//
// This pass also handles aggregate arguments that are passed into a function,
// scalarizing them if the elements of the aggregate are only loaded. Note that
-// it refuses to scalarize aggregates which would require passing in more than
-// three operands to the function, because passing thousands of operands for a
-// large array or structure is unprofitable!
+// by default it refuses to scalarize aggregates which would require passing in
+// more than three operands to the function, because passing thousands of
+// operands for a large array or structure is unprofitable! This limit can be
+// configured or disabled, however.
//
// Note that this transformation could also be done for arguments that are only
// stored to (returning the value instead), but does not currently. This case
#define DEBUG_TYPE "argpromotion"
#include "llvm/Transforms/IPO.h"
-#include "llvm/Constants.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/Module.h"
-#include "llvm/CallGraphSCCPass.h"
-#include "llvm/Instructions.h"
-#include "llvm/ParameterAttributes.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringExtras.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/CallGraph.h"
-#include "llvm/Target/TargetData.h"
-#include "llvm/Support/CallSite.h"
+#include "llvm/CallGraphSCCPass.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
#include "llvm/Support/CFG.h"
+#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
-#include "llvm/ADT/DepthFirstIterator.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/StringExtras.h"
-#include "llvm/Support/Compiler.h"
+#include "llvm/Support/raw_ostream.h"
#include <set>
using namespace llvm;
STATISTIC(NumArgumentsPromoted , "Number of pointer arguments promoted");
STATISTIC(NumAggregatesPromoted, "Number of aggregate arguments promoted");
+STATISTIC(NumByValArgsPromoted , "Number of byval arguments promoted");
STATISTIC(NumArgumentsDead , "Number of dead pointer args eliminated");
namespace {
/// ArgPromotion - The 'by reference' to 'by value' argument promotion pass.
///
- struct VISIBILITY_HIDDEN ArgPromotion : public CallGraphSCCPass {
+ struct ArgPromotion : public CallGraphSCCPass {
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<AliasAnalysis>();
- AU.addRequired<TargetData>();
CallGraphSCCPass::getAnalysisUsage(AU);
}
- virtual bool runOnSCC(const std::vector<CallGraphNode *> &SCC);
+ virtual bool runOnSCC(CallGraphSCC &SCC);
static char ID; // Pass identification, replacement for typeid
- ArgPromotion() : CallGraphSCCPass((intptr_t)&ID) {}
+ explicit ArgPromotion(unsigned maxElements = 3)
+ : CallGraphSCCPass(ID), maxElements(maxElements) {
+ initializeArgPromotionPass(*PassRegistry::getPassRegistry());
+ }
+
+ /// A vector used to hold the indices of a single GEP instruction
+ typedef std::vector<uint64_t> IndicesVector;
private:
- bool PromoteArguments(CallGraphNode *CGN);
+ CallGraphNode *PromoteArguments(CallGraphNode *CGN);
bool isSafeToPromoteArgument(Argument *Arg, bool isByVal) const;
- Function *DoPromotion(Function *F,
- SmallPtrSet<Argument*, 8> &ArgsToPromote);
+ CallGraphNode *DoPromotion(Function *F,
+ SmallPtrSet<Argument*, 8> &ArgsToPromote,
+ SmallPtrSet<Argument*, 8> &ByValArgsToTransform);
+ /// The maximum number of elements to expand, or 0 for unlimited.
+ unsigned maxElements;
};
-
- char ArgPromotion::ID = 0;
- RegisterPass<ArgPromotion> X("argpromotion",
- "Promote 'by reference' arguments to scalars");
}
-Pass *llvm::createArgumentPromotionPass() {
- return new ArgPromotion();
+char ArgPromotion::ID = 0;
+INITIALIZE_PASS_BEGIN(ArgPromotion, "argpromotion",
+ "Promote 'by reference' arguments to scalars", false, false)
+INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
+INITIALIZE_AG_DEPENDENCY(CallGraph)
+INITIALIZE_PASS_END(ArgPromotion, "argpromotion",
+ "Promote 'by reference' arguments to scalars", false, false)
+
+Pass *llvm::createArgumentPromotionPass(unsigned maxElements) {
+ return new ArgPromotion(maxElements);
}
-bool ArgPromotion::runOnSCC(const std::vector<CallGraphNode *> &SCC) {
+bool ArgPromotion::runOnSCC(CallGraphSCC &SCC) {
bool Changed = false, LocalChange;
do { // Iterate until we stop promoting from this SCC.
LocalChange = false;
// Attempt to promote arguments from all functions in this SCC.
- for (unsigned i = 0, e = SCC.size(); i != e; ++i)
- LocalChange |= PromoteArguments(SCC[i]);
+ for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
+ if (CallGraphNode *CGN = PromoteArguments(*I)) {
+ LocalChange = true;
+ SCC.ReplaceNode(*I, CGN);
+ }
+ }
Changed |= LocalChange; // Remember that we changed something.
} while (LocalChange);
-
+
return Changed;
}
/// example, all callers are direct). If safe to promote some arguments, it
/// calls the DoPromotion method.
///
-bool ArgPromotion::PromoteArguments(CallGraphNode *CGN) {
+CallGraphNode *ArgPromotion::PromoteArguments(CallGraphNode *CGN) {
Function *F = CGN->getFunction();
// Make sure that it is local to this module.
- if (!F || !F->hasInternalLinkage()) return false;
+ if (!F || !F->hasLocalLinkage()) return 0;
// First check: see if there are any pointer arguments! If not, quick exit.
