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Remove all JIT specific code and switch the code generator over to emitting
relocations for global references. llvm-svn: 18068
This commit is contained in:
Chris Lattner
parent
b9a44893e9
commit
4a340e281e
@ -8,12 +8,12 @@
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//===----------------------------------------------------------------------===//
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//
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// This file contains the pass that transforms the X86 machine instructions into
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// actual executable machine code.
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// relocatable machine code.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "jit"
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#include "X86TargetMachine.h"
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#include "X86Relocations.h"
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#include "X86.h"
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#include "llvm/PassManager.h"
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#include "llvm/CodeGen/MachineCodeEmitter.h"
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@ -21,170 +21,14 @@
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#include "llvm/CodeGen/MachineInstr.h"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/Function.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Config/alloca.h"
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using namespace llvm;
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namespace {
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Statistic<>
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NumEmitted("x86-emitter", "Number of machine instructions emitted");
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class JITResolver {
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MachineCodeEmitter &MCE;
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// LazyCodeGenMap - Keep track of call sites for functions that are to be
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// lazily resolved.
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std::map<unsigned, Function*> LazyCodeGenMap;
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// LazyResolverMap - Keep track of the lazy resolver created for a
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// particular function so that we can reuse them if necessary.
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std::map<Function*, unsigned> LazyResolverMap;
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public:
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JITResolver(MachineCodeEmitter &mce) : MCE(mce) {}
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unsigned getLazyResolver(Function *F);
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unsigned addFunctionReference(unsigned Address, Function *F);
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private:
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unsigned emitStubForFunction(Function *F);
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static void CompilationCallback();
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unsigned resolveFunctionReference(unsigned RetAddr);
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};
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static JITResolver &getResolver(MachineCodeEmitter &MCE) {
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static JITResolver *TheJITResolver = 0;
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if (TheJITResolver == 0)
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TheJITResolver = new JITResolver(MCE);
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return *TheJITResolver;
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}
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}
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void *X86JITInfo::getJITStubForFunction(Function *F, MachineCodeEmitter &MCE) {
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return (void*)(intptr_t)getResolver(MCE).getLazyResolver(F);
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}
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void X86JITInfo::replaceMachineCodeForFunction (void *Old, void *New) {
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unsigned char *OldByte = (unsigned char *) Old;
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*OldByte++ = 0xE9; // Emit JMP opcode.
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int32_t *OldWord = (int32_t *) OldByte;
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int32_t NewAddr = (intptr_t) New;
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int32_t OldAddr = (intptr_t) OldWord;
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*OldWord = NewAddr - OldAddr - 4; // Emit PC-relative addr of New code.
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}
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/// addFunctionReference - This method is called when we need to emit the
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/// address of a function that has not yet been emitted, so we don't know the
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/// address. Instead, we emit a call to the CompilationCallback method, and
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/// keep track of where we are.
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///
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unsigned JITResolver::addFunctionReference(unsigned Address, Function *F) {
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DEBUG(std::cerr << "Emitting lazily resolved reference to function '"
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<< F->getName() << "' at address " << std::hex << Address
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<< std::dec << "\n");
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LazyCodeGenMap[Address] = F;
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return (intptr_t)&JITResolver::CompilationCallback;
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}
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unsigned JITResolver::resolveFunctionReference(unsigned RetAddr) {
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std::map<unsigned, Function*>::iterator I = LazyCodeGenMap.find(RetAddr);
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assert(I != LazyCodeGenMap.end() && "Not in map!");
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Function *F = I->second;
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LazyCodeGenMap.erase(I);
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return MCE.forceCompilationOf(F);
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}
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unsigned JITResolver::getLazyResolver(Function *F) {
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std::map<Function*, unsigned>::iterator I = LazyResolverMap.lower_bound(F);
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if (I != LazyResolverMap.end() && I->first == F) return I->second;
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//std::cerr << "Getting lazy resolver for : " << ((Value*)F)->getName() << "\n";
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unsigned Stub = emitStubForFunction(F);
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LazyResolverMap.insert(I, std::make_pair(F, Stub));
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return Stub;
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}
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#ifdef _MSC_VER
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#pragma optimize("y", off)
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#endif
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void JITResolver::CompilationCallback() {
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#ifdef _MSC_VER
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unsigned *StackPtr, RetAddr;
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__asm mov StackPtr, ebp;
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__asm mov eax, DWORD PTR [ebp + 4];
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__asm mov RetAddr, eax;
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#else
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unsigned *StackPtr = (unsigned*)__builtin_frame_address(0);
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unsigned RetAddr = (unsigned)(intptr_t)__builtin_return_address(0);
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// FIXME: __builtin_frame_address doesn't work if frame pointer elimination
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// has been performed. Having a variable sized alloca disables frame pointer
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// elimination currently, even if it's dead. This is a gross hack.
