llvm-6502/lib/Target/X86/X86Subtarget.h
Sanjay Patel e7c966f067 Use rcpss/rcpps (X86) to speed up reciprocal calcs (PR21385).
This is a first step for generating SSE rcp instructions for reciprocal
calcs when fast-math allows it. This is very similar to the rsqrt optimization
enabled in D5658 ( http://reviews.llvm.org/rL220570 ).

For now, be conservative and only enable this for AMD btver2 where performance
improves significantly both in terms of latency and throughput.

We may never enable this codegen for Intel Core* chips because the divider circuits
are just too fast. On SandyBridge, divss can be as fast as 10 cycles versus the 21
cycle critical path for the rcp + mul + sub + mul + add estimate.

Follow-on patches may allow configuration of the number of Newton-Raphson refinement
steps, add AVX512 support, and enable the optimization for more chips.

More background here: http://llvm.org/bugs/show_bug.cgi?id=21385

Differential Revision: http://reviews.llvm.org/D6175



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221706 91177308-0d34-0410-b5e6-96231b3b80d8
2014-11-11 20:51:00 +00:00

507 lines
17 KiB
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//===-- X86Subtarget.h - Define Subtarget for the X86 ----------*- C++ -*--===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares the X86 specific subclass of TargetSubtargetInfo.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_TARGET_X86_X86SUBTARGET_H
#define LLVM_LIB_TARGET_X86_X86SUBTARGET_H
#include "X86FrameLowering.h"
#include "X86ISelLowering.h"
#include "X86InstrInfo.h"
#include "X86SelectionDAGInfo.h"
#include "llvm/ADT/Triple.h"
#include "llvm/IR/CallingConv.h"
#include "llvm/Target/TargetSubtargetInfo.h"
#include <string>
#define GET_SUBTARGETINFO_HEADER
#include "X86GenSubtargetInfo.inc"
namespace llvm {
class GlobalValue;
class StringRef;
class TargetMachine;
/// PICStyles - The X86 backend supports a number of different styles of PIC.
///
namespace PICStyles {
enum Style {
StubPIC, // Used on i386-darwin in -fPIC mode.
StubDynamicNoPIC, // Used on i386-darwin in -mdynamic-no-pic mode.
GOT, // Used on many 32-bit unices in -fPIC mode.
RIPRel, // Used on X86-64 when not in -static mode.
None // Set when in -static mode (not PIC or DynamicNoPIC mode).
};
}
class X86Subtarget final : public X86GenSubtargetInfo {
protected:
enum X86SSEEnum {
NoMMXSSE, MMX, SSE1, SSE2, SSE3, SSSE3, SSE41, SSE42, AVX, AVX2, AVX512F
};
enum X863DNowEnum {
NoThreeDNow, ThreeDNow, ThreeDNowA
};
enum X86ProcFamilyEnum {
Others, IntelAtom, IntelSLM
};
/// X86ProcFamily - X86 processor family: Intel Atom, and others
X86ProcFamilyEnum X86ProcFamily;
/// PICStyle - Which PIC style to use
///
PICStyles::Style PICStyle;
/// X86SSELevel - MMX, SSE1, SSE2, SSE3, SSSE3, SSE41, SSE42, or
/// none supported.
X86SSEEnum X86SSELevel;
/// X863DNowLevel - 3DNow or 3DNow Athlon, or none supported.
///
X863DNowEnum X863DNowLevel;
/// HasCMov - True if this processor has conditional move instructions
/// (generally pentium pro+).
bool HasCMov;
/// HasX86_64 - True if the processor supports X86-64 instructions.
