/*
===========================================================================
Copyright (C) 1999-2005 Id Software, Inc.
Copyright (C) 2005 Ludwig Nussel <ludwig.nussel@web.de>

This file is part of Quake III Arena source code.

Quake III Arena source code is free software; you can redistribute it
and/or modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the License,
or (at your option) any later version.

Quake III Arena source code is distributed in the hope that it will be
useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Quake III Arena source code; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
===========================================================================
*/
// vm_x86_64.c -- load time compiler and execution environment for x86-64

#include "vm_local.h"

#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>

#ifdef DEBUG_VM
#define Dfprintf(fd, args...) fprintf(fd, ##args)
static FILE* qdasmout;
#else
#define Dfprintf(args...)
#endif

static void VM_Destroy_Compiled(vm_t* self);

/*

  eax	scratch
  ebx	scratch
  ecx	scratch (required for shifts)
  edx	scratch (required for divisions)
  rsi	stack pointer
  rdi	program frame pointer
  r8    pointer to begin of real stack memory
  r9    return address to real program
  r10   start of generated code
*/


static long callAsmCall(long callProgramStack, long callSyscallNum)
{
	vm_t *savedVM;
	long ret = 0x77;
	long args[11];
//	int iargs[11];
	int i;

//	Dfprintf(stderr, "callAsmCall(%ld, %ld)\n", callProgramStack, callSyscallNum);
//	Com_Printf("-> callAsmCall %s, level %d, num %ld\n", currentVM->name, currentVM->callLevel, callSyscallNum);

	savedVM = currentVM;

	// save the stack to allow recursive VM entry
	currentVM->programStack = callProgramStack - 4;

	args[0] = callSyscallNum;
//	iargs[0] = callSyscallNum;
	for(i = 0; i < 10; ++i)
	{
//		iargs[i+1] = *(int *)((byte *)currentVM->dataBase + callProgramStack + 8 + 4*i);
		args[i+1] = *(int *)((byte *)currentVM->dataBase + callProgramStack + 8 + 4*i);
	}
	ret = currentVM->systemCall(args);

 	currentVM = savedVM;
//	Com_Printf("<- callAsmCall %s, level %d, num %ld\n", currentVM->name, currentVM->callLevel, callSyscallNum);

	return ret;
}

#ifdef DEBUG_VM // bk001204
static char	*opnames[256] = {
	"OP_UNDEF", 

	"OP_IGNORE", 

	"OP_BREAK",

	"OP_ENTER",
	"OP_LEAVE",
	"OP_CALL",
	"OP_PUSH",
	"OP_POP",

	"OP_CONST",

	"OP_LOCAL",

	"OP_JUMP",

	//-------------------

	"OP_EQ",
	"OP_NE",

	"OP_LTI",
	"OP_LEI",
	"OP_GTI",
	"OP_GEI",

	"OP_LTU",
	"OP_LEU",
	"OP_GTU",
	"OP_GEU",

	"OP_EQF",
	"OP_NEF",

	"OP_LTF",
	"OP_LEF",
	"OP_GTF",
	"OP_GEF",

	//-------------------

	"OP_LOAD1",
	"OP_LOAD2",
	"OP_LOAD4",
	"OP_STORE1",
	"OP_STORE2",
	"OP_STORE4",
	"OP_ARG",

	"OP_BLOCK_COPY",

	//-------------------

	"OP_SEX8",
	"OP_SEX16",

	"OP_NEGI",
	"OP_ADD",
	"OP_SUB",
	"OP_DIVI",
	"OP_DIVU",
	"OP_MODI",
	"OP_MODU",
	"OP_MULI",
	"OP_MULU",

	"OP_BAND",
	"OP_BOR",
	"OP_BXOR",
	"OP_BCOM",

	"OP_LSH",
	"OP_RSHI",
	"OP_RSHU",

	"OP_NEGF",
	"OP_ADDF",
	"OP_SUBF",
	"OP_DIVF",
	"OP_MULF",

	"OP_CVIF",
	"OP_CVFI"
};
#endif // DEBUG_VM

static unsigned char op_argsize[256] = 
{
	[OP_ENTER]      = 4,
	[OP_LEAVE]      = 4,
	[OP_CONST]      = 4,
	[OP_LOCAL]      = 4,
	[OP_EQ]         = 4,
	[OP_NE]         = 4,
	[OP_LTI]        = 4,
	[OP_LEI]        = 4,
	[OP_GTI]        = 4,
	[OP_GEI]        = 4,
	[OP_LTU]        = 4,
	[OP_LEU]        = 4,
	[OP_GTU]        = 4,
	[OP_GEU]        = 4,
	[OP_EQF]        = 4,
	[OP_NEF]        = 4,
	[OP_LTF]        = 4,
	[OP_LEF]        = 4,
	[OP_GTF]        = 4,
	[OP_GEF]        = 4,
	[OP_ARG]        = 1,
	[OP_BLOCK_COPY] = 4,
};

