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llvm-project/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp

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//===-- PPCTargetTransformInfo.cpp - PPC specific TTI ---------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "PPCTargetTransformInfo.h"
#include "llvm/Analysis/CodeMetrics.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/CodeGen/BasicTTIImpl.h"
#include "llvm/CodeGen/CostTable.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/CodeGen/TargetSchedule.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
using namespace llvm;
#define DEBUG_TYPE "ppctti"
static cl::opt<bool> DisablePPCConstHoist("disable-ppc-constant-hoisting",
cl::desc("disable constant hoisting on PPC"), cl::init(false), cl::Hidden);
// This is currently only used for the data prefetch pass which is only enabled
// for BG/Q by default.
static cl::opt<unsigned>
CacheLineSize("ppc-loop-prefetch-cache-line", cl::Hidden, cl::init(64),
cl::desc("The loop prefetch cache line size"));
static cl::opt<bool>
EnablePPCColdCC("ppc-enable-coldcc", cl::Hidden, cl::init(false),
cl::desc("Enable using coldcc calling conv for cold "
"internal functions"));
// The latency of mtctr is only justified if there are more than 4
// comparisons that will be removed as a result.
static cl::opt<unsigned>
SmallCTRLoopThreshold("min-ctr-loop-threshold", cl::init(4), cl::Hidden,
cl::desc("Loops with a constant trip count smaller than "
"this value will not use the count register."));
//===----------------------------------------------------------------------===//
//
// PPC cost model.
//
//===----------------------------------------------------------------------===//
TargetTransformInfo::PopcntSupportKind
PPCTTIImpl::getPopcntSupport(unsigned TyWidth) {
assert(isPowerOf2_32(TyWidth) && "Ty width must be power of 2");
if (ST->hasPOPCNTD() != PPCSubtarget::POPCNTD_Unavailable && TyWidth <= 64)
return ST->hasPOPCNTD() == PPCSubtarget::POPCNTD_Slow ?
TTI::PSK_SlowHardware : TTI::PSK_FastHardware;
return TTI::PSK_Software;
}
int PPCTTIImpl::getIntImmCost(const APInt &Imm, Type *Ty) {
if (DisablePPCConstHoist)
return BaseT::getIntImmCost(Imm, Ty);
assert(Ty->isIntegerTy());
unsigned BitSize = Ty->getPrimitiveSizeInBits();
if (BitSize == 0)
return ~0U;
if (Imm == 0)
return TTI::TCC_Free;
if (Imm.getBitWidth() <= 64) {
if (isInt<16>(Imm.getSExtValue()))
return TTI::TCC_Basic;
if (isInt<32>(Imm.getSExtValue())) {
// A constant that can be materialized using lis.
if ((Imm.getZExtValue() & 0xFFFF) == 0)
return TTI::TCC_Basic;
return 2 * TTI::TCC_Basic;
}
}
return 4 * TTI::TCC_Basic;
}
int PPCTTIImpl::getIntImmCostIntrin(Intrinsic::ID IID, unsigned Idx,
const APInt &Imm, Type *Ty) {
if (DisablePPCConstHoist)
return BaseT::getIntImmCostIntrin(IID, Idx, Imm, Ty);
assert(Ty->isIntegerTy());
unsigned BitSize = Ty->getPrimitiveSizeInBits();
if (BitSize == 0)
return ~0U;
switch (IID) {
default:
return TTI::TCC_Free;
case Intrinsic::sadd_with_overflow:
case Intrinsic::uadd_with_overflow:
case Intrinsic::ssub_with_overflow:
case Intrinsic::usub_with_overflow:
if ((Idx == 1) && Imm.getBitWidth() <= 64 && isInt<16>(Imm.getSExtValue()))
return TTI::TCC_Free;
break;
case Intrinsic::experimental_stackmap:
if ((Idx < 2) || (Imm.getBitWidth() <= 64 && isInt<64>(Imm.getSExtValue())))
return TTI::TCC_Free;
break;
case Intrinsic::experimental_patchpoint_void:
case Intrinsic::experimental_patchpoint_i64:
if ((Idx < 4) || (Imm.getBitWidth() <= 64 && isInt<64>(Imm.getSExtValue())))
return TTI::TCC_Free;
break;
}
return PPCTTIImpl::getIntImmCost(Imm, Ty);
}
int PPCTTIImpl::getIntImmCostInst(unsigned Opcode, unsigned Idx,
const APInt &Imm, Type *Ty) {
if (DisablePPCConstHoist)
return BaseT::getIntImmCostInst(Opcode, Idx, Imm, Ty);
assert(Ty->isIntegerTy());
unsigned BitSize = Ty->getPrimitiveSizeInBits();
if (BitSize == 0)
return ~0U;
unsigned ImmIdx = ~0U;
bool ShiftedFree = false, RunFree = false, UnsignedFree = false,
ZeroFree = false;
switch (Opcode) {
default:
return TTI::TCC_Free;
case Instruction::GetElementPtr:
// Always hoist the base address of a GetElementPtr. This prevents the
// creation of new constants for every base constant that gets constant
// folded with the offset.
