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x86-32_backend.c
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x86-32_backend.c
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#include "mcp_forth.h"
#include "x86-32_backend_generated.h"
#define ARRAY_LEN(arr) (sizeof(arr) / sizeof(*(arr)))
static bool asm_num_is_small(int num)
{
return num >= -128 && num <= 127;
}
static int get_flags(const m4_fragment_t * fragment)
{
switch (fragment->op) {
case M4_OPCODE_BUILTIN_WORD:
return m4_x86_32_backend_table[fragment->param].flags;
case M4_OPCODE_DEFINED_WORD:
return 0; /*call (relative lit) ; e8 xx xx xx xx*/
case M4_OPCODE_RUNTIME_WORD:
return M4_X86_32_ADD4 | M4_X86_32_MVBA | M4_X86_32_CLOB | M4_X86_32_SUB4 | M4_X86_32_MVAB;
case M4_OPCODE_PUSH_LITERAL:
return M4_X86_32_ADD4 | M4_X86_32_MVBA | M4_X86_32_CLOB; /*mov eax, (lit)*/
case M4_OPCODE_EXIT_WORD:
return 0;
case M4_OPCODE_DEFINED_WORD_LOCATION:
return 0;
case M4_OPCODE_PUSH_DATA_ADDRESS:
return M4_X86_32_ADD4 | M4_X86_32_MVBA | M4_X86_32_CLOB;
case M4_OPCODE_DECLARE_VARIABLE:
return 0;
case M4_OPCODE_USE_VARIABLE_OR_CONSTANT:
return M4_X86_32_ADD4 | M4_X86_32_MVBA | M4_X86_32_CLOB;
case M4_OPCODE_HALT:
return 0;
case M4_OPCODE_BRANCH_LOCATION:
return 0;
case M4_OPCODE_BRANCH_IF_ZERO:
return 0;
case M4_OPCODE_BRANCH:
return 0;
case M4_OPCODE_DO:
return M4_X86_32_SUB4 | M4_X86_32_MVAB;
case M4_OPCODE_LOOP:
return 0;
case M4_OPCODE_PUSH_OFFSET_ADDRESS:
return M4_X86_32_ADD4 | M4_X86_32_MVBA | M4_X86_32_CLOB;
case M4_OPCODE_PUSH_CALLBACK:
return M4_X86_32_ADD4 | M4_X86_32_MVBA | M4_X86_32_CLOB;
case M4_OPCODE_DECLARE_CONSTANT:
return M4_X86_32_SUB4 | M4_X86_32_MVAB;
default:
assert(0);
}
}
static int get_needs(const m4_fragment_t * all_fragments, const int * sequence, int sequence_len, int sequence_i)
{
const m4_fragment_t * fragment = &all_fragments[sequence[sequence_i]];
int needs = get_flags(fragment);
if(sequence_i > 0) {
const m4_fragment_t * frag_up = &all_fragments[sequence[sequence_i - 1]];
int frag_up_flags = get_flags(frag_up);
if(frag_up_flags & M4_X86_32_SUB4) {
needs &= ~M4_X86_32_ADD4;
if(frag_up_flags & M4_X86_32_MVAB) {
needs &= ~M4_X86_32_MVBA;
}
}
}
if(sequence_i + 1 < sequence_len) {
const m4_fragment_t * frag_down = &all_fragments[sequence[sequence_i + 1]];
int frag_down_flags = get_flags(frag_down);
if(frag_down_flags & M4_X86_32_ADD4) {
needs &= ~M4_X86_32_SUB4;
if((frag_down_flags & M4_X86_32_MVBA) && (frag_down_flags & M4_X86_32_CLOB)) {
needs &= ~M4_X86_32_MVAB;
}
}
}
return needs;
}
static int fragment_bin_size(const m4_fragment_t * all_fragments, const int * sequence, int sequence_len, int sequence_i) {
int needs = get_needs(all_fragments, sequence, sequence_len, sequence_i);
int size;
const m4_fragment_t * fragment = &all_fragments[sequence[sequence_i]];
switch(fragment->op) {
case M4_OPCODE_BUILTIN_WORD:
