//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "argpromotion"
#include "llvm/Transforms/IPO.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LLVMContext.h"
#include <set>
using namespace llvm;
+#define DEBUG_TYPE "argpromotion"
+
STATISTIC(NumArgumentsPromoted , "Number of pointer arguments promoted");
STATISTIC(NumAggregatesPromoted, "Number of aggregate arguments promoted");
STATISTIC(NumByValArgsPromoted , "Number of byval arguments promoted");
/// ArgPromotion - The 'by reference' to 'by value' argument promotion pass.
///
struct ArgPromotion : public CallGraphSCCPass {
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<AliasAnalysis>();
CallGraphSCCPass::getAnalysisUsage(AU);
}
- virtual bool runOnSCC(CallGraphSCC &SCC);
+ bool runOnSCC(CallGraphSCC &SCC) override;
static char ID; // Pass identification, replacement for typeid
explicit ArgPromotion(unsigned maxElements = 3)
- : CallGraphSCCPass(ID), maxElements(maxElements) {
+ : CallGraphSCCPass(ID), DL(nullptr), maxElements(maxElements) {
initializeArgPromotionPass(*PassRegistry::getPassRegistry());
}
/// A vector used to hold the indices of a single GEP instruction
typedef std::vector<uint64_t> IndicesVector;
+ const DataLayout *DL;
private:
+ bool isDenselyPacked(Type *type);
+ bool canPaddingBeAccessed(Argument *Arg);
CallGraphNode *PromoteArguments(CallGraphNode *CGN);
bool isSafeToPromoteArgument(Argument *Arg, bool isByVal) const;
CallGraphNode *DoPromotion(Function *F,
- SmallPtrSet<Argument*, 8> &ArgsToPromote,
- SmallPtrSet<Argument*, 8> &ByValArgsToTransform);
+ SmallPtrSetImpl<Argument*> &ArgsToPromote,
+ SmallPtrSetImpl<Argument*> &ByValArgsToTransform);
+
+ using llvm::Pass::doInitialization;
+ bool doInitialization(CallGraph &CG) override;
/// The maximum number of elements to expand, or 0 for unlimited.
unsigned maxElements;
+ DenseMap<const Function *, DISubprogram> FunctionDIs;
};
}
return Changed;
}
+/// \brief Checks if a type could have padding bytes.
+bool ArgPromotion::isDenselyPacked(Type *type) {
+
+ // There is no size information, so be conservative.
+ if (!type->isSized())
+ return false;
+
+ // If the alloc size is not equal to the storage size, then there are padding
+ // bytes. For x86_fp80 on x86-64, size: 80 alloc size: 128.
+ if (!DL || DL->getTypeSizeInBits(type) != DL->getTypeAllocSizeInBits(type))
+ return false;
+
+ if (!isa<CompositeType>(type))
+ return true;
+
+ // For homogenous sequential types, check for padding within members.
+ if (SequentialType *seqTy = dyn_cast<SequentialType>(type))
+ return isa<PointerType>(seqTy) || isDenselyPacked(seqTy->getElementType());
+
+ // Check for padding within and between elements of a struct.
+ StructType *StructTy = cast<StructType>(type);
+ const StructLayout *Layout = DL->getStructLayout(StructTy);
+ uint64_t StartPos = 0;
+ for (unsigned i = 0, E = StructTy->getNumElements(); i < E; ++i) {
+ Type *ElTy = StructTy->getElementType(i);
+ if (!isDenselyPacked(ElTy))
+ return false;
+ if (StartPos != Layout->getElementOffsetInBits(i))
+ return false;
+ StartPos += DL->getTypeAllocSizeInBits(ElTy);
+ }
+
+ return true;
+}
+
+/// \brief Checks if the padding bytes of an argument could be accessed.
+bool ArgPromotion::canPaddingBeAccessed(Argument *arg) {
+
+ assert(arg->hasByValAttr());
+
+ // Track all the pointers to the argument to make sure they are not captured.
