#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/Support/CallSite.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/StringExtras.h"
#include <map>
#include <set>
using namespace llvm;
STATISTIC(NumArgumentsEliminated, "Number of unread args removed");
STATISTIC(NumRetValsEliminated , "Number of unused return values removed");
-
+STATISTIC(NumArgumentsReplacedWithUndef,
+ "Number of unread args replaced with undef");
namespace {
/// DAE - The dead argument elimination pass.
///
/// Struct that represents (part of) either a return value or a function
/// argument. Used so that arguments and return values can be used
- /// interchangably.
+ /// interchangeably.
struct RetOrArg {
RetOrArg(const Function *F, unsigned Idx, bool IsArg) : F(F), Idx(Idx),
IsArg(IsArg) {}
std::string getDescription() const {
return std::string((IsArg ? "Argument #" : "Return value #"))
- + utostr(Idx) + " of function " + F->getNameStr();
+ + utostr(Idx) + " of function " + F->getName().str();
}
};
typedef SmallVector<RetOrArg, 5> UseVector;
+ // Map each LLVM function to corresponding metadata with debug info. If
+ // the function is replaced with another one, we should patch the pointer
+ // to LLVM function in metadata.
+ // 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;
+
protected:
// DAH uses this to specify a different ID.
- explicit DAE(void *ID) : ModulePass(ID) {}
+ explicit DAE(char &ID) : ModulePass(ID) {}
public:
static char ID; // Pass identification, replacement for typeid
- DAE() : ModulePass(&ID) {}
+ DAE() : ModulePass(ID) {
+ initializeDAEPass(*PassRegistry::getPassRegistry());
+ }
bool runOnModule(Module &M);
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);
void PropagateLiveness(const RetOrArg &RA);
bool RemoveDeadStuffFromFunction(Function *F);
bool DeleteDeadVarargs(Function &Fn);
+ bool RemoveDeadArgumentsFromCallers(Function &Fn);
};
}
char DAE::ID = 0;
-static RegisterPass<DAE>
-X("deadargelim", "Dead Argument Elimination");
+INITIALIZE_PASS(DAE, "deadargelim", "Dead Argument Elimination", false, false)
namespace {
/// DAH - DeadArgumentHacking pass - Same as dead argument elimination, but
/// by bugpoint.
struct DAH : public DAE {
static char ID;
- DAH() : DAE(&ID) {}
+ DAH() : DAE(ID) {}
virtual bool ShouldHackArguments() const { return true; }
};
}
char DAH::ID = 0;
-static RegisterPass<DAH>
-Y("deadarghaX0r", "Dead Argument Hacking (BUGPOINT USE ONLY; DO NOT USE)");
+INITIALIZE_PASS(DAH, "deadarghaX0r",
+ "Dead Argument Hacking (BUGPOINT USE ONLY; DO NOT USE)",
+ false, false)
/// createDeadArgEliminationPass - This pass removes arguments from functions
/// which are not used by the body of the function.
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) {
// Start by computing a new prototype for the function, which is the same as
// the old function, but doesn't have isVarArg set.
- const FunctionType *FTy = Fn.getFunctionType();
+ FunctionType *FTy = Fn.getFunctionType();
- std::vector<const Type*> Params(FTy->param_begin(), FTy->param_end());
+ std::vector<Type*> Params(FTy->param_begin(), FTy->param_end());
FunctionType *NFTy = FunctionType::get(FTy->getReturnType(),
Params, false);
unsigned NumArgs = Params.size();
//
std::vector<Value*> Args;
while (!Fn.use_empty()) {
- CallSite CS = CallSite::get(Fn.use_back());
+ CallSite CS(Fn.use_back());
Instruction *Call = CS.getInstruction();
// Pass all the same arguments.
- Args.assign(CS.arg_begin(), CS.arg_begin()+NumArgs);
+ Args.assign(CS.arg_begin(), CS.arg_begin() + NumArgs);
// Drop any attributes that were on the vararg arguments.