size = m4_x86_32_backend_table[fragment->param].len;
break;
case M4_OPCODE_DEFINED_WORD:
size = 5; /*call (relative lit) ; e8 xx xx xx xx*/
break;
case M4_OPCODE_RUNTIME_WORD:
size = 3 + (asm_num_is_small((fragment->param + 1) * 4) ? 3 : 6);
break;
case M4_OPCODE_PUSH_LITERAL:
size = fragment->param ? 5 : 2; /*mov eax, (lit)*/ /* xor eax, eax */
break;
case M4_OPCODE_EXIT_WORD:
size = 1 + (all_fragments[fragment->param].param ? 1 : 0);
break;
case M4_OPCODE_DEFINED_WORD_LOCATION:
size = fragment->param ? 3 : 0;
break;
case M4_OPCODE_PUSH_DATA_ADDRESS:
/* add eax, (lit) is 83 c0 xx for small and 05 xx xx xx xx for large */
size = 3 + (!fragment->param ? 0 : asm_num_is_small(fragment->param) ? 3 : 5);
break;
case M4_OPCODE_DECLARE_VARIABLE:
size = 9 + (asm_num_is_small(-fragment->param * 4) ? 3 : 6);
break;
case M4_OPCODE_USE_VARIABLE_OR_CONSTANT:
size = asm_num_is_small(-fragment->param * 4) ? 3 : 6;
break;
case M4_OPCODE_HALT:
size = 1;
break;
case M4_OPCODE_BRANCH_LOCATION:
size = 0;
break;
case M4_OPCODE_BRANCH_IF_ZERO:
size = 8 + (asm_num_is_small(all_fragments[fragment->param].position
- all_fragments[sequence[sequence_i + 1]].position)
? 2 : 6);
break;
case M4_OPCODE_BRANCH:
size = asm_num_is_small(all_fragments[fragment->param].position
- all_fragments[sequence[sequence_i + 1]].position)
? 2 : 5;
break;
case M4_OPCODE_DO:
size = 6;
break;
case M4_OPCODE_LOOP:
size = 9 + (asm_num_is_small(all_fragments[fragment->param].position
- (all_fragments[sequence[sequence_i + 1]].position
- 3))
? 2 : 6);
break;
case M4_OPCODE_PUSH_OFFSET_ADDRESS: {
int offset = all_fragments[fragment->param].position
- (fragment->position
+ ((needs & M4_X86_32_ADD4) ? sizeof(m4_x86_32_add4) : 0)
+ ((needs & M4_X86_32_MVBA) ? sizeof(m4_x86_32_mvba) : 0)
+ 5);
size = 6 + (!offset ? 0 : asm_num_is_small(offset) ? 3 : 5);
break;
}
case M4_OPCODE_PUSH_CALLBACK:
size = 3 + (asm_num_is_small(fragment->param * 4) ? 3 : 6);
break;
case M4_OPCODE_DECLARE_CONSTANT:
size = asm_num_is_small(-fragment->param * 4) ? 3 : 6;
break;
default:
assert(0);
}
if(needs & M4_X86_32_ADD4) size += sizeof(m4_x86_32_add4);
if(needs & M4_X86_32_MVBA) size += sizeof(m4_x86_32_mvba);
if(needs & M4_X86_32_SUB4) size += sizeof(m4_x86_32_sub4);
if(needs & M4_X86_32_MVAB) size += sizeof(m4_x86_32_mvab);
return size;
}
static void cpy_and_inc(uint8_t ** dst, const uint8_t * src, int n)
{
memcpy(*dst, src, n);
*dst += n;
}
static void ser_le32_and_inc(uint8_t ** dst, int x)
{
union {int i; unsigned u;} iu = {.i=x};
uint8_t * d = *dst;
for(int i = 0; i < 4; i++) {
*(d++) = iu.u & 0xffu;
iu.u >>= 8;
}
*dst = d;
}
static uint8_t i8_as_byte(int x) {
union {int8_t i; uint8_t u;} iu = {.i=x};
return iu.u;
}
static void ser_i8_or_le32_and_inc(uint8_t ** dst, int x)
{
if(asm_num_is_small(x)) {
**dst = i8_as_byte(x);
*dst += 1;
} else {
ser_le32_and_inc(dst, x);
}
}
