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#include "wasm_compile.h"
#include "stack_machine_instruction.h"
/* WebAssembly opcodes */
#define WASM_END 0x0B
#define WASM_LOCAL_GET 0x20
#define WASM_I32_LOAD 0x28
#define WASM_I32_LOAD8_S 0x2C
#define WASM_I32_LOAD8_U 0x2D
#define WASM_I32_LOAD16_S 0x2E
#define WASM_I32_LOAD16_U 0x2F
#define WASM_I32_STORE 0x36
#define WASM_I32_STORE8 0x3A
#define WASM_I32_STORE16 0x3B
#define WASM_I64_STORE32 0x3E
#define WASM_I32_CONST 0x41
#define WASM_I32_SUB 0x6B
int translate(FILE *handle, struct function *function, struct module *module)
{
struct instruction *expr = NULL;
uint32_t args_count = function->type->arguments_count;
uint32_t locals_count = function->locals_count;
uint32_t all_locals_count = args_count + locals_count;
size_t i;
int wasm_opcode;
int matched;
if (locals_count + (uint64_t) args_count > STACK_TOP_ADDR * 4) {
PRERR("Too many locals in a function\n");
goto fail;
}
for (i = locals_count + 3; i; i--) {
if (i_const(im(0), &expr))
goto fail;
}
/* function prologue */
if (i_get_frame( &expr) ||
i_tee ( &expr) ||
i_load (im(STACK_FRAME_BACKUP_ADDR), &expr) ||
i_store_p (im(0x0), &expr) ||
i_store (im(STACK_FRAME_BACKUP_ADDR), &expr))
goto fail;
/* actual function body */
i = 0;
while (1) {
matched = 0;
wasm_opcode = fgetc(handle);
if (wasm_opcode == EOF) {
PRERR(MSG_EOF);
goto fail;
}
// TODO: make a function for each instruction type,
// call them through some table...
if (wasm_opcode == WASM_I32_SUB) {
if (i_sub(&expr))
goto fail;
matched = 1;
} else if (wasm_opcode <= WASM_I64_STORE32 &&
wasm_opcode >= WASM_I32_LOAD) {
uint32_t align, offset;
if (leb_u32(handle, &align) ||
leb_u32(handle, &offset)) {
PRERR(MSG_BAD_NUM);
goto fail;
}
offset += MEMORY_BOTTOM_ADDR;
// TODO: rewrite it some cleaner way
#define TRY(opcode, instr) \
if (wasm_opcode == opcode) { \
matched = 1; \
\
if (i_##instr(im(offset), &expr)) \
goto fail; \
}
TRY(WASM_I32_LOAD, load_p);
TRY(WASM_I32_LOAD8_S, loadbsx_p);
TRY(WASM_I32_LOAD8_U, loadbzx_p);
TRY(WASM_I32_LOAD16_S, loadwsx_p);
TRY(WASM_I32_LOAD16_U, loadwzx_p);
TRY(WASM_I32_STORE, store_p);
TRY(WASM_I32_STORE8, storeb_p);
TRY(WASM_I32_STORE16, storew_p);
} else if (wasm_opcode == WASM_LOCAL_GET) {
uint32_t localidx;
uint64_t offset_on_frame;
if (leb_u32(handle, &localidx)) {
PRERR(MSG_BAD_NUM);
goto fail;
}
if (localidx >= all_locals_count) {
PRERR(MSG_BAD_IDX("localidx"));
goto fail;
}
offset_on_frame = all_locals_count - localidx + 1;
if (localidx >= args_count)
offset_on_frame -= 1;
if (i_load (im(STACK_FRAME_BACKUP_ADDR), &expr) ||
i_load_p(im(4 * offset_on_frame), &expr))
goto fail;
matched = 1;
} else if (wasm_opcode == WASM_I32_CONST) {
uint32_t constant;
if (leb_u32(handle, &constant)) {
PRERR(MSG_BAD_NUM);
goto fail;
}
if (i_const(im(constant), &expr))
goto fail;
matched = 1;
} else if (wasm_opcode == WASM_END) {
break;
}
if (!matched) {
PRERR("Unknown Wasm opcode: %02x\n", wasm_opcode);
goto fail;
}
}
/* function epilogue */
if (function->type->result) {
if (i_load (im(STACK_FRAME_BACKUP_ADDR), &expr) ||
i_swap ( &expr) ||
i_store_p(im(4 * (2 + all_locals_count - 1)), &expr) ||
i_load (im(STACK_FRAME_BACKUP_ADDR), &expr) ||
i_tee ( &expr) ||
i_tee ( &expr) ||
i_load_p (im(4 * (1 + locals_count)), &expr) ||
i_store_p(im(4 * (2 + all_locals_count - 2)), &expr) ||
i_load_p (im(0), &expr) ||
i_store (im(STACK_FRAME_BACKUP_ADDR), &expr))
goto fail;
} else {
/* It's a bit shorter if we don't return anything */
if (i_load (im(STACK_FRAME_BACKUP_ADDR), &expr) ||
i_tee ( &expr) ||
i_tee ( &expr) ||
i_load_p (im(4 * (1 + locals_count)), &expr) ||
i_store_p(im(4 * (2 + all_locals_count - 1)), &expr) ||
i_load_p (im(0), &expr) ||
i_store (im(STACK_FRAME_BACKUP_ADDR), &expr))
goto fail;
}
i = locals_count + args_count + 2 + (function->type->result ? 0 : 1);
while (i--) {
if (i_drop(&expr))
goto fail;
}
if (i_ret(&expr))
goto fail;
function->translated_body = expr;
return 0;
fail:
PRERR("Couldn't translate function to stack machine\n");
free_expr(expr);
return -1;
}
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