+ SmallPtrSet<Value *, 16> PtrValues;
+ PtrValues.insert(arg);
+
+ // Track all of the stores.
+ SmallVector<StoreInst *, 16> Stores;
+
+ // Scan through the uses recursively to make sure the pointer is always used
+ // sanely.
+ SmallVector<Value *, 16> WorkList;
+ WorkList.insert(WorkList.end(), arg->user_begin(), arg->user_end());
+ while (!WorkList.empty()) {
+ Value *V = WorkList.back();
+ WorkList.pop_back();
+ if (isa<GetElementPtrInst>(V) || isa<PHINode>(V)) {
+ if (PtrValues.insert(V).second)
+ WorkList.insert(WorkList.end(), V->user_begin(), V->user_end());
+ } else if (StoreInst *Store = dyn_cast<StoreInst>(V)) {
+ Stores.push_back(Store);
+ } else if (!isa<LoadInst>(V)) {
+ return true;
+ }
+ }
+
+// Check to make sure the pointers aren't captured
+ for (StoreInst *Store : Stores)
+ if (PtrValues.count(Store->getValueOperand()))
+ return true;
+
+ return false;
+}
+
/// PromoteArguments - This method checks the specified function to see if there
/// are any promotable arguments and if it is safe to promote the function (for
/// example, all callers are direct). If safe to promote some arguments, it
Function *F = CGN->getFunction();
// Make sure that it is local to this module.
- if (!F || !F->hasLocalLinkage()) return 0;
+ if (!F || !F->hasLocalLinkage()) return nullptr;
+
+ DL = &F->getParent()->getDataLayout();
// First check: see if there are any pointer arguments! If not, quick exit.
SmallVector<Argument*, 16> PointerArgs;
for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; ++I)
if (I->getType()->isPointerTy())
PointerArgs.push_back(I);
- if (PointerArgs.empty()) return 0;
+ if (PointerArgs.empty()) return nullptr;
// Second check: make sure that all callers are direct callers. We can't
// transform functions that have indirect callers. Also see if the function
// is self-recursive.
bool isSelfRecursive = false;
- for (Value::use_iterator UI = F->use_begin(), E = F->use_end();
- UI != E; ++UI) {
- CallSite CS(*UI);
+ for (Use &U : F->uses()) {
+ CallSite CS(U.getUser());
// Must be a direct call.
- if (CS.getInstruction() == 0 || !CS.isCallee(UI)) return 0;
+ if (CS.getInstruction() == nullptr || !CS.isCallee(&U)) return nullptr;
if (CS.getInstruction()->getParent()->getParent() == F)
isSelfRecursive = true;
}
+ // Don't promote arguments for variadic functions. Adding, removing, or
+ // changing non-pack parameters can change the classification of pack
+ // parameters. Frontends encode that classification at the call site in the
+ // IR, while in the callee the classification is determined dynamically based
+ // on the number of registers consumed so far.
+ if (F->isVarArg()) return nullptr;
+
// Check to see which arguments are promotable. If an argument is promotable,
// add it to ArgsToPromote.
SmallPtrSet<Argument*, 8> ArgsToPromote;
Type *AgTy = cast<PointerType>(PtrArg->getType())->getElementType();
// If this is a byval argument, and if the aggregate type is small, just
- // pass the elements, which is always safe. This does not apply to
- // inalloca.
- if (PtrArg->hasByValAttr()) {
+ // pass the elements, which is always safe, if the passed value is densely
+ // packed or if we can prove the padding bytes are never accessed. This does
+ // not apply to inalloca.
+ bool isSafeToPromote =
+ PtrArg->hasByValAttr() &&
+ (isDenselyPacked(AgTy) || !canPaddingBeAccessed(PtrArg));
+ if (isSafeToPromote) {
if (StructType *STy = dyn_cast<StructType>(AgTy)) {
if (maxElements > 0 && STy->getNumElements() > maxElements) {
DEBUG(dbgs() << "argpromotion disable promoting argument '"
// No promotable pointer arguments.
if (ArgsToPromote.empty() && ByValArgsToTransform.empty())
- return 0;
+ return nullptr;
return DoPromotion(F, ArgsToPromote, ByValArgsToTransform);
}
/// AllCallersPassInValidPointerForArgument - Return true if we can prove that
/// all callees pass in a valid pointer for the specified function argument.
