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+//===-- Analysis.cpp - CodeGen LLVM IR Analysis Utilities -----------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines several CodeGen-specific LLVM IR analysis utilties.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/Analysis.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Target/TargetLowering.h"
+using namespace llvm;
+
+/// ComputeLinearIndex - Given an LLVM IR aggregate type and a sequence
+/// of insertvalue or extractvalue indices that identify a member, return
+/// the linearized index of the start of the member.
+///
+unsigned llvm::ComputeLinearIndex(Type *Ty,
+ const unsigned *Indices,
+ const unsigned *IndicesEnd,
+ unsigned CurIndex) {
+ // Base case: We're done.
+ if (Indices && Indices == IndicesEnd)
+ return CurIndex;
+
+ // Given a struct type, recursively traverse the elements.
+ if (StructType *STy = dyn_cast<StructType>(Ty)) {
+ for (StructType::element_iterator EB = STy->element_begin(),
+ EI = EB,
+ EE = STy->element_end();
+ EI != EE; ++EI) {
+ if (Indices && *Indices == unsigned(EI - EB))
+ return ComputeLinearIndex(*EI, Indices+1, IndicesEnd, CurIndex);
+ CurIndex = ComputeLinearIndex(*EI, 0, 0, CurIndex);
+ }
+ return CurIndex;
+ }
+ // Given an array type, recursively traverse the elements.
+ else if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
+ Type *EltTy = ATy->getElementType();
+ for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i) {
+ if (Indices && *Indices == i)
+ return ComputeLinearIndex(EltTy, Indices+1, IndicesEnd, CurIndex);
+ CurIndex = ComputeLinearIndex(EltTy, 0, 0, CurIndex);
+ }
+ return CurIndex;
+ }
+ // We haven't found the type we're looking for, so keep searching.
+ return CurIndex + 1;
+}
+
+/// ComputeValueVTs - Given an LLVM IR type, compute a sequence of
+/// EVTs that represent all the individual underlying
+/// non-aggregate types that comprise it.
+///
+/// If Offsets is non-null, it points to a vector to be filled in
+/// with the in-memory offsets of each of the individual values.
+///
+void llvm::ComputeValueVTs(const TargetLowering &TLI, Type *Ty,
+ SmallVectorImpl<EVT> &ValueVTs,
+ SmallVectorImpl<uint64_t> *Offsets,
+ uint64_t StartingOffset) {
+ // Given a struct type, recursively traverse the elements.
+ if (StructType *STy = dyn_cast<StructType>(Ty)) {
+ const StructLayout *SL = TLI.getDataLayout()->getStructLayout(STy);
+ for (StructType::element_iterator EB = STy->element_begin(),
+ EI = EB,
+ EE = STy->element_end();
+ EI != EE; ++EI)
+ ComputeValueVTs(TLI, *EI, ValueVTs, Offsets,
+ StartingOffset + SL->getElementOffset(EI - EB));
+ return;
+ }
+ // Given an array type, recursively traverse the elements.
+ if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
+ Type *EltTy = ATy->getElementType();
+ uint64_t EltSize = TLI.getDataLayout()->getTypeAllocSize(EltTy);
+ for (unsigned i = 0, e = ATy->getNumElements(); i != e; ++i)
+ ComputeValueVTs(TLI, EltTy, ValueVTs, Offsets,
+ StartingOffset + i * EltSize);
+ return;
+ }
+ // Interpret void as zero return values.
+ if (Ty->isVoidTy())
+ return;
+ // Base case: we can get an EVT for this LLVM IR type.
+ ValueVTs.push_back(TLI.getValueType(Ty));
+ if (Offsets)
+ Offsets->push_back(StartingOffset);
+}
+
+/// ExtractTypeInfo - Returns the type info, possibly bitcast, encoded in V.
+GlobalVariable *llvm::ExtractTypeInfo(Value *V) {
+ V = V->stripPointerCasts();
+ GlobalVariable *GV = dyn_cast<GlobalVariable>(V);
+
+ if (GV && GV->getName() == "llvm.eh.catch.all.value") {
+ assert(GV->hasInitializer() &&
+ "The EH catch-all value must have an initializer");
+ Value *Init = GV->getInitializer();
+ GV = dyn_cast<GlobalVariable>(Init);
+ if (!GV) V = cast<ConstantPointerNull>(Init);
+ }
+
+ assert((GV || isa<ConstantPointerNull>(V)) &&
+ "TypeInfo must be a global variable or NULL");
+ return GV;
+}
+
+/// hasInlineAsmMemConstraint - Return true if the inline asm instruction being
+/// processed uses a memory 'm' constraint.
