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llvm-mirror/lib/Analysis/TargetTransformInfo.cpp
Arnold Schwaighofer 861251004b CostModel: Add parameter to instruction cost to further classify operand values
On certain architectures we can support efficient vectorized version of
instructions if the operand value is uniform (splat) or a constant scalar.
An example of this is a vector shift on x86.

We can efficiently support

for (i = 0 ; i < ; i += 4)
  w[0:3] = v[0:3] << <2, 2, 2, 2>

but not

for (i = 0; i < ; i += 4)
  w[0:3] = v[0:3] << x[0:3]

This patch adds a parameter to getArithmeticInstrCost to further qualify operand
values as uniform or uniform constant.

Targets can then choose to return a different cost for instructions with such
operand values.

A follow-up commit will test this feature on x86.

radar://13576547

llvm-svn: 178807
2013-04-04 23:26:21 +00:00

559 lines
18 KiB
C++

//===- llvm/Analysis/TargetTransformInfo.cpp ------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "tti"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Instructions.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/ErrorHandling.h"
using namespace llvm;
// Setup the analysis group to manage the TargetTransformInfo passes.
INITIALIZE_ANALYSIS_GROUP(TargetTransformInfo, "Target Information", NoTTI)
char TargetTransformInfo::ID = 0;
TargetTransformInfo::~TargetTransformInfo() {
}
void TargetTransformInfo::pushTTIStack(Pass *P) {
TopTTI = this;
PrevTTI = &P->getAnalysis<TargetTransformInfo>();
// Walk up the chain and update the top TTI pointer.
for (TargetTransformInfo *PTTI = PrevTTI; PTTI; PTTI = PTTI->PrevTTI)
PTTI->TopTTI = this;
}
void TargetTransformInfo::popTTIStack() {
TopTTI = 0;
// Walk up the chain and update the top TTI pointer.
for (TargetTransformInfo *PTTI = PrevTTI; PTTI; PTTI = PTTI->PrevTTI)
PTTI->TopTTI = PrevTTI;
PrevTTI = 0;
}
void TargetTransformInfo::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<TargetTransformInfo>();
}
unsigned TargetTransformInfo::getOperationCost(unsigned Opcode, Type *Ty,
Type *OpTy) const {
return PrevTTI->getOperationCost(Opcode, Ty, OpTy);
}
unsigned TargetTransformInfo::getGEPCost(
const Value *Ptr, ArrayRef<const Value *> Operands) const {
return PrevTTI->getGEPCost(Ptr, Operands);
}
unsigned TargetTransformInfo::getCallCost(FunctionType *FTy,
int NumArgs) const {
return PrevTTI->getCallCost(FTy, NumArgs);
}
unsigned TargetTransformInfo::getCallCost(const Function *F,
int NumArgs) const {
return PrevTTI->getCallCost(F, NumArgs);
}
unsigned TargetTransformInfo::getCallCost(
const Function *F, ArrayRef<const Value *> Arguments) const {
return PrevTTI->getCallCost(F, Arguments);
}
unsigned TargetTransformInfo::getIntrinsicCost(
Intrinsic::ID IID, Type *RetTy, ArrayRef<Type *> ParamTys) const {
return PrevTTI->getIntrinsicCost(IID, RetTy, ParamTys);
}
unsigned TargetTransformInfo::getIntrinsicCost(
Intrinsic::ID IID, Type *RetTy, ArrayRef<const Value *> Arguments) const {
return PrevTTI->getIntrinsicCost(IID, RetTy, Arguments);
}
unsigned TargetTransformInfo::getUserCost(const User *U) const {
return PrevTTI->getUserCost(U);
}
bool TargetTransformInfo::isLoweredToCall(const Function *F) const {
return PrevTTI->isLoweredToCall(F);