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alloca(10+(RetAddr >> 31));
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#endif
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assert(StackPtr[1] == RetAddr &&
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"Could not find return address on the stack!");
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// It's a stub if there is an interrupt marker after the call...
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bool isStub = ((unsigned char*)(intptr_t)RetAddr)[0] == 0xCD;
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// The call instruction should have pushed the return value onto the stack...
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RetAddr -= 4; // Backtrack to the reference itself...
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#if 0
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DEBUG(std::cerr << "In callback! Addr=0x" << std::hex << RetAddr
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<< " ESP=0x" << (unsigned)StackPtr << std::dec
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<< ": Resolving call to function: "
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<< TheVM->getFunctionReferencedName((void*)RetAddr) << "\n");
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#endif
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// Sanity check to make sure this really is a call instruction...
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assert(((unsigned char*)(intptr_t)RetAddr)[-1] == 0xE8 &&"Not a call instr!");
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JITResolver &JR = getResolver(*(MachineCodeEmitter*)0);
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unsigned NewVal = JR.resolveFunctionReference(RetAddr);
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// Rewrite the call target... so that we don't fault every time we execute
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// the call.
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*(unsigned*)(intptr_t)RetAddr = NewVal-RetAddr-4;
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if (isStub) {
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// If this is a stub, rewrite the call into an unconditional branch
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// instruction so that two return addresses are not pushed onto the stack
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// when the requested function finally gets called. This also makes the
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// 0xCD byte (interrupt) dead, so the marker doesn't effect anything.
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((unsigned char*)(intptr_t)RetAddr)[-1] = 0xE9;
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}
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// Change the return address to reexecute the call instruction...
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StackPtr[1] -= 5;
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}
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#ifdef _MSC_VER
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#pragma optimize( "", on )
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#endif
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/// emitStubForFunction - This method is used by the JIT when it needs to emit
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/// the address of a function for a function whose code has not yet been
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/// generated. In order to do this, it generates a stub which jumps to the lazy
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/// function compiler, which will eventually get fixed to call the function
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/// directly.
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///
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unsigned JITResolver::emitStubForFunction(Function *F) {
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MCE.startFunctionStub(*F, 6);
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MCE.emitByte(0xE8); // Call with 32 bit pc-rel destination...
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unsigned Address = addFunctionReference(MCE.getCurrentPCValue(), F);
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MCE.emitWord(Address-MCE.getCurrentPCValue()-4);
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MCE.emitByte(0xCD); // Interrupt - Just a marker identifying the stub!
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return (intptr_t)MCE.finishFunctionStub(*F);
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}
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namespace {
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class Emitter : public MachineFunctionPass {
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const X86InstrInfo *II;
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@ -211,6 +55,7 @@ namespace {
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void emitPCRelativeValue(unsigned Address);
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void emitGlobalAddressForCall(GlobalValue *GV);
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void emitGlobalAddressForPtr(GlobalValue *GV, int Disp = 0);
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void emitExternalSymbolAddress(const char *ES, bool isPCRelative);
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void emitRegModRMByte(unsigned ModRMReg, unsigned RegOpcodeField);
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void emitSIBByte(unsigned SS, unsigned Index, unsigned Base);
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@ -265,6 +110,12 @@ void Emitter::emitBasicBlock(const MachineBasicBlock &MBB) {
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emitInstruction(*I);
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}
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/// emitPCRelativeValue - Emit a 32-bit PC relative address.
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///
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void Emitter::emitPCRelativeValue(unsigned Address) {
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MCE.emitWord(Address-MCE.getCurrentPCValue()-4);
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}
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/// emitPCRelativeBlockAddress - This method emits the PC relative address of
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/// the specified basic block, or if the basic block hasn't been emitted yet
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/// (because this is a forward branch), it keeps track of the information
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@ -276,8 +127,7 @@ void Emitter::emitPCRelativeBlockAddress(const MachineBasicBlock *MBB) {
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std::map<const MachineBasicBlock*, unsigned>::iterator I =
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BasicBlockAddrs.find(MBB);
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if (I != BasicBlockAddrs.end()) {
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unsigned Location = I->second;
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MCE.emitWord(Location-MCE.getCurrentPCValue()-4);
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emitPCRelativeValue(I->second);
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} else {
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// Otherwise, remember where this reference was and where it is to so we can
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// deal with it later.
