#include "llvm/LLVMContext.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/CallGraph.h"
-#include "llvm/Target/TargetData.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Debug.h"
virtual bool runOnSCC(CallGraphSCC &SCC);
static char ID; // Pass identification, replacement for typeid
explicit ArgPromotion(unsigned maxElements = 3)
- : CallGraphSCCPass(&ID), maxElements(maxElements) {}
+ : 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;
}
char ArgPromotion::ID = 0;
-INITIALIZE_PASS(ArgPromotion, "argpromotion",
- "Promote 'by reference' arguments to scalars", false, false);
+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);
if (PointerArgs.empty()) return 0;
// Second check: make sure that all callers are direct callers. We can't
- // transform functions that have indirect callers.
- if (F->hasAddressTaken())
- return 0;
-
+ // 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);
+ // 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+1, Attribute::ByVal);
+ Argument *PtrArg = PointerArgs[i].first;
+ const 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.
- Argument *PtrArg = PointerArgs[i].first;
if (isByVal) {
- const Type *AgTy = cast<PointerType>(PtrArg->getType())->getElementType();
if (const 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");
- } else {
- // 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;
- }
-
- // 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;
+ 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;
}
}
+
+ // 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;
+ }
}
}
+ // 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 (const 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);
return DoPromotion(F, ArgsToPromote, ByValArgsToTransform);
}
-/// 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;
-}
-
-/// 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(),
CallSite CS(*UI);
assert(CS && "Should only have direct calls!");
- if (!IsAlwaysValidPointer(CS.getArgument(ArgNo)))
+ if (!CS.getArgument(ArgNo)->isDereferenceablePointer())
return false;
}
return true;
GEPIndicesSet ToPromote;
// If the pointer is always valid, any load with first index 0 is valid.
- if (isByVal || AllCalleesPassInValidPointerForArgument(Arg))
+ if (isByVal || AllCallersPassInValidPointerForArgument(Arg))
SafeToUnconditionallyLoad.insert(IndicesVector(1, 0));
// First, iterate the entry block and mark loads of (geps of) arguments as
SmallPtrSet<BasicBlock*, 16> TranspBlocks;
AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
- TargetData *TD = getAnalysisIfAvailable<TargetData>();
- if (!TD) return false; // Without TargetData, assume the worst.
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->getPointerOperand()->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.
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, Arg, LoadSize))
+ if (AA.canBasicBlockModify(**I, Loc))
return false;
}
}
// 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;
+ std::vector<Type*> Params;
typedef std::set<IndicesVector> ScalarizeTable;
// 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());
}
// 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) {
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