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tinycc/i386-asm.c
bellard 68c800981e added % constraint
2003-04-27 11:46:10 +00:00

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/*
* i386 specific functions for TCC assembler
*
* Copyright (c) 2001, 2002 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.
*/
#define MAX_OPERANDS 3
typedef struct ASMInstr {
uint16_t sym;
uint16_t opcode;
uint16_t instr_type;
#define OPC_JMP 0x01 /* jmp operand */
#define OPC_B 0x02 /* only used zith OPC_WL */
#define OPC_WL 0x04 /* accepts w, l or no suffix */
#define OPC_BWL (OPC_B | OPC_WL) /* accepts b, w, l or no suffix */
#define OPC_REG 0x08 /* register is added to opcode */
#define OPC_MODRM 0x10 /* modrm encoding */
#define OPC_FWAIT 0x20 /* add fwait opcode */
#define OPC_TEST 0x40 /* test opcodes */
#define OPC_SHIFT 0x80 /* shift opcodes */
#define OPC_D16 0x0100 /* generate data16 prefix */
#define OPC_ARITH 0x0200 /* arithmetic opcodes */
#define OPC_SHORTJMP 0x0400 /* short jmp operand */
#define OPC_FARITH 0x0800 /* FPU arithmetic opcodes */
#define OPC_GROUP_SHIFT 13
/* in order to compress the operand type, we use specific operands and
we or only with EA */
#define OPT_REG8 0 /* warning: value is hardcoded from TOK_ASM_xxx */
#define OPT_REG16 1 /* warning: value is hardcoded from TOK_ASM_xxx */
#define OPT_REG32 2 /* warning: value is hardcoded from TOK_ASM_xxx */
#define OPT_MMX 3 /* warning: value is hardcoded from TOK_ASM_xxx */
#define OPT_SSE 4 /* warning: value is hardcoded from TOK_ASM_xxx */
#define OPT_CR 5 /* warning: value is hardcoded from TOK_ASM_xxx */
#define OPT_TR 6 /* warning: value is hardcoded from TOK_ASM_xxx */
#define OPT_DB 7 /* warning: value is hardcoded from TOK_ASM_xxx */
#define OPT_SEG 8
#define OPT_ST 9
#define OPT_IM8 10
#define OPT_IM8S 11
#define OPT_IM16 12
#define OPT_IM32 13
#define OPT_EAX 14 /* %al, %ax or %eax register */
#define OPT_ST0 15 /* %st(0) register */
#define OPT_CL 16 /* %cl register */
#define OPT_DX 17 /* %dx register */
#define OPT_ADDR 18 /* OP_EA with only offset */
#define OPT_INDIR 19 /* *(expr) */
/* composite types */
#define OPT_COMPOSITE_FIRST 20
#define OPT_IM 20 /* IM8 | IM16 | IM32 */
#define OPT_REG 21 /* REG8 | REG16 | REG32 */
#define OPT_REGW 22 /* REG16 | REG32 */
#define OPT_IMW 23 /* IM16 | IM32 */
/* can be ored with any OPT_xxx */
#define OPT_EA 0x80
uint8_t nb_ops;
uint8_t op_type[MAX_OPERANDS]; /* see OP_xxx */
} ASMInstr;
typedef struct Operand {
uint32_t type;
#define OP_REG8 (1 << OPT_REG8)
#define OP_REG16 (1 << OPT_REG16)
#define OP_REG32 (1 << OPT_REG32)
#define OP_MMX (1 << OPT_MMX)
#define OP_SSE (1 << OPT_SSE)
#define OP_CR (1 << OPT_CR)
#define OP_TR (1 << OPT_TR)
#define OP_DB (1 << OPT_DB)
#define OP_SEG (1 << OPT_SEG)
#define OP_ST (1 << OPT_ST)
#define OP_IM8 (1 << OPT_IM8)
#define OP_IM8S (1 << OPT_IM8S)
#define OP_IM16 (1 << OPT_IM16)
#define OP_IM32 (1 << OPT_IM32)
#define OP_EAX (1 << OPT_EAX)