-static bool AllCallersPassInValidPointerForArgument(Argument *Arg) {
+static bool AllCallersPassInValidPointerForArgument(Argument *Arg,
+ const DataLayout *DL) {
Function *Callee = Arg->getParent();
unsigned ArgNo = Arg->getArgNo();
// Look at all call sites of the function. At this pointer we know we only
// have direct callees.
- for (Value::use_iterator UI = Callee->use_begin(), E = Callee->use_end();
- UI != E; ++UI) {
- CallSite CS(*UI);
+ for (User *U : Callee->users()) {
+ CallSite CS(U);
assert(CS && "Should only have direct calls!");
- if (!CS.getArgument(ArgNo)->isDereferenceablePointer())
+ if (!CS.getArgument(ArgNo)->isDereferenceablePointer(DL))
return false;
}
return true;
GEPIndicesSet ToPromote;
// If the pointer is always valid, any load with first index 0 is valid.
- if (isByValOrInAlloca || AllCallersPassInValidPointerForArgument(Arg))
+ if (isByValOrInAlloca || AllCallersPassInValidPointerForArgument(Arg, DL))
SafeToUnconditionallyLoad.insert(IndicesVector(1, 0));
// First, iterate the entry block and mark loads of (geps of) arguments as
// not (GEP+)loads, or any (GEP+)loads that are not safe to promote.
SmallVector<LoadInst*, 16> Loads;
IndicesVector Operands;
- for (Value::use_iterator UI = Arg->use_begin(), E = Arg->use_end();
- UI != E; ++UI) {
- User *U = *UI;
+ for (Use &U : Arg->uses()) {
+ User *UR = U.getUser();
Operands.clear();
- if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
+ if (LoadInst *LI = dyn_cast<LoadInst>(UR)) {
// Don't hack volatile/atomic loads
if (!LI->isSimple()) return false;
Loads.push_back(LI);
// Direct loads are equivalent to a GEP with a zero index and then a load.
Operands.push_back(0);
- } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) {
+ } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(UR)) {
if (GEP->use_empty()) {
// Dead GEP's cause trouble later. Just remove them if we run into
// them.
return false; // Not a constant operand GEP!
// Ensure that the only users of the GEP are load instructions.
- for (Value::use_iterator UI = GEP->use_begin(), E = GEP->use_end();
- UI != E; ++UI)
- if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
+ for (User *GEPU : GEP->users())
+ if (LoadInst *LI = dyn_cast<LoadInst>(GEPU)) {
// Don't hack volatile/atomic loads
if (!LI->isSimple()) return false;
Loads.push_back(LI);
// of elements of the aggregate.
return false;
}
- ToPromote.insert(Operands);
+ ToPromote.insert(std::move(Operands));
}
}
BasicBlock *BB = Load->getParent();
AliasAnalysis::Location Loc = AA.getLocation(Load);
- if (AA.canInstructionRangeModify(BB->front(), *Load, Loc))
+ if (AA.canInstructionRangeModRef(BB->front(), *Load, Loc,
+ AliasAnalysis::Mod))
return false; // Pointer is invalidated!
// Now check every path from the entry block to the load for transparency.
// To do this, we perform a depth first search on the inverse CFG from the
// loading block.
- for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
- BasicBlock *P = *PI;
- for (idf_ext_iterator<BasicBlock*, SmallPtrSet<BasicBlock*, 16> >
- I = idf_ext_begin(P, TranspBlocks),
- E = idf_ext_end(P, TranspBlocks); I != E; ++I)
- if (AA.canBasicBlockModify(**I, Loc))
+ for (BasicBlock *P : predecessors(BB)) {
+ for (BasicBlock *TranspBB : inverse_depth_first_ext(P, TranspBlocks))
+ if (AA.canBasicBlockModify(*TranspBB, Loc))
return false;
}
}
/// arguments, and returns the new function. At this point, we know that it's
/// safe to do so.
