mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-02-21 21:29:41 +00:00
94dc061e85
Function pointers under PPC64 ELFv1 (which is used on PPC64/Linux on the
POWER7, A2 and earlier cores) are really pointers to a function descriptor, a
structure with three pointers: the actual pointer to the code to which to jump,
the pointer to the TOC needed by the callee, and an environment pointer. We
used to chain these loads, and make them opaque to the rest of the optimizer,
so that they'd always occur directly before the call. This is not necessary,
and in fact, highly suboptimal on embedded cores. Once the function pointer is
known, the loads can be performed ahead of time; in fact, they can be hoisted
out of loops.
Now these function descriptors are almost always generated by the linker, and
thus the contents of the descriptors are invariant. As a result, by default,
we'll mark the associated loads as invariant (allowing them to be hoisted out
of loops). I've added a target feature to turn this off, however, just in case
someone needs that option (constructing an on-stack descriptor, casting it to a
function pointer, and then calling it cannot be well-defined C/C++ code, but I
can imagine some JIT-compilation system doing so).
Consider this simple test:
$ cat call.c
typedef void (*fp)();
void bar(fp x) {
for (int i = 0; i < 1600000000; ++i)
x();
}
$ cat main.c
typedef void (*fp)();
void bar(fp x);
void foo() {}
int main() {
bar(foo);
}
On the PPC A2 (the BG/Q supercomputer), marking the function-descriptor loads
as invariant brings the execution time down to ~8 seconds from ~32 seconds with
the loads in the loop.
The difference on the POWER7 is smaller. Compiling with:
gcc -std=c99 -O3 -mcpu=native call.c main.c : ~6 seconds [this is 4.8.2]
clang -O3 -mcpu=native call.c main.c : ~5.3 seconds
clang -O3 -mcpu=native call.c main.c -mno-invariant-function-descriptors : ~4 seconds
(looks like we'd benefit from additional loop unrolling here, as a first
guess, because this is faster with the extra loads)
The -mno-invariant-function-descriptors will be added to Clang shortly.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226207 91177308-0d34-0410-b5e6-96231b3b80d8
274 lines
8.7 KiB
C++
274 lines
8.7 KiB
C++
//===-- PPCSubtarget.h - Define Subtarget for the PPC ----------*- 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 PowerPC specific subclass of TargetSubtargetInfo.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_LIB_TARGET_POWERPC_PPCSUBTARGET_H
|
|
#define LLVM_LIB_TARGET_POWERPC_PPCSUBTARGET_H
|
|
|
|
#include "PPCFrameLowering.h"
|
|
#include "PPCISelLowering.h"
|
|
#include "PPCInstrInfo.h"
|
|
#include "PPCSelectionDAGInfo.h"
|
|
#include "llvm/ADT/Triple.h"
|
|
#include "llvm/IR/DataLayout.h"
|
|
#include "llvm/MC/MCInstrItineraries.h"
|
|
#include "llvm/Target/TargetSubtargetInfo.h"
|
|
#include <string>
|
|
|
|
#define GET_SUBTARGETINFO_HEADER
|
|
#include "PPCGenSubtargetInfo.inc"
|
|
|
|
// GCC #defines PPC on Linux but we use it as our namespace name
|
|
#undef PPC
|
|
|
|
namespace llvm {
|
|
class StringRef;
|
|
|
|
namespace PPC {
|
|
// -m directive values.
|
|
enum {
|
|
DIR_NONE,
|
|
DIR_32,
|
|
DIR_440,
|
|
DIR_601,
|
|
DIR_602,
|
|
DIR_603,
|
|
DIR_7400,
|
|
DIR_750,
|
|
DIR_970,
|
|
DIR_A2,
|
|
DIR_E500mc,
|
|
DIR_E5500,
|
|
DIR_PWR3,
|
|
DIR_PWR4,
|
|
DIR_PWR5,
|
|
DIR_PWR5X,
|
|
DIR_PWR6,
|
|
DIR_PWR6X,
|
|
DIR_PWR7,
|
|
DIR_PWR8,
|
|
DIR_64
|
|
};
|
|
}
|
|
|
|
class GlobalValue;
|
|
class TargetMachine;
|
|
|
|
class PPCSubtarget : public PPCGenSubtargetInfo {
|
|
protected:
|
|
/// TargetTriple - What processor and OS we're targeting.
|
|
Triple TargetTriple;
|
|
|
|
// Calculates type size & alignment
|
|
const DataLayout DL;
|
|
|
|
/// 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;
|
|
|
|
/// Selected instruction itineraries (one entry per itinerary class.)
|
|
InstrItineraryData InstrItins;
|
|
|
|
/// Which cpu directive was used.
