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Remove all JIT specific code and switch the code generator over to emitting

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relocations for global references.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18068 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-11-20 23:55:15 +00:00
parent 7ddde32ead
commit e72e445ed5
1 changed files with 26 additions and 194 deletions
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220
lib/Target/X86/X86CodeEmitter.cpp
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@ -8,12 +8,12 @@
//===----------------------------------------------------------------------===//
//
// This file contains the pass that transforms the X86 machine instructions into
// actual executable machine code.
// relocatable machine code.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "jit"
#include "X86TargetMachine.h"
#include "X86Relocations.h"
#include "X86.h"
#include "llvm/PassManager.h"
#include "llvm/CodeGen/MachineCodeEmitter.h"
@ -21,170 +21,14 @@
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Function.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Config/alloca.h"
using namespace llvm;
namespace {
Statistic<>
NumEmitted("x86-emitter", "Number of machine instructions emitted");
class JITResolver {
MachineCodeEmitter &MCE;
// LazyCodeGenMap - Keep track of call sites for functions that are to be
// lazily resolved.
std::map<unsigned, Function*> LazyCodeGenMap;
// LazyResolverMap - Keep track of the lazy resolver created for a
// particular function so that we can reuse them if necessary.
std::map<Function*, unsigned> LazyResolverMap;
public:
JITResolver(MachineCodeEmitter &mce) : MCE(mce) {}
unsigned getLazyResolver(Function *F);
unsigned addFunctionReference(unsigned Address, Function *F);
private:
unsigned emitStubForFunction(Function *F);
static void CompilationCallback();
unsigned resolveFunctionReference(unsigned RetAddr);
};
static JITResolver &getResolver(MachineCodeEmitter &MCE) {
static JITResolver *TheJITResolver = 0;
if (TheJITResolver == 0)
TheJITResolver = new JITResolver(MCE);
return *TheJITResolver;
}
}
void *X86JITInfo::getJITStubForFunction(Function *F, MachineCodeEmitter &MCE) {
return (void*)(intptr_t)getResolver(MCE).getLazyResolver(F);
}
void X86JITInfo::replaceMachineCodeForFunction (void *Old, void *New) {
unsigned char *OldByte = (unsigned char *) Old;
*OldByte++ = 0xE9; // Emit JMP opcode.
int32_t *OldWord = (int32_t *) OldByte;
int32_t NewAddr = (intptr_t) New;
int32_t OldAddr = (intptr_t) OldWord;
*OldWord = NewAddr - OldAddr - 4; // Emit PC-relative addr of New code.
}
/// addFunctionReference - This method is called when we need to emit the
/// address of a function that has not yet been emitted, so we don't know the
/// address. Instead, we emit a call to the CompilationCallback method, and
/// keep track of where we are.
///
unsigned JITResolver::addFunctionReference(unsigned Address, Function *F) {
DEBUG(std::cerr << "Emitting lazily resolved reference to function '"
<< F->getName() << "' at address " << std::hex << Address
<< std::dec << "\n");
LazyCodeGenMap[Address] = F;
return (intptr_t)&JITResolver::CompilationCallback;
}
unsigned JITResolver::resolveFunctionReference(unsigned RetAddr) {
std::map<unsigned, Function*>::iterator I = LazyCodeGenMap.find(RetAddr);
assert(I != LazyCodeGenMap.end() && "Not in map!");
Function *F = I->second;
LazyCodeGenMap.erase(I);
return MCE.forceCompilationOf(F);
}
unsigned JITResolver::getLazyResolver(Function *F) {
std::map<Function*, unsigned>::iterator I = LazyResolverMap.lower_bound(F);
if (I != LazyResolverMap.end() && I->first == F) return I->second;
//std::cerr << "Getting lazy resolver for : " << ((Value*)F)->getName() << "\n";
unsigned Stub = emitStubForFunction(F);
LazyResolverMap.insert(I, std::make_pair(F, Stub));
return Stub;
}
#ifdef _MSC_VER
#pragma optimize("y", off)
#endif
void JITResolver::CompilationCallback() {
#ifdef _MSC_VER
unsigned *StackPtr, RetAddr;
__asm mov StackPtr, ebp;
__asm mov eax, DWORD PTR [ebp + 4];
__asm mov RetAddr, eax;
#else
unsigned *StackPtr = (unsigned*)__builtin_frame_address(0);
unsigned RetAddr = (unsigned)(intptr_t)__builtin_return_address(0);
// FIXME: __builtin_frame_address doesn't work if frame pointer elimination
// has been performed. Having a variable sized alloca disables frame pointer
// elimination currently, even if it's dead. This is a gross hack.