}
bool TargetTransformInfo::isLegalAddImmediate(int64_t Imm) const {
return PrevTTI->isLegalAddImmediate(Imm);
}
bool TargetTransformInfo::isLegalICmpImmediate(int64_t Imm) const {
return PrevTTI->isLegalICmpImmediate(Imm);
}
bool TargetTransformInfo::isLegalAddressingMode(Type *Ty, GlobalValue *BaseGV,
int64_t BaseOffset,
bool HasBaseReg,
int64_t Scale) const {
return PrevTTI->isLegalAddressingMode(Ty, BaseGV, BaseOffset, HasBaseReg,
Scale);
}
bool TargetTransformInfo::isTruncateFree(Type *Ty1, Type *Ty2) const {
return PrevTTI->isTruncateFree(Ty1, Ty2);
}
bool TargetTransformInfo::isTypeLegal(Type *Ty) const {
return PrevTTI->isTypeLegal(Ty);
}
unsigned TargetTransformInfo::getJumpBufAlignment() const {
return PrevTTI->getJumpBufAlignment();
}
unsigned TargetTransformInfo::getJumpBufSize() const {
return PrevTTI->getJumpBufSize();
}
bool TargetTransformInfo::shouldBuildLookupTables() const {
return PrevTTI->shouldBuildLookupTables();
}
TargetTransformInfo::PopcntSupportKind
TargetTransformInfo::getPopcntSupport(unsigned IntTyWidthInBit) const {
return PrevTTI->getPopcntSupport(IntTyWidthInBit);
}
unsigned TargetTransformInfo::getIntImmCost(const APInt &Imm, Type *Ty) const {
return PrevTTI->getIntImmCost(Imm, Ty);
}
unsigned TargetTransformInfo::getNumberOfRegisters(bool Vector) const {
return PrevTTI->getNumberOfRegisters(Vector);
}
unsigned TargetTransformInfo::getRegisterBitWidth(bool Vector) const {
return PrevTTI->getRegisterBitWidth(Vector);
}
unsigned TargetTransformInfo::getMaximumUnrollFactor() const {
return PrevTTI->getMaximumUnrollFactor();
}
unsigned TargetTransformInfo::getArithmeticInstrCost(unsigned Opcode,
Type *Ty,
OperandValueKind Op1Info,
OperandValueKind Op2Info) const {
return PrevTTI->getArithmeticInstrCost(Opcode, Ty, Op1Info, Op2Info);
}
unsigned TargetTransformInfo::getShuffleCost(ShuffleKind Kind, Type *Tp,
int Index, Type *SubTp) const {
return PrevTTI->getShuffleCost(Kind, Tp, Index, SubTp);
}
unsigned TargetTransformInfo::getCastInstrCost(unsigned Opcode, Type *Dst,
Type *Src) const {
return PrevTTI->getCastInstrCost(Opcode, Dst, Src);
}
unsigned TargetTransformInfo::getCFInstrCost(unsigned Opcode) const {
return PrevTTI->getCFInstrCost(Opcode);
}
unsigned TargetTransformInfo::getCmpSelInstrCost(unsigned Opcode, Type *ValTy,
Type *CondTy) const {
return PrevTTI->getCmpSelInstrCost(Opcode, ValTy, CondTy);
}
unsigned TargetTransformInfo::getVectorInstrCost(unsigned Opcode, Type *Val,
unsigned Index) const {
return PrevTTI->getVectorInstrCost(Opcode, Val, Index);
}
unsigned TargetTransformInfo::getMemoryOpCost(unsigned Opcode, Type *Src,
unsigned Alignment,
unsigned AddressSpace) const {
return PrevTTI->getMemoryOpCost(Opcode, Src, Alignment, AddressSpace);
;
}
unsigned
TargetTransformInfo::getIntrinsicInstrCost(Intrinsic::ID ID,
Type *RetTy,
ArrayRef<Type *> Tys) const {
return PrevTTI->getIntrinsicInstrCost(ID, RetTy, Tys);
}
unsigned TargetTransformInfo::getNumberOfParts(Type *Tp) const {
return PrevTTI->getNumberOfParts(Tp);
}
unsigned TargetTransformInfo::getAddressComputationCost(Type *Tp) const {
return PrevTTI->getAddressComputationCost(Tp);
}
namespace {
struct NoTTI : ImmutablePass, TargetTransformInfo {
const DataLayout *DL;