static void fragment_bin_dump(const m4_fragment_t * all_fragments, const int * sequence, int sequence_len, int sequence_i, uint8_t * dst) {
int needs = get_needs(all_fragments, sequence, sequence_len, sequence_i);
if(needs & M4_X86_32_ADD4) cpy_and_inc(&dst, m4_x86_32_add4, sizeof(m4_x86_32_add4));
if(needs & M4_X86_32_MVBA) cpy_and_inc(&dst, m4_x86_32_mvba, sizeof(m4_x86_32_mvba));
const m4_fragment_t * fragment = &all_fragments[sequence[sequence_i]];
switch(fragment->op) {
case M4_OPCODE_BUILTIN_WORD:
cpy_and_inc(&dst,
&m4_x86_32_backend_code[m4_x86_32_backend_table[fragment->param].pos],
m4_x86_32_backend_table[fragment->param].len);
break;
case M4_OPCODE_DEFINED_WORD:
*(dst++) = 0xe8; /* call <label> */
ser_le32_and_inc(&dst, all_fragments[fragment->param].position
- all_fragments[sequence[sequence_i + 1]].position);
break;
case M4_OPCODE_RUNTIME_WORD: {
int offset = (fragment->param + 1) * 4;
*(dst++) = 0x8b; /* mov ecx, [edi+...] */
*(dst++) = asm_num_is_small(offset) ? 0x4f : 0x8f;
ser_i8_or_le32_and_inc(&dst, offset);
*(dst++) = 0xff; /* call [esi+36] */
*(dst++) = 0x56;
*(dst++) = 0x24;
break;
}
case M4_OPCODE_PUSH_LITERAL:
if(fragment->param) { /* mov eax, ... */
*(dst++) = 0xb8;
ser_le32_and_inc(&dst, fragment->param);
} else { /* xor eax, eax*/
*(dst++) = 0x31;
*(dst++) = 0xc0;
}
break;
case M4_OPCODE_EXIT_WORD:
if(all_fragments[fragment->param].param) {
*(dst++) = 0xc9; /* leave */
}
*(dst++) = 0xc3; /* ret */
break;
case M4_OPCODE_DEFINED_WORD_LOCATION:
if(fragment->param) {
*(dst++) = 0x55; /* push ebp */
*(dst++) = 0x89; /* mov ebp, esp */
*(dst++) = 0xe5;
}
break;
case M4_OPCODE_PUSH_DATA_ADDRESS:
*(dst++) = 0x8b; /* mov eax, [esi+16] */
*(dst++) = 0x46;
*(dst++) = 0x10;
if(fragment->param) {
/* add eax, ... */
if(asm_num_is_small(fragment->param)) {
*(dst++) = 0x83;
*(dst++) = 0xc0;
} else {
*(dst++) = 0x05;
}
ser_i8_or_le32_and_inc(&dst, fragment->param);
}
break;
case M4_OPCODE_DECLARE_VARIABLE: {
static const uint8_t mach_code_1[] = {
0x83, 0xc2, 0x03, /* add edx, 3 ; align data-space pointer */
0x83, 0xe2, 0xfc, /* and edx, ~3 */
};
cpy_and_inc(&dst, mach_code_1, sizeof(mach_code_1));
int offset = -fragment->param * 4;
*(dst++) = 0x89; /* mov [edi+...], edx */
*(dst++) = asm_num_is_small(offset) ? 0x57 : 0x97;
ser_i8_or_le32_and_inc(&dst, offset);
static const uint8_t mach_code_2[] = {
0x83, 0xc2, 0x04, /* add edx, 4 */
};
cpy_and_inc(&dst, mach_code_2, sizeof(mach_code_2));
break;
}
case M4_OPCODE_USE_VARIABLE_OR_CONSTANT: {
int offset = -fragment->param * 4;
*(dst++) = 0x8b; /* mov eax, [edi+...] */
*(dst++) = asm_num_is_small(offset) ? 0x47 : 0x87;
ser_i8_or_le32_and_inc(&dst, offset);
break;
}
case M4_OPCODE_HALT:
*(dst++) = 0xc3; /* ret */
break;
case M4_OPCODE_BRANCH_LOCATION:
break;
case M4_OPCODE_BRANCH_IF_ZERO: {
static const uint8_t mach_code[] = {
0x83, 0xeb, 0x04, /* sub ebx, 4 */