if (Idx == 0)
return 2 * TTI::TCC_Basic;
return TTI::TCC_Free;
case Instruction::And:
RunFree = true; // (for the rotate-and-mask instructions)
LLVM_FALLTHROUGH;
case Instruction::Add:
case Instruction::Or:
case Instruction::Xor:
ShiftedFree = true;
LLVM_FALLTHROUGH;
case Instruction::Sub:
case Instruction::Mul:
case Instruction::Shl:
case Instruction::LShr:
case Instruction::AShr:
ImmIdx = 1;
break;
case Instruction::ICmp:
UnsignedFree = true;
ImmIdx = 1;
// Zero comparisons can use record-form instructions.
LLVM_FALLTHROUGH;
case Instruction::Select:
ZeroFree = true;
break;
case Instruction::PHI:
case Instruction::Call:
case Instruction::Ret:
case Instruction::Load:
case Instruction::Store:
break;
}
if (ZeroFree && Imm == 0)
return TTI::TCC_Free;
if (Idx == ImmIdx && Imm.getBitWidth() <= 64) {
if (isInt<16>(Imm.getSExtValue()))
return TTI::TCC_Free;
if (RunFree) {
if (Imm.getBitWidth() <= 32 &&
(isShiftedMask_32(Imm.getZExtValue()) ||
isShiftedMask_32(~Imm.getZExtValue())))
return TTI::TCC_Free;
if (ST->isPPC64() &&
(isShiftedMask_64(Imm.getZExtValue()) ||
isShiftedMask_64(~Imm.getZExtValue())))
return TTI::TCC_Free;
}
if (UnsignedFree && isUInt<16>(Imm.getZExtValue()))
return TTI::TCC_Free;
if (ShiftedFree && (Imm.getZExtValue() & 0xFFFF) == 0)
return TTI::TCC_Free;
}
return PPCTTIImpl::getIntImmCost(Imm, Ty);
}
unsigned PPCTTIImpl::getUserCost(const User *U,
ArrayRef<const Value *> Operands) {
if (U->getType()->isVectorTy()) {
// Instructions that need to be split should cost more.
std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, U->getType());
return LT.first * BaseT::getUserCost(U, Operands);
}
return BaseT::getUserCost(U, Operands);
}
bool PPCTTIImpl::mightUseCTR(BasicBlock *BB,
TargetLibraryInfo *LibInfo) {
const PPCTargetMachine &TM = ST->getTargetMachine();
// Loop through the inline asm constraints and look for something that
// clobbers ctr.
auto asmClobbersCTR = [](InlineAsm *IA) {
InlineAsm::ConstraintInfoVector CIV = IA->ParseConstraints();
for (unsigned i = 0, ie = CIV.size(); i < ie; ++i) {
InlineAsm::ConstraintInfo &C = CIV[i];
if (C.Type != InlineAsm::isInput)
for (unsigned j = 0, je = C.Codes.size(); j < je; ++j)
if (StringRef(C.Codes[j]).equals_lower("{ctr}"))
return true;
}
return false;
};
// Determining the address of a TLS variable results in a function call in
// certain TLS models.
std::function<bool(const Value*)> memAddrUsesCTR =
[&memAddrUsesCTR, &TM](const Value *MemAddr) -> bool {
const auto *GV = dyn_cast<GlobalValue>(MemAddr);
if (!GV) {
// Recurse to check for constants that refer to TLS global variables.
if (const auto *CV = dyn_cast<Constant>(MemAddr))
for (const auto &CO : CV->operands())
if (memAddrUsesCTR(CO))
return true;
return false;
}
if (!GV->isThreadLocal())
return false;
TLSModel::Model Model = TM.getTLSModel(GV);
return Model == TLSModel::GeneralDynamic ||
Model == TLSModel::LocalDynamic;
};
auto isLargeIntegerTy = [](bool Is32Bit, Type *Ty) {
if (IntegerType *ITy = dyn_cast<IntegerType>(Ty))
return ITy->getBitWidth() > (Is32Bit ? 32U : 64U);
return false;
};
for (BasicBlock::iterator J = BB->begin(), JE = BB->end();
J != JE; ++J) {
if (CallInst *CI = dyn_cast<CallInst>(J)) {
// Inline ASM is okay, unless it clobbers the ctr register.
if (InlineAsm *IA = dyn_cast<InlineAsm>(CI->getCalledValue())) {
if (asmClobbersCTR(IA))
return true;
continue;
}
if (Function *F = CI->getCalledFunction()) {
// Most intrinsics don't become function calls, but some might.
