SLJIT_API_FUNC_ATTRIBUTE sljit_s32 sljit_emit_enter()

in pcre/sljit/sljitNativeX86_64.c [90:238]

• 130 lines of code
• 23 McCabe index (conditional complexity)

SLJIT_API_FUNC_ATTRIBUTE sljit_s32 sljit_emit_enter(struct sljit_compiler *compiler,
	sljit_s32 options, sljit_s32 args, sljit_s32 scratches, sljit_s32 saveds,
	sljit_s32 fscratches, sljit_s32 fsaveds, sljit_s32 local_size)
{
	sljit_s32 i, tmp, size, saved_register_size;
	sljit_u8 *inst;

	CHECK_ERROR();
	CHECK(check_sljit_emit_enter(compiler, options, args, scratches, saveds, fscratches, fsaveds, local_size));
	set_emit_enter(compiler, options, args, scratches, saveds, fscratches, fsaveds, local_size);

	compiler->flags_saved = 0;

	/* Including the return address saved by the call instruction. */
	saved_register_size = GET_SAVED_REGISTERS_SIZE(scratches, saveds, 1);

	tmp = saveds < SLJIT_NUMBER_OF_SAVED_REGISTERS ? (SLJIT_S0 + 1 - saveds) : SLJIT_FIRST_SAVED_REG;
	for (i = SLJIT_S0; i >= tmp; i--) {
		size = reg_map[i] >= 8 ? 2 : 1;
		inst = (sljit_u8*)ensure_buf(compiler, 1 + size);
		FAIL_IF(!inst);
		INC_SIZE(size);
		if (reg_map[i] >= 8)
			*inst++ = REX_B;
		PUSH_REG(reg_lmap[i]);
	}

	for (i = scratches; i >= SLJIT_FIRST_SAVED_REG; i--) {
		size = reg_map[i] >= 8 ? 2 : 1;
		inst = (sljit_u8*)ensure_buf(compiler, 1 + size);
		FAIL_IF(!inst);
		INC_SIZE(size);
		if (reg_map[i] >= 8)
			*inst++ = REX_B;
		PUSH_REG(reg_lmap[i]);
	}

	if (args > 0) {
		size = args * 3;
		inst = (sljit_u8*)ensure_buf(compiler, 1 + size);
		FAIL_IF(!inst);

		INC_SIZE(size);

#ifndef _WIN64
		if (args > 0) {
			*inst++ = REX_W;
			*inst++ = MOV_r_rm;
			*inst++ = MOD_REG | (reg_map[SLJIT_S0] << 3) | 0x7 /* rdi */;
		}
		if (args > 1) {
			*inst++ = REX_W | REX_R;
			*inst++ = MOV_r_rm;
			*inst++ = MOD_REG | (reg_lmap[SLJIT_S1] << 3) | 0x6 /* rsi */;
		}
		if (args > 2) {
			*inst++ = REX_W | REX_R;
			*inst++ = MOV_r_rm;
			*inst++ = MOD_REG | (reg_lmap[SLJIT_S2] << 3) | 0x2 /* rdx */;
		}
#else
		if (args > 0) {
			*inst++ = REX_W;
			*inst++ = MOV_r_rm;
			*inst++ = MOD_REG | (reg_map[SLJIT_S0] << 3) | 0x1 /* rcx */;
		}
		if (args > 1) {
			*inst++ = REX_W;
			*inst++ = MOV_r_rm;
			*inst++ = MOD_REG | (reg_map[SLJIT_S1] << 3) | 0x2 /* rdx */;
		}
		if (args > 2) {
			*inst++ = REX_W | REX_B;
			*inst++ = MOV_r_rm;
			*inst++ = MOD_REG | (reg_map[SLJIT_S2] << 3) | 0x0 /* r8 */;
		}
#endif
	}

	local_size = ((local_size + SLJIT_LOCALS_OFFSET + saved_register_size + 15) & ~15) - saved_register_size;
	compiler->local_size = local_size;

#ifdef _WIN64
	if (local_size > 1024) {
		/* Allocate stack for the callback, which grows the stack. */
		inst = (sljit_u8*)ensure_buf(compiler, 1 + 4 + (3 + sizeof(sljit_s32)));
		FAIL_IF(!inst);
		INC_SIZE(4 + (3 + sizeof(sljit_s32)));
		*inst++ = REX_W;
		*inst++ = GROUP_BINARY_83;
		*inst++ = MOD_REG | SUB | 4;
		/* Allocated size for registers must be divisible by 8. */
		SLJIT_ASSERT(!(saved_register_size & 0x7));
		/* Aligned to 16 byte. */
		if (saved_register_size & 0x8) {
			*inst++ = 5 * sizeof(sljit_sw);
			local_size -= 5 * sizeof(sljit_sw);
		} else {
			*inst++ = 4 * sizeof(sljit_sw);
			local_size -= 4 * sizeof(sljit_sw);
		}
		/* Second instruction */
		SLJIT_COMPILE_ASSERT(reg_map[SLJIT_R0] < 8, temporary_reg1_is_loreg);
		*inst++ = REX_W;
		*inst++ = MOV_rm_i32;
		*inst++ = MOD_REG | reg_lmap[SLJIT_R0];
		*(sljit_s32*)inst = local_size;
#if (defined SLJIT_VERBOSE && SLJIT_VERBOSE) \
			|| (defined SLJIT_ARGUMENT_CHECKS && SLJIT_ARGUMENT_CHECKS)
		compiler->skip_checks = 1;
#endif
		FAIL_IF(sljit_emit_ijump(compiler, SLJIT_CALL1, SLJIT_IMM, SLJIT_FUNC_OFFSET(sljit_grow_stack)));
	}
#endif

	SLJIT_ASSERT(local_size > 0);
	if (local_size <= 127) {
		inst = (sljit_u8*)ensure_buf(compiler, 1 + 4);
		FAIL_IF(!inst);
		INC_SIZE(4);
		*inst++ = REX_W;
		*inst++ = GROUP_BINARY_83;
		*inst++ = MOD_REG | SUB | 4;
		*inst++ = local_size;
	}
	else {
		inst = (sljit_u8*)ensure_buf(compiler, 1 + 7);
		FAIL_IF(!inst);
		INC_SIZE(7);
		*inst++ = REX_W;
		*inst++ = GROUP_BINARY_81;
		*inst++ = MOD_REG | SUB | 4;
		*(sljit_s32*)inst = local_size;
		inst += sizeof(sljit_s32);
	}

#ifdef _WIN64
	/* Save xmm6 register: movaps [rsp + 0x20], xmm6 */
	if (fscratches >= 6 || fsaveds >= 1) {
		inst = (sljit_u8*)ensure_buf(compiler, 1 + 5);
		FAIL_IF(!inst);
		INC_SIZE(5);
		*inst++ = GROUP_0F;
		*(sljit_s32*)inst = 0x20247429;
	}
#endif

	return SLJIT_SUCCESS;
}