+bool
+llvm::hasInlineAsmMemConstraint(InlineAsm::ConstraintInfoVector &CInfos,
+ const TargetLowering &TLI) {
+ for (unsigned i = 0, e = CInfos.size(); i != e; ++i) {
+ InlineAsm::ConstraintInfo &CI = CInfos[i];
+ for (unsigned j = 0, ee = CI.Codes.size(); j != ee; ++j) {
+ TargetLowering::ConstraintType CType = TLI.getConstraintType(CI.Codes[j]);
+ if (CType == TargetLowering::C_Memory)
+ return true;
+ }
+
+ // Indirect operand accesses access memory.
+ if (CI.isIndirect)
+ return true;
+ }
+
+ return false;
+}
+
+/// getFCmpCondCode - Return the ISD condition code corresponding to
+/// the given LLVM IR floating-point condition code. This includes
+/// consideration of global floating-point math flags.
+///
+ISD::CondCode llvm::getFCmpCondCode(FCmpInst::Predicate Pred) {
+ switch (Pred) {
+ case FCmpInst::FCMP_FALSE: return ISD::SETFALSE;
+ case FCmpInst::FCMP_OEQ: return ISD::SETOEQ;
+ case FCmpInst::FCMP_OGT: return ISD::SETOGT;
+ case FCmpInst::FCMP_OGE: return ISD::SETOGE;
+ case FCmpInst::FCMP_OLT: return ISD::SETOLT;
+ case FCmpInst::FCMP_OLE: return ISD::SETOLE;
+ case FCmpInst::FCMP_ONE: return ISD::SETONE;
+ case FCmpInst::FCMP_ORD: return ISD::SETO;
+ case FCmpInst::FCMP_UNO: return ISD::SETUO;
+ case FCmpInst::FCMP_UEQ: return ISD::SETUEQ;
+ case FCmpInst::FCMP_UGT: return ISD::SETUGT;
+ case FCmpInst::FCMP_UGE: return ISD::SETUGE;
+ case FCmpInst::FCMP_ULT: return ISD::SETULT;
+ case FCmpInst::FCMP_ULE: return ISD::SETULE;
+ case FCmpInst::FCMP_UNE: return ISD::SETUNE;
+ case FCmpInst::FCMP_TRUE: return ISD::SETTRUE;
+ default: llvm_unreachable("Invalid FCmp predicate opcode!");
+ }
+}
+
+ISD::CondCode llvm::getFCmpCodeWithoutNaN(ISD::CondCode CC) {
+ switch (CC) {
+ case ISD::SETOEQ: case ISD::SETUEQ: return ISD::SETEQ;
+ case ISD::SETONE: case ISD::SETUNE: return ISD::SETNE;
+ case ISD::SETOLT: case ISD::SETULT: return ISD::SETLT;
+ case ISD::SETOLE: case ISD::SETULE: return ISD::SETLE;
+ case ISD::SETOGT: case ISD::SETUGT: return ISD::SETGT;
+ case ISD::SETOGE: case ISD::SETUGE: return ISD::SETGE;
+ default: return CC;
+ }
+}
+
+/// getICmpCondCode - Return the ISD condition code corresponding to
+/// the given LLVM IR integer condition code.
+///
+ISD::CondCode llvm::getICmpCondCode(ICmpInst::Predicate Pred) {
+ switch (Pred) {
+ case ICmpInst::ICMP_EQ: return ISD::SETEQ;
+ case ICmpInst::ICMP_NE: return ISD::SETNE;
+ case ICmpInst::ICMP_SLE: return ISD::SETLE;
+ case ICmpInst::ICMP_ULE: return ISD::SETULE;
+ case ICmpInst::ICMP_SGE: return ISD::SETGE;
+ case ICmpInst::ICMP_UGE: return ISD::SETUGE;
+ case ICmpInst::ICMP_SLT: return ISD::SETLT;
+ case ICmpInst::ICMP_ULT: return ISD::SETULT;
+ case ICmpInst::ICMP_SGT: return ISD::SETGT;
+ case ICmpInst::ICMP_UGT: return ISD::SETUGT;
+ default:
+ llvm_unreachable("Invalid ICmp predicate opcode!");
+ }
+}
+
+static bool isNoopBitcast(Type *T1, Type *T2,
+ const TargetLowering& TLI) {
+ return T1 == T2 || (T1->isPointerTy() && T2->isPointerTy()) ||
+ (isa<VectorType>(T1) && isa<VectorType>(T2) &&
+ TLI.isTypeLegal(EVT::getEVT(T1)) && TLI.isTypeLegal(EVT::getEVT(T2)));
+}
+
+/// sameNoopInput - Return true if V1 == V2, else if either V1 or V2 is a noop
+/// (i.e., lowers to no machine code), look through it (and any transitive noop
+/// operands to it) and check if it has the same noop input value. This is
+/// used to determine if a tail call can be formed.