// sin, cos, exp and log are always calls.
unsigned Opcode = 0;
if (F->getIntrinsicID() != Intrinsic::not_intrinsic) {
switch (F->getIntrinsicID()) {
default: continue;
// If we have a call to ppc_is_decremented_ctr_nonzero, or ppc_mtctr
// we're definitely using CTR.
case Intrinsic::set_loop_iterations:
case Intrinsic::loop_decrement:
return true;
// VisualStudio defines setjmp as _setjmp
#if defined(_MSC_VER) && defined(setjmp) && \
!defined(setjmp_undefined_for_msvc)
# pragma push_macro("setjmp")
# undef setjmp
# define setjmp_undefined_for_msvc
#endif
case Intrinsic::setjmp:
#if defined(_MSC_VER) && defined(setjmp_undefined_for_msvc)
// let's return it to _setjmp state
# pragma pop_macro("setjmp")
# undef setjmp_undefined_for_msvc
#endif
case Intrinsic::longjmp:
// Exclude eh_sjlj_setjmp; we don't need to exclude eh_sjlj_longjmp
// because, although it does clobber the counter register, the
// control can't then return to inside the loop unless there is also
// an eh_sjlj_setjmp.
case Intrinsic::eh_sjlj_setjmp:
case Intrinsic::memcpy:
case Intrinsic::memmove:
case Intrinsic::memset:
case Intrinsic::powi:
case Intrinsic::log:
case Intrinsic::log2:
case Intrinsic::log10:
case Intrinsic::exp:
case Intrinsic::exp2:
case Intrinsic::pow:
case Intrinsic::sin:
case Intrinsic::cos:
return true;
case Intrinsic::copysign:
if (CI->getArgOperand(0)->getType()->getScalarType()->
isPPC_FP128Ty())
return true;
else
continue; // ISD::FCOPYSIGN is never a library call.
case Intrinsic::sqrt: Opcode = ISD::FSQRT; break;
case Intrinsic::floor: Opcode = ISD::FFLOOR; break;
case Intrinsic::ceil: Opcode = ISD::FCEIL; break;
case Intrinsic::trunc: Opcode = ISD::FTRUNC; break;
case Intrinsic::rint: Opcode = ISD::FRINT; break;
case Intrinsic::lrint: Opcode = ISD::LRINT; break;
case Intrinsic::llrint: Opcode = ISD::LLRINT; break;
case Intrinsic::nearbyint: Opcode = ISD::FNEARBYINT; break;
case Intrinsic::round: Opcode = ISD::FROUND; break;
case Intrinsic::lround: Opcode = ISD::LROUND; break;
case Intrinsic::llround: Opcode = ISD::LLROUND; break;
case Intrinsic::minnum: Opcode = ISD::FMINNUM; break;
case Intrinsic::maxnum: Opcode = ISD::FMAXNUM; break;
case Intrinsic::umul_with_overflow: Opcode = ISD::UMULO; break;
case Intrinsic::smul_with_overflow: Opcode = ISD::SMULO; break;
}
}
// PowerPC does not use [US]DIVREM or other library calls for
// operations on regular types which are not otherwise library calls
// (i.e. soft float or atomics). If adapting for targets that do,
// additional care is required here.
LibFunc Func;
if (!F->hasLocalLinkage() && F->hasName() && LibInfo &&
LibInfo->getLibFunc(F->getName(), Func) &&
LibInfo->hasOptimizedCodeGen(Func)) {
// Non-read-only functions are never treated as intrinsics.
if (!CI->onlyReadsMemory())
return true;
// Conversion happens only for FP calls.
if (!CI->getArgOperand(0)->getType()->isFloatingPointTy())
return true;
switch (Func) {
default: return true;
case LibFunc_copysign:
case LibFunc_copysignf:
continue; // ISD::FCOPYSIGN is never a library call.
case LibFunc_copysignl:
return true;
case LibFunc_fabs:
case LibFunc_fabsf:
case LibFunc_fabsl:
continue; // ISD::FABS is never a library call.
