ if (StructType *STy = dyn_cast<StructType>(RetTy))
+ return STy->getElementType(Idx);
+ else if (ArrayType *ATy = dyn_cast<ArrayType>(RetTy))
+ return ATy->getElementType();
+ else
+ return RetTy;
+}
+
/// MarkIfNotLive - This checks Use for liveness in LiveValues. If Use is not
/// live, it adds Use to the MaybeLiveUses argument. Returns the determined
/// liveness of Use.
/// RetValNum is the return value number to use when this use is used in a
/// return instruction. This is used in the recursion, you should always leave
/// it at 0.
-DAE::Liveness DAE::SurveyUse(Value::const_use_iterator U,
+DAE::Liveness DAE::SurveyUse(const Use *U,
UseVector &MaybeLiveUses, unsigned RetValNum) {
- const User *V = *U;
+ const User *V = U->getUser();
if (const ReturnInst *RI = dyn_cast<ReturnInst>(V)) {
// The value is returned from a function. It's only live when the
// function's return value is live. We use RetValNum here, for the case
return MarkIfNotLive(Use, MaybeLiveUses);
}
if (const InsertValueInst *IV = dyn_cast<InsertValueInst>(V)) {
- if (U.getOperandNo() != InsertValueInst::getAggregateOperandIndex()
+ if (U->getOperandNo() != InsertValueInst::getAggregateOperandIndex()
&& IV->hasIndices())
// The use we are examining is inserted into an aggregate. Our liveness
// depends on all uses of that aggregate, but if it is used as a return
// we don't change RetValNum, but do survey all our uses.
Liveness Result = MaybeLive;
- for (Value::const_use_iterator I = IV->use_begin(),
- E = V->use_end(); I != E; ++I) {
- Result = SurveyUse(I, MaybeLiveUses, RetValNum);
+ for (const Use &UU : IV->uses()) {
+ Result = SurveyUse(&UU, MaybeLiveUses, RetValNum);
if (Result == Live)
break;
}
return Live;
assert(CS.getArgument(ArgNo)
- == CS->getOperand(U.getOperandNo())
+ == CS->getOperand(U->getOperandNo())
&& "Argument is not where we expected it");
// Value passed to a normal call. It's only live when the corresponding
// Assume it's dead (which will only hold if there are no uses at all..).
Liveness Result = MaybeLive;
// Check each use.
- for (Value::const_use_iterator I = V->use_begin(),
- E = V->use_end(); I != E; ++I) {
- Result = SurveyUse(I, MaybeLiveUses);
+ for (const Use &U : V->uses()) {
+ Result = SurveyUse(&U, MaybeLiveUses);
if (Result == Live)
break;
}
// well as arguments to functions which have their "address taken".
//
void DAE::SurveyFunction(const Function &F) {
+ // Functions with inalloca parameters are expecting args in a particular
+ // register and memory layout.
+ if (F.getAttributes().hasAttrSomewhere(Attribute::InAlloca)) {
+ MarkLive(F);
+ return;
+ }
+
unsigned RetCount = NumRetVals(&F);
// Assume all return values are dead
typedef SmallVector<Liveness, 5> RetVals;
// Keep track of the number of live retvals, so we can skip checks once all
// of them turn out to be live.
unsigned NumLiveRetVals = 0;
- Type *STy = dyn_cast<StructType>(F.getReturnType());
// Loop all uses of the function.
- for (Value::const_use_iterator I = F.use_begin(), E = F.use_end();
- I != E; ++I) {
+ for (const Use &U : F.uses()) {
// If the function is PASSED IN as an argument, its address has been
// taken.
- ImmutableCallSite CS(*I);
- if (!CS || !CS.isCallee(I)) {
+ ImmutableCallSite CS(U.getUser());
+ if (!CS || !CS.isCallee(&U)) {
MarkLive(F);
return;
}
// Now, check how our return value(s) is/are used in this caller. Don't
// bother checking return values if all of them are live already.
- if (NumLiveRetVals != RetCount) {
- if (STy) {
- // Check all uses of the return value.
- for (Value::const_use_iterator I = TheCall->use_begin(),
- E = TheCall->use_end(); I != E; ++I) {
- const ExtractValueInst *Ext = dyn_cast<ExtractValueInst>(*I);
- if (Ext && Ext->hasIndices()) {
- // This use uses a part of our return value, survey the uses of
- // that part and store the results for this index only.