alloca(10+(RetAddr >> 31));
#endif
assert(StackPtr[1] == RetAddr &&
"Could not find return address on the stack!");
// It's a stub if there is an interrupt marker after the call...
bool isStub = ((unsigned char*)(intptr_t)RetAddr)[0] == 0xCD;
// The call instruction should have pushed the return value onto the stack...
RetAddr -= 4; // Backtrack to the reference itself...
#if 0
DEBUG(std::cerr << "In callback! Addr=0x" << std::hex << RetAddr
<< " ESP=0x" << (unsigned)StackPtr << std::dec
<< ": Resolving call to function: "
<< TheVM->getFunctionReferencedName((void*)RetAddr) << "\n");
#endif
// Sanity check to make sure this really is a call instruction...
assert(((unsigned char*)(intptr_t)RetAddr)[-1] == 0xE8 &&"Not a call instr!");
JITResolver &JR = getResolver(*(MachineCodeEmitter*)0);
unsigned NewVal = JR.resolveFunctionReference(RetAddr);
// Rewrite the call target... so that we don't fault every time we execute
// the call.
*(unsigned*)(intptr_t)RetAddr = NewVal-RetAddr-4;
if (isStub) {
// If this is a stub, rewrite the call into an unconditional branch
// instruction so that two return addresses are not pushed onto the stack
// when the requested function finally gets called. This also makes the
// 0xCD byte (interrupt) dead, so the marker doesn't effect anything.
((unsigned char*)(intptr_t)RetAddr)[-1] = 0xE9;
}
// Change the return address to reexecute the call instruction...
StackPtr[1] -= 5;
}
#ifdef _MSC_VER
#pragma optimize( "", on )
#endif
/// emitStubForFunction - This method is used by the JIT when it needs to emit
/// the address of a function for a function whose code has not yet been
/// generated. In order to do this, it generates a stub which jumps to the lazy
/// function compiler, which will eventually get fixed to call the function
/// directly.
///
unsigned JITResolver::emitStubForFunction(Function *F) {
MCE.startFunctionStub(*F, 6);
MCE.emitByte(0xE8); // Call with 32 bit pc-rel destination...
unsigned Address = addFunctionReference(MCE.getCurrentPCValue(), F);
MCE.emitWord(Address-MCE.getCurrentPCValue()-4);
MCE.emitByte(0xCD); // Interrupt - Just a marker identifying the stub!
return (intptr_t)MCE.finishFunctionStub(*F);
}
namespace {
class Emitter : public MachineFunctionPass {
const X86InstrInfo *II;
@ -211,6 +55,7 @@ namespace {
void emitPCRelativeValue(unsigned Address);
void emitGlobalAddressForCall(GlobalValue *GV);
void emitGlobalAddressForPtr(GlobalValue *GV, int Disp = 0);
void emitExternalSymbolAddress(const char *ES, bool isPCRelative);
void emitRegModRMByte(unsigned ModRMReg, unsigned RegOpcodeField);
void emitSIBByte(unsigned SS, unsigned Index, unsigned Base);
@ -265,6 +110,12 @@ void Emitter::emitBasicBlock(const MachineBasicBlock &MBB) {
emitInstruction(*I);
}
/// emitPCRelativeValue - Emit a 32-bit PC relative address.