#define OP_ST0 (1 << OPT_ST0)
#define OP_CL (1 << OPT_CL)
#define OP_DX (1 << OPT_DX)
#define OP_ADDR (1 << OPT_ADDR)
#define OP_INDIR (1 << OPT_INDIR)
#define OP_EA 0x40000000
#define OP_REG (OP_REG8 | OP_REG16 | OP_REG32)
#define OP_IM OP_IM32
int8_t reg; /* register, -1 if none */
int8_t reg2; /* second register, -1 if none */
uint8_t shift;
ExprValue e;
} Operand;
static const uint8_t reg_to_size[5] = {
[OP_REG8] = 0,
[OP_REG16] = 1,
[OP_REG32] = 2,
};
#define WORD_PREFIX_OPCODE 0x66
#define NB_TEST_OPCODES 30
static const uint8_t test_bits[NB_TEST_OPCODES] = {
0x00, /* o */
0x01, /* no */
0x02, /* b */
0x02, /* c */
0x02, /* nae */
0x03, /* nb */
0x03, /* nc */
0x03, /* ae */
0x04, /* e */
0x04, /* z */
0x05, /* ne */
0x05, /* nz */
0x06, /* be */
0x06, /* na */
0x07, /* nbe */
0x07, /* a */
0x08, /* s */
0x09, /* ns */
0x0a, /* p */
0x0a, /* pe */
0x0b, /* np */
0x0b, /* po */
0x0c, /* l */
0x0c, /* nge */
0x0d, /* nl */
0x0d, /* ge */
0x0e, /* le */
0x0e, /* ng */
0x0f, /* nle */
0x0f, /* g */
};
static const ASMInstr asm_instrs[] = {
#define ALT(x) x
#define DEF_ASM_OP0(name, opcode)
#define DEF_ASM_OP0L(name, opcode, group, instr_type) { TOK_ASM_ ## name, opcode, (instr_type | group << OPC_GROUP_SHIFT), 0 },
#define DEF_ASM_OP1(name, opcode, group, instr_type, op0) { TOK_ASM_ ## name, opcode, (instr_type | group << OPC_GROUP_SHIFT), 1, { op0 }},
#define DEF_ASM_OP2(name, opcode, group, instr_type, op0, op1) { TOK_ASM_ ## name, opcode, (instr_type | group << OPC_GROUP_SHIFT), 2, { op0, op1 }},
#define DEF_ASM_OP3(name, opcode, group, instr_type, op0, op1, op2) { TOK_ASM_ ## name, opcode, (instr_type | group << OPC_GROUP_SHIFT), 3, { op0, op1, op2 }},
#include "i386-asm.h"
/* last operation */
{ 0, },
};
static const uint16_t op0_codes[] = {
#define ALT(x)
#define DEF_ASM_OP0(x, opcode) opcode,
#define DEF_ASM_OP0L(name, opcode, group, instr_type)
#define DEF_ASM_OP1(name, opcode, group, instr_type, op0)
#define DEF_ASM_OP2(name, opcode, group, instr_type, op0, op1)
#define DEF_ASM_OP3(name, opcode, group, instr_type, op0, op1, op2)
#include "i386-asm.h"
};
static inline int get_reg_shift(TCCState *s1)
{
int shift, v;
v = asm_int_expr(s1);
switch(v) {
case 1:
shift = 0;
break;
case 2:
shift = 1;
break;
case 4:
shift = 2;
break;
case 8:
shift = 3;
break;
default:
expect("1, 2, 4 or 8 constant");
shift = 0;
break;
}
return shift;
}
static int asm_parse_reg(void)
{
int reg;
if (tok != '%')
goto error_32;
next();
if (tok >= TOK_ASM_eax && tok <= TOK_ASM_edi) {
reg = tok - TOK_ASM_eax;
next();
return reg;
} else {
error_32:
expect("32 bit register");
return 0;
}
}
static void parse_operand(TCCState *s1, Operand *op)
{
ExprValue e;
int reg, indir;
const char *p;
indir = 0;
if (tok == '*') {
next();
indir = OP_INDIR;
}
if (tok == '%') {
next();
if (tok >= TOK_ASM_al && tok <= TOK_ASM_db7) {
reg = tok - TOK_ASM_al;
op->type = 1 << (reg >> 3); /* WARNING: do not change constant order */
