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#include <assert.h>
#include <qbt/unreachable.h>
static void add_val(struct vec *map, struct val v)
{
assert(v.class == TMP);
size_t i = v.r;
while (vec_len(map) <= i) {
struct val no = noclass();
vec_append(map, &no);
}
blk_param_at(*map, i) = v;
}
static void remove_val(struct vec *map, struct val v)
{
assert(v.class == TMP);
size_t i = v.r;
if (vec_len(map) <= i)
return;
blk_param_at(*map, i) = noclass();
}
static bool has_val(struct vec *map, struct val v)
{
assert(v.class == TMP);
size_t i = v.r;
if (vec_len(map) <= i)
return false;
struct val p = blk_param_at(*map, i);
return p.class != NOCLASS;
}
static void build_params(struct blk *b, int visited)
{
if (b->visited > visited)
return;
b->visited++;
if (return_blk(b)) {
b->s1 = NULL;
b->s2 = NULL;
}
if (b->s1)
build_params(b->s1, visited);
if (b->s2)
build_params(b->s2, visited);
struct vec generated = vec_create(sizeof(struct val));
struct vec forward = vec_create(sizeof(struct val));
struct vec required = vec_create(sizeof(struct val));
/* first, collect all forwards */
if (b->s1) {
foreach_blk_param(pi, b->s1->params) {
struct val p = blk_param_at(b->s1->params, pi);
add_val(&forward, p);
}
}
if (b->s2) {
foreach_blk_param(pi, b->s2->params) {
struct val p = blk_param_at(b->s2->params, pi);
add_val(&forward, p);
}
}
/* go through each instruction and add inputs to required and outputs to
* generated */
foreach_insn(ii, b->insns) {
struct insn i = insn_at(b->insns, ii);
struct val in1 = i.in[0];
if (in1.class == TMP && !has_val(&generated, in1))
add_val(&required, in1);
struct val in2 = i.in[1];
if (in2.class == TMP && !has_val(&generated, in2))
add_val(&required, in2);
struct val out = i.out;
if (out.class == TMP) {
add_val(&generated, out);
/* we generate this value so no need to forward it */
if (has_val(&forward, out))
remove_val(&forward, out);
}
}
if (b->cmp[0].class == TMP && !has_val(&generated, b->cmp[0]))
add_val(&required, b->cmp[0]);
if (b->cmp[1].class == TMP && !has_val(&generated, b->cmp[1]))
add_val(&required, b->cmp[1]);
/* add values that need forwarding to our required list */
foreach_blk_param(pi, forward) {
/* if value already is in list, don't do anything */
struct val p = blk_param_at(forward, pi);
/* skip empty slots */
if (p.class == NOCLASS)
continue;
if (has_val(&required, p))
continue;
add_val(&required, p);
}
/* convert from the hashmap-like structure to regular vector */
foreach_blk_param(pi, required) {
struct val p = blk_param_at(required, pi);
if (p.class == NOCLASS)
continue;
vec_append(&b->params, &p);
}
vec_destroy(&required);
vec_destroy(&forward);
vec_destroy(&generated);
}
static void collect_params(struct blk *b, int visited)
{
if (b->visited > visited)
return;
b->visited++;
if (b->s1) {
collect_params(b->s1, visited);
foreach_blk_param(pi, b->s1->params) {
struct val p = blk_param_at(b->s1->params, pi);
vec_append(&b->args1, &p);
}
}
if (b->s2) {
collect_params(b->s2, visited);
foreach_blk_param(pi, b->s2->params) {
struct val p = blk_param_at(b->s2->params, pi);
vec_append(&b->args2, &p);
}
}
}
static void add_rewrite_rule(struct vec *rmap, struct val from, struct val to)
{
assert(from.class == TMP);
assert(to.class == TMP);
while ((int64_t)vec_len(rmap) <= from.r) {
struct val no = noclass();
vec_append(rmap, &no);
}
val_at(*rmap, from.r) = to;
}
static struct val rewrite_tmp(struct vec *rmap, struct val from)
{
assert(from.class == TMP);
assert(from.r <= (int64_t)vec_len(rmap));
struct val v = val_at(*rmap, from.r);
assert(v.class == TMP);
return v;
}
static size_t rename_temps(struct blk *b, size_t i)
{
struct vec rmap = vec_create(sizeof(struct val));
foreach_blk_param(pi, b->params) {
struct val p = blk_param_at(b->params, pi);
/* this is very similar to what's going on in regalloc.c, hmm */
add_rewrite_rule(&rmap, p, tmp_val(i++));
blk_param_at(b->params, pi) = rewrite_tmp(&rmap, p);
}
foreach_insn(ii, b->insns) {
struct insn n = insn_at(b->insns, ii);
if (n.in[0].class == TMP)
n.in[0] = rewrite_tmp(&rmap, n.in[0]);
if (n.in[1].class == TMP)
n.in[1] = rewrite_tmp(&rmap, n.in[1]);
if (n.out.class == TMP) {
add_rewrite_rule(&rmap, n.out, tmp_val(i++));
n.out = rewrite_tmp(&rmap, n.out);
}
insn_at(b->insns, ii) = n;
}
if (b->cmp[0].class == TMP)
b->cmp[0] = rewrite_tmp(&rmap, b->cmp[0]);
if (b->cmp[1].class == TMP)
b->cmp[1] = rewrite_tmp(&rmap, b->cmp[1]);
foreach_blk_param(pi, b->args1) {
struct val p = blk_param_at(b->args1, pi);
blk_param_at(b->args1, pi) = rewrite_tmp(&rmap, p);
}
foreach_blk_param(pi, b->args2) {
struct val p = blk_param_at(b->args2, pi);
blk_param_at(b->args2, pi) = rewrite_tmp(&rmap, p);
}
vec_destroy(&rmap);
return i;
}
size_t ssa(struct fn *f)
{
/* do a depth-first traversal of blocks, mark locations within as either
* generated (i.e. we assign something to the register) or required
* (i.e. it must be taken as a block parameter) */
struct blk *b = blk_at(f->blks, 0);
build_params(b, b->visited);
remove_unvisited(f, b->visited);
collect_params(b, b->visited);
size_t i = 0;
foreach_blk(bi, f->blks) {
struct blk *b = blk_at(f->blks, bi);
i = rename_temps(b, i);
}
return i;
}
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