SmallVector<std::pair<Argument*, unsigned>, 16> PointerArgs;
unsigned ArgNo = 0;
for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end();
I != E; ++I, ++ArgNo)
- if (isa<PointerType>(I->getType()))
+ if (I->getType()->isPointerTy())
PointerArgs.push_back(std::pair<Argument*, unsigned>(I, ArgNo));
- if (PointerArgs.empty()) return false;
+ if (PointerArgs.empty()) return 0;
// Second check: make sure that all callers are direct callers. We can't
- // transform functions that have indirect callers.
+ // 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 = CallSite::get(*UI);
- if (!CS.getInstruction()) // "Taking the address" of the function
- return false;
-
- // Ensure that this call site is CALLING the function, not passing it as
- // an argument.
- if (UI.getOperandNo() != 0)
- return false;
+ CallSite CS(*UI);
+ // Must be a direct call.
+ if (CS.getInstruction() == 0 || !CS.isCallee(UI)) return 0;
+
+ if (CS.getInstruction()->getParent()->getParent() == F)
+ isSelfRecursive = true;
}
-
+
// Check to see which arguments are promotable. If an argument is promotable,
// add it to ArgsToPromote.
SmallPtrSet<Argument*, 8> ArgsToPromote;
+ SmallPtrSet<Argument*, 8> ByValArgsToTransform;
for (unsigned i = 0; i != PointerArgs.size(); ++i) {
- bool isByVal = F->paramHasAttr(PointerArgs[i].second, ParamAttr::ByVal);
- if (isSafeToPromoteArgument(PointerArgs[i].first, isByVal))
- ArgsToPromote.insert(PointerArgs[i].first);
- }
-
- // No promotable pointer arguments.
- if (ArgsToPromote.empty()) return false;
+ bool isByVal=F->getAttributes().
+ hasAttribute(PointerArgs[i].second+1, Attribute::ByVal);
+ Argument *PtrArg = PointerArgs[i].first;
+ 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.
+ if (isByVal) {
+ if (StructType *STy = dyn_cast<StructType>(AgTy)) {
+ if (maxElements > 0 && STy->getNumElements() > maxElements) {
+ DEBUG(dbgs() << "argpromotion disable promoting argument '"
+ << PtrArg->getName() << "' because it would require adding more"
+ << " than " << maxElements << " arguments to the function.\n");
+ continue;
+ }
+
+ // If all the elements are single-value types, we can promote it.
+ bool AllSimple = true;
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
+ if (!STy->getElementType(i)->isSingleValueType()) {
+ AllSimple = false;
+ break;
+ }
+ }
- Function *NewF = DoPromotion(F, ArgsToPromote);
+ // Safe to transform, don't even bother trying to "promote" it.
+ // Passing the elements as a scalar will allow scalarrepl to hack on
+ // the new alloca we introduce.
+ if (AllSimple) {
+ ByValArgsToTransform.insert(PtrArg);
+ continue;
+ }
+ }
+ }
- // Update the call graph to know that the function has been transformed.
- getAnalysis<CallGraph>().changeFunction(F, NewF);
- return true;
-}
+ // If the argument is a recursive type and we're in a recursive
+ // function, we could end up infinitely peeling the function argument.
+ if (isSelfRecursive) {
+ if (StructType *STy = dyn_cast<StructType>(AgTy)) {
+ bool RecursiveType = false;
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
+ if (STy->getElementType(i) == PtrArg->getType()) {
+ RecursiveType = true;
+ break;
+ }
+ }
+ if (RecursiveType)
+ continue;
+ }
+ }
+
+ // Otherwise, see if we can promote the pointer to its value.
+ if (isSafeToPromoteArgument(PtrArg, isByVal))
+ ArgsToPromote.insert(PtrArg);
+ }
-/// IsAlwaysValidPointer - Return true if the specified pointer is always legal
-/// to load.
-static bool IsAlwaysValidPointer(Value *V) {
- if (isa<AllocaInst>(V) || isa<GlobalVariable>(V)) return true;
- if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V))
- return IsAlwaysValidPointer(GEP->getOperand(0));
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
- if (CE->getOpcode() == Instruction::GetElementPtr)
- return IsAlwaysValidPointer(CE->getOperand(0));
-
- return false;
+ // No promotable pointer arguments.
+ if (ArgsToPromote.empty() && ByValArgsToTransform.empty())
+ return 0;
+
+ return DoPromotion(F, ArgsToPromote, ByValArgsToTransform);
}
-/// AllCalleesPassInValidPointerForArgument - Return true if we can prove that
+/// AllCallersPassInValidPointerForArgument - Return true if we can prove that
/// all callees pass in a valid pointer for the specified function argument.
-static bool AllCalleesPassInValidPointerForArgument(Argument *Arg) {
+static bool AllCallersPassInValidPointerForArgument(Argument *Arg) {
Function *Callee = Arg->getParent();
unsigned ArgNo = std::distance(Callee->arg_begin(),
// have direct callees.
for (Value::use_iterator UI = Callee->use_begin(), E = Callee->use_end();
UI != E; ++UI) {
- CallSite CS = CallSite::get(*UI);
- assert(CS.getInstruction() && "Should only have direct calls!");
+ CallSite CS(*UI);
+ assert(CS && "Should only have direct calls!");
- if (!IsAlwaysValidPointer(CS.getArgument(ArgNo)))
+ if (!CS.getArgument(ArgNo)->isDereferenceablePointer())
return false;
}
return true;
}
+/// Returns true if Prefix is a prefix of longer. That means, Longer has a size
+/// that is greater than or equal to the size of prefix, and each of the
+/// elements in Prefix is the same as the corresponding elements in Longer.
