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Move jump threading into the dead-code removal loop. 

Dead code removal can give more opportunities to the useless branch removal
in the jump threading code.
This commit is contained in:
Bill Currie 2012-12-25 13:33:31 +09:00
parent 07187cae7c
commit e414117fe8
1 changed files with 14 additions and 8 deletions
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22
tools/qfcc/source/statements.c
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@ -1398,13 +1398,14 @@ unuse_label (ex_label_t *label)
remove_label_from_dest (label);
}
static void
static int
thread_jumps (sblock_t *blocks)
{
sblock_t *sblock;
int did_something = 0;
if (!blocks)
return;
return 0;
for (sblock = blocks; sblock; sblock = sblock->next) {
statement_t *s;
ex_label_t **label, *l;
@ -1426,6 +1427,7 @@ thread_jumps (sblock_t *blocks)
unuse_label (*label);
l->used++;
*label = l;
did_something = 1;
}
if ((statement_is_goto (s) || statement_is_cond (s))
&& (*label)->dest == sblock->next) {
@ -1436,8 +1438,10 @@ thread_jumps (sblock_t *blocks)
free_statement (s);
*p = 0;
sblock->tail = p;
did_something = 1;
}
}
return did_something;
}
static int
@ -1565,21 +1569,23 @@ make_statements (expr_t *e)
{
sblock_t *sblock = new_sblock ();
int did_something;
int pass = 0;
if (options.block_dot.expr)
dump_dot ("expr", e, dump_dot_expr);
statement_slist (sblock, e);
if (options.block_dot.initial)
dump_dot ("initial", sblock, dump_dot_sblock);
thread_jumps (sblock);
if (options.block_dot.thread)
dump_dot ("thread", sblock, dump_dot_sblock);
do {
did_something = remove_dead_blocks (sblock);
did_something = thread_jumps (sblock);
if (options.block_dot.thread)
dump_dot (va ("thread-%d", pass), sblock, dump_dot_sblock);
did_something |= remove_dead_blocks (sblock);
sblock = merge_blocks (sblock);
if (options.block_dot.dead)
dump_dot (va ("dead-%d", pass), sblock, dump_dot_sblock);
pass++;
} while (did_something);
if (options.block_dot.dead)
dump_dot ("dead", sblock, dump_dot_sblock);
check_final_block (sblock);
if (options.block_dot.final)
dump_dot ("final", sblock, dump_dot_sblock);