- unsigned Idx = *Ext->idx_begin();
- if (RetValLiveness[Idx] != Live) {
- RetValLiveness[Idx] = SurveyUses(Ext, MaybeLiveRetUses[Idx]);
- if (RetValLiveness[Idx] == Live)
- NumLiveRetVals++;
- }
- } else {
- // Used by something else than extractvalue. Mark all return
- // values as live.
- for (unsigned i = 0; i != RetCount; ++i )
- RetValLiveness[i] = Live;
- NumLiveRetVals = RetCount;
- break;
- }
+ if (NumLiveRetVals == RetCount)
+ continue;
+
+ // Check all uses of the return value.
+ for (const Use &U : TheCall->uses()) {
+ if (ExtractValueInst *Ext = dyn_cast<ExtractValueInst>(U.getUser())) {
+ // This use uses a part of our return value, survey the uses of
+ // that part and store the results for this index only.
+ unsigned Idx = *Ext->idx_begin();
+ if (RetValLiveness[Idx] != Live) {
+ RetValLiveness[Idx] = SurveyUses(Ext, MaybeLiveRetUses[Idx]);
+ if (RetValLiveness[Idx] == Live)
+ NumLiveRetVals++;
}
} else {
- // Single return value
- RetValLiveness[0] = SurveyUses(TheCall, MaybeLiveRetUses[0]);
- if (RetValLiveness[0] == Live)
+ // Used by something else than extractvalue. Survey, but assume that the
+ // result applies to all sub-values.
+ UseVector MaybeLiveAggregateUses;
+ if (SurveyUse(&U, MaybeLiveAggregateUses) == Live) {
NumLiveRetVals = RetCount;
+ RetValLiveness.assign(RetCount, Live);
+ break;
+ } else {
+ for (unsigned i = 0; i != RetCount; ++i) {
+ if (RetValLiveness[i] != Live)
+ MaybeLiveRetUses[i].append(MaybeLiveAggregateUses.begin(),
+ MaybeLiveAggregateUses.end());
+ }
+ }
}
}
}
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<AttributeWithIndex, 8> AttributesVec;
+ SmallVector<AttributeSet, 8> AttributesVec;
const AttributeSet &PAL = F->getAttributes();
- // The existing function return attributes.
- Attributes RAttrs = PAL.getRetAttributes();
- Attributes FnAttrs = PAL.getFnAttributes();
+ // 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;
- // Find out the new return value.
+ // 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;
+ Type *NRetTy = nullptr;
unsigned RetCount = NumRetVals(F);
// -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 (STy)
- // Look at each of the original return values individually.
- for (unsigned i = 0; i != RetCount; ++i) {
- RetOrArg Ret = CreateRet(F, i);
- if (LiveValues.erase(Ret)) {
- RetTypes.push_back(STy->getElementType(i));
- NewRetIdxs[i] = RetTypes.size() - 1;
- } else {
- ++NumRetValsEliminated;
- DEBUG(dbgs() << "DAE - Removing return value " << i << " from "
- << F->getName() << "\n");
- }
- }
- else
- // We used to return a single value.
- if (LiveValues.erase(CreateRet(F, 0))) {
- RetTypes.push_back(RetTy);
- NewRetIdxs[0] = 0;
+ // Look at each of the original return values individually.
+ for (unsigned i = 0; i != RetCount; ++i) {
+ RetOrArg Ret = CreateRet(F, i);
+ if (LiveValues.erase(Ret)) {
+ RetTypes.push_back(getRetComponentType(F, i));
+ NewRetIdxs[i] = RetTypes.size() - 1;
} else {
- DEBUG(dbgs() << "DAE - Removing return value from " << F->getName()
- << "\n");
++NumRetValsEliminated;
+ DEBUG(dbgs() << "DAE - Removing return value " << i << " from "
+ << F->getName() << "\n");
+ }
+ }
+ if (RetTypes.size() > 1) {
+ // More than one return type? Reduce it down to size.
+ if (StructType *STy = dyn_cast<StructType>(RetTy)) {
+ // Make the new struct packed if we used to return a packed struct
+ // already.
+ NRetTy = StructType::get(STy->getContext(), RetTypes, STy->isPacked());
+ } else {
+ assert(isa<ArrayType>(RetTy) && "unexpected multi-value return");
+ NRetTy = ArrayType::get(RetTypes[0], RetTypes.size());
}
- if (RetTypes.size() > 1)
- // More than one return type? Return a struct with them. Also, if we used
- // to return a struct and didn't change the number of return values,
- // return a struct again. This prevents changing {something} into
- // something and {} into void.