case LibFunc_sqrt:
case LibFunc_sqrtf:
case LibFunc_sqrtl:
Opcode = ISD::FSQRT; break;
case LibFunc_floor:
case LibFunc_floorf:
case LibFunc_floorl:
Opcode = ISD::FFLOOR; break;
case LibFunc_nearbyint:
case LibFunc_nearbyintf:
case LibFunc_nearbyintl:
Opcode = ISD::FNEARBYINT; break;
case LibFunc_ceil:
case LibFunc_ceilf:
case LibFunc_ceill:
Opcode = ISD::FCEIL; break;
case LibFunc_rint:
case LibFunc_rintf:
case LibFunc_rintl:
Opcode = ISD::FRINT; break;
case LibFunc_round:
case LibFunc_roundf:
case LibFunc_roundl:
Opcode = ISD::FROUND; break;
case LibFunc_trunc:
case LibFunc_truncf:
case LibFunc_truncl:
Opcode = ISD::FTRUNC; break;
case LibFunc_fmin:
case LibFunc_fminf:
case LibFunc_fminl:
Opcode = ISD::FMINNUM; break;
case LibFunc_fmax:
case LibFunc_fmaxf:
case LibFunc_fmaxl:
Opcode = ISD::FMAXNUM; break;
}
}
if (Opcode) {
EVT EVTy =
TLI->getValueType(DL, CI->getArgOperand(0)->getType(), true);
if (EVTy == MVT::Other)
return true;
if (TLI->isOperationLegalOrCustom(Opcode, EVTy))
continue;
else if (EVTy.isVector() &&
TLI->isOperationLegalOrCustom(Opcode, EVTy.getScalarType()))
continue;
return true;
}
}
return true;
} else if (isa<BinaryOperator>(J) &&
J->getType()->getScalarType()->isPPC_FP128Ty()) {
// Most operations on ppc_f128 values become calls.
return true;
} else if (isa<UIToFPInst>(J) || isa<SIToFPInst>(J) ||
isa<FPToUIInst>(J) || isa<FPToSIInst>(J)) {
CastInst *CI = cast<CastInst>(J);
if (CI->getSrcTy()->getScalarType()->isPPC_FP128Ty() ||
CI->getDestTy()->getScalarType()->isPPC_FP128Ty() ||
isLargeIntegerTy(!TM.isPPC64(), CI->getSrcTy()->getScalarType()) ||
isLargeIntegerTy(!TM.isPPC64(), CI->getDestTy()->getScalarType()))
return true;
} else if (isLargeIntegerTy(!TM.isPPC64(),
J->getType()->getScalarType()) &&
(J->getOpcode() == Instruction::UDiv ||
J->getOpcode() == Instruction::SDiv ||
J->getOpcode() == Instruction::URem ||
J->getOpcode() == Instruction::SRem)) {
return true;
} else if (!TM.isPPC64() &&
isLargeIntegerTy(false, J->getType()->getScalarType()) &&
(J->getOpcode() == Instruction::Shl ||
J->getOpcode() == Instruction::AShr ||
J->getOpcode() == Instruction::LShr)) {
// Only on PPC32, for 128-bit integers (specifically not 64-bit
// integers), these might be runtime calls.
return true;
} else if (isa<IndirectBrInst>(J) || isa<InvokeInst>(J)) {
// On PowerPC, indirect jumps use the counter register.
return true;
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(J)) {
if (SI->getNumCases() + 1 >= (unsigned)TLI->getMinimumJumpTableEntries())
return true;
}
// FREM is always a call.
if (J->getOpcode() == Instruction::FRem)
return true;
if (ST->useSoftFloat()) {
switch(J->getOpcode()) {
case Instruction::FAdd:
case Instruction::FSub:
case Instruction::FMul:
case Instruction::FDiv:
case Instruction::FPTrunc:
case Instruction::FPExt:
case Instruction::FPToUI:
case Instruction::FPToSI:
case Instruction::UIToFP:
case Instruction::SIToFP:
case Instruction::FCmp:
return true;
}
}
for (Value *Operand : J->operands())
if (memAddrUsesCTR(Operand))
return true;
}
return false;
}
bool PPCTTIImpl::isHardwareLoopProfitable(Loop *L, ScalarEvolution &SE,
AssumptionCache &AC,
TargetLibraryInfo *LibInfo,
HardwareLoopInfo &HWLoopInfo) {
const PPCTargetMachine &TM = ST->getTargetMachine();
TargetSchedModel SchedModel;
SchedModel.init(ST);
// Do not convert small short loops to CTR loop.
unsigned ConstTripCount = SE.getSmallConstantTripCount(L);
if (ConstTripCount && ConstTripCount < SmallCTRLoopThreshold) {
SmallPtrSet<const Value *, 32> EphValues;
CodeMetrics::collectEphemeralValues(L, &AC, EphValues);
CodeMetrics Metrics;
for (BasicBlock *BB : L->blocks())
Metrics.analyzeBasicBlock(BB, *this, EphValues);
// 6 is an approximate latency for the mtctr instruction.
if (Metrics.NumInsts <= (6 * SchedModel.getIssueWidth()))
return false;
}
// We don't want to spill/restore the counter register, and so we don't
// want to use the counter register if the loop contains calls.