+///
+/// This means it also returns true when Prefix and Longer are equal!
+static bool IsPrefix(const ArgPromotion::IndicesVector &Prefix,
+ const ArgPromotion::IndicesVector &Longer) {
+ if (Prefix.size() > Longer.size())
+ return false;
+ return std::equal(Prefix.begin(), Prefix.end(), Longer.begin());
+}
+
+
+/// Checks if Indices, or a prefix of Indices, is in Set.
+static bool PrefixIn(const ArgPromotion::IndicesVector &Indices,
+ std::set<ArgPromotion::IndicesVector> &Set) {
+ std::set<ArgPromotion::IndicesVector>::iterator Low;
+ Low = Set.upper_bound(Indices);
+ if (Low != Set.begin())
+ Low--;
+ // Low is now the last element smaller than or equal to Indices. This means
+ // it points to a prefix of Indices (possibly Indices itself), if such
+ // prefix exists.
+ //
+ // This load is safe if any prefix of its operands is safe to load.
+ return Low != Set.end() && IsPrefix(*Low, Indices);
+}
+
+/// Mark the given indices (ToMark) as safe in the given set of indices
+/// (Safe). Marking safe usually means adding ToMark to Safe. However, if there
+/// is already a prefix of Indices in Safe, Indices are implicitely marked safe
+/// already. Furthermore, any indices that Indices is itself a prefix of, are
+/// removed from Safe (since they are implicitely safe because of Indices now).
+static void MarkIndicesSafe(const ArgPromotion::IndicesVector &ToMark,
+ std::set<ArgPromotion::IndicesVector> &Safe) {
+ std::set<ArgPromotion::IndicesVector>::iterator Low;
+ Low = Safe.upper_bound(ToMark);
+ // Guard against the case where Safe is empty
+ if (Low != Safe.begin())
+ Low--;
+ // Low is now the last element smaller than or equal to Indices. This
+ // means it points to a prefix of Indices (possibly Indices itself), if
+ // such prefix exists.
+ if (Low != Safe.end()) {
+ if (IsPrefix(*Low, ToMark))
+ // If there is already a prefix of these indices (or exactly these
+ // indices) marked a safe, don't bother adding these indices
+ return;
+
+ // Increment Low, so we can use it as a "insert before" hint
+ ++Low;
+ }
+ // Insert
+ Low = Safe.insert(Low, ToMark);
+ ++Low;
+ // If there we're a prefix of longer index list(s), remove those
+ std::set<ArgPromotion::IndicesVector>::iterator End = Safe.end();
+ while (Low != End && IsPrefix(ToMark, *Low)) {
+ std::set<ArgPromotion::IndicesVector>::iterator Remove = Low;
+ ++Low;
+ Safe.erase(Remove);
+ }
+}
/// isSafeToPromoteArgument - As you might guess from the name of this method,
/// it checks to see if it is both safe and useful to promote the argument.
/// elements of the aggregate in order to avoid exploding the number of
/// arguments passed in.
bool ArgPromotion::isSafeToPromoteArgument(Argument *Arg, bool isByVal) const {
+ typedef std::set<IndicesVector> GEPIndicesSet;
+
+ // Quick exit for unused arguments
+ if (Arg->use_empty())
+ return true;
+
// We can only promote this argument if all of the uses are loads, or are GEP
// instructions (with constant indices) that are subsequently loaded.
- bool HasLoadInEntryBlock = false;
+ //
+ // Promoting the argument causes it to be loaded in the caller
+ // unconditionally. This is only safe if we can prove that either the load
+ // would have happened in the callee anyway (ie, there is a load in the entry
+ // block) or the pointer passed in at every call site is guaranteed to be
+ // valid.
+ // In the former case, invalid loads can happen, but would have happened
+ // anyway, in the latter case, invalid loads won't happen. This prevents us
+ // from introducing an invalid load that wouldn't have happened in the
+ // original code.
+ //
+ // This set will contain all sets of indices that are loaded in the entry
+ // block, and thus are safe to unconditionally load in the caller.
+ GEPIndicesSet SafeToUnconditionallyLoad;
+
+ // This set contains all the sets of indices that we are planning to promote.
+ // This makes it possible to limit the number of arguments added.
+ GEPIndicesSet ToPromote;
+
+ // If the pointer is always valid, any load with first index 0 is valid.
+ if (isByVal || AllCallersPassInValidPointerForArgument(Arg))
+ SafeToUnconditionallyLoad.insert(IndicesVector(1, 0));
+
+ // First, iterate the entry block and mark loads of (geps of) arguments as
+ // safe.
BasicBlock *EntryBlock = Arg->getParent()->begin();
+ // Declare this here so we can reuse it
+ IndicesVector Indices;
+ for (BasicBlock::iterator I = EntryBlock->begin(), E = EntryBlock->end();
+ I != E; ++I)
+ if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+ Value *V = LI->getPointerOperand();
+ if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) {
+ V = GEP->getPointerOperand();
+ if (V == Arg) {
+ // This load actually loads (part of) Arg? Check the indices then.
+ Indices.reserve(GEP->getNumIndices());
+ for (User::op_iterator II = GEP->idx_begin(), IE = GEP->idx_end();
+ II != IE; ++II)
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(*II))
+ Indices.push_back(CI->getSExtValue());
+ else
+ // We found a non-constant GEP index for this argument? Bail out
+ // right away, can't promote this argument at all.
+ return false;
+
+ // Indices checked out, mark them as safe
+ MarkIndicesSafe(Indices, SafeToUnconditionallyLoad);
+ Indices.clear();
+ }
+ } else if (V == Arg) {
+ // Direct loads are equivalent to a GEP with a single 0 index.
