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llvm-mirror/lib/Target/PowerPC/PPC32CodeEmitter.cpp
Nate Begeman 6405f5e9b3 Enable optimization suggested by Chris Lattner to not emit reloc stubs for
static global variables whose addresses are taken.  This allows us to
convert the following code for taking the address of a static function foo

        addis r2, r30, ha16(Ll1__2E_foo_2$non_lazy_ptr-"L00001$pb")
        lwz r3, lo16(Ll1__2E_foo_2$non_lazy_ptr-"L00001$pb")(r2)

which also includes linker stub code emitted at the end of the .s file not
shown here, and replace it with this:

        addis r2, r30, ha16(l1__2E_foo_2-"L00001$pb")
        la r3, lo16(l1__2E_foo_2-"L00001$pb")(r2)

which in addition to not needing linker help, also has no load instruction.
For those not up on PowerPC mnemonics, la is shorthand for add immediate.

llvm-svn: 18239
2004-11-25 07:09:01 +00:00

255 lines
9.3 KiB
C++

//===-- PPC32CodeEmitter.cpp - JIT Code Emitter for PowerPC32 -----*- C++ -*-=//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the PowerPC 32-bit CodeEmitter and associated machinery to
// JIT-compile bytecode to native PowerPC.
//
//===----------------------------------------------------------------------===//
#include "PPC32TargetMachine.h"
#include "PPC32Relocations.h"
#include "PowerPC.h"
#include "llvm/Module.h"
#include "llvm/CodeGen/MachineCodeEmitter.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Support/Debug.h"
using namespace llvm;
namespace {
class PPC32CodeEmitter : public MachineFunctionPass {
TargetMachine &TM;
MachineCodeEmitter &MCE;
/// MovePCtoLROffset - When/if we see a MovePCtoLR instruction, we record
/// its address in the function into this pointer.
void *MovePCtoLROffset;
// Tracks which instruction references which BasicBlock
std::vector<std::pair<MachineBasicBlock*, unsigned*> > BBRefs;
// Tracks where each BasicBlock starts
std::map<MachineBasicBlock*, long> BBLocations;
/// getMachineOpValue - evaluates the MachineOperand of a given MachineInstr
///
int getMachineOpValue(MachineInstr &MI, MachineOperand &MO);
public:
PPC32CodeEmitter(TargetMachine &T, MachineCodeEmitter &M)
: TM(T), MCE(M) {}
const char *getPassName() const { return "PowerPC Machine Code Emitter"; }
/// runOnMachineFunction - emits the given MachineFunction to memory
///
bool runOnMachineFunction(MachineFunction &MF);
/// emitBasicBlock - emits the given MachineBasicBlock to memory
///
void emitBasicBlock(MachineBasicBlock &MBB);
/// emitWord - write a 32-bit word to memory at the current PC
///
void emitWord(unsigned w) { MCE.emitWord(w); }
/// getValueBit - return the particular bit of Val
///
unsigned getValueBit(int64_t Val, unsigned bit) { return (Val >> bit) & 1; }
/// getBinaryCodeForInstr - This function, generated by the
/// CodeEmitterGenerator using TableGen, produces the binary encoding for
/// machine instructions.
///
unsigned getBinaryCodeForInstr(MachineInstr &MI);
};
}
/// addPassesToEmitMachineCode - Add passes to the specified pass manager to get
/// machine code emitted. This uses a MachineCodeEmitter object to handle
/// actually outputting the machine code and resolving things like the address
/// of functions. This method should returns true if machine code emission is
/// not supported.
///
bool PPC32TargetMachine::addPassesToEmitMachineCode(FunctionPassManager &PM,
MachineCodeEmitter &MCE) {
// Machine code emitter pass for PowerPC
PM.add(new PPC32CodeEmitter(*this, MCE));
// Delete machine code for this function after emitting it
PM.add(createMachineCodeDeleter());
return false;
}
bool PPC32CodeEmitter::runOnMachineFunction(MachineFunction &MF) {
MovePCtoLROffset = 0;
MCE.startFunction(MF);
MCE.emitConstantPool(MF.getConstantPool());
for (MachineFunction::iterator BB = MF.begin(), E = MF.end(); BB != E; ++BB)
emitBasicBlock(*BB);
MCE.finishFunction(MF);
// Resolve branches to BasicBlocks for the entire function
for (unsigned i = 0, e = BBRefs.size(); i != e; ++i) {
intptr_t Location = BBLocations[BBRefs[i].first];
unsigned *Ref = BBRefs[i].second;
DEBUG(std::cerr << "Fixup @ " << (void*)Ref << " to " << (void*)Location
<< "\n");
unsigned Instr = *Ref;
intptr_t BranchTargetDisp = (Location - (intptr_t)Ref) >> 2;
switch (Instr >> 26) {
default: assert(0 && "Unknown branch user!");
case 18: // This is B or BL
*Ref |= (BranchTargetDisp & ((1 << 24)-1)) << 2;
break;
case 16: // This is BLT,BLE,BEQ,BGE,BGT,BNE, or other bcx instruction
*Ref |= (BranchTargetDisp & ((1 << 14)-1)) << 2;
break;
}
}
