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tinycc/i386-gen.c

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/*
* X86 code generator for TCC
*
* Copyright (c) 2001 Fabrice Bellard
*
* This program 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.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/* number of available registers */
#define NB_REGS 4
#define NB_REG_CLASSES 2
/* a register can belong to several classes */
#define REG_CLASS_INT 0x0001
#define REG_CLASS_FLOAT 0x0002
/* pretty names for the registers */
enum {
REG_EAX = 0,
REG_ECX,
REG_EDX,
REG_ST0,
};
int reg_classes[NB_REGS] = {
REG_CLASS_INT, /* eax */
REG_CLASS_INT, /* ecx */
REG_CLASS_INT, /* edx */
REG_CLASS_FLOAT, /* st0 */
};
/* integer return register for functions */
#define FUNC_RET_REG 0
/* float return register for functions */
#define FUNC_RET_FREG 3
/* defined if function parameters must be evaluated in reverse order */
#define INVERT_FUNC_PARAMS
/* defined if structures are passed as pointers. Otherwise structures
are directly pushed on stack. */
//#define FUNC_STRUCT_PARAM_AS_PTR
/* pointer size, in bytes */
#define PTR_SIZE 4
/* long double size and alignment, in bytes */
#define LDOUBLE_SIZE 12
#define LDOUBLE_ALIGN 4
/* function call context */
typedef struct GFuncContext {
int args_size;
} GFuncContext;
/******************************************************/
void g(int c)
{
*(char *)ind++ = c;
}
void o(int c)
{
while (c) {
g(c);
c = c / 256;
}
}
void gen_le32(int c)
{
g(c);
g(c >> 8);
g(c >> 16);
g(c >> 24);
}
/* add a new relocation entry to symbol 's' */
void greloc(Sym *s, int addr, int type)
{
Reloc *p;
p = malloc(sizeof(Reloc));
if (!p)
error("memory full");
p->type = type;
p->addr = addr;
p->next = (Reloc *)s->c;
s->c = (int)p;
}
/* patch each relocation entry with value 'val' */
void greloc_patch(Sym *s, int val)
{
Reloc *p, *p1;
p = (Reloc *)s->c;
while (p != NULL) {
p1 = p->next;
switch(p->type) {
case RELOC_ADDR32:
*(int *)p->addr = val;
break;
case RELOC_REL32:
*(int *)p->addr = val - p->addr - 4;
break;
}
free(p);
p = p1;
}
s->c = val;
s->t &= ~VT_FORWARD;
}
/* output a symbol and patch all calls to it */
void gsym_addr(t, a)
{
int n;
while (t) {
n = *(int *)t; /* next value */
*(int *)t = a - t - 4;
t = n;
}
}
void gsym(t)
{
gsym_addr(t, ind);
}
/* psym is used to put an instruction with a data field which is a
reference to a symbol. It is in fact the same as oad ! */
#define psym oad
/* instruction + 4 bytes data. Return the address of the data */
int oad(int c, int s)
{
o(c);
*(int *)ind = s;
s = ind;
ind = ind + 4;
return s;
}
/* output constant with relocation if 't & VT_FORWARD' is true */
void gen_addr32(int c, int t)
{
if (!(t & VT_FORWARD)) {
gen_le32(c);
} else {
greloc((Sym *)c, ind, RELOC_ADDR32);
gen_le32(0);
}
}