0x85, 0xc0, /* test eax, eax */
0x8b, 0x43, 0x04, /* mov eax, [ebx+4] */
};
cpy_and_inc(&dst, mach_code, sizeof(mach_code));
int offset = all_fragments[fragment->param].position
- all_fragments[sequence[sequence_i + 1]].position;
/* jz ... */
if(asm_num_is_small(offset)) {
*(dst++) = 0x74;
} else {
*(dst++) = 0x0f;
*(dst++) = 0x84;
}
ser_i8_or_le32_and_inc(&dst, offset);
break;
}
case M4_OPCODE_BRANCH: {
int offset = all_fragments[fragment->param].position
- all_fragments[sequence[sequence_i + 1]].position;
/* jmp ... */
*(dst++) = asm_num_is_small(offset) ? 0xeb : 0xe9;
ser_i8_or_le32_and_inc(&dst, offset);
break;
}
case M4_OPCODE_DO: {
static const uint8_t mach_code[] = {
0xff, 0x33, /* push dword [ebx] */
0x50, /* push eax */
0x83, 0xeb, 0x04, /* sub ebx, 4 */
/* ; mov eax, [ebx] */
/* ; sub ebx, 4 */
};
cpy_and_inc(&dst, mach_code, sizeof(mach_code));
break;
}
case M4_OPCODE_LOOP: {
static const uint8_t mach_code_1[] = {
0x59, /* pop ecx */
0x41, /* inc ecx */
0x3b, 0x0c, 0x24, /* cmp ecx, [esp] */
0x51, /* push ecx */
};
cpy_and_inc(&dst, mach_code_1, sizeof(mach_code_1));
int offset = all_fragments[fragment->param].position
- (all_fragments[sequence[sequence_i + 1]].position
- 3);
/* jl ... */
if(asm_num_is_small(offset)) {
*(dst++) = 0x7c;
} else {
*(dst++) = 0x0f;
*(dst++) = 0x8c;
}
ser_i8_or_le32_and_inc(&dst, offset);
*(dst++) = 0x83; /* add esp, 8 */
*(dst++) = 0xc4;
*(dst++) = 0x08;
break;
}
case M4_OPCODE_PUSH_OFFSET_ADDRESS: {
static const uint8_t mach_code[] = {
/* ; add ebx, 4 */
/* ; mov [ebx], eax */
0xe8, 0x00, 0x00, 0x00, 0x00, /* call .L0 */
/* .L0: */
0x58, /* pop eax */
};
cpy_and_inc(&dst, mach_code, sizeof(mach_code));
int offset = all_fragments[fragment->param].position
- (fragment->position
+ ((needs & M4_X86_32_ADD4) ? sizeof(m4_x86_32_add4) : 0)
+ ((needs & M4_X86_32_MVBA) ? sizeof(m4_x86_32_mvba) : 0)
+ 5);
if(offset) {
/* add eax, ... */
if(asm_num_is_small(offset)) {
*(dst++) = 0x83;
*(dst++) = 0xc0;
} else {
*(dst++) = 0x05;
}
ser_i8_or_le32_and_inc(&dst, offset);
}
break;
}
case M4_OPCODE_PUSH_CALLBACK: {
int offset = fragment->param * 4;
*(dst++) = 0x8b; /* mov eax, [esi+40] */
*(dst++) = 0x46;
*(dst++) = 0x28;
*(dst++) = 0x8b; /* mov eax, [eax+...] */
*(dst++) = asm_num_is_small(offset) ? 0x40 : 0x80;
ser_i8_or_le32_and_inc(&dst, offset);
break;
}
case M4_OPCODE_DECLARE_CONSTANT: {
int offset = -fragment->param * 4;
*(dst++) = 0x89; /* mov [edi+...], eax */
*(dst++) = asm_num_is_small(offset) ? 0x47 : 0x87;
ser_i8_or_le32_and_inc(&dst, offset);
break;
}
default:
assert(0);
}
if(needs & M4_X86_32_MVAB) cpy_and_inc(&dst, m4_x86_32_mvab, sizeof(m4_x86_32_mvab));
if(needs & M4_X86_32_SUB4) cpy_and_inc(&dst, m4_x86_32_sub4, sizeof(m4_x86_32_sub4));
}
const m4_backend_t m4_x86_32_backend = {
.fragment_bin_size=fragment_bin_size,
.fragment_bin_dump=fragment_bin_dump
};