///
void Emitter::emitPCRelativeValue(unsigned Address) {
MCE.emitWord(Address-MCE.getCurrentPCValue()-4);
}
/// emitPCRelativeBlockAddress - This method emits the PC relative address of
/// the specified basic block, or if the basic block hasn't been emitted yet
/// (because this is a forward branch), it keeps track of the information
@ -276,8 +127,7 @@ void Emitter::emitPCRelativeBlockAddress(const MachineBasicBlock *MBB) {
std::map<const MachineBasicBlock*, unsigned>::iterator I =
BasicBlockAddrs.find(MBB);
if (I != BasicBlockAddrs.end()) {
unsigned Location = I->second;
MCE.emitWord(Location-MCE.getCurrentPCValue()-4);
emitPCRelativeValue(I->second);
} else {
// Otherwise, remember where this reference was and where it is to so we can
// deal with it later.
@ -286,25 +136,13 @@ void Emitter::emitPCRelativeBlockAddress(const MachineBasicBlock *MBB) {
}
}
/// emitPCRelativeValue - Emit a 32-bit PC relative address.
///
void Emitter::emitPCRelativeValue(unsigned Address) {
MCE.emitWord(Address-MCE.getCurrentPCValue()-4);
}
/// emitGlobalAddressForCall - Emit the specified address to the code stream
/// assuming this is part of a function call, which is PC relative.
///
void Emitter::emitGlobalAddressForCall(GlobalValue *GV) {
// Get the address from the backend...
unsigned Address = MCE.getGlobalValueAddress(GV);
if (Address == 0) {
// FIXME: this is JIT specific!
Address = getResolver(MCE).addFunctionReference(MCE.getCurrentPCValue(),
cast<Function>(GV));
}
emitPCRelativeValue(Address);
MCE.addRelocation(MachineRelocation(MCE.getCurrentPCOffset(),
X86::reloc_pcrel_word, GV));
MCE.emitWord(0);
}
/// emitGlobalAddress - Emit the specified address to the code stream assuming
@ -312,21 +150,19 @@ void Emitter::emitGlobalAddressForCall(GlobalValue *GV) {
/// PC relative.
///
void Emitter::emitGlobalAddressForPtr(GlobalValue *GV, int Disp /* = 0 */) {
// Get the address from the backend...
unsigned Address = MCE.getGlobalValueAddress(GV);
// If the machine code emitter doesn't know what the address IS yet, we have
// to take special measures.
//
if (Address == 0) {
// FIXME: this is JIT specific!
Address = getResolver(MCE).getLazyResolver((Function*)GV);
}
MCE.emitWord(Address + Disp);
MCE.addRelocation(MachineRelocation(MCE.getCurrentPCOffset(),
X86::reloc_absolute_word, GV));
MCE.emitWord(Disp); // The relocated value will be added to the displacement
}
/// emitExternalSymbolAddress - Arrange for the address of an external symbol to
/// be emitted to the current location in the function, and allow it to be PC
/// relative.
void Emitter::emitExternalSymbolAddress(const char *ES, bool isPCRelative) {
MCE.addRelocation(MachineRelocation(MCE.getCurrentPCOffset(),
isPCRelative ? X86::reloc_pcrel_word : X86::reloc_absolute_word, ES));
MCE.emitWord(0);
}
/// N86 namespace - Native X86 Register numbers... used by X86 backend.
///
@ -560,9 +396,7 @@ void Emitter::emitInstruction(const MachineInstr &MI) {
assert(MO.isPCRelative() && "Call target is not PC Relative?");
emitGlobalAddressForCall(MO.getGlobal());
} else if (MO.isExternalSymbol()) {
unsigned Address = MCE.getGlobalValueAddress(MO.getSymbolName());
assert(Address && "Unknown external symbol!");
emitPCRelativeValue(Address);
emitExternalSymbolAddress(MO.getSymbolName(), true);
} else if (MO.isImmediate()) {
emitConstant(MO.getImmedValue(), sizeOfImm(Desc));
} else {
@ -587,9 +421,7 @@ void Emitter::emitInstruction(const MachineInstr &MI) {
} else if (MO1.isExternalSymbol()) {
assert(sizeOfImm(Desc) == 4 &&
"Don't know how to emit non-pointer values!");
unsigned Address = MCE.getGlobalValueAddress(MO1.getSymbolName());
assert(Address && "Unknown external symbol!");
MCE.emitWord(Address);
emitExternalSymbolAddress(MO1.getSymbolName(), false);
} else {
emitConstant(MO1.getImmedValue(), sizeOfImm(Desc));
}