/* XXX: generate correct pointer for forward references to functions */
/* r = (ft, fc) */
void load(int r, int ft, int fc)
{
int v, t;
v = ft & VT_VALMASK;
if (ft & VT_LVAL) {
if (v == VT_LLOCAL) {
load(r, VT_LOCAL | VT_LVAL, fc);
v = r;
}
if ((ft & VT_BTYPE) == VT_FLOAT) {
o(0xd9); /* flds */
r = 0;
} else if ((ft & VT_BTYPE) == VT_DOUBLE) {
o(0xdd); /* fldl */
r = 0;
} else if ((ft & VT_BTYPE) == VT_LDOUBLE) {
o(0xdb); /* fldt */
r = 5;
} else if ((ft & VT_TYPE) == VT_BYTE)
o(0xbe0f); /* movsbl */
else if ((ft & VT_TYPE) == (VT_BYTE | VT_UNSIGNED))
o(0xb60f); /* movzbl */
else if ((ft & VT_TYPE) == VT_SHORT)
o(0xbf0f); /* movswl */
else if ((ft & VT_TYPE) == (VT_SHORT | VT_UNSIGNED))
o(0xb70f); /* movzwl */
else
o(0x8b); /* movl */
if (v == VT_CONST) {
o(0x05 + r * 8); /* 0xXX, r */
gen_addr32(fc, ft);
} else if (v == VT_LOCAL) {
oad(0x85 + r * 8, fc); /* xx(%ebp), r */
} else {
g(0x00 + r * 8 + v); /* (v), r */
}
} else {
if (v == VT_CONST) {
o(0xb8 + r); /* mov $xx, r */
gen_addr32(fc, ft);
} else if (v == VT_LOCAL) {
o(0x8d);
oad(0x85 + r * 8, fc); /* lea xxx(%ebp), r */
} else if (v == VT_CMP) {
oad(0xb8 + r, 0); /* mov $0, r */
o(0x0f); /* setxx %br */
o(fc);
o(0xc0 + r);
} else if (v == VT_JMP || v == VT_JMPI) {
t = v & 1;
oad(0xb8 + r, t); /* mov $1, r */
oad(0xe9, 5); /* jmp after */
gsym(fc);
oad(0xb8 + r, t ^ 1); /* mov $0, r */
} else if (v != r) {
o(0x89);
o(0xc0 + r + v * 8); /* mov v, r */
}
}
}
/* (ft, fc) = r */
/* WARNING: r must not be allocated on the stack */
void store(r, ft, fc)
{
int fr, bt;
fr = ft & VT_VALMASK;
bt = ft & VT_BTYPE;
/* XXX: incorrect if reg to reg */
/* XXX: should not flush float stack */
if (bt == VT_FLOAT) {
o(0xd9); /* fstps */
r = 3;
} else if (bt == VT_DOUBLE) {
o(0xdd); /* fstpl */
r = 3;
} else if (bt == VT_LDOUBLE) {
o(0xdb); /* fstpt */
r = 7;
} else {
if (bt == VT_SHORT)
o(0x66);
if (bt == VT_BYTE)
o(0x88);
else
o(0x89);
}
if (fr == VT_CONST) {
o(0x05 + r * 8); /* mov r,xxx */
gen_addr32(fc, ft);
} else if (fr == VT_LOCAL) {
oad(0x85 + r * 8, fc); /* mov r,xxx(%ebp) */
} else if (ft & VT_LVAL) {
g(fr + r * 8); /* mov r, (fr) */
} else if (fr != r) {
o(0xc0 + fr + r * 8); /* mov r, fr */
}
}
/* start function call and return function call context */
void gfunc_start(GFuncContext *c)
{
c->args_size = 0;
}
/* push function parameter which is in (vtop->t, vtop->c). Stack entry
is then popped. */
void gfunc_param(GFuncContext *c)
{
int size, align, r;
if ((vtop->t & (VT_BTYPE | VT_LVAL)) == (VT_STRUCT | VT_LVAL)) {
size = type_size(vtop->t, &align);
/* align to stack align size */
size = (size + 3) & ~3;
/* allocate the necessary size on stack */
oad(0xec81, size); /* sub $xxx, %esp */
/* generate structure store */
r = get_reg(REG_CLASS_INT);
o(0x89); /* mov %esp, r */
o(0xe0 + r);
vset(VT_INT | r, 0);
