/*
 * This file is part of libFirm.
 * Copyright (C) 2012 University of Karlsruhe.
 */

/**
 * @file
 * @brief   emit assembler for a backend graph
 */
#include "TEMPLATE_emitter.h"

#include "TEMPLATE_new_nodes.h"
#include "bearch.h"
#include "beblocksched.h"
#include "beemithlp.h"
#include "beemitter.h"
#include "begnuas.h"
#include "benode.h"
#include "besched.h"
#include "gen_TEMPLATE_emitter.h"
#include "irgwalk.h"
#include "panic.h"
#include "util.h"

static void TEMPLATE_emit_immediate(const ir_node *node)
{
	TEMPLATE_attr_t const *const attr = get_TEMPLATE_attr_const(node);
	ir_entity             *const ent  = attr->entity;
	ir_tarval             *const val  = attr->value;
	if (ent) {
		be_emit_irprintf("&%s", get_entity_ld_name(ent));
		if (val)
			be_emit_char('+');
	}
	if (val)
		be_emit_irprintf("%T", val);
}

static void emit_register(const arch_register_t *reg)
{
	be_emit_string(reg->name);
}

static void TEMPLATE_emit_source_register(const ir_node *node, int pos)
{
	const arch_register_t *reg = arch_get_irn_register_in(node, pos);
	emit_register(reg);
}

static void TEMPLATE_emit_dest_register(const ir_node *node, int pos)
{
	const arch_register_t *reg = arch_get_irn_register_out(node, pos);
	emit_register(reg);
}

void TEMPLATE_emitf(const ir_node *node, const char *format, ...)
{
	BE_EMITF(node, format, ap, false) {
		switch (*format++) {
		case 'S': {
			if (!is_digit(*format))
				goto unknown;
			unsigned const pos = *format++ - '0';
			TEMPLATE_emit_source_register(node, pos);
			break;
		}

		case 'D': {
			if (!is_digit(*format))
				goto unknown;
			unsigned const pos = *format++ - '0';
			TEMPLATE_emit_dest_register(node, pos);
			break;
		}

		case 'I':
			TEMPLATE_emit_immediate(node);
			break;

		case 'X': {
			int num = va_arg(ap, int);
			be_emit_irprintf("%X", num);
			break;
		}

		default:
unknown:
			panic("unknown format conversion");
		}
	}
}

/**
 * Emits code for a unconditional jump.
 */
static void emit_TEMPLATE_Jmp(const ir_node *node)
{
	TEMPLATE_emitf(node, "jmp %L", node);
}

static void emit_be_IncSP(const ir_node *node)
{
	int offset = be_get_IncSP_offset(node);
	if (offset == 0)
		return;

	/* downwards growing stack */
	const char *op = "add";
	if (offset < 0) {
		op = "sub";
		offset = -offset;
	}

	TEMPLATE_emitf(node, "%s %S0, %d, %D0", op, offset);
}

static void emit_Return(const ir_node *node)
{
	ir_graph *irg        = get_irn_irg(node);
	ir_type  *frame_type = get_irg_frame_type(irg);
	unsigned  size       = get_type_size(frame_type);

	/* emit function epilog here */

	/* deallocate stackframe */
	if (size > 0) {
		TEMPLATE_emitf(node, "add %%sp, %u, %%sp", size);
	}

	/* return */
	unsigned    const n_res = get_irn_arity(node) - n_TEMPLATE_Return_first_result;
	char const *const fmt   =
		n_res == 0 ? "ret" :
		n_res == 1 ? "ret %S2" :
		"ret %S2, ...";
	TEMPLATE_emitf(node, fmt);
}

/**
 * Enters the emitter functions for handled nodes into the generic
 * pointer of an opcode.
 */
static void TEMPLATE_register_emitters(void)
{
	be_init_emitters();

	/* register all emitter functions defined in spec */
	TEMPLATE_register_spec_emitters();

	/* custom emitters not provided by the spec */
	be_set_emitter(op_TEMPLATE_Jmp,    emit_TEMPLATE_Jmp);
	be_set_emitter(op_TEMPLATE_Return, emit_Return);
	be_set_emitter(op_be_IncSP,        emit_be_IncSP);
}

/**
 * Walks over the nodes in a block connected by scheduling edges
 * and emits code for each node.
 */
static void TEMPLATE_emit_block(ir_node *block)
{
	be_gas_begin_block(block);

	sched_foreach(block, node) {
		be_emit_node(node);
	}
}

void TEMPLATE_emit_function(ir_graph *irg)
{
	/* register all emitter functions */
	TEMPLATE_register_emitters();

	/* create the block schedule */
	ir_node **block_schedule = be_create_block_schedule(irg);

	/* emit assembler prolog */
	ir_entity *entity = get_irg_entity(irg);
	be_gas_emit_function_prolog(entity, 4, NULL);

	/* populate jump link fields with their destinations */
	ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);

	be_emit_init_cf_links(block_schedule);

	for (size_t i = 0, n = ARR_LEN(block_schedule); i < n; ++i) {
		ir_node *block = block_schedule[i];
		TEMPLATE_emit_block(block);
	}
	ir_free_resources(irg, IR_RESOURCE_IRN_LINK);

	be_gas_emit_function_epilog(entity);
}