for (Loop::block_iterator I = L->block_begin(), IE = L->block_end();
I != IE; ++I)
if (mightUseCTR(*I, LibInfo))
return false;
SmallVector<BasicBlock*, 4> ExitingBlocks;
L->getExitingBlocks(ExitingBlocks);
// If there is an exit edge known to be frequently taken,
// we should not transform this loop.
for (auto &BB : ExitingBlocks) {
Instruction *TI = BB->getTerminator();
if (!TI) continue;
if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
uint64_t TrueWeight = 0, FalseWeight = 0;
if (!BI->isConditional() ||
!BI->extractProfMetadata(TrueWeight, FalseWeight))
continue;
// If the exit path is more frequent than the loop path,
// we return here without further analysis for this loop.
bool TrueIsExit = !L->contains(BI->getSuccessor(0));
if (( TrueIsExit && FalseWeight < TrueWeight) ||
(!TrueIsExit && FalseWeight > TrueWeight))
return false;
}
}
LLVMContext &C = L->getHeader()->getContext();
HWLoopInfo.CountType = TM.isPPC64() ?
Type::getInt64Ty(C) : Type::getInt32Ty(C);
HWLoopInfo.LoopDecrement = ConstantInt::get(HWLoopInfo.CountType, 1);
return true;
}
void PPCTTIImpl::getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
TTI::UnrollingPreferences &UP) {
if (ST->getCPUDirective() == PPC::DIR_A2) {
// The A2 is in-order with a deep pipeline, and concatenation unrolling
// helps expose latency-hiding opportunities to the instruction scheduler.
UP.Partial = UP.Runtime = true;
// We unroll a lot on the A2 (hundreds of instructions), and the benefits
// often outweigh the cost of a division to compute the trip count.
UP.AllowExpensiveTripCount = true;
}
BaseT::getUnrollingPreferences(L, SE, UP);
}
// This function returns true to allow using coldcc calling convention.
// Returning true results in coldcc being used for functions which are cold at
// all call sites when the callers of the functions are not calling any other
// non coldcc functions.
bool PPCTTIImpl::useColdCCForColdCall(Function &F) {
return EnablePPCColdCC;
}
bool PPCTTIImpl::enableAggressiveInterleaving(bool LoopHasReductions) {
// On the A2, always unroll aggressively. For QPX unaligned loads, we depend
// on combining the loads generated for consecutive accesses, and failure to
// do so is particularly expensive. This makes it much more likely (compared
// to only using concatenation unrolling).
if (ST->getCPUDirective() == PPC::DIR_A2)
return true;
return LoopHasReductions;
}
PPCTTIImpl::TTI::MemCmpExpansionOptions
PPCTTIImpl::enableMemCmpExpansion(bool OptSize, bool IsZeroCmp) const {
TTI::MemCmpExpansionOptions Options;
Options.LoadSizes = {8, 4, 2, 1};
Options.MaxNumLoads = TLI->getMaxExpandSizeMemcmp(OptSize);
return Options;
}
bool PPCTTIImpl::enableInterleavedAccessVectorization() {
return true;
}
unsigned PPCTTIImpl::getNumberOfRegisters(unsigned ClassID) const {
assert(ClassID == GPRRC || ClassID == FPRRC ||
ClassID == VRRC || ClassID == VSXRC);
if (ST->hasVSX()) {
assert(ClassID == GPRRC || ClassID == VSXRC);
return ClassID == GPRRC ? 32 : 64;
}
assert(ClassID == GPRRC || ClassID == FPRRC || ClassID == VRRC);
return 32;
}
unsigned PPCTTIImpl::getRegisterClassForType(bool Vector, Type *Ty) const {
if (Vector)
return ST->hasVSX() ? VSXRC : VRRC;
else if (Ty && Ty->getScalarType()->isFloatTy())
return ST->hasVSX() ? VSXRC : FPRRC;
else
return GPRRC;
}
const char* PPCTTIImpl::getRegisterClassName(unsigned ClassID) const {
switch (ClassID) {
default:
llvm_unreachable("unknown register class");
return "PPC::unknown register class";
case GPRRC: return "PPC::GPRRC";
case FPRRC: return "PPC::FPRRC";
case VRRC: return "PPC::VRRC";
case VSXRC: return "PPC::VSXRC";
}
}
unsigned PPCTTIImpl::getRegisterBitWidth(bool Vector) const {
if (Vector) {
if (ST->hasQPX()) return 256;
if (ST->hasAltivec()) return 128;
return 0;
}
if (ST->isPPC64())
return 64;
return 32;
}
unsigned PPCTTIImpl::getCacheLineSize() const {
// Check first if the user specified a custom line size.