#define emit(x...) \
	do { fprintf(fh_s, ##x); fputc('\n', fh_s); } while(0)
 
// integer compare and jump
#define IJ(op) \
	emit("subq $8, %%rsi"); \
	emit("movl 4(%%rsi), %%eax"); \
	emit("cmpl 8(%%rsi), %%eax"); \
	emit(op " i_%08x", instruction+1); \
	emit("jmp i_%08x", iarg);

#ifdef USE_X87
#define FJ(bits, op) \
	emit("subq $8, %%rsi");\
	emit("flds 4(%%rsi)");\
	emit("fcomps 8(%%rsi)");\
	emit("fnstsw %%ax");\
	emit("testb $" #bits ", %%ah");\
	emit(op " i_%08x", instruction+1);\
	emit("jmp i_%08x", iarg);
#define XJ(x)
#else
#define FJ(x, y)
#define XJ(op) \
	emit("subq $8, %%rsi");\
	emit("movss 4(%%rsi), %%xmm0");\
	emit("ucomiss 8(%%rsi), %%xmm0");\
	emit("jp i_%08x", instruction+1);\
	emit(op " i_%08x", instruction+1);\
	emit("jmp i_%08x", iarg);
#endif

#define SIMPLE(op) \
	emit("subq $4, %%rsi"); \
	emit("movl 4(%%rsi), %%eax"); \
	emit(op " %%eax, 0(%%rsi)");

#ifdef USE_X87
#define FSIMPLE(op) \
	emit("subq $4, %%rsi"); \
	emit("flds 0(%%rsi)"); \
	emit(op " 4(%%rsi)"); \
	emit("fstps 0(%%rsi)");
#define XSIMPLE(op)
#else
#define FSIMPLE(op)
#define XSIMPLE(op) \
	emit("subq $4, %%rsi"); \
	emit("movss 0(%%rsi), %%xmm0"); \
	emit(op " 4(%%rsi), %%xmm0"); \
	emit("movss %%xmm0, 0(%%rsi)");
#endif

#define SHIFT(op) \
	emit("subq $4, %%rsi"); \
	emit("movl 4(%%rsi), %%ecx"); \
	emit("movl 0(%%rsi), %%eax"); \
	emit(op " %%cl, %%eax"); \
	emit("movl %%eax, 0(%%rsi)");

#if 1
#define RANGECHECK(reg) \
	emit("andl $0x%x, %%" #reg, vm->dataMask);
#else
#define RANGECHECK(reg)
#endif

#ifdef DEBUG_VM
#define NOTIMPL(x) \
	do { Com_Error(ERR_DROP, "instruction not implemented: %s\n", opnames[x]); } while(0)
#else
#define NOTIMPL(x) \
	do { Com_Printf(S_COLOR_RED "instruction not implemented: %x\n", x); vm->compiled = qfalse; return; } while(0)
#endif

static void* getentrypoint(vm_t* vm)
{
       return vm->codeBase+64; // skip ELF header
}

char* mmapfile(const char* fn, size_t* size)
{
	int fd = -1;
	char* mem = NULL;
	struct stat stb;

	fd = open(fn, O_RDONLY);
	if(fd == -1)
		goto out;

	if(fstat(fd, &stb) == -1)
		goto out;

	*size = stb.st_size;

	mem = mmap(NULL, stb.st_size, PROT_READ|PROT_EXEC, MAP_SHARED, fd, 0);
	if(mem == (void*)-1)
		mem = NULL;

out:
	if(fd != -1)
		close(fd);

	return mem;
}

static int doas(char* in, char* out, unsigned char** compiledcode)
{
	unsigned char* mem;
	size_t size = -1;
	pid_t pid;

