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https://github.com/c64scene-ar/llvm-6502.git
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078d1826d2
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28630 91177308-0d34-0410-b5e6-96231b3b80d8
211 lines
7.5 KiB
C++
211 lines
7.5 KiB
C++
//===-- X86JITInfo.cpp - Implement the JIT interfaces for the X86 target --===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the JIT interfaces for the X86 target.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "jit"
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#include "X86JITInfo.h"
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#include "X86Relocations.h"
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#include "llvm/CodeGen/MachineCodeEmitter.h"
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#include "llvm/Config/alloca.h"
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#include <cstdlib>
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#include <iostream>
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using namespace llvm;
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#ifdef _MSC_VER
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extern "C" void *_AddressOfReturnAddress(void);
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#pragma intrinsic(_AddressOfReturnAddress)
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#endif
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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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unsigned *OldWord = (unsigned *)OldByte;
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unsigned NewAddr = (intptr_t)New;
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unsigned 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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/// JITCompilerFunction - This contains the address of the JIT function used to
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/// compile a function lazily.
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static TargetJITInfo::JITCompilerFn JITCompilerFunction;
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// Provide a wrapper for X86CompilationCallback2 that saves non-traditional
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// callee saved registers, for the fastcc calling convention.
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extern "C" {
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#if defined(__i386__) || defined(i386) || defined(_M_IX86)
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#ifndef _MSC_VER
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void X86CompilationCallback(void);
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asm(
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".text\n"
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".align 8\n"
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#if defined(__CYGWIN__) || defined(__APPLE__) || defined(__MINGW32__)
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".globl _X86CompilationCallback\n"
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"_X86CompilationCallback:\n"
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#else
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".globl X86CompilationCallback\n"
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"X86CompilationCallback:\n"
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#endif
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"pushl %ebp\n"
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"movl %esp, %ebp\n" // Standard prologue
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"pushl %eax\n"
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"pushl %edx\n" // save EAX/EDX
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#if defined(__CYGWIN__) || defined(__MINGW32__)
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"call _X86CompilationCallback2\n"
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#elif defined(__APPLE__)
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"movl 4(%ebp), %eax\n" // load the address of return address
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"movl $24, %edx\n" // if the opcode of the instruction at the
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"cmpb $-51, (%eax)\n" // return address is our 0xCD marker, then
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"movl $12, %eax\n" // subtract 24 from %esp to realign it to 16
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"cmovne %eax, %edx\n" // bytes after the push of edx, the amount to.
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"subl %edx, %esp\n" // the push of edx to keep it aligned.
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"pushl %edx\n" // subtract. Otherwise, subtract 12 bytes after
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"call _X86CompilationCallback2\n"
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"popl %edx\n"
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"addl %edx, %esp\n"
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#else
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"call X86CompilationCallback2\n"
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#endif
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"popl %edx\n"
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"popl %eax\n"
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"popl %ebp\n"
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"ret\n");
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#else
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void X86CompilationCallback2(void);
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_declspec(naked) void X86CompilationCallback(void) {
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__asm {
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push eax
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push edx
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call X86CompilationCallback2
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pop edx
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pop eax
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ret
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}
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}
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#endif // _MSC_VER
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#else // Not an i386 host
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void X86CompilationCallback() {
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std::cerr << "Cannot call X86CompilationCallback() on a non-x86 arch!\n";
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abort();
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}
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#endif
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}
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/// X86CompilationCallback - This is the target-specific function invoked by the
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/// function stub when we did not know the real target of a call. This function
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/// must locate the start of the stub or call site and pass it into the JIT
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/// compiler function.
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extern "C" void X86CompilationCallback2() {
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#ifdef _MSC_VER
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assert(sizeof(size_t) == 4); // FIXME: handle Win64
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unsigned *RetAddrLoc = (unsigned *)_AddressOfReturnAddress();
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RetAddrLoc += 3; // skip over ret addr, edx, eax
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unsigned RetAddr = *RetAddrLoc;
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#else
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unsigned *StackPtr = (unsigned*)__builtin_frame_address(1);
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unsigned RetAddr = (unsigned)(intptr_t)__builtin_return_address(1);
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unsigned *RetAddrLoc = &StackPtr[1];
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// NOTE: __builtin_frame_address doesn't work if frame pointer elimination has
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// 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(*RetAddrLoc == 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=" << (void*)RetAddr
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<< " ESP=" << (void*)StackPtr
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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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unsigned NewVal = (intptr_t)JITCompilerFunction((void*)(intptr_t)RetAddr);
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// Rewrite the call target... so that we don't end up here every time we
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// execute 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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*RetAddrLoc -= 5;
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}
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TargetJITInfo::LazyResolverFn
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X86JITInfo::getLazyResolverFunction(JITCompilerFn F) {
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JITCompilerFunction = F;
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return X86CompilationCallback;
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}
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void *X86JITInfo::emitFunctionStub(void *Fn, MachineCodeEmitter &MCE) {
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// Note, we cast to intptr_t here to silence a -pedantic warning that
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// complains about casting a function pointer to a normal pointer.
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if (Fn != (void*)(intptr_t)X86CompilationCallback) {
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MCE.startFunctionStub(5);
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MCE.emitByte(0xE9);
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MCE.emitWordLE((intptr_t)Fn-MCE.getCurrentPCValue()-4);
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return MCE.finishFunctionStub(0);
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}
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MCE.startFunctionStub(6);
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MCE.emitByte(0xE8); // Call with 32 bit pc-rel destination...
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MCE.emitWordLE((intptr_t)Fn-MCE.getCurrentPCValue()-4);
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MCE.emitByte(0xCD); // Interrupt - Just a marker identifying the stub!
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return MCE.finishFunctionStub(0);
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}
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/// relocate - Before the JIT can run a block of code that has been emitted,
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/// it must rewrite the code to contain the actual addresses of any
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/// referenced global symbols.
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void X86JITInfo::relocate(void *Function, MachineRelocation *MR,
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unsigned NumRelocs, unsigned char* GOTBase) {
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for (unsigned i = 0; i != NumRelocs; ++i, ++MR) {
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void *RelocPos = (char*)Function + MR->getMachineCodeOffset();
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intptr_t ResultPtr = (intptr_t)MR->getResultPointer();
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switch ((X86::RelocationType)MR->getRelocationType()) {
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case X86::reloc_pcrel_word:
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// PC relative relocation, add the relocated value to the value already in
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// memory, after we adjust it for where the PC is.
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ResultPtr = ResultPtr-(intptr_t)RelocPos-4;
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*((intptr_t*)RelocPos) += ResultPtr;
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break;
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case X86::reloc_absolute_word:
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// Absolute relocation, just add the relocated value to the value already
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// in memory.
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*((intptr_t*)RelocPos) += ResultPtr;
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break;
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}
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}
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}
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