vswap();
vstore();
c->args_size += size;
} else if ((vtop->t & VT_BTYPE) == VT_LDOUBLE ||
(vtop->t & VT_BTYPE) == VT_DOUBLE ||
(vtop->t & VT_BTYPE) == VT_FLOAT) {
gv(); /* only one float register */
if ((vtop->t & VT_BTYPE) == VT_FLOAT)
size = 4;
else if ((vtop->t & VT_BTYPE) == VT_DOUBLE)
size = 8;
else
size = 12;
oad(0xec81, size); /* sub $xxx, %esp */
if (size == 12)
o(0x7cdb);
else
o(0x5cd9 + size - 4); /* fstp[s|l] 0(%esp) */
g(0x24);
g(0x00);
c->args_size += size;
} else {
/* simple type (currently always same size) */
/* XXX: implicit cast ? */
r = gv();
o(0x50 + r); /* push r */
c->args_size += 4;
}
vtop--;
}
/* generate function call with address in (vtop->t, vtop->c) and free function
context. Stack entry is popped */
void gfunc_call(GFuncContext *c)
{
int r;
if ((vtop->t & (VT_VALMASK | VT_LVAL)) == VT_CONST) {
/* constant case */
/* forward reference */
if (vtop->t & VT_FORWARD) {
greloc((Sym *)vtop->c, ind + 1, RELOC_REL32);
oad(0xe8, 0);
} else {
oad(0xe8, vtop->c - ind - 5);
}
} else {
/* otherwise, indirect call */
r = gv();
o(0xff); /* call *r */
o(0xd0 + r);
}
if (c->args_size)
oad(0xc481, c->args_size); /* add $xxx, %esp */
vtop--;
}
int gjmp(int t)
{
return psym(0xe9, t);
}
/* generate a test. set 'inv' to invert test. Stack entry is popped */
int gtst(int inv, int t)
{
int v, *p;
v = vtop->t & VT_VALMASK;
if (v == VT_CMP) {
/* fast case : can jump directly since flags are set */
g(0x0f);
t = psym((vtop->c - 16) ^ inv, t);
} else if (v == VT_JMP || v == VT_JMPI) {
/* && or || optimization */
if ((v & 1) == inv) {
/* insert vtop->c jump list in t */
p = &vtop->c;
while (*p != 0)
p = (int *)*p;
*p = t;
t = vtop->c;
} else {
t = gjmp(t);
gsym(vtop->c);
}
} else if ((vtop->t & (VT_VALMASK | VT_LVAL)) == VT_CONST) {
/* constant jmp optimization */
if ((vtop->c != 0) != inv)
t = gjmp(t);
} else {
/* XXX: floats */
v = gv();
o(0x85);
o(0xc0 + v * 9);
g(0x0f);
t = psym(0x85 ^ inv, t);
}
vtop--;
return t;
}
/* generate an integer binary operation */
void gen_opi(int op)
{
int t, r, fr;
vswap();
r = gv();
vswap();
fr = gv();
vtop--;
if (op == '+') {
o(0x01);
o(0xc0 + r + fr * 8);
} else if (op == '-') {
o(0x29);
o(0xc0 + r + fr * 8);
} else if (op == '&') {
o(0x21);
o(0xc0 + r + fr * 8);
} else if (op == '^') {
o(0x31);
o(0xc0 + r + fr * 8);
} else if (op == '|') {
o(0x09);
o(0xc0 + r + fr * 8);
} else if (op == '*') {
o(0xaf0f); /* imul fr, r */
o(0xc0 + fr + r * 8);
} else if (op == TOK_SHL | op == TOK_SHR | op == TOK_SAR) {
/* op2 is %ecx */
if (fr != 1) {
if (r == 1) {
r = fr;
fr = 1;
o(0x87); /* xchg r, %ecx */
o(0xc1 + r * 8);
} else
move_reg(1, fr);
}
o(0xd3); /* shl/shr/sar %cl, r */
if (op == TOK_SHL)
o(0xe0 + r);
else if (op == TOK_SHR)
o(0xe8 + r);
else
o(0xf8 + r);
vtop->t = (vtop->t & VT_TYPE) | r;