op->reg = reg & 7;
if ((op->type & OP_REG) && op->reg == TREG_EAX)
op->type |= OP_EAX;
else if (op->type == OP_REG8 && op->reg == TREG_ECX)
op->type |= OP_CL;
else if (op->type == OP_REG16 && op->reg == TREG_EDX)
op->type |= OP_DX;
} else if (tok >= TOK_ASM_dr0 && tok <= TOK_ASM_dr7) {
op->type = OP_DB;
op->reg = tok - TOK_ASM_dr0;
} else if (tok >= TOK_ASM_es && tok <= TOK_ASM_gs) {
op->type = OP_SEG;
op->reg = tok - TOK_ASM_es;
} else if (tok == TOK_ASM_st) {
op->type = OP_ST;
op->reg = 0;
next();
if (tok == '(') {
next();
if (tok != TOK_PPNUM)
goto reg_error;
p = tokc.cstr->data;
reg = p[0] - '0';
if ((unsigned)reg >= 8 || p[1] != '\0')
goto reg_error;
op->reg = reg;
next();
skip(')');
}
if (op->reg == 0)
op->type |= OP_ST0;
goto no_skip;
} else {
reg_error:
error("unknown register");
}
next();
no_skip: ;
} else if (tok == '$') {
/* constant value */
next();
asm_expr(s1, &e);
op->type = OP_IM32;
op->e.v = e.v;
op->e.sym = e.sym;
if (!op->e.sym) {
if (op->e.v == (uint8_t)op->e.v)
op->type |= OP_IM8;
if (op->e.v == (int8_t)op->e.v)
op->type |= OP_IM8S;
if (op->e.v == (uint16_t)op->e.v)
op->type |= OP_IM16;
}
} else {
/* address(reg,reg2,shift) with all variants */
op->type = OP_EA;
op->reg = -1;
op->reg2 = -1;
op->shift = 0;
if (tok != '(') {
asm_expr(s1, &e);
op->e.v = e.v;
op->e.sym = e.sym;
} else {
op->e.v = 0;
op->e.sym = NULL;
}
if (tok == '(') {
next();
if (tok != ',') {
op->reg = asm_parse_reg();
}
if (tok == ',') {
next();
if (tok != ',') {
op->reg2 = asm_parse_reg();
}
skip(',');
op->shift = get_reg_shift(s1);
}
skip(')');
}
if (op->reg == -1 && op->reg2 == -1)
op->type |= OP_ADDR;
}
op->type |= indir;
}
/* XXX: unify with C code output ? */
static void gen_expr32(ExprValue *pe)
{
if (pe->sym)
greloc(cur_text_section, pe->sym, ind, R_386_32);
gen_le32(pe->v);
}
/* XXX: unify with C code output ? */
static void gen_disp32(ExprValue *pe)
{
Sym *sym;
sym = pe->sym;
if (sym) {
if (sym->r == cur_text_section->sh_num) {
/* same section: we can output an absolute value. Note
that the TCC compiler behaves differently here because
it always outputs a relocation to ease (future) code
elimination in the linker */
gen_le32(pe->v + (long)sym->next - ind - 4);
} else {
greloc(cur_text_section, sym, ind, R_386_PC32);
gen_le32(pe->v - 4);
}
} else {
/* put an empty PC32 relocation */
put_elf_reloc(symtab_section, cur_text_section,
ind, R_386_PC32, 0);
gen_le32(pe->v - 4);
}
}
static void gen_le16(int v)
{
g(v);
g(v >> 8);
}
/* generate the modrm operand */
static inline void asm_modrm(int reg, Operand *op)
{
int mod, reg1, reg2;
if (op->type & (OP_REG | OP_MMX | OP_SSE)) {
g(0xc0 + (reg << 3) + op->reg);
} else if (op->reg == -1 && op->reg2 == -1) {
/* displacement only */
g(0x05 + (reg << 3));
gen_expr32(&op->e);
} else {
/* fist compute displacement encoding */
if (op->e.v == 0 && !op->e.sym && op->reg != 5) {
mod = 0x00;
} else if (op->e.v == (int8_t)op->e.v && !op->e.sym) {
mod = 0x40;