+ MarkIndicesSafe(IndicesVector(1, 0), SafeToUnconditionallyLoad);
+ }
+ }
+
+ // Now, iterate all uses of the argument to see if there are any uses that are
+ // not (GEP+)loads, or any (GEP+)loads that are not safe to promote.
SmallVector<LoadInst*, 16> Loads;
- std::vector<SmallVector<ConstantInt*, 8> > GEPIndices;
+ IndicesVector Operands;
for (Value::use_iterator UI = Arg->use_begin(), E = Arg->use_end();
- UI != E; ++UI)
- if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
- if (LI->isVolatile()) return false; // Don't hack volatile loads
+ UI != E; ++UI) {
+ User *U = *UI;
+ Operands.clear();
+ if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
+ // Don't hack volatile/atomic loads
+ if (!LI->isSimple()) return false;
Loads.push_back(LI);
- HasLoadInEntryBlock |= LI->getParent() == EntryBlock;
- } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(*UI)) {
+ // 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)) {
if (GEP->use_empty()) {
// Dead GEP's cause trouble later. Just remove them if we run into
// them.
getAnalysis<AliasAnalysis>().deleteValue(GEP);
GEP->eraseFromParent();
+ // TODO: This runs the above loop over and over again for dead GEPs
+ // Couldn't we just do increment the UI iterator earlier and erase the
+ // use?
return isSafeToPromoteArgument(Arg, isByVal);
}
+
// Ensure that all of the indices are constants.
- SmallVector<ConstantInt*, 8> Operands;
- for (unsigned i = 1, e = GEP->getNumOperands(); i != e; ++i)
- if (ConstantInt *C = dyn_cast<ConstantInt>(GEP->getOperand(i)))
- Operands.push_back(C);
+ for (User::op_iterator i = GEP->idx_begin(), e = GEP->idx_end();
+ i != e; ++i)
+ if (ConstantInt *C = dyn_cast<ConstantInt>(*i))
+ Operands.push_back(C->getSExtValue());
else
return false; // Not a constant operand GEP!
for (Value::use_iterator UI = GEP->use_begin(), E = GEP->use_end();
UI != E; ++UI)
if (LoadInst *LI = dyn_cast<LoadInst>(*UI)) {
- if (LI->isVolatile()) return false; // Don't hack volatile loads
+ // Don't hack volatile/atomic loads
+ if (!LI->isSimple()) return false;
Loads.push_back(LI);
- HasLoadInEntryBlock |= LI->getParent() == EntryBlock;
} else {
+ // Other uses than load?
return false;
}
-
- // See if there is already a GEP with these indices. If not, check to
- // make sure that we aren't promoting too many elements. If so, nothing
- // to do.
- if (std::find(GEPIndices.begin(), GEPIndices.end(), Operands) ==
- GEPIndices.end()) {
- if (GEPIndices.size() == 3) {
- DOUT << "argpromotion disable promoting argument '"
- << Arg->getName() << "' because it would require adding more "
- << "than 3 arguments to the function.\n";
- // We limit aggregate promotion to only promoting up to three elements
- // of the aggregate.
- return false;
- }
- GEPIndices.push_back(Operands);
- }
} else {
return false; // Not a load or a GEP.
}
- if (Loads.empty()) return true; // No users, this is a dead argument.
+ // Now, see if it is safe to promote this load / loads of this GEP. Loading
+ // is safe if Operands, or a prefix of Operands, is marked as safe.
+ if (!PrefixIn(Operands, SafeToUnconditionallyLoad))
+ return false;
- // If we decide that we want to promote this argument, the value is going to
- // be unconditionally loaded in all callees. This is only safe to do if the
- // pointer was going to be unconditionally loaded anyway (i.e. there is a load
- // of the pointer in the entry block of the function) or if we can prove that
- // all pointers passed in are always to legal locations (for example, no null
- // pointers are passed in, no pointers to free'd memory, etc).
- if (!HasLoadInEntryBlock && !AllCalleesPassInValidPointerForArgument(Arg))
- return false; // Cannot prove that this is safe!!
+ // See if we are already promoting a load with these indices. If not, check
+ // to make sure that we aren't promoting too many elements. If so, nothing
+ // to do.
+ if (ToPromote.find(Operands) == ToPromote.end()) {
+ if (maxElements > 0 && ToPromote.size() == maxElements) {
+ DEBUG(dbgs() << "argpromotion not promoting argument '"
+ << Arg->getName() << "' because it would require adding more "
+ << "than " << maxElements << " arguments to the function.\n");
+ // We limit aggregate promotion to only promoting up to a fixed number
+ // of elements of the aggregate.
+ return false;
+ }
+ ToPromote.insert(Operands);
+ }
+ }
+
+ if (Loads.empty()) return true; // No users, this is a dead argument.
// Okay, now we know that the argument is only used by load instructions and
- // it is safe to unconditionally load the pointer. Use alias analysis to
+ // it is safe to unconditionally perform all of them. Use alias analysis to
// check to see if the pointer is guaranteed to not be modified from entry of
// the function to each of the load instructions.
// Because there could be several/many load instructions, remember which
// blocks we know to be transparent to the load.