- // Make the new struct packed if we used to return a packed struct
- // already.
- NRetTy = StructType::get(STy->getContext(), RetTypes, STy->isPacked());
- else if (RetTypes.size() == 1)
+ } else if (RetTypes.size() == 1)
// One return type? Just a simple value then, but only if we didn't use to
// return a struct with that simple value before.
NRetTy = RetTypes.front();
assert(NRetTy && "No new return type found?");
+ // The existing function return attributes.
+ AttributeSet RAttrs = PAL.getRetAttributes();
+
// Remove any incompatible attributes, but only if we removed all return
// values. Otherwise, ensure that we don't have any conflicting attributes
// here. Currently, this should not be possible, but special handling might be
// required when new return value attributes are added.
if (NRetTy->isVoidTy())
RAttrs =
- Attributes::get(NRetTy->getContext(), AttrBuilder(RAttrs).
- removeAttributes(Attributes::typeIncompatible(NRetTy)));
+ AttributeSet::get(NRetTy->getContext(), AttributeSet::ReturnIndex,
+ AttrBuilder(RAttrs, AttributeSet::ReturnIndex).
+ removeAttributes(AttributeFuncs::
+ typeIncompatible(NRetTy, AttributeSet::ReturnIndex),
+ AttributeSet::ReturnIndex));
else
- assert(!AttrBuilder(RAttrs).
- hasAttributes(Attributes::typeIncompatible(NRetTy)) &&
+ assert(!AttrBuilder(RAttrs, AttributeSet::ReturnIndex).
+ hasAttributes(AttributeFuncs::
+ typeIncompatible(NRetTy, AttributeSet::ReturnIndex),
+ AttributeSet::ReturnIndex) &&
"Return attributes no longer compatible?");
- if (RAttrs.hasAttributes())
- AttributesVec.push_back(AttributeWithIndex::get(AttributeSet::ReturnIndex,
- 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.
- Attributes Attrs = PAL.getParamAttributes(i + 1);
- if (Attrs.hasAttributes())
- AttributesVec.push_back(AttributeWithIndex::get(Params.size(), Attrs));
- } else {
- ++NumArgumentsEliminated;
- DEBUG(dbgs() << "DAE - Removing argument " << i << " (" << I->getName()
- << ") from " << F->getName() << "\n");
- }
- }
+ if (RAttrs.hasAttributes(AttributeSet::ReturnIndex))
+ AttributesVec.push_back(AttributeSet::get(NRetTy->getContext(), RAttrs));
- if (FnAttrs.hasAttributes())
- AttributesVec.push_back(AttributeWithIndex::get(AttributeSet::FunctionIndex,
- FnAttrs));
+ if (PAL.hasAttributes(AttributeSet::FunctionIndex))
+ AttributesVec.push_back(AttributeSet::get(F->getContext(),
+ PAL.getFnAttributes()));
// Reconstruct the AttributesList based on the vector we constructed.
AttributeSet NewPAL = AttributeSet::get(F->getContext(), AttributesVec);
//
std::vector<Value*> Args;
while (!F->use_empty()) {
- CallSite CS(F->use_back());
+ CallSite CS(F->user_back());
Instruction *Call = CS.getInstruction();
AttributesVec.clear();
const AttributeSet &CallPAL = CS.getAttributes();
// The call return attributes.
- Attributes RAttrs = CallPAL.getRetAttributes();
- Attributes FnAttrs = CallPAL.getFnAttributes();
+ AttributeSet RAttrs = CallPAL.getRetAttributes();
+
// Adjust in case the function was changed to return void.
RAttrs =
- Attributes::get(NF->getContext(), AttrBuilder(RAttrs).
- removeAttributes(Attributes::typeIncompatible(NF->getReturnType())));
- if (RAttrs.hasAttributes())
- AttributesVec.push_back(AttributeWithIndex::get(AttributeSet::ReturnIndex,
- RAttrs));
+ AttributeSet::get(NF->getContext(), AttributeSet::ReturnIndex,
+ AttrBuilder(RAttrs, AttributeSet::ReturnIndex).