|
|
unsigned DarwinDirective;
|
|
|
|
/// Used by the ISel to turn in optimizations for POWER4-derived architectures
|
|
bool HasMFOCRF;
|
|
bool Has64BitSupport;
|
|
bool Use64BitRegs;
|
|
bool UseCRBits;
|
|
bool IsPPC64;
|
|
bool HasAltivec;
|
|
bool HasSPE;
|
|
bool HasQPX;
|
|
bool HasVSX;
|
|
bool HasP8Vector;
|
|
bool HasFCPSGN;
|
|
bool HasFSQRT;
|
|
bool HasFRE, HasFRES, HasFRSQRTE, HasFRSQRTES;
|
|
bool HasRecipPrec;
|
|
bool HasSTFIWX;
|
|
bool HasLFIWAX;
|
|
bool HasFPRND;
|
|
bool HasFPCVT;
|
|
bool HasISEL;
|
|
bool HasPOPCNTD;
|
|
bool HasCMPB;
|
|
bool HasLDBRX;
|
|
bool IsBookE;
|
|
bool HasOnlyMSYNC;
|
|
bool IsE500;
|
|
bool IsPPC4xx;
|
|
bool IsPPC6xx;
|
|
bool DeprecatedMFTB;
|
|
bool DeprecatedDST;
|
|
bool HasLazyResolverStubs;
|
|
bool IsLittleEndian;
|
|
bool HasICBT;
|
|
bool HasInvariantFunctionDescriptors;
|
|
|
|
enum {
|
|
PPC_ABI_UNKNOWN,
|
|
PPC_ABI_ELFv1,
|
|
PPC_ABI_ELFv2
|
|
} TargetABI;
|
|
|
|
PPCFrameLowering FrameLowering;
|
|
PPCInstrInfo InstrInfo;
|
|
PPCTargetLowering TLInfo;
|
|
PPCSelectionDAGInfo TSInfo;
|
|
|
|
public:
|
|
/// This constructor initializes the data members to match that
|
|
/// of the specified triple.
|
|
///
|
|
PPCSubtarget(const std::string &TT, const std::string &CPU,
|
|
const std::string &FS, const PPCTargetMachine &TM);
|
|
|
|
/// ParseSubtargetFeatures - Parses features string setting specified
|
|
/// subtarget options. Definition of function is auto generated by tblgen.
|
|
void ParseSubtargetFeatures(StringRef CPU, StringRef FS);
|
|
|
|
/// 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; }
|
|
|
|
/// getDarwinDirective - Returns the -m directive specified for the cpu.
|
|
///
|
|
unsigned getDarwinDirective() const { return DarwinDirective; }
|
|
|
|
/// getInstrItins - Return the instruction itineraries based on subtarget
|
|
/// selection.
|
|
const InstrItineraryData *getInstrItineraryData() const override {
|
|
return &InstrItins;
|
|
}
|
|
|
|
const PPCFrameLowering *getFrameLowering() const override {
|
|
return &FrameLowering;
|
|
}
|
|
const DataLayout *getDataLayout() const override { return &DL; }
|
|
const PPCInstrInfo *getInstrInfo() const override { return &InstrInfo; }
|
|
const PPCTargetLowering *getTargetLowering() const override {
|
|
return &TLInfo;
|
|
}
|
|
const PPCSelectionDAGInfo *getSelectionDAGInfo() const override {
|
|
return &TSInfo;
|
|
}
|
|
const PPCRegisterInfo *getRegisterInfo() const override {
|
|
return &getInstrInfo()->getRegisterInfo();
|
|
}
|
|
|
|
/// initializeSubtargetDependencies - Initializes using a CPU and feature string
|
|
/// so that we can use initializer lists for subtarget initialization.
|
|
PPCSubtarget &initializeSubtargetDependencies(StringRef CPU, StringRef FS);
|
|
|
|
private:
|
|
void initializeEnvironment();
|
|
void initSubtargetFeatures(StringRef CPU, StringRef FS);
|
|
|
|
public:
|
|
/// isPPC64 - Return true if we are generating code for 64-bit pointer mode.
|
|
///
|
|
bool isPPC64() const { return IsPPC64; }
|
|
|
|
/// has64BitSupport - Return true if the selected CPU supports 64-bit
|
|
/// instructions, regardless of whether we are in 32-bit or 64-bit mode.
|
|
bool has64BitSupport() const { return Has64BitSupport; }
|
|
|
|
/// use64BitRegs - Return true if in 64-bit mode or if we should use 64-bit
|
|
/// registers in 32-bit mode when possible. This can only true if
|
|
/// has64BitSupport() returns true.