} else {
mod = 0x80;
}
/* compute if sib byte needed */
reg1 = op->reg;
if (op->reg2 != -1)
reg1 = 4;
g(mod + (reg << 3) + reg1);
if (reg1 == 4) {
/* add sib byte */
reg2 = op->reg2;
if (reg2 == -1)
reg2 = 4; /* indicate no index */
g((op->shift << 6) + (reg2 << 3) + op->reg);
}
/* add offset */
if (mod == 0x40) {
g(op->e.v);
} else if (mod == 0x80) {
gen_expr32(&op->e);
}
}
}
static void asm_opcode(TCCState *s1, int opcode)
{
const ASMInstr *pa;
int i, modrm_index, reg, v, op1, is_short_jmp;
int nb_ops, s, ss;
Operand ops[MAX_OPERANDS], *pop;
int op_type[3]; /* decoded op type */
/* get operands */
pop = ops;
nb_ops = 0;
for(;;) {
if (tok == ';' || tok == TOK_LINEFEED)
break;
if (nb_ops >= MAX_OPERANDS) {
error("incorrect number of operands");
}
parse_operand(s1, pop);
pop++;
nb_ops++;
if (tok != ',')
break;
next();
}
is_short_jmp = 0;
s = 0; /* avoid warning */
/* optimize matching by using a lookup table (no hashing is needed
!) */
for(pa = asm_instrs; pa->sym != 0; pa++) {
s = 0;
if (pa->instr_type & OPC_FARITH) {
v = opcode - pa->sym;
if (!((unsigned)v < 8 * 6 && (v % 6) == 0))
continue;
} else if (pa->instr_type & OPC_ARITH) {
if (!(opcode >= pa->sym && opcode < pa->sym + 8 * 4))
continue;
goto compute_size;
} else if (pa->instr_type & OPC_SHIFT) {
if (!(opcode >= pa->sym && opcode < pa->sym + 7 * 4))
continue;
goto compute_size;
} else if (pa->instr_type & OPC_TEST) {
if (!(opcode >= pa->sym && opcode < pa->sym + NB_TEST_OPCODES))
continue;
} else if (pa->instr_type & OPC_B) {
if (!(opcode >= pa->sym && opcode <= pa->sym + 3))
continue;
compute_size:
s = (opcode - pa->sym) & 3;
} else if (pa->instr_type & OPC_WL) {
if (!(opcode >= pa->sym && opcode <= pa->sym + 2))
continue;
s = opcode - pa->sym + 1;
} else {
if (pa->sym != opcode)
continue;
}
if (pa->nb_ops != nb_ops)
continue;
/* now decode and check each operand */
for(i = 0; i < nb_ops; i++) {
int op1, op2;
op1 = pa->op_type[i];
op2 = op1 & 0x1f;
switch(op2) {
case OPT_IM:
v = OP_IM8 | OP_IM16 | OP_IM32;
break;
case OPT_REG:
v = OP_REG8 | OP_REG16 | OP_REG32;
break;
case OPT_REGW:
v = OP_REG16 | OP_REG32;
break;
case OPT_IMW:
v = OP_IM16 | OP_IM32;
break;
default:
v = 1 << op2;
break;
}
if (op1 & OPT_EA)
v |= OP_EA;
op_type[i] = v;
if ((ops[i].type & v) == 0)
goto next;
}
/* all is matching ! */
break;
next: ;
}
if (pa->sym == 0) {
if (opcode >= TOK_ASM_pusha && opcode <= TOK_ASM_emms) {
int b;
b = op0_codes[opcode - TOK_ASM_pusha];
if (b & 0xff00)
g(b >> 8);
g(b);
return;
} else {
error("unknown opcode '%s'",
get_tok_str(opcode, NULL));
}
}
/* if the size is unknown, then evaluate it (OPC_B or OPC_WL case) */
if (s == 3) {
for(i = 0; s == 3 && i < nb_ops; i++) {
if ((ops[i].type & OP_REG) && !(op_type[i] & (OP_CL | OP_DX)))
s = reg_to_size[ops[i].type & OP_REG];
}
if (s == 3) {
error("cannot infer opcode suffix");
}
}
/* generate data16 prefix if needed */
ss = s;
if (s == 1 || (pa->instr_type & OPC_D16))
g(WORD_PREFIX_OPCODE);