- std::set<BasicBlock*> TranspBlocks;
+ SmallPtrSet<BasicBlock*, 16> TranspBlocks;
AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
- TargetData &TD = getAnalysis<TargetData>();
for (unsigned i = 0, e = Loads.size(); i != e; ++i) {
// Check to see if the load is invalidated from the start of the block to
LoadInst *Load = Loads[i];
BasicBlock *BB = Load->getParent();
- const PointerType *LoadTy =
- cast<PointerType>(Load->getOperand(0)->getType());
- unsigned LoadSize = (unsigned)TD.getTypeStoreSize(LoadTy->getElementType());
-
- if (AA.canInstructionRangeModify(BB->front(), *Load, Arg, LoadSize))
+ AliasAnalysis::Location Loc = AA.getLocation(Load);
+ if (AA.canInstructionRangeModify(BB->front(), *Load, Loc))
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)
- for (idf_ext_iterator<BasicBlock*> I = idf_ext_begin(*PI, TranspBlocks),
- E = idf_ext_end(*PI, TranspBlocks); I != E; ++I)
- if (AA.canBasicBlockModify(**I, Arg, LoadSize))
+ 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))
return false;
+ }
}
// If the path from the entry of the function to each load is free of
return true;
}
-namespace {
- /// GEPIdxComparator - Provide a strong ordering for GEP indices. All Value*
- /// elements are instances of ConstantInt.
- ///
- struct GEPIdxComparator {
- bool operator()(const std::vector<Value*> &LHS,
- const std::vector<Value*> &RHS) const {
- unsigned idx = 0;
- for (; idx < LHS.size() && idx < RHS.size(); ++idx) {
- if (LHS[idx] != RHS[idx]) {
- return cast<ConstantInt>(LHS[idx])->getZExtValue() <
- cast<ConstantInt>(RHS[idx])->getZExtValue();
- }
- }
-
- // Return less than if we ran out of stuff in LHS and we didn't run out of
- // stuff in RHS.
- return idx == LHS.size() && idx != RHS.size();
- }
- };
-}
-
-
/// DoPromotion - This method actually performs the promotion of the specified
/// arguments, and returns the new function. At this point, we know that it's
/// safe to do so.
-Function *ArgPromotion::DoPromotion(Function *F,
- SmallPtrSet<Argument*, 8> &ArgsToPromote) {
+CallGraphNode *ArgPromotion::DoPromotion(Function *F,
+ SmallPtrSet<Argument*, 8> &ArgsToPromote,
+ SmallPtrSet<Argument*, 8> &ByValArgsToTransform) {
// Start by computing a new prototype for the function, which is the same as
// the old function, but has modified arguments.
- const FunctionType *FTy = F->getFunctionType();
- std::vector<const Type*> Params;
+ FunctionType *FTy = F->getFunctionType();
+ std::vector<Type*> Params;
- typedef std::set<std::vector<Value*>, GEPIdxComparator> ScalarizeTable;
+ typedef std::set<IndicesVector> ScalarizeTable;
// ScalarizedElements - If we are promoting a pointer that has elements
// accessed out of it, keep track of which elements are accessed so that we
// OriginalLoads - Keep track of a representative load instruction from the
// original function so that we can tell the alias analysis implementation
// what the new GEP/Load instructions we are inserting look like.
- std::map<std::vector<Value*>, LoadInst*> OriginalLoads;
+ std::map<IndicesVector, LoadInst*> OriginalLoads;
- // ParamAttrs - Keep track of the parameter attributes for the arguments
+ // Attribute - Keep track of the parameter attributes for the arguments
// that we are *not* promoting. For the ones that we do promote, the parameter
// attributes are lost
- ParamAttrsVector ParamAttrsVec;
- const ParamAttrsList *PAL = F->getParamAttrs();
+ SmallVector<AttributeWithIndex, 8> AttributesVec;
+ const AttributeSet &PAL = F->getAttributes();
+
+ // Add any return attributes.
+ Attribute attrs = PAL.getRetAttributes();
+ if (attrs.hasAttributes())
+ AttributesVec.push_back(AttributeWithIndex::get(AttributeSet::ReturnIndex,
+ attrs));
- unsigned index = 1;
+ // First, determine the new argument list
+ unsigned ArgIndex = 1;
for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E;
- ++I, ++index)
- if (!ArgsToPromote.count(I)) {
+ ++I, ++ArgIndex) {
+ if (ByValArgsToTransform.count(I)) {
+ // 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));
+ ++NumByValArgsPromoted;
+ } else if (!ArgsToPromote.count(I)) {
+ // Unchanged argument
Params.push_back(I->getType());
- if (PAL) {
- unsigned attrs = PAL->getParamAttrs(index);
- if (attrs)
- ParamAttrsVec.push_back(ParamAttrsWithIndex::get(Params.size(),
- attrs));
- }
+ Attribute attrs = PAL.getParamAttributes(ArgIndex);
+ if (attrs.hasAttributes())
+ AttributesVec.push_back(AttributeWithIndex::get(Params.size(), attrs));
} else if (I->use_empty()) {
+ // Dead argument (which are always marked as promotable)
++NumArgumentsDead;
} else {
- // Okay, this is being promoted. Check to see if there are any GEP uses
- // of the argument.
