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/*
* memops - try to combine memory ops.
*
* Copyright (C) 2004 Linus Torvalds
*/
#include <string.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <stddef.h>
#include <assert.h>
#include "parse.h"
#include "expression.h"
#include "linearize.h"
#include "flow.h"
static int find_dominating_parents(pseudo_t pseudo, struct instruction *insn,
struct basic_block *bb, unsigned long generation, struct pseudo_list **dominators,
int local)
{
struct basic_block *parent;
FOR_EACH_PTR(bb->parents, parent) {
struct instruction *one;
struct instruction *br;
pseudo_t phi;
FOR_EACH_PTR_REVERSE(parent->insns, one) {
int dominance;
if (!one->bb)
continue;
if (one == insn)
goto no_dominance;
dominance = dominates(pseudo, insn, one, local);
if (dominance < 0) {
if (one->opcode == OP_LOAD)
continue;
return 0;
}
if (!dominance)
continue;
goto found_dominator;
} END_FOR_EACH_PTR_REVERSE(one);
no_dominance:
if (parent->generation == generation)
continue;
parent->generation = generation;
if (!find_dominating_parents(pseudo, insn, parent, generation, dominators, local))
return 0;
continue;
found_dominator:
br = delete_last_instruction(&parent->insns);
phi = alloc_phi(parent, one->target, one->type);
phi->ident = phi->ident ? : one->target->ident;
add_instruction(&parent->insns, br);
use_pseudo(insn, phi, add_pseudo(dominators, phi));
} END_FOR_EACH_PTR(parent);
return 1;
}
static int address_taken(pseudo_t pseudo)
{
struct pseudo_user *pu;
FOR_EACH_PTR(pseudo->users, pu) {
struct instruction *insn = pu->insn;
if (insn->bb && (insn->opcode != OP_LOAD && insn->opcode != OP_STORE))
return 1;
if (pu->userp != &insn->src)
return 1;
} END_FOR_EACH_PTR(pu);
return 0;
}
static int local_pseudo(pseudo_t pseudo)
{
return pseudo->type == PSEUDO_SYM
&& !(pseudo->sym->ctype.modifiers & (MOD_STATIC | MOD_NONLOCAL))
&& !address_taken(pseudo);
}
static bool compatible_loads(struct instruction *a, struct instruction *b)
{
if (is_integral_type(a->type) && is_float_type(b->type))
return false;
if (is_float_type(a->type) && is_integral_type(b->type))
return false;
return true;
}
static void simplify_loads(struct basic_block *bb)
{
struct instruction *insn;
FOR_EACH_PTR_REVERSE(bb->insns, insn) {
if (!insn->bb)
continue;
if (insn->opcode == OP_LOAD) {
struct instruction *dom;
pseudo_t pseudo = insn->src;
int local = local_pseudo(pseudo);
struct pseudo_list *dominators;
unsigned long generation;
/* Check for illegal offsets.. */
check_access(insn);
if (insn->is_volatile)
continue;
RECURSE_PTR_REVERSE(insn, dom) {
int dominance;
if (!dom->bb)
continue;
dominance = dominates(pseudo, insn, dom, local);
if (dominance) {
/* possible partial dominance? */
if (dominance < 0) {
if (dom->opcode == OP_LOAD)
continue;
goto next_load;
}
if (!compatible_loads(insn, dom))
goto next_load;
/* Yeehaa! Found one! */
convert_load_instruction(insn, dom->target);
goto next_load;
}
} END_FOR_EACH_PTR_REVERSE(dom);
/* OK, go find the parents */
generation = ++bb_generation;
bb->generation = generation;
dominators = NULL;
if (find_dominating_parents(pseudo, insn, bb, generation, &dominators, local)) {
/* This happens with initial assignments to structures etc.. */
if (!dominators) {
if (local) {
assert(pseudo->type != PSEUDO_ARG);
convert_load_instruction(insn, value_pseudo(0));
}
goto next_load;
}
rewrite_load_instruction(insn, dominators);
} else { // cleanup pending phi-sources
pseudo_t phi;
FOR_EACH_PTR(dominators, phi) {
kill_instruction(phi->def);
} END_FOR_EACH_PTR(phi);
}
}
next_load:
/* Do the next one */;
} END_FOR_EACH_PTR_REVERSE(insn);
}
static void kill_dominated_stores(struct basic_block *bb)
{
struct instruction *insn;
FOR_EACH_PTR_REVERSE(bb->insns, insn) {
if (!insn->bb)
continue;
if (insn->opcode == OP_STORE) {
struct instruction *dom;
pseudo_t pseudo = insn->src;
int local;
if (!insn->type)
continue;
if (insn->is_volatile)
continue;
local = local_pseudo(pseudo);
RECURSE_PTR_REVERSE(insn, dom) {
int dominance;
if (!dom->bb)
continue;
dominance = dominates(pseudo, insn, dom, local);
if (dominance) {
/* possible partial dominance? */
if (dominance < 0)
goto next_store;
if (dom->opcode == OP_LOAD)
goto next_store;
/* Yeehaa! Found one! */
kill_instruction_force(dom);
}
} END_FOR_EACH_PTR_REVERSE(dom);
/* OK, we should check the parents now */
}
next_store:
/* Do the next one */;
} END_FOR_EACH_PTR_REVERSE(insn);
}
void simplify_memops(struct entrypoint *ep)
{
struct basic_block *bb;
pseudo_t pseudo;
FOR_EACH_PTR_REVERSE(ep->bbs, bb) {
simplify_loads(bb);
} END_FOR_EACH_PTR_REVERSE(bb);
FOR_EACH_PTR_REVERSE(ep->bbs, bb) {
kill_dominated_stores(bb);
} END_FOR_EACH_PTR_REVERSE(bb);
FOR_EACH_PTR(ep->accesses, pseudo) {
struct symbol *var = pseudo->sym;
unsigned long mod;
if (!var)
continue;
mod = var->ctype.modifiers;
if (mod & (MOD_VOLATILE | MOD_NONLOCAL | MOD_STATIC))
continue;
kill_dead_stores(ep, pseudo, local_pseudo(pseudo));
} END_FOR_EACH_PTR(pseudo);
}
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