BBRefs.clear();
BBLocations.clear();
return false;
}
void PPC32CodeEmitter::emitBasicBlock(MachineBasicBlock &MBB) {
BBLocations[&MBB] = MCE.getCurrentPCValue();
for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); I != E; ++I){
MachineInstr &MI = *I;
unsigned Opcode = MI.getOpcode();
switch (MI.getOpcode()) {
default:
emitWord(getBinaryCodeForInstr(*I));
break;
case PPC::IMPLICIT_DEF:
break; // pseudo opcode, no side effects
case PPC::MovePCtoLR:
assert(MovePCtoLROffset == 0 &&
"Multiple MovePCtoLR instructions in the function?");
MovePCtoLROffset = (void*)(intptr_t)MCE.getCurrentPCValue();
emitWord(0x48000005); // bl 1
break;
}
}
}
static unsigned enumRegToMachineReg(unsigned enumReg) {
switch (enumReg) {
case PPC::R0 : case PPC::F0 : case PPC::CR0: return 0;
case PPC::R1 : case PPC::F1 : case PPC::CR1: return 1;
case PPC::R2 : case PPC::F2 : case PPC::CR2: return 2;
case PPC::R3 : case PPC::F3 : case PPC::CR3: return 3;
case PPC::R4 : case PPC::F4 : case PPC::CR4: return 4;
case PPC::R5 : case PPC::F5 : case PPC::CR5: return 5;
case PPC::R6 : case PPC::F6 : case PPC::CR6: return 6;
case PPC::R7 : case PPC::F7 : case PPC::CR7: return 7;
case PPC::R8 : case PPC::F8 : return 8;
case PPC::R9 : case PPC::F9 : return 9;
case PPC::R10: case PPC::F10: return 10;
case PPC::R11: case PPC::F11: return 11;
case PPC::R12: case PPC::F12: return 12;
case PPC::R13: case PPC::F13: return 13;
case PPC::R14: case PPC::F14: return 14;
case PPC::R15: case PPC::F15: return 15;
case PPC::R16: case PPC::F16: return 16;
case PPC::R17: case PPC::F17: return 17;
case PPC::R18: case PPC::F18: return 18;
case PPC::R19: case PPC::F19: return 19;
case PPC::R20: case PPC::F20: return 20;
case PPC::R21: case PPC::F21: return 21;
case PPC::R22: case PPC::F22: return 22;
case PPC::R23: case PPC::F23: return 23;
case PPC::R24: case PPC::F24: return 24;
case PPC::R25: case PPC::F25: return 25;
case PPC::R26: case PPC::F26: return 26;
case PPC::R27: case PPC::F27: return 27;
case PPC::R28: case PPC::F28: return 28;
case PPC::R29: case PPC::F29: return 29;
case PPC::R30: case PPC::F30: return 30;
case PPC::R31: case PPC::F31: return 31;
default:
std::cerr << "Unhandled reg in enumRegToRealReg!\n";
abort();
}
}
int PPC32CodeEmitter::getMachineOpValue(MachineInstr &MI, MachineOperand &MO) {
int rv = 0; // Return value; defaults to 0 for unhandled cases
// or things that get fixed up later by the JIT.
if (MO.isRegister()) {
rv = enumRegToMachineReg(MO.getReg());
} else if (MO.isImmediate()) {
rv = MO.getImmedValue();
} else if (MO.isGlobalAddress()) {
GlobalValue *GV = MO.getGlobal();
unsigned Reloc = 0;
int Offset = 0;
if (MI.getOpcode() == PPC::CALLpcrel)
Reloc = PPC::reloc_pcrel_bx;
else {
assert(MovePCtoLROffset && "MovePCtoLR not seen yet?");
Offset = -((intptr_t)MovePCtoLROffset+4);
if (MI.getOpcode() == PPC::LOADHiAddr) {
if (GV->hasWeakLinkage() || GV->isExternal())
Reloc = PPC::reloc_absolute_ptr_high; // Pointer to stub
else
Reloc = PPC::reloc_absolute_high; // Pointer to symbol
} else if (MI.getOpcode() == PPC::LA) {
assert(!(GV->hasWeakLinkage() || GV->isExternal())
&& "Something in the ISEL changed\n");
Reloc = PPC::reloc_absolute_low;
} else if (MI.getOpcode() == PPC::LWZ) {
Reloc = PPC::reloc_absolute_ptr_low;
assert((GV->hasWeakLinkage() || GV->isExternal()) &&
"Something in the ISEL changed\n");
} else {
// These don't show up for global value references AFAIK, only for
// constant pool refs: PPC::LFS, PPC::LFD
assert(0 && "Unknown instruction for relocation!");
}
}
MCE.addRelocation(MachineRelocation(MCE.getCurrentPCOffset(),
Reloc, MO.getGlobal(), Offset));
} else if (MO.isMachineBasicBlock()) {
unsigned* CurrPC = (unsigned*)(intptr_t)MCE.getCurrentPCValue();
BBRefs.push_back(std::make_pair(MO.getMachineBasicBlock(), CurrPC));
} else if (MO.isConstantPoolIndex()) {
unsigned index = MO.getConstantPoolIndex();
assert(MovePCtoLROffset && "MovePCtoLR not seen yet?");
rv = MCE.getConstantPoolEntryAddress(index) - (intptr_t)MovePCtoLROffset-4;
unsigned Opcode = MI.getOpcode();
if (Opcode == PPC::LOADHiAddr) {
// LoadHiAddr wants hi16(addr - &MovePCtoLR)
if ((short)rv < 0) rv += 1 << 16;
rv >>= 16;
} else if (Opcode == PPC::LWZ || Opcode == PPC::LA ||
Opcode == PPC::LFS || Opcode == PPC::LFD) {
// These load opcodes want lo16(addr - &MovePCtoLR)
rv &= 0xffff;
} else {
assert(0 && "Unknown constant pool using instruction!");
}
} else {
std::cerr << "ERROR: Unknown type of MachineOperand: " << MO << "\n";
abort();
}
return rv;
}
#include "PPC32GenCodeEmitter.inc"