///
bool HasX86_64;
/// HasPOPCNT - True if the processor supports POPCNT.
bool HasPOPCNT;
/// HasSSE4A - True if the processor supports SSE4A instructions.
bool HasSSE4A;
/// HasAES - Target has AES instructions
bool HasAES;
/// HasPCLMUL - Target has carry-less multiplication
bool HasPCLMUL;
/// HasFMA - Target has 3-operand fused multiply-add
bool HasFMA;
/// HasFMA4 - Target has 4-operand fused multiply-add
bool HasFMA4;
/// HasXOP - Target has XOP instructions
bool HasXOP;
/// HasTBM - Target has TBM instructions.
bool HasTBM;
/// HasMOVBE - True if the processor has the MOVBE instruction.
bool HasMOVBE;
/// HasRDRAND - True if the processor has the RDRAND instruction.
bool HasRDRAND;
/// HasF16C - Processor has 16-bit floating point conversion instructions.
bool HasF16C;
/// HasFSGSBase - Processor has FS/GS base insturctions.
bool HasFSGSBase;
/// HasLZCNT - Processor has LZCNT instruction.
bool HasLZCNT;
/// HasBMI - Processor has BMI1 instructions.
bool HasBMI;
/// HasBMI2 - Processor has BMI2 instructions.
bool HasBMI2;
/// HasRTM - Processor has RTM instructions.
bool HasRTM;
/// HasHLE - Processor has HLE.
bool HasHLE;
/// HasADX - Processor has ADX instructions.
bool HasADX;
/// HasSHA - Processor has SHA instructions.
bool HasSHA;
/// HasSGX - Processor has SGX instructions.
bool HasSGX;
/// HasPRFCHW - Processor has PRFCHW instructions.
bool HasPRFCHW;
/// HasRDSEED - Processor has RDSEED instructions.
bool HasRDSEED;
/// HasSMAP - Processor has SMAP instructions.
bool HasSMAP;
/// IsBTMemSlow - True if BT (bit test) of memory instructions are slow.
bool IsBTMemSlow;
/// IsSHLDSlow - True if SHLD instructions are slow.
bool IsSHLDSlow;
/// IsUAMemFast - True if unaligned memory access is fast.
bool IsUAMemFast;
/// HasVectorUAMem - True if SIMD operations can have unaligned memory
/// operands. This may require setting a feature bit in the processor.
bool HasVectorUAMem;
/// HasCmpxchg16b - True if this processor has the CMPXCHG16B instruction;
/// this is true for most x86-64 chips, but not the first AMD chips.
bool HasCmpxchg16b;
/// UseLeaForSP - True if the LEA instruction should be used for adjusting
/// the stack pointer. This is an optimization for Intel Atom processors.
bool UseLeaForSP;
/// HasSlowDivide - True if smaller divides are significantly faster than
/// full divides and should be used when possible.
bool HasSlowDivide;
/// PadShortFunctions - True if the short functions should be padded to prevent
/// a stall when returning too early.
bool PadShortFunctions;
/// CallRegIndirect - True if the Calls with memory reference should be converted
/// to a register-based indirect call.
bool CallRegIndirect;
/// LEAUsesAG - True if the LEA instruction inputs have to be ready at
/// address generation (AG) time.
bool LEAUsesAG;
/// SlowLEA - True if the LEA instruction with certain arguments is slow
bool SlowLEA;
/// SlowIncDec - True if INC and DEC instructions are slow when writing to flags
bool SlowIncDec;
/// Use the RSQRT* instructions to optimize square root calculations.
/// For this to be profitable, the cost of FSQRT and FDIV must be
/// substantially higher than normal FP ops like FADD and FMUL.
bool UseSqrtEst;
/// Use the RCP* instructions to optimize FP division calculations.
/// For this to be profitable, the cost of FDIV must be
/// substantially higher than normal FP ops like FADD and FMUL.
bool UseReciprocalEst;
/// Processor has AVX-512 PreFetch Instructions
bool HasPFI;
/// Processor has AVX-512 Exponential and Reciprocal Instructions
bool HasERI;
/// Processor has AVX-512 Conflict Detection Instructions
bool HasCDI;
/// Processor has AVX-512 Doubleword and Quadword instructions
bool HasDQI;
/// Processor has AVX-512 Byte and Word instructions
bool HasBWI;
/// Processor has AVX-512 Vector Length eXtenstions
bool HasVLX;
/// stackAlignment - The minimum alignment known to hold of the stack frame on
/// entry to the function and which must be maintained by every function.
unsigned stackAlignment;
/// Max. memset / memcpy size that is turned into rep/movs, rep/stos ops.