	Com_Printf("running assembler < %s > %s\n", in, out);
	pid = fork();
	if(pid == -1)
	{
		Com_Printf(S_COLOR_RED "can't fork\n");
		return -1;
	}

	if(!pid)
	{
		char* const argv[] = {
			"as",
			"-o",
			out,
			in,
			NULL
		};

		execvp(argv[0], argv);
		_exit(-1);
	}
	else
	{
		int status;
		if(waitpid(pid, &status, 0) == -1)
		{
			Com_Printf(S_COLOR_RED "can't wait for as: %s\n", strerror(errno));
			return -1;
		}

		if(!WIFEXITED(status))
		{
			Com_Printf(S_COLOR_RED "as died\n");
			return -1;
		}
		if(WEXITSTATUS(status))
		{
			Com_Printf(S_COLOR_RED "as failed with status %d\n", WEXITSTATUS(status));
			return -1;
		}
	}

	Com_Printf("done\n");

	mem = (unsigned char*)mmapfile(out, &size);
	if(!mem)
	{
		Com_Printf(S_COLOR_RED "can't mmap object file %s: %s\n", out, strerror(errno));
		return -1;
	}

	*compiledcode = mem;

	return size;
}

static void block_copy_vm(unsigned dest, unsigned src, unsigned count)
{
	unsigned dataMask = currentVM->dataMask;

	if ((dest & dataMask) != dest
	|| (src & dataMask) != src
	|| ((dest+count) & dataMask) != dest + count
	|| ((src+count) & dataMask) != src + count)
	{
		Com_Error(ERR_DROP, "OP_BLOCK_COPY out of range!\n");
	}

	memcpy(currentVM->dataBase+dest, currentVM->dataBase+src, count);
}

/*
=================
VM_Compile
=================
*/
void VM_Compile( vm_t *vm, vmHeader_t *header ) {
	unsigned char op;
	int pc;
	unsigned instruction;
	char* code;
	unsigned iarg = 0;
	unsigned char barg = 0;
	void* entryPoint;

	char fn_s[2*MAX_QPATH]; // output file for assembler code
	char fn_o[2*MAX_QPATH]; // file written by as
#ifdef DEBUG_VM
	char fn_d[MAX_QPATH]; // disassembled
#endif
	FILE* fh_s;
	int fd_s, fd_o;
	byte* compiledcode;
	int   compiledsize;

	Com_Printf("compiling %s\n", vm->name);

	snprintf(fn_s, sizeof(fn_s), "/tmp/%.63s.s_XXXXXX", vm->name);
	snprintf(fn_o, sizeof(fn_o), "/tmp/%.63s.o_XXXXXX", vm->name);
	fd_s = mkstemp(fn_s);
	fd_o = mkstemp(fn_o);
	if(fd_s == -1 || fd_o == -1)
	{
		if(fd_s != -1) close(fd_s);
		if(fd_o != -1) close(fd_o);
		unlink(fn_s);
		unlink(fn_o);

		Com_Printf(S_COLOR_RED "can't create temporary files for vm\n", fn_s);
		vm->compiled = qfalse;
		return;
	}

#ifdef DEBUG_VM
	strcpy(fn_d,vm->name);
	strcat(fn_d, ".qdasm");

	qdasmout = fopen(fn_d, "w");
#endif

	fh_s = fdopen(fd_s, "wb");
	if(!fh_s)
	{
		Com_Printf(S_COLOR_RED "can't write %s\n", fn_s);
		vm->compiled = qfalse;
		return;
	}

	// translate all instructions
	pc = 0;
	code = (char *)header + header->codeOffset;

	emit("start:");
	emit("or %%r8, %%r8"); // check whether to set up instruction pointers
	emit("jnz main");
	emit("jmp setupinstructionpointers");
	emit("exit:");
	emit("jmp *%%r9");

	emit("main:");

	for ( instruction = 0; instruction < header->instructionCount; ++instruction )
	{
		op = code[ pc ];
		++pc;

		vm->instructionPointers[instruction] = pc;