} else if (op == '/' | op == TOK_UDIV | op == TOK_PDIV |
op == '%' | op == TOK_UMOD) {
save_reg(2); /* save edx */
t = save_reg_forced(fr); /* save fr and get op2 location */
move_reg(0, r); /* op1 is %eax */
if (op == TOK_UDIV | op == TOK_UMOD) {
o(0xf7d231); /* xor %edx, %edx, div t(%ebp), %eax */
oad(0xb5, t);
} else {
o(0xf799); /* cltd, idiv t(%ebp), %eax */
oad(0xbd, t);
}
if (op == '%' | op == TOK_UMOD)
r = 2;
else
r = 0;
vtop->t = (vtop->t & VT_TYPE) | r;
} else {
vtop--;
o(0x39);
o(0xc0 + r + fr * 8); /* cmp fr, r */
vset(VT_CMP, op);
}
}
/* generate a floating point operation 'v = t1 op t2' instruction. The
two operands are guaranted to have the same floating point type */
/* NOTE: currently floats can only be lvalues */
void gen_opf(int op)
{
int a, ft, fc, swapped, r;
/* must put at least one value in the floating point register */
if ((vtop[-1].t & VT_LVAL) &&
(vtop[0].t & VT_LVAL)) {
vswap();
gv();
vswap();
}
if (op >= TOK_EQ && op <= TOK_GT) {
/* load on stack second operand */
load(REG_ST0, vtop->t, vtop->c);
if (op == TOK_GE || op == TOK_GT)
o(0xc9d9); /* fxch %st(1) */
o(0xe9da); /* fucompp */
o(0xe0df); /* fnstsw %ax */
if (op == TOK_EQ) {
o(0x45e480); /* and $0x45, %ah */
o(0x40fC80); /* cmp $0x40, %ah */
} else if (op == TOK_NE) {
o(0x45e480); /* and $0x45, %ah */
o(0x40f480); /* xor $0x40, %ah */
op = TOK_NE;
} else if (op == TOK_GE || op == TOK_LE) {
o(0x05c4f6); /* test $0x05, %ah */
op = TOK_EQ;
} else {
o(0x45c4f6); /* test $0x45, %ah */
op = TOK_EQ;
}
vtop--;
vtop->t = (vtop->t & VT_TYPE) | VT_CMP;
vtop->c = op;
} else {
/* swap the stack if needed so that t1 is the register and t2 is
the memory reference */
swapped = 0;
if (vtop[-1].t & VT_LVAL) {
vswap();
swapped = 1;
}
switch(op) {
default:
case '+':
a = 0;
break;
case '-':
a = 0x20;
if (swapped)
a += 8;
break;
case '*':
a = 0x08;
break;
case '/':
a = 0x30;
if (swapped)
a += 8;
break;
}
ft = vtop->t;
fc = vtop->c;
if ((ft & VT_BTYPE) == VT_DOUBLE)
o(0xdc);
else
o(0xd8);
r = ft & VT_VALMASK;
if (r == VT_CONST) {
o(0x05 + a);
gen_addr32(fc, ft);
} else if (r == VT_LOCAL) {
oad(0x85 + a, fc);
} else {
g(0x00 + a + r);
}
vtop--;
}
}
/* convert integers to floating point 't' type (float/double/long
double) */
void gen_cvtf(int t)
{
if ((vtop->t & (VT_BTYPE | VT_UNSIGNED)) == (VT_INT | VT_UNSIGNED)) {
/* unsigned int to float/double/long double */
o(0x6a); /* push $0 */
g(0x00);
o(0x50 + (vtop->t & VT_VALMASK)); /* push r */
o(0x242cdf); /* fildll (%esp) */
o(0x08c483); /* add $8, %esp */
} else {
/* int to float/double/long double */
o(0x50 + (vtop->t & VT_VALMASK)); /* push r */
o(0x2404db); /* fildl (%esp) */
o(0x04c483); /* add $4, %esp */
}
}
/* end of X86 code generator */
/*************************************************************/
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