if (CacheLineSize.getNumOccurrences() > 0)
return CacheLineSize;
// On P7, P8 or P9 we have a cache line size of 128.
unsigned Directive = ST->getCPUDirective();
// Assume that Future CPU has the same cache line size as the others.
if (Directive == PPC::DIR_PWR7 || Directive == PPC::DIR_PWR8 ||
Directive == PPC::DIR_PWR9 || Directive == PPC::DIR_PWR_FUTURE)
return 128;
// On other processors return a default of 64 bytes.
return 64;
}
unsigned PPCTTIImpl::getPrefetchDistance() const {
// This seems like a reasonable default for the BG/Q (this pass is enabled, by
// default, only on the BG/Q).
return 300;
}
unsigned PPCTTIImpl::getMaxInterleaveFactor(unsigned VF) {
unsigned Directive = ST->getCPUDirective();
// The 440 has no SIMD support, but floating-point instructions
// have a 5-cycle latency, so unroll by 5x for latency hiding.
if (Directive == PPC::DIR_440)
return 5;
// The A2 has no SIMD support, but floating-point instructions
// have a 6-cycle latency, so unroll by 6x for latency hiding.
if (Directive == PPC::DIR_A2)
return 6;
// FIXME: For lack of any better information, do no harm...
if (Directive == PPC::DIR_E500mc || Directive == PPC::DIR_E5500)
return 1;
// For P7 and P8, floating-point instructions have a 6-cycle latency and
// there are two execution units, so unroll by 12x for latency hiding.
// FIXME: the same for P9 as previous gen until POWER9 scheduling is ready
// Assume that future is the same as the others.
if (Directive == PPC::DIR_PWR7 || Directive == PPC::DIR_PWR8 ||
Directive == PPC::DIR_PWR9 || Directive == PPC::DIR_PWR_FUTURE)
return 12;
// For most things, modern systems have two execution units (and
// out-of-order execution).
return 2;
}
// Adjust the cost of vector instructions on targets which there is overlap
// between the vector and scalar units, thereby reducing the overall throughput
// of vector code wrt. scalar code.
int PPCTTIImpl::vectorCostAdjustment(int Cost, unsigned Opcode, Type *Ty1,
Type *Ty2) {
if (!ST->vectorsUseTwoUnits() || !Ty1->isVectorTy())
return Cost;
std::pair<int, MVT> LT1 = TLI->getTypeLegalizationCost(DL, Ty1);
// If type legalization involves splitting the vector, we don't want to
// double the cost at every step - only the last step.
if (LT1.first != 1 || !LT1.second.isVector())
return Cost;
int ISD = TLI->InstructionOpcodeToISD(Opcode);
if (TLI->isOperationExpand(ISD, LT1.second))
return Cost;
if (Ty2) {
std::pair<int, MVT> LT2 = TLI->getTypeLegalizationCost(DL, Ty2);
if (LT2.first != 1 || !LT2.second.isVector())
return Cost;
}
return Cost * 2;
}
int PPCTTIImpl::getArithmeticInstrCost(unsigned Opcode, Type *Ty,
TTI::OperandValueKind Op1Info,
TTI::OperandValueKind Op2Info,
TTI::OperandValueProperties Opd1PropInfo,
TTI::OperandValueProperties Opd2PropInfo,
ArrayRef<const Value *> Args,
const Instruction *CxtI) {
assert(TLI->InstructionOpcodeToISD(Opcode) && "Invalid opcode");
// Fallback to the default implementation.
int Cost = BaseT::getArithmeticInstrCost(Opcode, Ty, Op1Info, Op2Info,
Opd1PropInfo, Opd2PropInfo);
return vectorCostAdjustment(Cost, Opcode, Ty, nullptr);
}
int PPCTTIImpl::getShuffleCost(TTI::ShuffleKind Kind, Type *Tp, int Index,
Type *SubTp) {
// Legalize the type.
std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Tp);
// PPC, for both Altivec/VSX and QPX, support cheap arbitrary permutations
// (at least in the sense that there need only be one non-loop-invariant
// instruction). We need one such shuffle instruction for each actual
// register (this is not true for arbitrary shuffles, but is true for the
// structured types of shuffles covered by TTI::ShuffleKind).
