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//===-- PowerPCSubtarget.cpp - PPC Subtarget Information ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the PPC specific subclass of TargetSubtargetInfo.
//
//===----------------------------------------------------------------------===//
#include "PPCSubtarget.h"
#include "PPC.h"
#include "PPCRegisterInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineScheduler.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Target/TargetMachine.h"
#include <cstdlib>
#define GET_SUBTARGETINFO_TARGET_DESC
#define GET_SUBTARGETINFO_CTOR
#include "PPCGenSubtargetInfo.inc"
using namespace llvm;
PPCSubtarget::PPCSubtarget(const std::string &TT, const std::string &CPU,
const std::string &FS, bool is64Bit)
: PPCGenSubtargetInfo(TT, CPU, FS)
, IsPPC64(is64Bit)
, TargetTriple(TT) {
initializeEnvironment();
resetSubtargetFeatures(CPU, FS);
}
/// SetJITMode - This is called to inform the subtarget info that we are
/// producing code for the JIT.
void PPCSubtarget::SetJITMode() {
// JIT mode doesn't want lazy resolver stubs, it knows exactly where
// everything is. This matters for PPC64, which codegens in PIC mode without
// stubs.
HasLazyResolverStubs = false;
// Calls to external functions need to use indirect calls
IsJITCodeModel = true;
}
void PPCSubtarget::resetSubtargetFeatures(const MachineFunction *MF) {
AttributeSet FnAttrs = MF->getFunction()->getAttributes();
Attribute CPUAttr = FnAttrs.getAttribute(AttributeSet::FunctionIndex,
"target-cpu");
Attribute FSAttr = FnAttrs.getAttribute(AttributeSet::FunctionIndex,
"target-features");
std::string CPU =
!CPUAttr.hasAttribute(Attribute::None) ? CPUAttr.getValueAsString() : "";
std::string FS =
!FSAttr.hasAttribute(Attribute::None) ? FSAttr.getValueAsString() : "";
if (!FS.empty()) {
initializeEnvironment();
resetSubtargetFeatures(CPU, FS);
}
}
void PPCSubtarget::initializeEnvironment() {
StackAlignment = 16;
DarwinDirective = PPC::DIR_NONE;
HasMFOCRF = false;
Has64BitSupport = false;
Use64BitRegs = false;
HasAltivec = false;
HasQPX = false;
HasFCPSGN = false;
HasFSQRT = false;
HasFRE = false;
HasFRES = false;
HasFRSQRTE = false;
HasFRSQRTES = false;
HasRecipPrec = false;
HasSTFIWX = false;
HasLFIWAX = false;
HasFPRND = false;
HasFPCVT = false;
HasISEL = false;
HasPOPCNTD = false;
HasLDBRX = false;
IsBookE = false;
DeprecatedMFTB = false;
DeprecatedDST = false;
HasLazyResolverStubs = false;
IsJITCodeModel = false;
}
void PPCSubtarget::resetSubtargetFeatures(StringRef CPU, StringRef FS) {
// Determine default and user specified characteristics
std::string CPUName = CPU;
if (CPUName.empty())
CPUName = "generic";
#if (defined(__APPLE__) || defined(__linux__)) && \
(defined(__ppc__) || defined(__powerpc__))
if (CPUName == "generic")
CPUName = sys::getHostCPUName();
#endif
// Initialize scheduling itinerary for the specified CPU.
InstrItins = getInstrItineraryForCPU(CPUName);
// Make sure 64-bit features are available when CPUname is generic
std::string FullFS = FS;
// If we are generating code for ppc64, verify that options make sense.
if (IsPPC64) {
Has64BitSupport = true;
// Silently force 64-bit register use on ppc64.
Use64BitRegs = true;
if (!FullFS.empty())
FullFS = "+64bit," + FullFS;
else
FullFS = "+64bit";
}
// Parse features string.
ParseSubtargetFeatures(CPUName, FullFS);
// If the user requested use of 64-bit regs, but the cpu selected doesn't
// support it, ignore.
if (use64BitRegs() && !has64BitSupport())
Use64BitRegs = false;
// Set up darwin-specific properties.
if (isDarwin())
HasLazyResolverStubs = true;
// QPX requires a 32-byte aligned stack. Note that we need to do this if
// we're compiling for a BG/Q system regardless of whether or not QPX
// is enabled because external functions will assume this alignment.
if (hasQPX() || isBGQ())
StackAlignment = 32;
// Determine endianness.
IsLittleEndian = (TargetTriple.getArch() == Triple::ppc64le);
}
/// 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 PPCSubtarget::hasLazyResolverStub(const GlobalValue *GV,
const TargetMachine &TM) const {
// We never have stubs if HasLazyResolverStubs=false or if in static mode.
if (!HasLazyResolverStubs || TM.getRelocationModel() == Reloc::Static)
return false;
// If symbol visibility is hidden, the extra load is not needed if
// the symbol is definitely defined in the current translation unit.
bool isDecl = GV->isDeclaration() && !GV->isMaterializable();
if (GV->hasHiddenVisibility() && !isDecl && !GV->hasCommonLinkage())
return false;
return GV->hasWeakLinkage() || GV->hasLinkOnceLinkage() ||
GV->hasCommonLinkage() || isDecl;
}
bool PPCSubtarget::enablePostRAScheduler(
CodeGenOpt::Level OptLevel,
TargetSubtargetInfo::AntiDepBreakMode& Mode,
RegClassVector& CriticalPathRCs) const {
Mode = TargetSubtargetInfo::ANTIDEP_ALL;
CriticalPathRCs.clear();
if (isPPC64())
CriticalPathRCs.push_back(&PPC::G8RCRegClass);
else
CriticalPathRCs.push_back(&PPC::GPRCRegClass);
return OptLevel >= CodeGenOpt::Default;
}
// Embedded cores need aggressive scheduling.
static bool needsAggressiveScheduling(unsigned Directive) {
switch (Directive) {
default: return false;
case PPC::DIR_440:
case PPC::DIR_A2:
case PPC::DIR_E500mc:
case PPC::DIR_E5500:
return true;
}
}
bool PPCSubtarget::enableMachineScheduler() const {
// Enable MI scheduling for the embedded cores.
// FIXME: Enable this for all cores (some additional modeling
// may be necessary).
return needsAggressiveScheduling(DarwinDirective);
}
void PPCSubtarget::overrideSchedPolicy(MachineSchedPolicy &Policy,
MachineInstr *begin,
MachineInstr *end,
unsigned NumRegionInstrs) const {
if (needsAggressiveScheduling(DarwinDirective)) {
Policy.OnlyTopDown = false;
Policy.OnlyBottomUp = false;
}
// Spilling is generally expensive on all PPC cores, so always enable
// register-pressure tracking.
Policy.ShouldTrackPressure = true;
}
bool PPCSubtarget::useAA() const {
// Use AA during code generation for the embedded cores.
return needsAggressiveScheduling(DarwinDirective);
}
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