//
//===----------------------------------------------------------------------===//
-#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/DebugInfo.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/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,
// 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.
private:
Liveness MarkIfNotLive(RetOrArg Use, UseVector &MaybeLiveUses);
- Liveness SurveyUse(Value::const_use_iterator U, UseVector &MaybeLiveUses,
- unsigned RetValNum = 0);
+ Liveness SurveyUse(const Use *U, UseVector &MaybeLiveUses,
+ unsigned RetValNum = -1U);
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);
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));
- 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;
- }
- }
- }
-}
-
/// 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;
- for (Value::use_iterator I = Fn.use_begin(), E = Fn.use_end(); I != E; ) {
+ for (Value::user_iterator I = Fn.user_begin(), E = Fn.user_end(); I != E; ) {
CallSite CS(*I++);
if (!CS)
continue;
}
// 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()));
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
// that U is really a use of an insertvalue instruction that uses the
// original Use.
- RetOrArg Use = CreateRet(RI->getParent()->getParent(), RetValNum);
- // We might be live, depending on the liveness of Use.
- return MarkIfNotLive(Use, MaybeLiveUses);
+ const Function *F = RI->getParent()->getParent();
+ if (RetValNum != -1U) {
+ RetOrArg Use = CreateRet(F, RetValNum);
+ // We might be live, depending on the liveness of Use.
+ return MarkIfNotLive(Use, MaybeLiveUses);
+ } else {
+ DAE::Liveness Result = MaybeLive;
+ for (unsigned i = 0; i < NumRetVals(F); ++i) {
+ RetOrArg Use = CreateRet(F, i);
+ // We might be live, depending on the liveness of Use. If any
+ // sub-value is live, then the entire value is considered live. This
+ // is a conservative choice, and better tracking is possible.
+ DAE::Liveness SubResult = MarkIfNotLive(Use, MaybeLiveUses);
+ if (Result != Live)
+ Result = SubResult;
+ }
+ return Result;
+ }
}
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;
}
// 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());
+ }
+ }
}
}
}
// 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
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? 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)
+ }
+ 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());
+ }
+ } 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();
//
std::vector<Value*> Args;
while (!F->use_empty()) {
- CallSite CS(F->use_back());
+ CallSite CS(F->user_back());
Instruction *Call = CS.getInstruction();
AttributesVec.clear();
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