CallGraphNode *ArgPromotion::DoPromotion(Function *F,
- SmallPtrSet<Argument*, 8> &ArgsToPromote,
- SmallPtrSet<Argument*, 8> &ByValArgsToTransform) {
+ SmallPtrSetImpl<Argument*> &ArgsToPromote,
+ SmallPtrSetImpl<Argument*> &ByValArgsToTransform) {
// Start by computing a new prototype for the function, which is the same as
// the old function, but has modified arguments.
// Simple byval argument? Just add all the struct element types.
Type *AgTy = cast<PointerType>(I->getType())->getElementType();
StructType *STy = cast<StructType>(AgTy);
- for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
- Params.push_back(STy->getElementType(i));
+ Params.insert(Params.end(), STy->element_begin(), STy->element_end());
++NumByValArgsPromoted;
} else if (!ArgsToPromote.count(I)) {
// Unchanged argument
// In this table, we will track which indices are loaded from the argument
// (where direct loads are tracked as no indices).
ScalarizeTable &ArgIndices = ScalarizedElements[I];
- for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E;
- ++UI) {
- Instruction *User = cast<Instruction>(*UI);
- assert(isa<LoadInst>(User) || isa<GetElementPtrInst>(User));
+ for (User *U : I->users()) {
+ Instruction *UI = cast<Instruction>(U);
+ assert(isa<LoadInst>(UI) || isa<GetElementPtrInst>(UI));
IndicesVector Indices;
- Indices.reserve(User->getNumOperands() - 1);
+ Indices.reserve(UI->getNumOperands() - 1);
// Since loads will only have a single operand, and GEPs only a single
// non-index operand, this will record direct loads without any indices,
// and gep+loads with the GEP indices.
- for (User::op_iterator II = User->op_begin() + 1, IE = User->op_end();
+ for (User::op_iterator II = UI->op_begin() + 1, IE = UI->op_end();
II != IE; ++II)
Indices.push_back(cast<ConstantInt>(*II)->getSExtValue());
// GEPs with a single 0 index can be merged with direct loads
Indices.clear();
ArgIndices.insert(Indices);
LoadInst *OrigLoad;
- if (LoadInst *L = dyn_cast<LoadInst>(User))
+ if (LoadInst *L = dyn_cast<LoadInst>(UI))
OrigLoad = L;
else
// Take any load, we will use it only to update Alias Analysis
- OrigLoad = cast<LoadInst>(User->use_back());
+ OrigLoad = cast<LoadInst>(UI->user_back());
OriginalLoads[std::make_pair(I, Indices)] = OrigLoad;
}
Function *NF = Function::Create(NFTy, F->getLinkage(), F->getName());
NF->copyAttributesFrom(F);
-
+ // Patch the pointer to LLVM function in debug info descriptor.
+ auto DI = FunctionDIs.find(F);
+ if (DI != FunctionDIs.end()) {
+ DISubprogram SP = DI->second;
+ SP.replaceFunction(NF);
+ // Ensure the map is updated so it can be reused on subsequent argument
+ // promotions of the same function.
+ FunctionDIs.erase(DI);
+ FunctionDIs[NF] = SP;
+ }
+
DEBUG(dbgs() << "ARG PROMOTION: Promoting to:" << *NF << "\n"
<< "From: " << *F);
//
SmallVector<Value*, 16> Args;
while (!F->use_empty()) {
- CallSite CS(F->use_back());
+ CallSite CS(F->user_back());
assert(CS.getCalledFunction() == F);
Instruction *Call = CS.getInstruction();
const AttributeSet &CallPAL = CS.getAttributes();
Type *AgTy = cast<PointerType>(I->getType())->getElementType();
StructType *STy = cast<StructType>(AgTy);
Value *Idxs[2] = {
- ConstantInt::get(Type::getInt32Ty(F->getContext()), 0), 0 };
+ ConstantInt::get(Type::getInt32Ty(F->getContext()), 0), nullptr };
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
Idxs[1] = ConstantInt::get(Type::getInt32Ty(F->getContext()), i);
Value *Idx = GetElementPtrInst::Create(*AI, Idxs,
// of the previous load.