+ // Okay, this is being promoted. This means that the only uses are loads
+ // or GEPs which are only used by loads
+
+ // 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));
- std::vector<Value*> Indices(User->op_begin()+1, User->op_end());
+ IndicesVector Indices;
+ Indices.reserve(User->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();
+ II != IE; ++II)
+ Indices.push_back(cast<ConstantInt>(*II)->getSExtValue());
+ // GEPs with a single 0 index can be merged with direct loads
+ if (Indices.size() == 1 && Indices.front() == 0)
+ Indices.clear();
ArgIndices.insert(Indices);
LoadInst *OrigLoad;
if (LoadInst *L = dyn_cast<LoadInst>(User))
OrigLoad = L;
else
+ // Take any load, we will use it only to update Alias Analysis
OrigLoad = cast<LoadInst>(User->use_back());
OriginalLoads[Indices] = OrigLoad;
}
// Add a parameter to the function for each element passed in.
for (ScalarizeTable::iterator SI = ArgIndices.begin(),
- E = ArgIndices.end(); SI != E; ++SI)
- Params.push_back(GetElementPtrInst::getIndexedType(I->getType(),
- SI->begin(),
- SI->end()));
+ E = ArgIndices.end(); SI != E; ++SI) {
+ // not allowed to dereference ->begin() if size() is 0
+ Params.push_back(GetElementPtrInst::getIndexedType(I->getType(), *SI));
+ assert(Params.back());
+ }
if (ArgIndices.size() == 1 && ArgIndices.begin()->empty())
++NumArgumentsPromoted;
else
++NumAggregatesPromoted;
}
+ }
- const Type *RetTy = FTy->getReturnType();
+ // Add any function attributes.
+ attrs = PAL.getFnAttributes();
+ if (attrs.hasAttributes())
+ AttributesVec.push_back(AttributeWithIndex::get(AttributeSet::FunctionIndex,
+ attrs));
- // Recompute the parameter attributes list based on the new arguments for
- // the function.
- if (ParamAttrsVec.empty())
- PAL = 0;
- else
- PAL = ParamAttrsList::get(ParamAttrsVec);
-
- // Work around LLVM bug PR56: the CWriter cannot emit varargs functions which
- // have zero fixed arguments.
- bool ExtraArgHack = false;
- if (Params.empty() && FTy->isVarArg()) {
- ExtraArgHack = true;
- Params.push_back(Type::Int32Ty);
- }
+ Type *RetTy = FTy->getReturnType();
// Construct the new function type using the new arguments.
FunctionType *NFTy = FunctionType::get(RetTy, Params, FTy->isVarArg());
- // Create the new function body and insert it into the module...
- Function *NF = new Function(NFTy, F->getLinkage(), F->getName());
- NF->setCallingConv(F->getCallingConv());
- NF->setParamAttrs(PAL);
- if (F->hasCollector())
- NF->setCollector(F->getCollector());
+ // Create the new function body and insert it into the module.
+ Function *NF = Function::Create(NFTy, F->getLinkage(), F->getName());
+ NF->copyAttributesFrom(F);
+
+
+ DEBUG(dbgs() << "ARG PROMOTION: Promoting to:" << *NF << "\n"
+ << "From: " << *F);
+
+ // Recompute the parameter attributes list based on the new arguments for
+ // the function.
+ NF->setAttributes(AttributeSet::get(F->getContext(), AttributesVec));
+ AttributesVec.clear();
+
F->getParent()->getFunctionList().insert(F, NF);
+ NF->takeName(F);
// Get the alias analysis information that we need to update to reflect our
// changes.
AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
+ // Get the callgraph information that we need to update to reflect our
+ // changes.
+ CallGraph &CG = getAnalysis<CallGraph>();
+
+ // Get a new callgraph node for NF.
+ CallGraphNode *NF_CGN = CG.getOrInsertFunction(NF);
+
// Loop over all of the callers of the function, transforming the call sites
// to pass in the loaded pointers.
//
- std::vector<Value*> Args;
+ SmallVector<Value*, 16> Args;
while (!F->use_empty()) {
- CallSite CS = CallSite::get(F->use_back());
+ CallSite CS(F->use_back());
+ assert(CS.getCalledFunction() == F);
Instruction *Call = CS.getInstruction();
+ const AttributeSet &CallPAL = CS.getAttributes();
+
+ // Add any return attributes.
+ Attribute attrs = CallPAL.getRetAttributes();
+ if (attrs.hasAttributes())
+ AttributesVec.push_back(AttributeWithIndex::get(AttributeSet::ReturnIndex,
+ attrs));
// Loop over the operands, inserting GEP and loads in the caller as
// appropriate.
CallSite::arg_iterator AI = CS.arg_begin();
+ ArgIndex = 1;
for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end();
- I != E; ++I, ++AI)
- if (!ArgsToPromote.count(I))
+ I != E; ++I, ++AI, ++ArgIndex)
+ if (!ArgsToPromote.count(I) && !ByValArgsToTransform.count(I)) {
Args.push_back(*AI); // Unmodified argument
- else if (!I->use_empty()) {
+
+ Attribute Attrs = CallPAL.getParamAttributes(ArgIndex);
+ if (Attrs.hasAttributes())
+ AttributesVec.push_back(AttributeWithIndex::get(Args.size(), Attrs));
+
+ } else if (ByValArgsToTransform.count(I)) {
+ // Emit a GEP and load for each element of the struct.
+ Type *AgTy = cast<PointerType>(I->getType())->getElementType();
+ StructType *STy = cast<StructType>(AgTy);
+ Value *Idxs[2] = {
+ ConstantInt::get(Type::getInt32Ty(F->getContext()), 0), 0 };
+ 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,
+ (*AI)->getName()+"."+utostr(i),
+ Call);
+ // TODO: Tell AA about the new values?
+ Args.push_back(new LoadInst(Idx, Idx->getName()+".val", Call));
+ }
+ } else if (!I->use_empty()) {
// Non-dead argument: insert GEPs and loads as appropriate.
ScalarizeTable &ArgIndices = ScalarizedElements[I];
+ // Store the Value* version of the indices in here, but declare it now
+ // for reuse.