+static bool sameNoopInput(const Value *V1, const Value *V2,
+ SmallVectorImpl<unsigned> &Els1,
+ SmallVectorImpl<unsigned> &Els2,
+ const TargetLowering &TLI) {
+ using std::swap;
+ bool swapParity = false;
+ bool equalEls = Els1 == Els2;
+ while (true) {
+ if ((equalEls && V1 == V2) || isa<UndefValue>(V1) || isa<UndefValue>(V2)) {
+ if (swapParity)
+ // Revert to original Els1 and Els2 to avoid confusing recursive calls
+ swap(Els1, Els2);
+ return true;
+ }
+
+ // Try to look through V1; if V1 is not an instruction, it can't be looked
+ // through.
+ const Instruction *I = dyn_cast<Instruction>(V1);
+ const Value *NoopInput = 0;
+ if (I != 0 && I->getNumOperands() > 0) {
+ Value *Op = I->getOperand(0);
+ if (isa<TruncInst>(I)) {
+ // Look through truly no-op truncates.
+ if (TLI.isTruncateFree(Op->getType(), I->getType()))
+ NoopInput = Op;
+ } else if (isa<BitCastInst>(I)) {
+ // Look through truly no-op bitcasts.
+ if (isNoopBitcast(Op->getType(), I->getType(), TLI))
+ NoopInput = Op;
+ } else if (isa<GetElementPtrInst>(I)) {
+ // Look through getelementptr
+ if (cast<GetElementPtrInst>(I)->hasAllZeroIndices())
+ NoopInput = Op;
+ } else if (isa<IntToPtrInst>(I)) {
+ // Look through inttoptr.
+ // Make sure this isn't a truncating or extending cast. We could
+ // support this eventually, but don't bother for now.
+ if (!isa<VectorType>(I->getType()) &&
+ TLI.getPointerTy().getSizeInBits() ==
+ cast<IntegerType>(Op->getType())->getBitWidth())
+ NoopInput = Op;
+ } else if (isa<PtrToIntInst>(I)) {
+ // Look through ptrtoint.
+ // Make sure this isn't a truncating or extending cast. We could
+ // support this eventually, but don't bother for now.
+ if (!isa<VectorType>(I->getType()) &&
+ TLI.getPointerTy().getSizeInBits() ==
+ cast<IntegerType>(I->getType())->getBitWidth())
+ NoopInput = Op;
+ } else if (isa<CallInst>(I)) {
+ // Look through call
+ for (User::const_op_iterator i = I->op_begin(),
+ // Skip Callee
+ e = I->op_end() - 1;
+ i != e; ++i) {
+ unsigned attrInd = i - I->op_begin() + 1;
+ if (cast<CallInst>(I)->paramHasAttr(attrInd, Attribute::Returned) &&
+ isNoopBitcast((*i)->getType(), I->getType(), TLI)) {
+ NoopInput = *i;
+ break;
+ }
+ }
+ } else if (isa<InvokeInst>(I)) {
+ // Look through invoke
+ for (User::const_op_iterator i = I->op_begin(),
+ // Skip BB, BB, Callee
+ e = I->op_end() - 3;
+ i != e; ++i) {
+ unsigned attrInd = i - I->op_begin() + 1;
+ if (cast<InvokeInst>(I)->paramHasAttr(attrInd, Attribute::Returned) &&
+ isNoopBitcast((*i)->getType(), I->getType(), TLI)) {
+ NoopInput = *i;
+ break;
+ }
+ }
+ }
+ }
+
+ if (NoopInput) {
+ V1 = NoopInput;
+ continue;
+ }
+
+ // If we already swapped, avoid infinite loop
+ if (swapParity)
+ break;
+
+ // Otherwise, swap V1<->V2, Els1<->Els2
+ swap(V1, V2);
+ swap(Els1, Els2);
+ swapParity = !swapParity;
+ }
+
+ for (unsigned n = 0; n < 2; ++n) {
+ if (isa<InsertValueInst>(V1)) {
+ if (isa<StructType>(V1->getType())) {
+ // Look through insertvalue
+ unsigned i, e;
+ for (i = 0, e = cast<StructType>(V1->getType())->getNumElements();
+ i != e; ++i) {
+ const Value *InScalar = FindInsertedValue(const_cast<Value*>(V1), i);
+ if (InScalar == 0)
+ break;
+ Els1.push_back(i);
+ if (!sameNoopInput(InScalar, V2, Els1, Els2, TLI)) {
+ Els1.pop_back();
+ break;
+ }
+ Els1.pop_back();
+ }
+ if (i == e) {
+ if (swapParity)
+ swap(Els1, Els2);
+ return true;
+ }
+ }
+ } else if (!Els1.empty() && isa<ExtractValueInst>(V1)) {
+ const ExtractValueInst *EVI = cast<ExtractValueInst>(V1);
+ unsigned i = Els1.back();
+ // If the scalar value being inserted is an extractvalue of the right
+ // index from the call, then everything is good.