LoadInst *newLoad = new LoadInst(V, V->getName()+".val", Call);
newLoad->setAlignment(OrigLoad->getAlignment());
- // Transfer the TBAA info too.
- newLoad->setMetadata(LLVMContext::MD_tbaa,
- OrigLoad->getMetadata(LLVMContext::MD_tbaa));
+ // Transfer the AA info too.
+ AAMDNodes AAInfo;
+ OrigLoad->getAAMetadata(AAInfo);
+ newLoad->setAAMetadata(AAInfo);
+
Args.push_back(newLoad);
AA.copyValue(OrigLoad, Args.back());
}
if (cast<CallInst>(Call)->isTailCall())
cast<CallInst>(New)->setTailCall();
}
+ New->setDebugLoc(Call->getDebugLoc());
Args.clear();
AttributesVec.clear();
// Just add all the struct element types.
Type *AgTy = cast<PointerType>(I->getType())->getElementType();
- Value *TheAlloca = new AllocaInst(AgTy, 0, "", InsertPt);
+ Value *TheAlloca = new AllocaInst(AgTy, nullptr, "", InsertPt);
StructType *STy = cast<StructType>(AgTy);
Value *Idxs[2] = {
- ConstantInt::get(Type::getInt32Ty(F->getContext()), 0), 0 };
+ ConstantInt::get(Type::getInt32Ty(F->getContext()), 0), nullptr };
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
Idxs[1] = ConstantInt::get(Type::getInt32Ty(F->getContext()), i);
// If the alloca is used in a call, we must clear the tail flag since
// the callee now uses an alloca from the caller.
- for (Value::use_iterator UI = TheAlloca->use_begin(),
- E = TheAlloca->use_end(); UI != E; ++UI) {
- CallInst *Call = dyn_cast<CallInst>(*UI);
+ for (User *U : TheAlloca->users()) {
+ CallInst *Call = dyn_cast<CallInst>(U);
if (!Call)
continue;
Call->setTailCall(false);
ScalarizeTable &ArgIndices = ScalarizedElements[I];
while (!I->use_empty()) {
- if (LoadInst *LI = dyn_cast<LoadInst>(I->use_back())) {
+ if (LoadInst *LI = dyn_cast<LoadInst>(I->user_back())) {
assert(ArgIndices.begin()->empty() &&
"Load element should sort to front!");
I2->setName(I->getName()+".val");
DEBUG(dbgs() << "*** Promoted load of argument '" << I->getName()
<< "' in function '" << F->getName() << "'\n");
} else {
- GetElementPtrInst *GEP = cast<GetElementPtrInst>(I->use_back());
+ GetElementPtrInst *GEP = cast<GetElementPtrInst>(I->user_back());
IndicesVector Operands;
Operands.reserve(GEP->getNumIndices());
for (User::op_iterator II = GEP->idx_begin(), IE = GEP->idx_end();
// All of the uses must be load instructions. Replace them all with
// the argument specified by ArgNo.
while (!GEP->use_empty()) {
- LoadInst *L = cast<LoadInst>(GEP->use_back());
+ LoadInst *L = cast<LoadInst>(GEP->user_back());
L->replaceAllUsesWith(TheArg);
AA.replaceWithNewValue(L, TheArg);
L->eraseFromParent();
return NF_CGN;
}
+
+bool ArgPromotion::doInitialization(CallGraph &CG) {
+ FunctionDIs = makeSubprogramMap(CG.getModule());
+ return CallGraphSCCPass::doInitialization(CG);
+}
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