///
unsigned MaxInlineSizeThreshold;
/// TargetTriple - What processor and OS we're targeting.
Triple TargetTriple;
/// Instruction itineraries for scheduling
InstrItineraryData InstrItins;
private:
// Calculates type size & alignment
const DataLayout DL;
/// StackAlignOverride - Override the stack alignment.
unsigned StackAlignOverride;
/// In64BitMode - True if compiling for 64-bit, false for 16-bit or 32-bit.
bool In64BitMode;
/// In32BitMode - True if compiling for 32-bit, false for 16-bit or 64-bit.
bool In32BitMode;
/// In16BitMode - True if compiling for 16-bit, false for 32-bit or 64-bit.
bool In16BitMode;
X86SelectionDAGInfo TSInfo;
// Ordering here is important. X86InstrInfo initializes X86RegisterInfo which
// X86TargetLowering needs.
X86InstrInfo InstrInfo;
X86TargetLowering TLInfo;
X86FrameLowering FrameLowering;
public:
/// This constructor initializes the data members to match that
/// of the specified triple.
///
X86Subtarget(const std::string &TT, const std::string &CPU,
const std::string &FS, const X86TargetMachine &TM,
unsigned StackAlignOverride);
const X86TargetLowering *getTargetLowering() const override {
return &TLInfo;
}
const X86InstrInfo *getInstrInfo() const override { return &InstrInfo; }
const DataLayout *getDataLayout() const override { return &DL; }
const X86FrameLowering *getFrameLowering() const override {
return &FrameLowering;
}
const X86SelectionDAGInfo *getSelectionDAGInfo() const override {
return &TSInfo;
}
const X86RegisterInfo *getRegisterInfo() const override {
return &getInstrInfo()->getRegisterInfo();
}
/// getStackAlignment - Returns the minimum alignment known to hold of the
/// stack frame on entry to the function and which must be maintained by every
/// function for this subtarget.
unsigned getStackAlignment() const { return stackAlignment; }
/// getMaxInlineSizeThreshold - Returns the maximum memset / memcpy size
/// that still makes it profitable to inline the call.
unsigned getMaxInlineSizeThreshold() const { return MaxInlineSizeThreshold; }
/// ParseSubtargetFeatures - Parses features string setting specified
/// subtarget options. Definition of function is auto generated by tblgen.
void ParseSubtargetFeatures(StringRef CPU, StringRef FS);
private:
/// \brief Initialize the full set of dependencies so we can use an initializer
/// list for X86Subtarget.
X86Subtarget &initializeSubtargetDependencies(StringRef CPU, StringRef FS);
void initializeEnvironment();
void initSubtargetFeatures(StringRef CPU, StringRef FS);
public:
/// Is this x86_64? (disregarding specific ABI / programming model)
bool is64Bit() const {
return In64BitMode;
}
bool is32Bit() const {
return In32BitMode;
}
bool is16Bit() const {
return In16BitMode;
}
/// Is this x86_64 with the ILP32 programming model (x32 ABI)?
bool isTarget64BitILP32() const {
return In64BitMode && (TargetTriple.getEnvironment() == Triple::GNUX32 ||
TargetTriple.getOS() == Triple::NaCl);
}
/// Is this x86_64 with the LP64 programming model (standard AMD64, no x32)?