else if (s == 2)
s = 1;
/* now generates the operation */
if (pa->instr_type & OPC_FWAIT)
g(0x9b);
v = pa->opcode;
if (v == 0x69 || v == 0x69) {
/* kludge for imul $im, %reg */
nb_ops = 3;
ops[2] = ops[1];
} else if (v == 0xcd && ops[0].e.v == 3 && !ops[0].e.sym) {
v--; /* int $3 case */
nb_ops = 0;
} else if ((v == 0x06 || v == 0x07)) {
if (ops[0].reg >= 4) {
/* push/pop %fs or %gs */
v = 0x0fa0 + (v - 0x06) + ((ops[0].reg - 4) << 3);
} else {
v += ops[0].reg << 3;
}
nb_ops = 0;
} else if (v <= 0x05) {
/* arith case */
v += ((opcode - TOK_ASM_addb) >> 2) << 3;
} else if ((pa->instr_type & (OPC_FARITH | OPC_MODRM)) == OPC_FARITH) {
/* fpu arith case */
v += ((opcode - pa->sym) / 6) << 3;
}
if (pa->instr_type & OPC_REG) {
for(i = 0; i < nb_ops; i++) {
if (op_type[i] & (OP_REG | OP_ST)) {
v += ops[i].reg;
break;
}
}
/* mov $im, %reg case */
if (pa->opcode == 0xb0 && s >= 1)
v += 7;
}
if (pa->instr_type & OPC_B)
v += s;
if (pa->instr_type & OPC_TEST)
v += test_bits[opcode - pa->sym];
if (pa->instr_type & OPC_SHORTJMP) {
Sym *sym;
int jmp_disp;
/* see if we can really generate the jump with a byte offset */
sym = ops[0].e.sym;
if (!sym)
goto no_short_jump;
if (sym->r != cur_text_section->sh_num)
goto no_short_jump;
jmp_disp = ops[0].e.v + (long)sym->next - ind - 2;
if (jmp_disp == (int8_t)jmp_disp) {
/* OK to generate jump */
is_short_jmp = 1;
ops[0].e.v = jmp_disp;
} else {
no_short_jump:
if (pa->instr_type & OPC_JMP) {
/* long jump will be allowed. need to modify the
opcode slightly */
if (v == 0xeb)
v = 0xe9;
else
v += 0x0f10;
} else {
error("invalid displacement");
}
}
}
op1 = v >> 8;
if (op1)
g(op1);
g(v);
/* search which operand will used for modrm */
modrm_index = 0;
if (pa->instr_type & OPC_SHIFT) {
reg = (opcode - pa->sym) >> 2;
if (reg == 6)
reg = 7;
} else if (pa->instr_type & OPC_ARITH) {
reg = (opcode - pa->sym) >> 2;
} else if (pa->instr_type & OPC_FARITH) {
reg = (opcode - pa->sym) / 6;
} else {
reg = (pa->instr_type >> OPC_GROUP_SHIFT) & 7;
}
if (pa->instr_type & OPC_MODRM) {
/* first look for an ea operand */
for(i = 0;i < nb_ops; i++) {
if (op_type[i] & OP_EA)
goto modrm_found;
}
/* then if not found, a register or indirection (shift instructions) */
for(i = 0;i < nb_ops; i++) {
if (op_type[i] & (OP_REG | OP_MMX | OP_SSE | OP_INDIR))
goto modrm_found;
}
#ifdef ASM_DEBUG
error("bad op table");
#endif
modrm_found:
modrm_index = i;
/* if a register is used in another operand then it is
used instead of group */
for(i = 0;i < nb_ops; i++) {
v = op_type[i];
if (i != modrm_index &&
(v & (OP_REG | OP_MMX | OP_SSE | OP_CR | OP_TR | OP_DB | OP_SEG))) {
reg = ops[i].reg;
break;
}
}
asm_modrm(reg, &ops[modrm_index]);
}
/* emit constants */
if (pa->opcode == 0x9a || pa->opcode == 0xea) {
/* ljmp or lcall kludge */
gen_expr32(&ops[1].e);
if (ops[0].e.sym)
error("cannot relocate");
gen_le16(ops[0].e.v);
} else {
for(i = 0;i < nb_ops; i++) {
v = op_type[i];
if (v & (OP_IM8 | OP_IM16 | OP_IM32 | OP_IM8S | OP_ADDR)) {