NoTTI() : ImmutablePass(ID), DL(0) {
initializeNoTTIPass(*PassRegistry::getPassRegistry());
}
virtual void initializePass() {
// Note that this subclass is special, and must *not* call initializeTTI as
// it does not chain.
TopTTI = this;
PrevTTI = 0;
DL = getAnalysisIfAvailable<DataLayout>();
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
// Note that this subclass is special, and must *not* call
// TTI::getAnalysisUsage as it breaks the recursion.
}
/// Pass identification.
static char ID;
/// Provide necessary pointer adjustments for the two base classes.
virtual void *getAdjustedAnalysisPointer(const void *ID) {
if (ID == &TargetTransformInfo::ID)
return (TargetTransformInfo*)this;
return this;
}
unsigned getOperationCost(unsigned Opcode, Type *Ty, Type *OpTy) const {
switch (Opcode) {
default:
// By default, just classify everything as 'basic'.
return TCC_Basic;
case Instruction::GetElementPtr:
llvm_unreachable("Use getGEPCost for GEP operations!");
case Instruction::BitCast:
assert(OpTy && "Cast instructions must provide the operand type");
if (Ty == OpTy || (Ty->isPointerTy() && OpTy->isPointerTy()))
// Identity and pointer-to-pointer casts are free.
return TCC_Free;
// Otherwise, the default basic cost is used.
return TCC_Basic;
case Instruction::IntToPtr:
// An inttoptr cast is free so long as the input is a legal integer type
// which doesn't contain values outside the range of a pointer.
if (DL && DL->isLegalInteger(OpTy->getScalarSizeInBits()) &&
OpTy->getScalarSizeInBits() <= DL->getPointerSizeInBits())
return TCC_Free;
// Otherwise it's not a no-op.
return TCC_Basic;
case Instruction::PtrToInt:
// A ptrtoint cast is free so long as the result is large enough to store
// the pointer, and a legal integer type.
if (DL && DL->isLegalInteger(Ty->getScalarSizeInBits()) &&
Ty->getScalarSizeInBits() >= DL->getPointerSizeInBits())
return TCC_Free;
// Otherwise it's not a no-op.
return TCC_Basic;
case Instruction::Trunc:
// trunc to a native type is free (assuming the target has compare and
// shift-right of the same width).
if (DL && DL->isLegalInteger(DL->getTypeSizeInBits(Ty)))
return TCC_Free;
return TCC_Basic;
}
}
unsigned getGEPCost(const Value *Ptr,
ArrayRef<const Value *> Operands) const {
// In the basic model, we just assume that all-constant GEPs will be folded
// into their uses via addressing modes.
for (unsigned Idx = 0, Size = Operands.size(); Idx != Size; ++Idx)
if (!isa<Constant>(Operands[Idx]))
return TCC_Basic;
return TCC_Free;
}
unsigned getCallCost(FunctionType *FTy, int NumArgs = -1) const {
assert(FTy && "FunctionType must be provided to this routine.");
// The target-independent implementation just measures the size of the
// function by approximating that each argument will take on average one
// instruction to prepare.
if (NumArgs < 0)
// Set the argument number to the number of explicit arguments in the
// function.
NumArgs = FTy->getNumParams();
return TCC_Basic * (NumArgs + 1);
}
unsigned getCallCost(const Function *F, int NumArgs = -1) const {
assert(F && "A concrete function must be provided to this routine.");
if (NumArgs < 0)
// Set the argument number to the number of explicit arguments in the
// function.
NumArgs = F->arg_size();