- AttrListPtr PAL = CS.getAttributes();
+ 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));
- if (Attributes FnAttrs = PAL.getFnAttributes())
- AttributesVec.push_back(AttributeWithIndex::get(~0, FnAttrs));
- PAL = AttrListPtr::get(AttributesVec.begin(), AttributesVec.end());
+ Attributes FnAttrs = PAL.getFnAttributes();
+ if (FnAttrs.hasAttributes())
+ AttributesVec.push_back(AttributeWithIndex::get(AttributeSet::FunctionIndex,
+ FnAttrs));
+ PAL = AttributeSet::get(Fn.getContext(), AttributesVec);
}
Instruction *New;
if (InvokeInst *II = dyn_cast<InvokeInst>(Call)) {
New = InvokeInst::Create(NF, II->getNormalDest(), II->getUnwindDest(),
- Args.begin(), Args.end(), "", Call);
+ Args, "", Call);
cast<InvokeInst>(New)->setCallingConv(CS.getCallingConv());
cast<InvokeInst>(New)->setAttributes(PAL);
} else {
- New = CallInst::Create(NF, Args.begin(), Args.end(), "", Call);
+ New = CallInst::Create(NF, Args, "", Call);
cast<CallInst>(New)->setCallingConv(CS.getCallingConv());
cast<CallInst>(New)->setAttributes(PAL);
if (cast<CallInst>(Call)->isTailCall())
cast<CallInst>(New)->setTailCall();
}
- if (MDNode *N = Call->getDbgMetadata())
- New->setDbgMetadata(N);
+ New->setDebugLoc(Call->getDebugLoc());
Args.clear();
// function empty.
NF->getBasicBlockList().splice(NF->begin(), Fn.getBasicBlockList());
- // Loop over the argument list, transfering uses of the old arguments over to
- // the new arguments, also transfering over the names as well. While we're at
+ // Loop over the argument list, transferring uses of the old arguments over to
+ // the new arguments, also transferring over the names as well. While we're at
// it, remove the dead arguments from the DeadArguments list.
//
for (Function::arg_iterator I = Fn.arg_begin(), E = Fn.arg_end(),
I2->takeName(I);
}
+ // Patch the pointer to LLVM function in debug info descriptor.
+ FunctionDIMap::iterator DI = FunctionDIs.find(&Fn);
+ if (DI != FunctionDIs.end())
+ DI->second.replaceFunction(NF);
+
// Finally, nuke the old function.
Fn.eraseFromParent();
return true;
}
+/// RemoveDeadArgumentsFromCallers - Checks if the given function has any
+/// arguments that are unused, and changes the caller parameters to be undefined
+/// instead.
+bool DAE::RemoveDeadArgumentsFromCallers(Function &Fn)
+{
+ if (Fn.isDeclaration() || Fn.mayBeOverridden())
+ return false;
+
+ // Functions with local linkage should already have been handled.
+ if (Fn.hasLocalLinkage())
+ return false;
+
+ if (Fn.use_empty())
+ return false;
+
+ llvm::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())
+ UnusedArgs.push_back(Arg->getArgNo());
+ }
+
+ if (UnusedArgs.empty())
+ return false;
+
+ 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))
+ continue;
+
+ // Now go through all unused args and replace them with "undef".
+ for (unsigned I = 0, E = UnusedArgs.size(); I != E; ++I) {
+ unsigned ArgNo = UnusedArgs[I];
+
+ Value *Arg = CS.getArgument(ArgNo);
+ CS.setArgument(ArgNo, UndefValue::get(Arg->getType()));
+ ++NumArgumentsReplacedWithUndef;
+ Changed = true;
+ }
+ }
+
+ return Changed;
+}
+
/// Convenience function that returns the number of return values. It returns 0
/// 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())
return 0;
- else if (const StructType *STy = dyn_cast<StructType>(F->getReturnType()))
+ else if (StructType *STy = dyn_cast<StructType>(F->getReturnType()))
return STy->getNumElements();
else
return 1;
// 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
// that U is really a use of an insertvalue instruction that uses the
- // orginal Use.
+ // original Use.
RetOrArg Use = CreateRet(RI->getParent()->getParent(), RetValNum);
// We might be live, depending on the liveness of Use.
return MarkIfNotLive(Use, MaybeLiveUses);
// 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;
- const Type *STy = dyn_cast<StructType>(F.getReturnType());
+ 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) {
// Start by computing a new prototype for the function, which is the same as
// the old function, but has fewer arguments and a different return type.
- const FunctionType *FTy = F->getFunctionType();
- std::vector<const Type*> Params;
+ FunctionType *FTy = F->getFunctionType();
+ std::vector<Type*> Params;
// Set up to build a new list of parameter attributes.