/* if multiple sizes are given it means we must look
at the op size */
if (v == (OP_IM8 | OP_IM16 | OP_IM32) ||
v == (OP_IM16 | OP_IM32)) {
if (ss == 0)
v = OP_IM8;
else if (ss == 1)
v = OP_IM16;
else
v = OP_IM32;
}
if (v & (OP_IM8 | OP_IM8S)) {
if (ops[i].e.sym)
goto error_relocate;
g(ops[i].e.v);
} else if (v & OP_IM16) {
if (ops[i].e.sym) {
error_relocate:
error("cannot relocate");
}
gen_le16(ops[i].e.v);
} else {
if (pa->instr_type & (OPC_JMP | OPC_SHORTJMP)) {
if (is_short_jmp)
g(ops[i].e.v);
else
gen_disp32(&ops[i].e);
} else {
gen_expr32(&ops[i].e);
}
}
}
}
}
}
#define NB_SAVED_REGS 3
#define NB_ASM_REGS 8
/* return the constraint priority (we allocate first the lowest
numbered constraints) */
static inline int constraint_priority(const char *str)
{
int priority, c, pr;
/* we take the lowest priority */
priority = 0;
for(;;) {
c = *str;
if (c == '\0')
break;
str++;
switch(c) {
case 'A':
pr = 0;
break;
case 'a':
case 'b':
case 'c':
case 'd':
case 'S':
case 'D':
pr = 1;
break;
case 'q':
pr = 2;
break;
case 'r':
pr = 3;
break;
case 'N':
case 'M':
case 'I':
case 'i':
case 'm':
case 'g':
pr = 4;
break;
default:
error("unknown constraint '%c'", c);
pr = 0;
}
if (pr > priority)
priority = pr;
}
return priority;
}
static const char *skip_constraint_modifiers(const char *p)
{
while (*p == '=' || *p == '&' || *p == '+' || *p == '%')
p++;
return p;
}
static void asm_compute_constraints(uint8_t *regs_allocated,
ASMOperand *operands,
int nb_operands1, int nb_outputs,
int is_output,
uint8_t *input_regs_allocated)
{
ASMOperand *op;
int sorted_op[MAX_ASM_OPERANDS];
int i, j, k, p1, p2, tmp, reg, c, base, nb_operands;
const char *str;
if (is_output) {
base = 0;
nb_operands = nb_outputs;
} else {
base = nb_outputs;
nb_operands = nb_operands1 - nb_outputs;
}
/* compute constraint priority and evaluate references to output
constraints if input constraints */
for(i=0;i<nb_operands;i++) {
j = base + i;
op = &operands[j];
str = op->constraint;
op->ref_index = -1;
op->reg = -1;
str = skip_constraint_modifiers(str);
if (!is_output && (isnum(*str) || *str == '[')) {
/* this is a reference to another constraint */
k = find_constraint(operands, nb_operands1, str, NULL);
if ((unsigned)k >= j)
error("invalid reference in constraint %d ('%s')",
j, str);
op->ref_index = k;
str = operands[k].constraint;
str = skip_constraint_modifiers(str);
}
op->priority = constraint_priority(str);
}
/* sort operands according to their priority */
for(i=0;i<nb_operands;i++)
sorted_op[i] = base + i;
for(i=0;i<nb_operands - 1;i++) {
for(j=i+1;j<nb_operands;j++) {
p1 = operands[sorted_op[i]].priority;
p2 = operands[sorted_op[j]].priority;
if (p2 < p1) {
tmp = sorted_op[i];
sorted_op[i] = sorted_op[j];
sorted_op[j] = tmp;
}
}
}
memset(regs_allocated, 0, NB_ASM_REGS);
regs_allocated[4] = 1; /* esp cannot be used */
regs_allocated[5] = 1; /* ebp cannot be used yet */
/* allocate registers and generate corresponding asm moves */