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@ -286,25 +136,13 @@ void Emitter::emitPCRelativeBlockAddress(const MachineBasicBlock *MBB) {
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}
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}
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/// emitPCRelativeValue - Emit a 32-bit PC relative address.
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///
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void Emitter::emitPCRelativeValue(unsigned Address) {
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MCE.emitWord(Address-MCE.getCurrentPCValue()-4);
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}
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/// emitGlobalAddressForCall - Emit the specified address to the code stream
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/// assuming this is part of a function call, which is PC relative.
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///
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void Emitter::emitGlobalAddressForCall(GlobalValue *GV) {
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// Get the address from the backend...
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unsigned Address = MCE.getGlobalValueAddress(GV);
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if (Address == 0) {
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// FIXME: this is JIT specific!
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Address = getResolver(MCE).addFunctionReference(MCE.getCurrentPCValue(),
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cast<Function>(GV));
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}
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emitPCRelativeValue(Address);
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MCE.addRelocation(MachineRelocation(MCE.getCurrentPCOffset(),
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X86::reloc_pcrel_word, GV));
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MCE.emitWord(0);
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}
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/// emitGlobalAddress - Emit the specified address to the code stream assuming
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@ -312,21 +150,19 @@ void Emitter::emitGlobalAddressForCall(GlobalValue *GV) {
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/// PC relative.
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///
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void Emitter::emitGlobalAddressForPtr(GlobalValue *GV, int Disp /* = 0 */) {
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// Get the address from the backend...
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unsigned Address = MCE.getGlobalValueAddress(GV);
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// If the machine code emitter doesn't know what the address IS yet, we have
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// to take special measures.
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//
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if (Address == 0) {
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// FIXME: this is JIT specific!
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Address = getResolver(MCE).getLazyResolver((Function*)GV);
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}
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MCE.emitWord(Address + Disp);
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MCE.addRelocation(MachineRelocation(MCE.getCurrentPCOffset(),
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X86::reloc_absolute_word, GV));
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MCE.emitWord(Disp); // The relocated value will be added to the displacement
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}
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/// emitExternalSymbolAddress - Arrange for the address of an external symbol to
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/// be emitted to the current location in the function, and allow it to be PC
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/// relative.
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void Emitter::emitExternalSymbolAddress(const char *ES, bool isPCRelative) {
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MCE.addRelocation(MachineRelocation(MCE.getCurrentPCOffset(),
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isPCRelative ? X86::reloc_pcrel_word : X86::reloc_absolute_word, ES));
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MCE.emitWord(0);
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}
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/// N86 namespace - Native X86 Register numbers... used by X86 backend.
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///
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@ -560,9 +396,7 @@ void Emitter::emitInstruction(const MachineInstr &MI) {
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assert(MO.isPCRelative() && "Call target is not PC Relative?");
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emitGlobalAddressForCall(MO.getGlobal());
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} else if (MO.isExternalSymbol()) {
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unsigned Address = MCE.getGlobalValueAddress(MO.getSymbolName());
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assert(Address && "Unknown external symbol!");
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emitPCRelativeValue(Address);
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emitExternalSymbolAddress(MO.getSymbolName(), true);
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} else if (MO.isImmediate()) {
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emitConstant(MO.getImmedValue(), sizeOfImm(Desc));
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} else {
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@ -587,9 +421,7 @@ void Emitter::emitInstruction(const MachineInstr &MI) {
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} else if (MO1.isExternalSymbol()) {
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assert(sizeOfImm(Desc) == 4 &&
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"Don't know how to emit non-pointer values!");
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unsigned Address = MCE.getGlobalValueAddress(MO1.getSymbolName());
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assert(Address && "Unknown external symbol!");
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MCE.emitWord(Address);
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emitExternalSymbolAddress(MO1.getSymbolName(), false);
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} else {
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emitConstant(MO1.getImmedValue(), sizeOfImm(Desc));
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}
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