if (Intrinsic::ID IID = (Intrinsic::ID)F->getIntrinsicID()) {
FunctionType *FTy = F->getFunctionType();
SmallVector<Type *, 8> ParamTys(FTy->param_begin(), FTy->param_end());
return TopTTI->getIntrinsicCost(IID, FTy->getReturnType(), ParamTys);
}
if (!TopTTI->isLoweredToCall(F))
return TCC_Basic; // Give a basic cost if it will be lowered directly.
return TopTTI->getCallCost(F->getFunctionType(), NumArgs);
}
unsigned getCallCost(const Function *F,
ArrayRef<const Value *> Arguments) const {
// Simply delegate to generic handling of the call.
// FIXME: We should use instsimplify or something else to catch calls which
// will constant fold with these arguments.
return TopTTI->getCallCost(F, Arguments.size());
}
unsigned getIntrinsicCost(Intrinsic::ID IID, Type *RetTy,
ArrayRef<Type *> ParamTys) const {
switch (IID) {
default:
// Intrinsics rarely (if ever) have normal argument setup constraints.
// Model them as having a basic instruction cost.
// FIXME: This is wrong for libc intrinsics.
return TCC_Basic;
case Intrinsic::dbg_declare:
case Intrinsic::dbg_value:
case Intrinsic::invariant_start:
case Intrinsic::invariant_end:
case Intrinsic::lifetime_start:
case Intrinsic::lifetime_end:
case Intrinsic::objectsize:
case Intrinsic::ptr_annotation:
case Intrinsic::var_annotation:
// These intrinsics don't actually represent code after lowering.
return TCC_Free;
}
}
unsigned getIntrinsicCost(Intrinsic::ID IID, Type *RetTy,
ArrayRef<const Value *> Arguments) const {
// Delegate to the generic intrinsic handling code. This mostly provides an
// opportunity for targets to (for example) special case the cost of
// certain intrinsics based on constants used as arguments.
SmallVector<Type *, 8> ParamTys;
ParamTys.reserve(Arguments.size());
for (unsigned Idx = 0, Size = Arguments.size(); Idx != Size; ++Idx)
ParamTys.push_back(Arguments[Idx]->getType());
return TopTTI->getIntrinsicCost(IID, RetTy, ParamTys);
}
unsigned getUserCost(const User *U) const {
if (isa<PHINode>(U))
return TCC_Free; // Model all PHI nodes as free.
if (const GEPOperator *GEP = dyn_cast<GEPOperator>(U))
// In the basic model we just assume that all-constant GEPs will be
// folded into their uses via addressing modes.
return GEP->hasAllConstantIndices() ? TCC_Free : TCC_Basic;
if (ImmutableCallSite CS = U) {
const Function *F = CS.getCalledFunction();
if (!F) {
// Just use the called value type.
Type *FTy = CS.getCalledValue()->getType()->getPointerElementType();
return TopTTI->getCallCost(cast<FunctionType>(FTy), CS.arg_size());
}
SmallVector<const Value *, 8> Arguments;
for (ImmutableCallSite::arg_iterator AI = CS.arg_begin(),
AE = CS.arg_end();
AI != AE; ++AI)
Arguments.push_back(*AI);
return TopTTI->getCallCost(F, Arguments);
}
if (const CastInst *CI = dyn_cast<CastInst>(U)) {
// Result of a cmp instruction is often extended (to be used by other
// cmp instructions, logical or return instructions). These are usually
// nop on most sane targets.
if (isa<CmpInst>(CI->getOperand(0)))
return TCC_Free;
}
// Otherwise delegate to the fully generic implementations.
return getOperationCost(Operator::getOpcode(U), U->getType(),
U->getNumOperands() == 1 ?
U->getOperand(0)->getType() : 0);
}
bool isLoweredToCall(const Function *F) const {