for(i=0;i<nb_operands;i++) {
j = sorted_op[i];
op = &operands[j];
str = op->constraint;
if (op->ref_index >= 0) {
str = operands[op->ref_index].constraint;
}
str = skip_constraint_modifiers(str);
try_next:
c = *str++;
switch(c) {
case 'A':
/* allocate both eax and edx */
if (regs_allocated[TREG_EAX] || regs_allocated[TREG_EDX])
goto try_next;
op->is_llong = 1;
op->reg = TREG_EAX;
regs_allocated[TREG_EAX] = 1;
regs_allocated[TREG_EDX] = 1;
break;
case 'a':
reg = TREG_EAX;
goto alloc_reg;
case 'b':
reg = 3;
goto alloc_reg;
case 'c':
reg = TREG_ECX;
goto alloc_reg;
case 'd':
reg = TREG_EDX;
goto alloc_reg;
case 'S':
reg = 6;
goto alloc_reg;
case 'D':
reg = 7;
alloc_reg:
if (regs_allocated[reg])
goto try_next;
goto reg_found;
case 'q':
/* eax, ebx, ecx or edx */
for(reg = 0; reg < 4; reg++) {
if (!regs_allocated[reg])
goto reg_found;
}
goto try_next;
case 'r':
/* any general register */
for(reg = 0; reg < 8; reg++) {
if (!regs_allocated[reg])
goto reg_found;
}
goto try_next;
reg_found:
/* now we can reload in the register */
op->is_llong = 0;
op->reg = reg;
regs_allocated[reg] = 1;
break;
case 'i':
if (!((op->vt->r & (VT_VALMASK | VT_LVAL)) == VT_CONST))
goto try_next;
break;
case 'I':
case 'N':
case 'M':
if (!((op->vt->r & (VT_VALMASK | VT_LVAL | VT_SYM)) == VT_CONST))
goto try_next;
break;
case 'm':
case 'g':
/* nothing special to do because the operand is
already in memory */
/* XXX: fix constant case */
if (is_output) {
/* if it is a reference to a memory zone, it must lie
in a register, so we reserve the register in the
input registers and a load will be generated
later */
if ((op->vt->r & VT_VALMASK) == VT_LLOCAL) {
/* any general register */
for(reg = 0; reg < 8; reg++) {
if (!input_regs_allocated[reg])
goto reg_found1;
}
goto try_next;
reg_found1:
/* now we can reload in the register */
input_regs_allocated[reg] = 1;
op->reg = reg;
}
}
break;
default:
error("asm constraint %d ('%s') could not be satisfied",
j, op->constraint);
break;
}
}
/* print sorted constraints */
#ifdef ASM_DEBUG
if (is_output)
printf("outputs=\n");
else
printf("inputs=\n");
for(i=0;i<nb_operands;i++) {
j = sorted_op[i];
op = &operands[j];
printf("%%%d [%s]: \"%s\" r=0x%04x reg=%d\n",
j,
op->id ? get_tok_str(op->id, NULL) : "",
op->constraint,
op->vt->r,
op->reg);
}
#endif
}
static void subst_asm_operand(CString *add_str,
SValue *sv, int modifier)
{
int r, reg, size, val;
char buf[64];
r = sv->r;
if ((r & VT_VALMASK) == VT_CONST) {
if (!(r & VT_LVAL) && modifier != 'c' && modifier != 'n')
cstr_ccat(add_str, '$');
if (r & VT_SYM) {
cstr_cat(add_str, get_tok_str(sv->sym->v, NULL));
if (sv->c.i != 0) {
cstr_ccat(add_str, '+');
} else {
return;
}
}
val = sv->c.i;
if (modifier == 'n')
val = -val;
snprintf(buf, sizeof(buf), "%d", sv->c.i);
cstr_cat(add_str, buf);
} else if ((r & VT_VALMASK) == VT_LOCAL) {
snprintf(buf, sizeof(buf), "%d(%%ebp)", sv->c.i);
cstr_cat(add_str, buf);
} else if (r & VT_LVAL) {