SmallVector<AttributeWithIndex, 8> AttributesVec;
- const AttrListPtr &PAL = F->getAttributes();
+ const AttributeSet &PAL = F->getAttributes();
// The existing function return attributes.
Attributes RAttrs = PAL.getRetAttributes();
// Find out the new return value.
- const Type *RetTy = FTy->getReturnType();
- const Type *NRetTy = NULL;
+ Type *RetTy = FTy->getReturnType();
+ Type *NRetTy = NULL;
unsigned RetCount = NumRetVals(F);
// -1 means unused, other numbers are the new index
SmallVector<int, 5> NewRetIdxs(RetCount, -1);
- std::vector<const Type*> RetTypes;
+ std::vector<Type*> RetTypes;
if (RetTy->isVoidTy()) {
NRetTy = RetTy;
} else {
- const StructType *STy = dyn_cast<StructType>(RetTy);
+ StructType *STy = dyn_cast<StructType>(RetTy);
if (STy)
// Look at each of the original return values individually.
for (unsigned i = 0; i != RetCount; ++i) {
// here. Currently, this should not be possible, but special handling might be
// required when new return value attributes are added.
if (NRetTy->isVoidTy())
- RAttrs &= ~Attribute::typeIncompatible(NRetTy);
+ RAttrs =
+ Attributes::get(NRetTy->getContext(), AttrBuilder(RAttrs).
+ removeAttributes(Attributes::typeIncompatible(NRetTy)));
else
- assert((RAttrs & Attribute::typeIncompatible(NRetTy)) == 0
- && "Return attributes no longer compatible?");
+ assert(!AttrBuilder(RAttrs).
+ hasAttributes(Attributes::typeIncompatible(NRetTy)) &&
+ "Return attributes no longer compatible?");
- if (RAttrs)
- AttributesVec.push_back(AttributeWithIndex::get(0, RAttrs));
+ if (RAttrs.hasAttributes())
+ AttributesVec.push_back(AttributeWithIndex::get(AttributeSet::ReturnIndex,
+ RAttrs));
// Remember which arguments are still alive.
SmallVector<bool, 10> ArgAlive(FTy->getNumParams(), false);
// Get the original parameter attributes (skipping the first one, that is
// for the return value.
- if (Attributes Attrs = PAL.getParamAttributes(i + 1))
+ Attributes Attrs = PAL.getParamAttributes(i + 1);
+ if (Attrs.hasAttributes())
AttributesVec.push_back(AttributeWithIndex::get(Params.size(), Attrs));
} else {
++NumArgumentsEliminated;
}
}
- if (FnAttrs != Attribute::None)
- AttributesVec.push_back(AttributeWithIndex::get(~0, FnAttrs));
+ if (FnAttrs.hasAttributes())
+ AttributesVec.push_back(AttributeWithIndex::get(AttributeSet::FunctionIndex,
+ FnAttrs));
// Reconstruct the AttributesList based on the vector we constructed.
- AttrListPtr NewPAL = AttrListPtr::get(AttributesVec.begin(),
- AttributesVec.end());
+ AttributeSet NewPAL = AttributeSet::get(F->getContext(), AttributesVec);
// Create the new function type based on the recomputed parameters.
FunctionType *NFTy = FunctionType::get(NRetTy, Params, FTy->isVarArg());
//
std::vector<Value*> Args;
while (!F->use_empty()) {
- CallSite CS = CallSite::get(F->use_back());
+ CallSite CS(F->use_back());
Instruction *Call = CS.getInstruction();
AttributesVec.clear();
- const AttrListPtr &CallPAL = CS.getAttributes();
+ const AttributeSet &CallPAL = CS.getAttributes();
// The call return attributes.
Attributes RAttrs = CallPAL.getRetAttributes();
Attributes FnAttrs = CallPAL.getFnAttributes();
// Adjust in case the function was changed to return void.
- RAttrs &= ~Attribute::typeIncompatible(NF->getReturnType());
- if (RAttrs)
- AttributesVec.push_back(AttributeWithIndex::get(0, RAttrs));
+ RAttrs =
+ Attributes::get(NF->getContext(), AttrBuilder(RAttrs).
+ removeAttributes(Attributes::typeIncompatible(NF->getReturnType())));
+ if (RAttrs.hasAttributes())
+ AttributesVec.push_back(AttributeWithIndex::get(AttributeSet::ReturnIndex,
+ 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.