+ std::vector<Value*> Ops;
for (ScalarizeTable::iterator SI = ArgIndices.begin(),
E = ArgIndices.end(); SI != E; ++SI) {
Value *V = *AI;
LoadInst *OrigLoad = OriginalLoads[*SI];
if (!SI->empty()) {
- V = new GetElementPtrInst(V, SI->begin(), SI->end(),
- V->getName()+".idx", Call);
+ Ops.reserve(SI->size());
+ Type *ElTy = V->getType();
+ for (IndicesVector::const_iterator II = SI->begin(),
+ IE = SI->end(); II != IE; ++II) {
+ // Use i32 to index structs, and i64 for others (pointers/arrays).
+ // This satisfies GEP constraints.
+ Type *IdxTy = (ElTy->isStructTy() ?
+ Type::getInt32Ty(F->getContext()) :
+ Type::getInt64Ty(F->getContext()));
+ Ops.push_back(ConstantInt::get(IdxTy, *II));
+ // Keep track of the type we're currently indexing.
+ ElTy = cast<CompositeType>(ElTy)->getTypeAtIndex(*II);
+ }
+ // And create a GEP to extract those indices.
+ V = GetElementPtrInst::Create(V, Ops, V->getName()+".idx", Call);
+ Ops.clear();
AA.copyValue(OrigLoad->getOperand(0), V);
}
- Args.push_back(new LoadInst(V, V->getName()+".val", Call));
+ // Since we're replacing a load make sure we take the alignment
+ // 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));
+ Args.push_back(newLoad);
AA.copyValue(OrigLoad, Args.back());
}
}
- if (ExtraArgHack)
- Args.push_back(Constant::getNullValue(Type::Int32Ty));
-
- // Push any varargs arguments on the list
- for (; AI != CS.arg_end(); ++AI)
+ // Push any varargs arguments on the list.
+ for (; AI != CS.arg_end(); ++AI, ++ArgIndex) {
Args.push_back(*AI);
+ Attribute Attrs = CallPAL.getParamAttributes(ArgIndex);
+ if (Attrs.hasAttributes())
+ AttributesVec.push_back(AttributeWithIndex::get(Args.size(), Attrs));
+ }
+
+ // Add any function attributes.
+ attrs = CallPAL.getFnAttributes();
+ if (attrs.hasAttributes())
+ AttributesVec.push_back(AttributeWithIndex::get(AttributeSet::FunctionIndex,
+ attrs));
Instruction *New;
if (InvokeInst *II = dyn_cast<InvokeInst>(Call)) {
- New = new InvokeInst(NF, II->getNormalDest(), II->getUnwindDest(),
- Args.begin(), Args.end(), "", Call);
+ New = InvokeInst::Create(NF, II->getNormalDest(), II->getUnwindDest(),
+ Args, "", Call);
cast<InvokeInst>(New)->setCallingConv(CS.getCallingConv());
- cast<InvokeInst>(New)->setParamAttrs(PAL);
+ cast<InvokeInst>(New)->setAttributes(AttributeSet::get(II->getContext(),
+ AttributesVec));
} else {
- New = new CallInst(NF, Args.begin(), Args.end(), "", Call);
+ New = CallInst::Create(NF, Args, "", Call);
cast<CallInst>(New)->setCallingConv(CS.getCallingConv());
- cast<CallInst>(New)->setParamAttrs(PAL);
+ cast<CallInst>(New)->setAttributes(AttributeSet::get(New->getContext(),
+ AttributesVec));
if (cast<CallInst>(Call)->isTailCall())
cast<CallInst>(New)->setTailCall();
}
Args.clear();
+ AttributesVec.clear();
// Update the alias analysis implementation to know that we are replacing
// the old call with a new one.
AA.replaceWithNewValue(Call, New);
+ // Update the callgraph to know that the callsite has been transformed.
+ CallGraphNode *CalleeNode = CG[Call->getParent()->getParent()];
+ CalleeNode->replaceCallEdge(Call, New, NF_CGN);
+
if (!Call->use_empty()) {
Call->replaceAllUsesWith(New);
New->takeName(Call);
// 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.
//
for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(),
- I2 = NF->arg_begin(); I != E; ++I)
- if (!ArgsToPromote.count(I)) {
+ I2 = NF->arg_begin(); I != E; ++I) {
+ if (!ArgsToPromote.count(I) && !ByValArgsToTransform.count(I)) {
// If this is an unmodified argument, move the name and users over to the
// new version.
I->replaceAllUsesWith(I2);
I2->takeName(I);
AA.replaceWithNewValue(I, I2);
++I2;
- } else if (I->use_empty()) {
- AA.deleteValue(I);
- } else {
- // Otherwise, if we promoted this argument, then all users are load
- // instructions, and all loads should be using the new argument that we
- // added.
- ScalarizeTable &ArgIndices = ScalarizedElements[I];
+ continue;
+ }
- while (!I->use_empty()) {
- if (LoadInst *LI = dyn_cast<LoadInst>(I->use_back())) {
- assert(ArgIndices.begin()->empty() &&
- "Load element should sort to front!");
- I2->setName(I->getName()+".val");
- LI->replaceAllUsesWith(I2);
- AA.replaceWithNewValue(LI, I2);
- LI->eraseFromParent();
- DOUT << "*** Promoted load of argument '" << I->getName()
- << "' in function '" << F->getName() << "'\n";
- } else {
- GetElementPtrInst *GEP = cast<GetElementPtrInst>(I->use_back());
- std::vector<Value*> Operands(GEP->op_begin()+1, GEP->op_end());
+ if (ByValArgsToTransform.count(I)) {
+ // In the callee, we create an alloca, and store each of the new incoming
+ // arguments into the alloca.