bool isTarget64BitLP64() const {
return In64BitMode && (TargetTriple.getEnvironment() != Triple::GNUX32 &&
TargetTriple.getOS() != Triple::NaCl);
}
PICStyles::Style getPICStyle() const { return PICStyle; }
void setPICStyle(PICStyles::Style Style) { PICStyle = Style; }
bool hasCMov() const { return HasCMov; }
bool hasMMX() const { return X86SSELevel >= MMX; }
bool hasSSE1() const { return X86SSELevel >= SSE1; }
bool hasSSE2() const { return X86SSELevel >= SSE2; }
bool hasSSE3() const { return X86SSELevel >= SSE3; }
bool hasSSSE3() const { return X86SSELevel >= SSSE3; }
bool hasSSE41() const { return X86SSELevel >= SSE41; }
bool hasSSE42() const { return X86SSELevel >= SSE42; }
bool hasAVX() const { return X86SSELevel >= AVX; }
bool hasAVX2() const { return X86SSELevel >= AVX2; }
bool hasAVX512() const { return X86SSELevel >= AVX512F; }
bool hasFp256() const { return hasAVX(); }
bool hasInt256() const { return hasAVX2(); }
bool hasSSE4A() const { return HasSSE4A; }
bool has3DNow() const { return X863DNowLevel >= ThreeDNow; }
bool has3DNowA() const { return X863DNowLevel >= ThreeDNowA; }
bool hasPOPCNT() const { return HasPOPCNT; }
bool hasAES() const { return HasAES; }
bool hasPCLMUL() const { return HasPCLMUL; }
bool hasFMA() const { return HasFMA; }
// FIXME: Favor FMA when both are enabled. Is this the right thing to do?
bool hasFMA4() const { return HasFMA4 && !HasFMA; }
bool hasXOP() const { return HasXOP; }
bool hasTBM() const { return HasTBM; }
bool hasMOVBE() const { return HasMOVBE; }
bool hasRDRAND() const { return HasRDRAND; }
bool hasF16C() const { return HasF16C; }
bool hasFSGSBase() const { return HasFSGSBase; }
bool hasLZCNT() const { return HasLZCNT; }
bool hasBMI() const { return HasBMI; }
bool hasBMI2() const { return HasBMI2; }
bool hasRTM() const { return HasRTM; }
bool hasHLE() const { return HasHLE; }
bool hasADX() const { return HasADX; }
bool hasSHA() const { return HasSHA; }
bool hasSGX() const { return HasSGX; }
bool hasPRFCHW() const { return HasPRFCHW; }
bool hasRDSEED() const { return HasRDSEED; }
bool hasSMAP() const { return HasSMAP; }
bool isBTMemSlow() const { return IsBTMemSlow; }
bool isSHLDSlow() const { return IsSHLDSlow; }
bool isUnalignedMemAccessFast() const { return IsUAMemFast; }
bool hasVectorUAMem() const { return HasVectorUAMem; }
bool hasCmpxchg16b() const { return HasCmpxchg16b; }
bool useLeaForSP() const { return UseLeaForSP; }
bool hasSlowDivide() const { return HasSlowDivide; }
bool padShortFunctions() const { return PadShortFunctions; }
bool callRegIndirect() const { return CallRegIndirect; }
bool LEAusesAG() const { return LEAUsesAG; }
bool slowLEA() const { return SlowLEA; }
bool slowIncDec() const { return SlowIncDec; }
bool useSqrtEst() const { return UseSqrtEst; }
bool useReciprocalEst() const { return UseReciprocalEst; }
bool hasCDI() const { return HasCDI; }
bool hasPFI() const { return HasPFI; }
bool hasERI() const { return HasERI; }
bool hasDQI() const { return HasDQI; }
bool hasBWI() const { return HasBWI; }
bool hasVLX() const { return HasVLX; }
bool isAtom() const { return X86ProcFamily == IntelAtom; }
bool isSLM() const { return X86ProcFamily == IntelSLM; }
const Triple &getTargetTriple() const { return TargetTriple; }
bool isTargetDarwin() const { return TargetTriple.isOSDarwin(); }
bool isTargetFreeBSD() const {
return TargetTriple.getOS() == Triple::FreeBSD;
}
bool isTargetSolaris() const {