+ if (isa<StructType>(EVI->getOperand(0)->getType()) &&
+ EVI->getNumIndices() == 1 && EVI->getIndices()[0] == i) {
+ // Look through extractvalue
+ Els1.pop_back();
+ if (sameNoopInput(EVI->getOperand(0), V2, Els1, Els2, TLI)) {
+ Els1.push_back(i);
+ if (swapParity)
+ swap(Els1, Els2);
+ return true;
+ }
+ Els1.push_back(i);
+ }
+ }
+
+ swap(V1, V2);
+ swap(Els1, Els2);
+ swapParity = !swapParity;
+ }
+
+ if (swapParity)
+ swap(Els1, Els2);
+ return false;
+}
+
+/// Test if the given instruction is in a position to be optimized
+/// with a tail-call. This roughly means that it's in a block with
+/// a return and there's nothing that needs to be scheduled
+/// between it and the return.
+///
+/// This function only tests target-independent requirements.
+bool llvm::isInTailCallPosition(ImmutableCallSite CS,
+ const TargetLowering &TLI) {
+ const Instruction *I = CS.getInstruction();
+ const BasicBlock *ExitBB = I->getParent();
+ const TerminatorInst *Term = ExitBB->getTerminator();
+ const ReturnInst *Ret = dyn_cast<ReturnInst>(Term);
+
+ // The block must end in a return statement or unreachable.
+ //
+ // FIXME: Decline tailcall if it's not guaranteed and if the block ends in
+ // an unreachable, for now. The way tailcall optimization is currently
+ // implemented means it will add an epilogue followed by a jump. That is
+ // not profitable. Also, if the callee is a special function (e.g.
+ // longjmp on x86), it can end up causing miscompilation that has not
+ // been fully understood.
+ if (!Ret &&
+ (!TLI.getTargetMachine().Options.GuaranteedTailCallOpt ||
+ !isa<UnreachableInst>(Term)))
+ return false;
+
+ // If I will have a chain, make sure no other instruction that will have a
+ // chain interposes between I and the return.
+ if (I->mayHaveSideEffects() || I->mayReadFromMemory() ||
+ !isSafeToSpeculativelyExecute(I))
+ for (BasicBlock::const_iterator BBI = prior(prior(ExitBB->end())); ;
+ --BBI) {
+ if (&*BBI == I)
+ break;
+ // Debug info intrinsics do not get in the way of tail call optimization.
+ if (isa<DbgInfoIntrinsic>(BBI))
+ continue;
+ if (BBI->mayHaveSideEffects() || BBI->mayReadFromMemory() ||
+ !isSafeToSpeculativelyExecute(BBI))
+ return false;
+ }
+
+ // If the block ends with a void return or unreachable, it doesn't matter
+ // what the call's return type is.
+ if (!Ret || Ret->getNumOperands() == 0) return true;
+
+ // If the return value is undef, it doesn't matter what the call's
+ // return type is.
+ if (isa<UndefValue>(Ret->getOperand(0))) return true;
+
+ // Conservatively require the attributes of the call to match those of
+ // the return. Ignore noalias because it doesn't affect the call sequence.
+ const Function *F = ExitBB->getParent();
+ AttributeSet CallerAttrs = F->getAttributes();
+ if (AttrBuilder(CallerAttrs, AttributeSet::ReturnIndex).
+ removeAttribute(Attribute::NoAlias) !=
+ AttrBuilder(CallerAttrs, AttributeSet::ReturnIndex).
+ removeAttribute(Attribute::NoAlias))
+ return false;
+
+ // It's not safe to eliminate the sign / zero extension of the return value.
+ if (CallerAttrs.hasAttribute(AttributeSet::ReturnIndex, Attribute::ZExt) ||
+ CallerAttrs.hasAttribute(AttributeSet::ReturnIndex, Attribute::SExt))
+ return false;
+
+ // Otherwise, make sure the return value and I have the same value
+ SmallVector<unsigned, 4> Els1, Els2;
+ return sameNoopInput(Ret->getOperand(0), I, Els1, Els2, TLI);
+}
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