|
|
bool use64BitRegs() const { return Use64BitRegs; }
|
|
|
|
/// useCRBits - Return true if we should store and manipulate i1 values in
|
|
/// the individual condition register bits.
|
|
bool useCRBits() const { return UseCRBits; }
|
|
|
|
/// hasLazyResolverStub - Return true if accesses to the specified global have
|
|
/// to go through a dyld lazy resolution stub. This means that an extra load
|
|
/// is required to get the address of the global.
|
|
bool hasLazyResolverStub(const GlobalValue *GV,
|
|
const TargetMachine &TM) const;
|
|
|
|
// isLittleEndian - True if generating little-endian code
|
|
bool isLittleEndian() const { return IsLittleEndian; }
|
|
|
|
// Specific obvious features.
|
|
bool hasFCPSGN() const { return HasFCPSGN; }
|
|
bool hasFSQRT() const { return HasFSQRT; }
|
|
bool hasFRE() const { return HasFRE; }
|
|
bool hasFRES() const { return HasFRES; }
|
|
bool hasFRSQRTE() const { return HasFRSQRTE; }
|
|
bool hasFRSQRTES() const { return HasFRSQRTES; }
|
|
bool hasRecipPrec() const { return HasRecipPrec; }
|
|
bool hasSTFIWX() const { return HasSTFIWX; }
|
|
bool hasLFIWAX() const { return HasLFIWAX; }
|
|
bool hasFPRND() const { return HasFPRND; }
|
|
bool hasFPCVT() const { return HasFPCVT; }
|
|
bool hasAltivec() const { return HasAltivec; }
|
|
bool hasSPE() const { return HasSPE; }
|
|
bool hasQPX() const { return HasQPX; }
|
|
bool hasVSX() const { return HasVSX; }
|
|
bool hasP8Vector() const { return HasP8Vector; }
|
|
bool hasMFOCRF() const { return HasMFOCRF; }
|
|
bool hasISEL() const { return HasISEL; }
|
|
bool hasPOPCNTD() const { return HasPOPCNTD; }
|
|
bool hasCMPB() const { return HasCMPB; }
|
|
bool hasLDBRX() const { return HasLDBRX; }
|
|
bool isBookE() const { return IsBookE; }
|
|
bool hasOnlyMSYNC() const { return HasOnlyMSYNC; }
|
|
bool isPPC4xx() const { return IsPPC4xx; }
|
|
bool isPPC6xx() const { return IsPPC6xx; }
|
|
bool isE500() const { return IsE500; }
|
|
bool isDeprecatedMFTB() const { return DeprecatedMFTB; }
|
|
bool isDeprecatedDST() const { return DeprecatedDST; }
|
|
bool hasICBT() const { return HasICBT; }
|
|
bool hasInvariantFunctionDescriptors() const {
|
|
return HasInvariantFunctionDescriptors;
|
|
}
|
|
|
|
const Triple &getTargetTriple() const { return TargetTriple; }
|
|
|
|
/// isDarwin - True if this is any darwin platform.
|
|
bool isDarwin() const { return TargetTriple.isMacOSX(); }
|
|
/// isBGQ - True if this is a BG/Q platform.
|
|
bool isBGQ() const { return TargetTriple.getVendor() == Triple::BGQ; }
|
|
|
|
bool isTargetELF() const { return TargetTriple.isOSBinFormatELF(); }
|
|
bool isTargetMachO() const { return TargetTriple.isOSBinFormatMachO(); }
|
|
|
|
bool isDarwinABI() const { return isDarwin(); }
|
|
bool isSVR4ABI() const { return !isDarwin(); }
|
|
bool isELFv2ABI() const { return TargetABI == PPC_ABI_ELFv2; }
|
|
|
|
bool enableEarlyIfConversion() const override { return hasISEL(); }
|
|
|
|
// Scheduling customization.
|
|
bool enableMachineScheduler() const override;
|
|
// This overrides the PostRAScheduler bit in the SchedModel for each CPU.
|
|
bool enablePostMachineScheduler() const override;
|
|
AntiDepBreakMode getAntiDepBreakMode() const override;
|
|
void getCriticalPathRCs(RegClassVector &CriticalPathRCs) const override;
|
|
|
|
void overrideSchedPolicy(MachineSchedPolicy &Policy,
|
|
MachineInstr *begin,
|
|
MachineInstr *end,
|
|
unsigned NumRegionInstrs) const override;
|
|
bool useAA() const override;
|
|
|
|
bool enableSubRegLiveness() const override;
|
|
};
|
|
} // End llvm namespace
|
|
|
|
#endif
|