return vectorCostAdjustment(LT.first, Instruction::ShuffleVector, Tp,
nullptr);
}
int PPCTTIImpl::getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src,
const Instruction *I) {
assert(TLI->InstructionOpcodeToISD(Opcode) && "Invalid opcode");
int Cost = BaseT::getCastInstrCost(Opcode, Dst, Src);
return vectorCostAdjustment(Cost, Opcode, Dst, Src);
}
int PPCTTIImpl::getCmpSelInstrCost(unsigned Opcode, Type *ValTy, Type *CondTy,
const Instruction *I) {
int Cost = BaseT::getCmpSelInstrCost(Opcode, ValTy, CondTy, I);
return vectorCostAdjustment(Cost, Opcode, ValTy, nullptr);
}
int PPCTTIImpl::getVectorInstrCost(unsigned Opcode, Type *Val, unsigned Index) {
assert(Val->isVectorTy() && "This must be a vector type");
int ISD = TLI->InstructionOpcodeToISD(Opcode);
assert(ISD && "Invalid opcode");
int Cost = BaseT::getVectorInstrCost(Opcode, Val, Index);
Cost = vectorCostAdjustment(Cost, Opcode, Val, nullptr);
if (ST->hasVSX() && Val->getScalarType()->isDoubleTy()) {
// Double-precision scalars are already located in index #0 (or #1 if LE).
if (ISD == ISD::EXTRACT_VECTOR_ELT &&
Index == (ST->isLittleEndian() ? 1 : 0))
return 0;
return Cost;
} else if (ST->hasQPX() && Val->getScalarType()->isFloatingPointTy()) {
// Floating point scalars are already located in index #0.
if (Index == 0)
return 0;
return Cost;
} else if (Val->getScalarType()->isIntegerTy() && Index != -1U) {
if (ST->hasP9Altivec()) {
if (ISD == ISD::INSERT_VECTOR_ELT)
// A move-to VSR and a permute/insert. Assume vector operation cost
// for both (cost will be 2x on P9).
return vectorCostAdjustment(2, Opcode, Val, nullptr);
// It's an extract. Maybe we can do a cheap move-from VSR.
unsigned EltSize = Val->getScalarSizeInBits();
if (EltSize == 64) {
unsigned MfvsrdIndex = ST->isLittleEndian() ? 1 : 0;
if (Index == MfvsrdIndex)
return 1;
} else if (EltSize == 32) {
unsigned MfvsrwzIndex = ST->isLittleEndian() ? 2 : 1;
if (Index == MfvsrwzIndex)
return 1;
}
// We need a vector extract (or mfvsrld). Assume vector operation cost.
// The cost of the load constant for a vector extract is disregarded
// (invariant, easily schedulable).
return vectorCostAdjustment(1, Opcode, Val, nullptr);
} else if (ST->hasDirectMove())
// Assume permute has standard cost.
// Assume move-to/move-from VSR have 2x standard cost.
return 3;
}
// Estimated cost of a load-hit-store delay. This was obtained
// experimentally as a minimum needed to prevent unprofitable
// vectorization for the paq8p benchmark. It may need to be
// raised further if other unprofitable cases remain.
unsigned LHSPenalty = 2;
if (ISD == ISD::INSERT_VECTOR_ELT)
LHSPenalty += 7;
// Vector element insert/extract with Altivec is very expensive,
// because they require store and reload with the attendant
// processor stall for load-hit-store. Until VSX is available,
// these need to be estimated as very costly.
if (ISD == ISD::EXTRACT_VECTOR_ELT ||
ISD == ISD::INSERT_VECTOR_ELT)
return LHSPenalty + Cost;
return Cost;
}
int PPCTTIImpl::getMemoryOpCost(unsigned Opcode, Type *Src,
MaybeAlign Alignment, unsigned AddressSpace,
const Instruction *I) {
// Legalize the type.
std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Src);
assert((Opcode == Instruction::Load || Opcode == Instruction::Store) &&
"Invalid Opcode");
int Cost = BaseT::getMemoryOpCost(Opcode, Src, Alignment, AddressSpace);
Cost = vectorCostAdjustment(Cost, Opcode, Src, nullptr);
bool IsAltivecType = ST->hasAltivec() &&
(LT.second == MVT::v16i8 || LT.second == MVT::v8i16 ||
LT.second == MVT::v4i32 || LT.second == MVT::v4f32);
bool IsVSXType = ST->hasVSX() &&
(LT.second == MVT::v2f64 || LT.second == MVT::v2i64);
bool IsQPXType = ST->hasQPX() &&
(LT.second == MVT::v4f64 || LT.second == MVT::v4f32);
// VSX has 32b/64b load instructions. Legalization can handle loading of
// 32b/64b to VSR correctly and cheaply. But BaseT::getMemoryOpCost and
// PPCTargetLowering can't compute the cost appropriately. So here we
// explicitly check this case.
unsigned MemBytes = Src->getPrimitiveSizeInBits();
if (Opcode == Instruction::Load && ST->hasVSX() && IsAltivecType &&
(MemBytes == 64 || (ST->hasP8Vector() && MemBytes == 32)))
return 1;
// Aligned loads and stores are easy.