- if (Attributes Attrs = CallPAL.getParamAttributes(i + 1))
+ Attributes Attrs = CallPAL.getParamAttributes(i + 1);
+ if (Attrs.hasAttributes())
AttributesVec.push_back(AttributeWithIndex::get(Args.size(), Attrs));
}
// 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);
- if (Attributes Attrs = CallPAL.getParamAttributes(i + 1))
+ Attributes Attrs = CallPAL.getParamAttributes(i + 1);
+ if (Attrs.hasAttributes())
AttributesVec.push_back(AttributeWithIndex::get(Args.size(), Attrs));
}
- if (FnAttrs != Attribute::None)
- AttributesVec.push_back(AttributeWithIndex::get(~0, FnAttrs));
+ if (FnAttrs.hasAttributes())
+ AttributesVec.push_back(AttributeWithIndex::get(AttributeSet::FunctionIndex,
+ FnAttrs));
// Reconstruct the AttributesList based on the vector we constructed.
- AttrListPtr NewCallPAL = AttrListPtr::get(AttributesVec.begin(),
- AttributesVec.end());
+ AttributeSet NewCallPAL = AttributeSet::get(F->getContext(), AttributesVec);
Instruction *New;
if (InvokeInst *II = dyn_cast<InvokeInst>(Call)) {
New = InvokeInst::Create(NF, II->getNormalDest(), II->getUnwindDest(),
- Args.begin(), Args.end(), "", Call);
+ Args, "", Call);
cast<InvokeInst>(New)->setCallingConv(CS.getCallingConv());
cast<InvokeInst>(New)->setAttributes(NewCallPAL);
} else {
- New = CallInst::Create(NF, Args.begin(), Args.end(), "", Call);
+ New = CallInst::Create(NF, Args, "", Call);
cast<CallInst>(New)->setCallingConv(CS.getCallingConv());
cast<CallInst>(New)->setAttributes(NewCallPAL);
if (cast<CallInst>(Call)->isTailCall())
cast<CallInst>(New)->setTailCall();
}
- if (MDNode *N = Call->getDbgMetadata())
- New->setDbgMetadata(N);
+ New->setDebugLoc(Call->getDebugLoc());
Args.clear();
} else if (New->getType()->isVoidTy()) {
// Our return value has uses, but they will get removed later on.
// Replace by null for now.
- Call->replaceAllUsesWith(Constant::getNullValue(Call->getType()));
+ if (!Call->getType()->isX86_MMXTy())
+ Call->replaceAllUsesWith(Constant::getNullValue(Call->getType()));
} else {
assert(RetTy->isStructTy() &&
"Return type changed, but not into a void. The old return type"
// function empty.
NF->getBasicBlockList().splice(NF->begin(), F->getBasicBlockList());
- // Loop over the argument list, transfering uses of the old arguments over to
- // the new arguments, also transfering over the names as well.
+ // Loop over the argument list, transferring uses of the old arguments over to
+ // the new arguments, also transferring over the names as well.
i = 0;
for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(),
I2 = NF->arg_begin(); I != E; ++I, ++i)
} else {
// If this argument is dead, replace any uses of it with null constants
// (these are guaranteed to become unused later on).
- I->replaceAllUsesWith(Constant::getNullValue(I->getType()));
+ if (!I->getType()->isX86_MMXTy())
+ I->replaceAllUsesWith(Constant::getNullValue(I->getType()));
}
// If we change the return value of the function we must rewrite any return
BB->getInstList().erase(RI);
}
+ // Patch the pointer to LLVM function in debug info descriptor.
+ FunctionDIMap::iterator DI = FunctionDIs.find(F);
+ if (DI != FunctionDIs.end())
+ DI->second.replaceFunction(NF);
+
// Now that the old function is dead, delete it.
F->eraseFromParent();
bool DAE::runOnModule(Module &M) {
bool Changed = false;
+ // Collect debug info descriptors for functions.
+ CollectFunctionDIs(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
// fused with the next loop, because deleting a function invalidates
Function *F = I++;
Changed |= RemoveDeadStuffFromFunction(F);
}
+
+ // 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;
+
+ Changed |= RemoveDeadArgumentsFromCallers(F);
+ }
+
return Changed;
}