+ Instruction *InsertPt = NF->begin()->begin();
+
+ // Just add all the struct element types.
+ Type *AgTy = cast<PointerType>(I->getType())->getElementType();
+ Value *TheAlloca = new AllocaInst(AgTy, 0, "", InsertPt);
+ StructType *STy = cast<StructType>(AgTy);
+ Value *Idxs[2] = {
+ ConstantInt::get(Type::getInt32Ty(F->getContext()), 0), 0 };
+
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
+ Idxs[1] = ConstantInt::get(Type::getInt32Ty(F->getContext()), i);
+ Value *Idx =
+ GetElementPtrInst::Create(TheAlloca, Idxs,
+ TheAlloca->getName()+"."+Twine(i),
+ InsertPt);
+ I2->setName(I->getName()+"."+Twine(i));
+ new StoreInst(I2++, Idx, InsertPt);
+ }
- Function::arg_iterator TheArg = I2;
- for (ScalarizeTable::iterator It = ArgIndices.begin();
- *It != Operands; ++It, ++TheArg) {
- assert(It != ArgIndices.end() && "GEP not handled??");
- }
+ // Anything that used the arg should now use the alloca.
+ I->replaceAllUsesWith(TheAlloca);
+ TheAlloca->takeName(I);
+ AA.replaceWithNewValue(I, TheAlloca);
+ continue;
+ }
- std::string NewName = I->getName();
- for (unsigned i = 0, e = Operands.size(); i != e; ++i)
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Operands[i]))
- NewName += "." + CI->getValue().toStringUnsigned(10);
- else
- NewName += ".x";
- TheArg->setName(NewName+".val");
-
- DOUT << "*** Promoted agg argument '" << TheArg->getName()
- << "' of function '" << F->getName() << "'\n";
-
- // 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());
- L->replaceAllUsesWith(TheArg);
- AA.replaceWithNewValue(L, TheArg);
- L->eraseFromParent();
- }
- AA.deleteValue(GEP);
- GEP->eraseFromParent();
+ if (I->use_empty()) {
+ AA.deleteValue(I);
+ continue;
+ }
+
+ // Otherwise, if we promoted this argument, then all users are load
+ // instructions (or GEPs with only load users), and all loads should be
+ // using the new argument that we added.
+ ScalarizeTable &ArgIndices = ScalarizedElements[I];
+
+ while (!I->use_empty()) {
+ if (LoadInst *LI = dyn_cast<LoadInst>(I->use_back())) {
+ assert(ArgIndices.begin()->empty() &&
+ "Load element should sort to front!");
+ I2->setName(I->getName()+".val");
+ LI->replaceAllUsesWith(I2);
+ AA.replaceWithNewValue(LI, I2);
+ LI->eraseFromParent();
+ DEBUG(dbgs() << "*** Promoted load of argument '" << I->getName()
+ << "' in function '" << F->getName() << "'\n");
+ } else {
+ GetElementPtrInst *GEP = cast<GetElementPtrInst>(I->use_back());
+ IndicesVector Operands;
+ Operands.reserve(GEP->getNumIndices());
+ for (User::op_iterator II = GEP->idx_begin(), IE = GEP->idx_end();
+ II != IE; ++II)
+ Operands.push_back(cast<ConstantInt>(*II)->getSExtValue());
+
+ // GEPs with a single 0 index can be merged with direct loads
+ if (Operands.size() == 1 && Operands.front() == 0)
+ Operands.clear();
+
+ Function::arg_iterator TheArg = I2;
+ for (ScalarizeTable::iterator It = ArgIndices.begin();
+ *It != Operands; ++It, ++TheArg) {
+ assert(It != ArgIndices.end() && "GEP not handled??");
}
- }
- // Increment I2 past all of the arguments added for this promoted pointer.
- for (unsigned i = 0, e = ArgIndices.size(); i != e; ++i)
- ++I2;
+ std::string NewName = I->getName();
+ for (unsigned i = 0, e = Operands.size(); i != e; ++i) {
+ NewName += "." + utostr(Operands[i]);
+ }
+ NewName += ".val";
+ TheArg->setName(NewName);
+
+ DEBUG(dbgs() << "*** Promoted agg argument '" << TheArg->getName()
+ << "' of function '" << NF->getName() << "'\n");
+
+ // 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());
+ L->replaceAllUsesWith(TheArg);
+ AA.replaceWithNewValue(L, TheArg);
+ L->eraseFromParent();
+ }
+ AA.deleteValue(GEP);
+ GEP->eraseFromParent();
+ }
}
- // Notify the alias analysis implementation that we inserted a new argument.
- if (ExtraArgHack)
- AA.copyValue(Constant::getNullValue(Type::Int32Ty), NF->arg_begin());
-
+ // Increment I2 past all of the arguments added for this promoted pointer.
+ std::advance(I2, ArgIndices.size());
+ }
// Tell the alias analysis that the old function is about to disappear.
AA.replaceWithNewValue(F, NF);
- // Now that the old function is dead, delete it.
- F->eraseFromParent();
- return NF;
+
+ NF_CGN->stealCalledFunctionsFrom(CG[F]);
+
+ // Now that the old function is dead, delete it. If there is a dangling
+ // reference to the CallgraphNode, just leave the dead function around for
+ // someone else to nuke.
+ CallGraphNode *CGN = CG[F];
+ if (CGN->getNumReferences() == 0)
+ delete CG.removeFunctionFromModule(CGN);
+ else
+ F->setLinkage(Function::ExternalLinkage);
+
+ return NF_CGN;
}
projects / oota-llvm.git / blobdiff