reg = r & VT_VALMASK;
if (reg >= VT_CONST)
error("internal compiler error");
snprintf(buf, sizeof(buf), "(%%%s)",
get_tok_str(TOK_ASM_eax + reg, NULL));
cstr_cat(add_str, buf);
} else {
/* register case */
reg = r & VT_VALMASK;
if (reg >= VT_CONST)
error("internal compiler error");
/* choose register operand size */
if ((sv->type.t & VT_BTYPE) == VT_BYTE)
size = 1;
else if ((sv->type.t & VT_BTYPE) == VT_SHORT)
size = 2;
else
size = 4;
if (size == 1 && reg >= 4)
size = 4;
if (modifier == 'b') {
if (reg >= 4)
error("cannot use byte register");
size = 1;
} else if (modifier == 'h') {
if (reg >= 4)
error("cannot use byte register");
size = -1;
} else if (modifier == 'w') {
size = 2;
}
switch(size) {
case -1:
reg = TOK_ASM_ah + reg;
break;
case 1:
reg = TOK_ASM_al + reg;
break;
case 2:
reg = TOK_ASM_ax + reg;
break;
default:
reg = TOK_ASM_eax + reg;
break;
}
snprintf(buf, sizeof(buf), "%%%s", get_tok_str(reg, NULL));
cstr_cat(add_str, buf);
}
}
/* generate prolog and epilog code for asm statment */
static void asm_gen_code(ASMOperand *operands, int nb_operands,
int nb_outputs, int is_output,
uint8_t *clobber_regs)
{
uint8_t regs_allocated[NB_ASM_REGS];
ASMOperand *op;
int i, reg;
static uint8_t reg_saved[NB_SAVED_REGS] = { 3, 6, 7 };
/* mark all used registers */
memcpy(regs_allocated, clobber_regs, sizeof(regs_allocated));
for(i = 0; i < nb_operands;i++) {
op = &operands[i];
if (op->reg >= 0)
regs_allocated[op->reg] = 1;
}
if (!is_output) {
/* generate reg save code */
for(i = 0; i < NB_SAVED_REGS; i++) {
reg = reg_saved[i];
if (regs_allocated[reg])
g(0x50 + reg);
}
/* generate load code */
for(i = nb_outputs ; i < nb_operands; i++) {
op = &operands[i];
if (op->reg >= 0) {
load(op->reg, op->vt);
if (op->is_llong) {
SValue sv;
sv = *op->vt;
sv.c.ul += 4;
load(TREG_EDX, &sv);
}
}
}
/* generate load code for output memory references */
for(i = 0 ; i < nb_outputs; i++) {
op = &operands[i];
if (op->reg >= 0 && ((op->vt->r & VT_VALMASK) == VT_LLOCAL)) {
SValue sv;
sv = *op->vt;
sv.r = (sv.r & ~VT_VALMASK) | VT_LOCAL;
load(op->reg, &sv);
}
}
} else {
/* generate save code */
for(i = 0 ; i < nb_outputs; i++) {
op = &operands[i];
if (op->reg >= 0 && ((op->vt->r & VT_VALMASK) != VT_LLOCAL)) {
store(op->reg, op->vt);
if (op->is_llong) {
SValue sv;
sv = *op->vt;
sv.c.ul += 4;
store(TREG_EDX, &sv);
}
}
}
/* generate reg restore code */
for(i = NB_SAVED_REGS - 1; i >= 0; i--) {
reg = reg_saved[i];
if (regs_allocated[reg])
g(0x58 + reg);
}
}
}
static void asm_clobber(uint8_t *clobber_regs, const char *str)
{
int reg;
TokenSym *ts;
if (!strcmp(str, "memory") ||
!strcmp(str, "cc"))
return;
ts = tok_alloc(str, strlen(str));
reg = ts->tok;
if (reg >= TOK_ASM_eax && reg <= TOK_ASM_edi) {
reg -= TOK_ASM_eax;
} else if (reg >= TOK_ASM_ax && reg <= TOK_ASM_di) {
reg -= TOK_ASM_ax;
} else {
error("invalid clobber register '%s'", str);
}
clobber_regs[reg] = 1;
}
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