+ removeAttributes(AttributeFuncs::
+ typeIncompatible(NF->getReturnType(),
+ AttributeSet::ReturnIndex),
+ AttributeSet::ReturnIndex));
+ if (RAttrs.hasAttributes(AttributeSet::ReturnIndex))
+ AttributesVec.push_back(AttributeSet::get(NF->getContext(), RAttrs));
// Declare these outside of the loops, so we can reuse them for the second
// loop, which loops the varargs.
if (ArgAlive[i]) {
Args.push_back(*I);
// Get original parameter attributes, but skip return attributes.
- Attributes Attrs = CallPAL.getParamAttributes(i + 1);
- if (Attrs.hasAttributes())
- AttributesVec.push_back(AttributeWithIndex::get(Args.size(), Attrs));
+ 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));
+ }
}
// Push any varargs arguments on the list. Don't forget their attributes.
for (CallSite::arg_iterator E = CS.arg_end(); I != E; ++I, ++i) {
Args.push_back(*I);
- Attributes Attrs = CallPAL.getParamAttributes(i + 1);
- if (Attrs.hasAttributes())
- AttributesVec.push_back(AttributeWithIndex::get(Args.size(), Attrs));
+ if (CallPAL.hasAttributes(i + 1)) {
+ AttrBuilder B(CallPAL, i + 1);
+ AttributesVec.
+ push_back(AttributeSet::get(F->getContext(), Args.size(), B));
+ }
}
- if (FnAttrs.hasAttributes())
- AttributesVec.push_back(AttributeWithIndex::get(AttributeSet::FunctionIndex,
- FnAttrs));
+ if (CallPAL.hasAttributes(AttributeSet::FunctionIndex))
+ AttributesVec.push_back(AttributeSet::get(Call->getContext(),
+ CallPAL.getFnAttributes()));
// Reconstruct the AttributesList based on the vector we constructed.
AttributeSet NewCallPAL = AttributeSet::get(F->getContext(), AttributesVec);
if (!Call->getType()->isX86_MMXTy())
Call->replaceAllUsesWith(Constant::getNullValue(Call->getType()));
} else {
- assert(RetTy->isStructTy() &&
+ assert((RetTy->isStructTy() || RetTy->isArrayTy()) &&
"Return type changed, but not into a void. The old return type"
- " must have been a struct!");
+ " must have been a struct or an array!");
Instruction *InsertPt = Call;
if (InvokeInst *II = dyn_cast<InvokeInst>(Call)) {
BasicBlock::iterator IP = II->getNormalDest()->begin();
InsertPt = IP;
}
- // We used to return a struct. Instead of doing smart stuff with all the
- // uses of this struct, we will just rebuild it using
- // extract/insertvalue chaining and let instcombine clean that up.
+ // We used to return a struct or array. Instead of doing smart stuff
+ // with all the uses, we will just rebuild it using extract/insertvalue
+ // chaining and let instcombine clean that up.
//
// Start out building up our return value from undef
Value *RetVal = UndefValue::get(RetTy);
Value *RetVal;
if (NFTy->getReturnType()->isVoidTy()) {
- RetVal = 0;
+ RetVal = nullptr;
} else {
- assert (RetTy->isStructTy());
- // The original return value was a struct, insert
+ assert(RetTy->isStructTy() || RetTy->isArrayTy());
+ // The original return value was a struct or array, insert
// extractvalue/insertvalue chains to extract only the values we need
// to return and insert them into our new result.
// This does generate messy code, but we'll let it to instcombine to
}
// Patch the pointer to LLVM function in debug info descriptor.
- FunctionDIMap::iterator DI = FunctionDIs.find(F);
+ auto DI = FunctionDIs.find(F);
if (DI != FunctionDIs.end())
DI->second.replaceFunction(NF);
bool Changed = false;
// Collect debug info descriptors for functions.
- CollectFunctionDIs(M);
+ FunctionDIs = makeSubprogramMap(M);
// First pass: Do a simple check to see if any functions can have their "..."
// removed. We can do this if they never call va_start. This loop cannot be
// determine that dead arguments passed into recursive functions are dead).
//
DEBUG(dbgs() << "DAE - Determining liveness\n");
- for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
- SurveyFunction(*I);
+ for (auto &F : M)
+ SurveyFunction(F);
// Now, remove all dead arguments and return values from each function in
// turn.
// Finally, look for any unused parameters in functions with non-local
// linkage and replace the passed in parameters with undef.
- for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
- Function& F = *I;
-
+ for (auto &F : M)
Changed |= RemoveDeadArgumentsFromCallers(F);
- }
return Changed;
}
projects / oota-llvm.git / blobdiff