// FIXME: These should almost certainly not be handled here, and instead
// handled with the help of TLI or the target itself. This was largely
// ported from existing analysis heuristics here so that such refactorings
// can take place in the future.
if (F->isIntrinsic())
return false;
if (F->hasLocalLinkage() || !F->hasName())
return true;
StringRef Name = F->getName();
// These will all likely lower to a single selection DAG node.
if (Name == "copysign" || Name == "copysignf" || Name == "copysignl" ||
Name == "fabs" || Name == "fabsf" || Name == "fabsl" || Name == "sin" ||
Name == "sinf" || Name == "sinl" || Name == "cos" || Name == "cosf" ||
Name == "cosl" || Name == "sqrt" || Name == "sqrtf" || Name == "sqrtl")
return false;
// These are all likely to be optimized into something smaller.
if (Name == "pow" || Name == "powf" || Name == "powl" || Name == "exp2" ||
Name == "exp2l" || Name == "exp2f" || Name == "floor" || Name ==
"floorf" || Name == "ceil" || Name == "round" || Name == "ffs" ||
Name == "ffsl" || Name == "abs" || Name == "labs" || Name == "llabs")
return false;
return true;
}
bool isLegalAddImmediate(int64_t Imm) const {
return false;
}
bool isLegalICmpImmediate(int64_t Imm) const {
return false;
}
bool isLegalAddressingMode(Type *Ty, GlobalValue *BaseGV, int64_t BaseOffset,
bool HasBaseReg, int64_t Scale) const {
// Guess that reg+reg addressing is allowed. This heuristic is taken from
// the implementation of LSR.
return !BaseGV && BaseOffset == 0 && Scale <= 1;
}
bool isTruncateFree(Type *Ty1, Type *Ty2) const {
return false;
}
bool isTypeLegal(Type *Ty) const {
return false;
}
unsigned getJumpBufAlignment() const {
return 0;
}
unsigned getJumpBufSize() const {
return 0;
}
bool shouldBuildLookupTables() const {
return true;
}
PopcntSupportKind getPopcntSupport(unsigned IntTyWidthInBit) const {
return PSK_Software;
}
unsigned getIntImmCost(const APInt &Imm, Type *Ty) const {
return 1;
}
unsigned getNumberOfRegisters(bool Vector) const {
return 8;
}
unsigned getRegisterBitWidth(bool Vector) const {
return 32;
}
unsigned getMaximumUnrollFactor() const {
return 1;
}
unsigned getArithmeticInstrCost(unsigned Opcode, Type *Ty, OperandValueKind,
OperandValueKind) const {
return 1;
}
unsigned getShuffleCost(ShuffleKind Kind, Type *Tp,
int Index = 0, Type *SubTp = 0) const {
return 1;
}
unsigned getCastInstrCost(unsigned Opcode, Type *Dst,
Type *Src) const {
return 1;
}
unsigned getCFInstrCost(unsigned Opcode) const {
return 1;
}
unsigned getCmpSelInstrCost(unsigned Opcode, Type *ValTy,
Type *CondTy = 0) const {
return 1;
}
unsigned getVectorInstrCost(unsigned Opcode, Type *Val,
unsigned Index = -1) const {
return 1;
}
unsigned getMemoryOpCost(unsigned Opcode, Type *Src,
unsigned Alignment,
unsigned AddressSpace) const {
return 1;
}
unsigned getIntrinsicInstrCost(Intrinsic::ID ID,
Type *RetTy,
ArrayRef<Type*> Tys) const {
return 1;
}
unsigned getNumberOfParts(Type *Tp) const {
return 0;
}
unsigned getAddressComputationCost(Type *Tp) const {
return 0;
}
};
} // end anonymous namespace
INITIALIZE_AG_PASS(NoTTI, TargetTransformInfo, "notti",
"No target information", true, true, true)
char NoTTI::ID = 0;
ImmutablePass *llvm::createNoTargetTransformInfoPass() {
return new NoTTI();
}