#if 0
		emit("nop");
		emit("movq $%d, %%r15", instruction);
		emit("nop");
#endif

		if(op_argsize[op] == 4)
		{
			iarg = *(int*)(code+pc);
			pc += 4;
			Dfprintf(qdasmout, "%s %8u\n", opnames[op], iarg);
		}
		else if(op_argsize[op] == 1)
		{
			barg = code[pc++];
			Dfprintf(qdasmout, "%s %8hhu\n", opnames[op], barg);
		}
		else
		{
			Dfprintf(qdasmout, "%s\n", opnames[op]);
		}
		emit("i_%08x:", instruction);
		switch ( op )
		{
			case OP_UNDEF:
				NOTIMPL(op);
				break;
			case OP_IGNORE:
				emit("nop");
				break;
			case OP_BREAK:
				emit("int3");
				break;
			case OP_ENTER:
				emit("subl $%d, %%edi", iarg);
				RANGECHECK(edi);
				break;
			case OP_LEAVE:
				emit("addl $%d, %%edi", iarg);          // get rid of stack frame
				RANGECHECK(edi);
				emit("movl 0(%%r8, %%rdi, 1), %%eax");  // get return address
				emit("movq $%lu, %%rbx", (unsigned long)vm->instructionPointers);
				emit("cmp $-1, %%eax");
				emit("je jumptoexit%d", instruction);
				emit("movl (%%rbx, %%rax, 4), %%eax"); // load new relative jump address
				emit("addq %%r10, %%rax");
				emit("jmp *%%rax");
				emit("jumptoexit%d:", instruction);
				emit("jmp exit");
				break;
			case OP_CALL:
				emit("movl 0(%%rsi), %%eax");  // get instr from stack
				emit("subq $4, %%rsi");
				emit("movl $%d, 0(%%r8, %%rdi, 1)", instruction+1);  // save next instruction
				emit("orl %%eax, %%eax");
				emit("jl callSyscall%d", instruction);
				emit("movq $%lu, %%rbx", (unsigned long)vm->instructionPointers);
				emit("movl (%%rbx, %%rax, 4), %%eax"); // load new relative jump address
				emit("addq %%r10, %%rax");
				emit("jmp *%%rax");
				emit("callSyscall%d:", instruction);
//				emit("fnsave 4(%%rsi)");
				emit("push %%rsi");
				emit("push %%rdi");
				emit("push %%r8");
				emit("push %%r9");
				emit("push %%r10");
				emit("push %%r10"); // align!
				emit("negl %%eax");        // convert to actual number
				emit("decl %%eax");
				                           // first argument already in rdi
				emit("movq %%rax, %%rsi"); // second argument in rsi
				emit("movq $%lu, %%rax", (unsigned long)callAsmCall);
				emit("callq *%%rax");
				emit("pop %%r10");
				emit("pop %%r10");
				emit("pop %%r9");
				emit("pop %%r8");
				emit("pop %%rdi");
				emit("pop %%rsi");
//				emit("frstor 4(%%rsi)");
				emit("addq $4, %%rsi");
				emit("movl %%eax, (%%rsi)");
				break;
			case OP_PUSH:
				emit("addq $4, %%rsi");
				break;
			case OP_POP:
				emit("subq $4, %%rsi");
				break;
			case OP_CONST:
				emit("addq $4, %%rsi");
				emit("movl $%d, 0(%%rsi)", iarg);
				break;
			case OP_LOCAL:
				emit("movl %%edi, %%ebx");
				emit("addl $%d,%%ebx", iarg);
				emit("addq $4, %%rsi");
				emit("movl %%ebx, 0(%%rsi)");
				break;
			case OP_JUMP:
				emit("movl 0(%%rsi), %%eax"); // get instr from stack
				emit("subq $4, %%rsi");
				emit("movq $%lu, %%rbx", (unsigned long)vm->instructionPointers);