unsigned SrcBytes = LT.second.getStoreSize();
if (!SrcBytes || !Alignment || Alignment >= SrcBytes)
return Cost;
// If we can use the permutation-based load sequence, then this is also
// relatively cheap (not counting loop-invariant instructions): one load plus
// one permute (the last load in a series has extra cost, but we're
// neglecting that here). Note that on the P7, we could do unaligned loads
// for Altivec types using the VSX instructions, but that's more expensive
// than using the permutation-based load sequence. On the P8, that's no
// longer true.
if (Opcode == Instruction::Load &&
((!ST->hasP8Vector() && IsAltivecType) || IsQPXType) &&
Alignment >= LT.second.getScalarType().getStoreSize())
return Cost + LT.first; // Add the cost of the permutations.
// For VSX, we can do unaligned loads and stores on Altivec/VSX types. On the
// P7, unaligned vector loads are more expensive than the permutation-based
// load sequence, so that might be used instead, but regardless, the net cost
// is about the same (not counting loop-invariant instructions).
if (IsVSXType || (ST->hasVSX() && IsAltivecType))
return Cost;
// Newer PPC supports unaligned memory access.
if (TLI->allowsMisalignedMemoryAccesses(LT.second, 0))
return Cost;
// PPC in general does not support unaligned loads and stores. They'll need
// to be decomposed based on the alignment factor.
// Add the cost of each scalar load or store.
assert(Alignment);
Cost += LT.first * ((SrcBytes / Alignment->value()) - 1);
// For a vector type, there is also scalarization overhead (only for
// stores, loads are expanded using the vector-load + permutation sequence,
// which is much less expensive).
if (Src->isVectorTy() && Opcode == Instruction::Store)
for (int i = 0, e = Src->getVectorNumElements(); i < e; ++i)
Cost += getVectorInstrCost(Instruction::ExtractElement, Src, i);
return Cost;
}
int PPCTTIImpl::getInterleavedMemoryOpCost(unsigned Opcode, Type *VecTy,
unsigned Factor,
ArrayRef<unsigned> Indices,
unsigned Alignment,
unsigned AddressSpace,
bool UseMaskForCond,
bool UseMaskForGaps) {
if (UseMaskForCond || UseMaskForGaps)
return BaseT::getInterleavedMemoryOpCost(Opcode, VecTy, Factor, Indices,
Alignment, AddressSpace,
UseMaskForCond, UseMaskForGaps);
assert(isa<VectorType>(VecTy) &&
"Expect a vector type for interleaved memory op");
// Legalize the type.
std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, VecTy);
// Firstly, the cost of load/store operation.
int Cost =
getMemoryOpCost(Opcode, VecTy, MaybeAlign(Alignment), AddressSpace);
// PPC, for both Altivec/VSX and QPX, support cheap arbitrary permutations
// (at least in the sense that there need only be one non-loop-invariant
// instruction). For each result vector, we need one shuffle per incoming
// vector (except that the first shuffle can take two incoming vectors
// because it does not need to take itself).
Cost += Factor*(LT.first-1);
return Cost;
}
unsigned PPCTTIImpl::getIntrinsicInstrCost(Intrinsic::ID ID, Type *RetTy,
ArrayRef<Value*> Args, FastMathFlags FMF, unsigned VF) {
return BaseT::getIntrinsicInstrCost(ID, RetTy, Args, FMF, VF);
}
unsigned PPCTTIImpl::getIntrinsicInstrCost(Intrinsic::ID ID, Type *RetTy,
ArrayRef<Type*> Tys, FastMathFlags FMF,
unsigned ScalarizationCostPassed) {
if (ID == Intrinsic::bswap && ST->hasP9Vector())
return TLI->getTypeLegalizationCost(DL, RetTy).first;
return BaseT::getIntrinsicInstrCost(ID, RetTy, Tys, FMF,
ScalarizationCostPassed);
}
bool PPCTTIImpl::canSaveCmp(Loop *L, BranchInst **BI, ScalarEvolution *SE,
LoopInfo *LI, DominatorTree *DT,
AssumptionCache *AC, TargetLibraryInfo *LibInfo) {
// Process nested loops first.
for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
if (canSaveCmp(*I, BI, SE, LI, DT, AC, LibInfo))
return false; // Stop search.
HardwareLoopInfo HWLoopInfo(L);
if (!HWLoopInfo.canAnalyze(*LI))
return false;
if (!isHardwareLoopProfitable(L, *SE, *AC, LibInfo, HWLoopInfo))
return false;
if (!HWLoopInfo.isHardwareLoopCandidate(*SE, *LI, *DT))
return false;
*BI = HWLoopInfo.ExitBranch;
return true;
}
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