return TargetTriple.getOS() == Triple::Solaris;
}
bool isTargetELF() const { return TargetTriple.isOSBinFormatELF(); }
bool isTargetCOFF() const { return TargetTriple.isOSBinFormatCOFF(); }
bool isTargetMacho() const { return TargetTriple.isOSBinFormatMachO(); }
bool isTargetLinux() const { return TargetTriple.isOSLinux(); }
bool isTargetNaCl() const { return TargetTriple.isOSNaCl(); }
bool isTargetNaCl32() const { return isTargetNaCl() && !is64Bit(); }
bool isTargetNaCl64() const { return isTargetNaCl() && is64Bit(); }
bool isTargetWindowsMSVC() const {
return TargetTriple.isWindowsMSVCEnvironment();
}
bool isTargetKnownWindowsMSVC() const {
return TargetTriple.isKnownWindowsMSVCEnvironment();
}
bool isTargetWindowsCygwin() const {
return TargetTriple.isWindowsCygwinEnvironment();
}
bool isTargetWindowsGNU() const {
return TargetTriple.isWindowsGNUEnvironment();
}
bool isTargetCygMing() const { return TargetTriple.isOSCygMing(); }
bool isOSWindows() const { return TargetTriple.isOSWindows(); }
bool isTargetWin64() const {
return In64BitMode && TargetTriple.isOSWindows();
}
bool isTargetWin32() const {
return !In64BitMode && (isTargetCygMing() || isTargetKnownWindowsMSVC());
}
bool isPICStyleSet() const { return PICStyle != PICStyles::None; }
bool isPICStyleGOT() const { return PICStyle == PICStyles::GOT; }
bool isPICStyleRIPRel() const { return PICStyle == PICStyles::RIPRel; }
bool isPICStyleStubPIC() const {
return PICStyle == PICStyles::StubPIC;
}
bool isPICStyleStubNoDynamic() const {
return PICStyle == PICStyles::StubDynamicNoPIC;
}
bool isPICStyleStubAny() const {
return PICStyle == PICStyles::StubDynamicNoPIC ||
PICStyle == PICStyles::StubPIC;
}
bool isCallingConvWin64(CallingConv::ID CC) const {
return (isTargetWin64() && CC != CallingConv::X86_64_SysV) ||
CC == CallingConv::X86_64_Win64;
}
/// ClassifyGlobalReference - Classify a global variable reference for the
/// current subtarget according to how we should reference it in a non-pcrel
/// context.
unsigned char ClassifyGlobalReference(const GlobalValue *GV,
const TargetMachine &TM)const;
/// ClassifyBlockAddressReference - Classify a blockaddress reference for the
/// current subtarget according to how we should reference it in a non-pcrel
/// context.
unsigned char ClassifyBlockAddressReference() const;
/// IsLegalToCallImmediateAddr - Return true if the subtarget allows calls
/// to immediate address.
bool IsLegalToCallImmediateAddr(const TargetMachine &TM) const;
/// This function returns the name of a function which has an interface
/// like the non-standard bzero function, if such a function exists on
/// the current subtarget and it is considered prefereable over
/// memset with zero passed as the second argument. Otherwise it
/// returns null.
const char *getBZeroEntry() const;
/// This function returns true if the target has sincos() routine in its
/// compiler runtime or math libraries.
bool hasSinCos() const;
/// Enable the MachineScheduler pass for all X86 subtargets.
bool enableMachineScheduler() const override { return true; }
bool enableEarlyIfConversion() const override;
/// getInstrItins = Return the instruction itineraries based on the
/// subtarget selection.
const InstrItineraryData *getInstrItineraryData() const override {
return &InstrItins;
}
AntiDepBreakMode getAntiDepBreakMode() const override {
return TargetSubtargetInfo::ANTIDEP_CRITICAL;
}
};
} // End llvm namespace
#endif