				emit("movl (%%rbx, %%rax, 4), %%eax"); // load new relative jump address
				emit("addq %%r10, %%rax");
				emit("jmp *%%rax");
				break;
			case OP_EQ:
				IJ("jne");
				break;
			case OP_NE:
				IJ("je");
				break;
			case OP_LTI:
				IJ("jnl");
				break;
			case OP_LEI:
				IJ("jnle");
				break;
			case OP_GTI:
				IJ("jng");
				break;
			case OP_GEI:
				IJ("jnge");
				break;
			case OP_LTU:
				IJ("jnb");
				break;
			case OP_LEU:
				IJ("jnbe");
				break;
			case OP_GTU:
				IJ("jna");
				break;
			case OP_GEU:
				IJ("jnae");
				break;
			case OP_EQF:
				FJ(0x40, "jz");
				XJ("jnz");
				break;
			case OP_NEF:
				FJ(0x40, "jnz");
#ifndef USE_X87
				emit("subq $8, %%rsi");
				emit("movss 4(%%rsi), %%xmm0");
				emit("ucomiss 8(%%rsi), %%xmm0");
				emit("jp dojump_i_%08x", instruction);
				emit("jz i_%08x", instruction+1);
				emit("dojump_i_%08x:", instruction);
				emit("jmp i_%08x", iarg);
#endif
				break;
			case OP_LTF:
				FJ(0x01, "jz");
				XJ("jnc");
				break;
			case OP_LEF:
				FJ(0x41, "jz");
				XJ("ja");
				break;
			case OP_GTF:
				FJ(0x41, "jnz");
				XJ("jbe");
				break;
			case OP_GEF:
				FJ(0x01, "jnz");
				XJ("jb");
				break;
			case OP_LOAD1:
				emit("movl 0(%%rsi), %%eax"); // get pointer from stack
				RANGECHECK(eax);
				emit("movb 0(%%r8, %%rax, 1), %%al"); // deref into eax
				emit("andq $255, %%rax");
				emit("movl %%eax, 0(%%rsi)"); // store on stack
				break;
			case OP_LOAD2:
				emit("movl 0(%%rsi), %%eax"); // get pointer from stack
				RANGECHECK(eax);
				emit("movw 0(%%r8, %%rax, 1), %%rax"); // deref into eax
				emit("movl %%eax, 0(%%rsi)"); // store on stack
				break;
			case OP_LOAD4:
				emit("movl 0(%%rsi), %%eax"); // get pointer from stack
				RANGECHECK(eax);
				emit("movl 0(%%r8, %%rax, 1), %%eax"); // deref into eax
				emit("movl %%eax, 0(%%rsi)"); // store on stack
				break;
			case OP_STORE1:
				emit("movl 0(%%rsi), %%eax"); // get value from stack
				emit("andq $255, %%rax");
				emit("movl -4(%%rsi), %%ebx"); // get pointer from stack
				RANGECHECK(ebx);
				emit("movb %%al, 0(%%r8, %%rbx, 1)"); // store in memory
				emit("subq $8, %%rsi");
				break;
			case OP_STORE2:
				emit("movl 0(%%rsi), %%eax"); // get value from stack
				emit("movl -4(%%rsi), %%ebx"); // get pointer from stack
				RANGECHECK(ebx);
				emit("movw %%rax, 0(%%r8, %%rbx, 1)"); // store in memory
				emit("subq $8, %%rsi");
				break;
			case OP_STORE4:
				emit("movl -4(%%rsi), %%ebx"); // get pointer from stack
				RANGECHECK(ebx);
				emit("movl 0(%%rsi), %%ecx"); // get value from stack
				emit("movl %%ecx, 0(%%r8, %%rbx, 1)"); // store in memory
				emit("subq $8, %%rsi");
				break;
			case OP_ARG:
				emit("subq $4, %%rsi");
				emit("movl 4(%%rsi), %%eax"); // get value from stack
				emit("movl $0x%hhx, %%ebx", barg);
				emit("addl %%edi, %%ebx");
				RANGECHECK(ebx);
				emit("movl %%eax, 0(%%r8,%%rbx, 1)"); // store in args space
				break;
			case OP_BLOCK_COPY:

				emit("subq $8, %%rsi");
				emit("push %%rsi");
				emit("push %%rdi");
				emit("push %%r8");
				emit("push %%r9");
				emit("push %%r10");
				emit("movl 4(%%rsi), %%edi");  // 1st argument dest
				emit("movl 8(%%rsi), %%esi");  // 2nd argument src
				emit("movl $%d, %%edx", iarg); // 3rd argument count
				emit("movq $%lu, %%rax", (unsigned long)block_copy_vm);
				emit("callq *%%rax");
				emit("pop %%r10");
				emit("pop %%r9");
				emit("pop %%r8");
				emit("pop %%rdi");
				emit("pop %%rsi");

				break;
			case OP_SEX8:
				emit("movw 0(%%rsi), %%rax");
				emit("andq $255, %%rax");
				emit("cbw");
				emit("cwde");
				emit("movl %%eax, 0(%%rsi)");
				break;
			case OP_SEX16:
				emit("movw 0(%%rsi), %%rax");
				emit("cwde");
				emit("movl %%eax, 0(%%rsi)");
				break;
			case OP_NEGI:
				emit("negl 0(%%rsi)");
				break;
			case OP_ADD:
				SIMPLE("addl");
				break;
			case OP_SUB:
				SIMPLE("subl");
				break;
			case OP_DIVI:
				emit("subq $4, %%rsi");
				emit("movl 0(%%rsi), %%eax");
				emit("cdq");
				emit("idivl 4(%%rsi)");
				emit("movl %%eax, 0(%%rsi)");
				break;
			case OP_DIVU:
				emit("subq $4, %%rsi");
				emit("movl 0(%%rsi), %%eax");
				emit("xorq %%rdx, %%rdx");
				emit("divl 4(%%rsi)");
				emit("movl %%eax, 0(%%rsi)");
				break;
			case OP_MODI:
				emit("subq $4, %%rsi");
				emit("movl 0(%%rsi), %%eax");
				emit("xorl %%edx, %%edx");
				emit("divl 4(%%rsi)");
				emit("movl %%edx, 0(%%rsi)");
				break;
			case OP_MODU:
				emit("subq $4, %%rsi");
				emit("movl 0(%%rsi), %%eax");
				emit("xorl %%edx, %%edx");
				emit("idivl 4(%%rsi)");
				emit("movl %%edx, 0(%%rsi)");
				break;
			case OP_MULI:
				emit("subq $4, %%rsi");
				emit("movl 0(%%rsi), %%eax");
				emit("imull 4(%%rsi)");
				emit("movl %%eax, 0(%%rsi)");
				break;
			case OP_MULU:
				emit("subq $4, %%rsi");
				emit("movl 0(%%rsi), %%eax");
				emit("mull 4(%%rsi)");
				emit("movl %%eax, 0(%%rsi)");
				break;
			case OP_BAND:
				SIMPLE("andl");
				break;
			case OP_BOR:
				SIMPLE("orl");
				break;
			case OP_BXOR:
				SIMPLE("xorl");
				break;
			case OP_BCOM:
				emit("notl 0(%%rsi)");
				break;
			case OP_LSH:
				SHIFT("shl");
				break;
			case OP_RSHI:
				SHIFT("sarl");
				break;
			case OP_RSHU:
				SHIFT("shrl");
				break;
			case OP_NEGF:
#ifdef USE_X87
				emit("flds 0(%%rsi)");
				emit("fchs");
				emit("fstps 0(%%rsi)");
#else
				emit("movl $0x80000000, %%eax");
				emit("xorl %%eax, 0(%%rsi)");
#endif
				break;
			case OP_ADDF:
				FSIMPLE("fadds");
				XSIMPLE("addss");
				break;
			case OP_SUBF:
				FSIMPLE("fsubs");
				XSIMPLE("subss");
				break;
			case OP_DIVF:
				FSIMPLE("fdivs");
				XSIMPLE("divss");
				break;
			case OP_MULF:
				FSIMPLE("fmuls");
				XSIMPLE("mulss");
				break;
			case OP_CVIF:
#ifdef USE_X87
				emit("filds 0(%%rsi)");
				emit("fstps 0(%%rsi)");
#else
				emit("movl 0(%%rsi), %%eax");
				emit("cvtsi2ss %%eax, %%xmm0");
				emit("movss %%xmm0, 0(%%rsi)");
#endif
				break;
			case OP_CVFI:
#ifdef USE_X87
				emit("flds 0(%%rsi)");
				emit("fnstcw 4(%%rsi)");
				emit("movw $0x0F7F, 8(%%rsi)"); // round toward zero
				emit("fldcw 8(%%rsi)");
				emit("fistpl 0(%%rsi)");
				emit("fldcw 4(%%rsi)");
#else
				emit("movss 0(%%rsi), %%xmm0");
				emit("cvttss2si %%xmm0, %%eax");
				emit("movl %%eax, 0(%%rsi)");
#endif
				break;
			default:
				NOTIMPL(op);
				break;
		}
	}


	emit("setupinstructionpointers:");
	emit("movq $%lu, %%rax", (unsigned long)vm->instructionPointers);
	for ( instruction = 0; instruction < header->instructionCount; ++instruction )
	{
		emit("movl $i_%08x-start, %d(%%rax)", instruction, instruction*4);
	}
	emit("jmp exit");

	emit("debugger:");
	if(1);
	{
		int i = 6;
		while(i--)
		{
			emit("nop");
			emit("int3");
		}
	}

	fflush(fh_s);
	fclose(fh_s);

	compiledsize = doas(fn_s, fn_o, &compiledcode);
	if(compiledsize == -1)
	{
		vm->compiled = qfalse;
		goto out;
	}

	vm->codeBase   = compiledcode; // remember to skip ELF header!
	vm->codeLength = compiledsize;

	vm->destroy = VM_Destroy_Compiled;
	
	entryPoint = getentrypoint(vm);

