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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/DerivedTypes.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/LLVMContext.h"
+#include "llvm/Module.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/SelectionDAG.h"
+#include "llvm/DataLayout.h"
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/Target/TargetOptions.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/MathExtras.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!");
+ }
+}
+
+
+/// getNoopInput - If V is a noop (i.e., lowers to no machine code), look
+/// through it (and any transitive noop operands to it) and return its input
+/// value. This is used to determine if a tail call can be formed.
+///
+static const Value *getNoopInput(const Value *V, const TargetLowering &TLI) {
+ // If V is not an instruction, it can't be looked through.
+ const Instruction *I = dyn_cast<Instruction>(V);
+ if (I == 0 || !I->hasOneUse() || I->getNumOperands() == 0) return V;
+
+ Value *Op = I->getOperand(0);
+
+ // Look through truly no-op truncates.
+ if (isa<TruncInst>(I) &&
+ TLI.isTruncateFree(I->getOperand(0)->getType(), I->getType()))
+ return getNoopInput(I->getOperand(0), TLI);
+
+ // Look through truly no-op bitcasts.
+ if (isa<BitCastInst>(I)) {
+ // No type change at all.
+ if (Op->getType() == I->getType())
+ return getNoopInput(Op, TLI);
+
+ // Pointer to pointer cast.
+ if (Op->getType()->isPointerTy() && I->getType()->isPointerTy())
+ return getNoopInput(Op, TLI);
+
+ if (isa<VectorType>(Op->getType()) && isa<VectorType>(I->getType()) &&
+ TLI.isTypeLegal(EVT::getEVT(Op->getType())) &&
+ TLI.isTypeLegal(EVT::getEVT(I->getType())))
+ return getNoopInput(Op, TLI);
+ }
+
+ // Look through inttoptr.
+ if (isa<IntToPtrInst>(I) && !isa<VectorType>(I->getType())) {
+ // Make sure this isn't a truncating or extending cast. We could support
+ // this eventually, but don't bother for now.
+ if (TLI.getPointerTy().getSizeInBits() ==
+ cast<IntegerType>(Op->getType())->getBitWidth())
+ return getNoopInput(Op, TLI);
+ }
+
+ // Look through ptrtoint.
+ if (isa<PtrToIntInst>(I) && !isa<VectorType>(I->getType())) {
+ // Make sure this isn't a truncating or extending cast. We could support
+ // this eventually, but don't bother for now.
+ if (TLI.getPointerTy().getSizeInBits() ==
+ cast<IntegerType>(I->getType())->getBitWidth())
+ return getNoopInput(Op, TLI);
+ }
+
+
+ // Otherwise it's not something we can look through.
+ return V;
+}
+
+
+/// 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, Attributes CalleeRetAttr,
+ 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();
+ Attributes CallerRetAttr = F->getAttributes().getRetAttributes();
+ if (AttrBuilder(CalleeRetAttr).removeAttribute(Attributes::NoAlias) !=
+ AttrBuilder(CallerRetAttr).removeAttribute(Attributes::NoAlias))
+ return false;
+
+ // It's not safe to eliminate the sign / zero extension of the return value.
+ if (CallerRetAttr.hasAttribute(Attributes::ZExt) ||
+ CallerRetAttr.hasAttribute(Attributes::SExt))
+ return false;
+
+ // Otherwise, make sure the unmodified return value of I is the return value.
+ // We handle two cases: multiple return values + scalars.
+ Value *RetVal = Ret->getOperand(0);
+ if (!isa<InsertValueInst>(RetVal) || !isa<StructType>(RetVal->getType()))
+ // Handle scalars first.
+ return getNoopInput(Ret->getOperand(0), TLI) == I;
+
+ // If this is an aggregate return, look through the insert/extract values and
+ // see if each is transparent.
+ for (unsigned i = 0, e =cast<StructType>(RetVal->getType())->getNumElements();
+ i != e; ++i) {
+ const Value *InScalar = FindInsertedValue(RetVal, i);
+ if (InScalar == 0) return false;
+ InScalar = getNoopInput(InScalar, TLI);
+
+ // If the scalar value being inserted is an extractvalue of the right index
+ // from the call, then everything is good.
+ const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(InScalar);
+ if (EVI == 0 || EVI->getOperand(0) != I || EVI->getNumIndices() != 1 ||
+ EVI->getIndices()[0] != i)
+ return false;
+ }
+
+ return true;
+}
+
+bool llvm::isInTailCallPosition(SelectionDAG &DAG, SDNode *Node,
+ SDValue &Chain, const TargetLowering &TLI) {
+ const Function *F = DAG.getMachineFunction().getFunction();
+
+ // Conservatively require the attributes of the call to match those of
+ // the return. Ignore noalias because it doesn't affect the call sequence.
+ Attributes CallerRetAttr = F->getAttributes().getRetAttributes();
+ if (AttrBuilder(CallerRetAttr)
+ .removeAttribute(Attributes::NoAlias).hasAttributes())
+ return false;
+
+ // It's not safe to eliminate the sign / zero extension of the return value.
+ if (CallerRetAttr.hasAttribute(Attributes::ZExt) ||
+ CallerRetAttr.hasAttribute(Attributes::SExt))
+ return false;
+
+ // Check if the only use is a function return node.
+ return TLI.isUsedByReturnOnly(Node, Chain);
+}
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