//	__asm__ __volatile__ ("int3");
	Com_Printf("computing jump table\n");

	// call code with r8 set to zero to set up instruction pointers
	__asm__ __volatile__ (
		"	xorq %%r8,%%r8		\r\n" \
		"	movq $doneinit,%%r9	\r\n" \
		"	movq %0,%%r10		\r\n" \
		"	jmp *%%r10		\r\n" \
		"doneinit:			\r\n" \
		:
		: "m" (entryPoint)
		: "%r8", "%r9", "%r10", "%rax"
	);

#ifdef DEBUG_VM
	fflush(qdasmout);
#endif

	Com_Printf( "VM file %s compiled to %i bytes of code (0x%lx - 0x%lx)\n", vm->name, vm->codeLength, vm->codeBase, vm->codeBase+vm->codeLength );

out:
	close(fd_o);
	if(!com_developer->integer)
	{
		unlink(fn_o);
		unlink(fn_s);
	}
}


void VM_Destroy_Compiled(vm_t* self)
{
	munmap(self->codeBase, self->codeLength);
}

/*
==============
VM_CallCompiled

This function is called directly by the generated code
==============
*/

#ifdef DEBUG_VM
static char* memData;
#endif

int	VM_CallCompiled( vm_t *vm, int *args ) {
	int		programCounter;
	int		programStack;
	int		stackOnEntry;
	byte	*image;
	void	*entryPoint;
	void	*opStack;
	int stack[1024] = { 0xDEADBEEF };

	currentVM = vm;

	++vm->callLevel;
//	Com_Printf("entering %s level %d, call %d, arg1 = 0x%x\n", vm->name, vm->callLevel, args[0], args[1]);

	// interpret the code
	vm->currentlyInterpreting = qtrue;

//	callMask = vm->dataMask;

	// we might be called recursively, so this might not be the very top
	programStack = vm->programStack;
	stackOnEntry = programStack;

	// set up the stack frame 
	image = vm->dataBase;
#ifdef DEBUG_VM
	memData = (char*)image;
#endif

	programCounter = 0;

	programStack -= 48;

	*(int *)&image[ programStack + 44] = args[9];
	*(int *)&image[ programStack + 40] = args[8];
	*(int *)&image[ programStack + 36] = args[7];
	*(int *)&image[ programStack + 32] = args[6];
	*(int *)&image[ programStack + 28] = args[5];
	*(int *)&image[ programStack + 24] = args[4];
	*(int *)&image[ programStack + 20] = args[3];
	*(int *)&image[ programStack + 16] = args[2];
	*(int *)&image[ programStack + 12] = args[1];
	*(int *)&image[ programStack + 8 ] = args[0];
	*(int *)&image[ programStack + 4 ] = 0x77777777;	// return stack
	*(int *)&image[ programStack ] = -1;	// will terminate the loop on return

	// off we go into generated code...
	entryPoint = getentrypoint(vm);
	opStack = &stack;

	__asm__ __volatile__ (
		"	movq %5,%%rsi		\r\n" \
		"	movl %4,%%edi		\r\n" \
		"	movq $done,%%r9		\r\n" \
		"	movq %2,%%r10		\r\n" \
		"	movq %3,%%r8		\r\n" \
		"	jmp *%%r10		\r\n" \
		"done:				\r\n" \
		"	movl %%edi, %0		\r\n" \
		"	movq %%rsi, %1		\r\n" \
		: "=m" (programStack), "=m" (opStack)
		: "m" (entryPoint), "m" (vm->dataBase), "m" (programStack), "m" (opStack)
		: "%rsi", "%rdi", "%rax", "%rbx", "%rcx", "%rdx", "%r8", "%r9", "%r10", "%r15", "%xmm0"
	);

	if ( opStack != &stack[1] ) {
		Com_Error( ERR_DROP, "opStack corrupted in compiled code (offset %d)\n", (void*)&stack[1] - opStack);
	}
	if ( programStack != stackOnEntry - 48 ) {
		Com_Error( ERR_DROP, "programStack corrupted in compiled code\n" );
	}

//	Com_Printf("exiting %s level %d\n", vm->name, vm->callLevel);
	--vm->callLevel;
	vm->programStack = stackOnEntry;

	return *(int *)opStack;
}