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[qfcc] Merge code blocks more aggressively

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The merge_blocks function wasn't reporting whether it had done anything
so the thread/merge/dead blocks loop was bailing early. With this,
simple functions (ie, no control flow) are fully visible to the CSE
optimizer and it can get quite aggressive (removed 3 assignments and a
cross product from my barycenter test code).
This commit is contained in:
Bill Currie 2023-09-07 21:42:46 +09:00
parent 6096edb1ca
commit 51fbdfe87d
1 changed files with 11 additions and 9 deletions
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20
tools/qfcc/source/statements.c
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@ -2333,17 +2333,18 @@ move_code (sblock_t *dst, sblock_t *src)
src->tail = &src->statements; src->tail = &src->statements;
} }
static sblock_t * static int
merge_blocks (sblock_t *blocks) merge_blocks (sblock_t **blocks)
{ {
sblock_t **sb; sblock_t **sb;
sblock_t *sblock; sblock_t *sblock;
statement_t *s; statement_t *s;
int did_something = 0;
if (!blocks) if (!*blocks)
return blocks; return did_something;
// merge any blocks that can be merged // merge any blocks that can be merged
for (sblock = blocks; sblock; sblock = sblock->next) { for (sblock = *blocks; sblock; sblock = sblock->next) {
if (sblock->statements && sblock->next) { if (sblock->statements && sblock->next) {
s = (statement_t *) sblock->tail; s = (statement_t *) sblock->tail;
// func and flow statements end blocks // func and flow statements end blocks
@ -2354,9 +2355,10 @@ merge_blocks (sblock_t *blocks)
continue; continue;
// blocks can be merged // blocks can be merged
move_code (sblock, sblock->next); move_code (sblock, sblock->next);
did_something = 1;
} }
} }
for (sb = &blocks; (*sb)->next;) { for (sb = blocks; (*sb)->next;) {
if (!(*sb)->statements) { if (!(*sb)->statements) {
// empty non-final block // empty non-final block
// move labels from empty block to next block // move labels from empty block to next block
@ -2370,7 +2372,7 @@ merge_blocks (sblock_t *blocks)
sb = &(*sb)->next; sb = &(*sb)->next;
} }
// so long as blocks doesn't become null, remove an empty final block // so long as blocks doesn't become null, remove an empty final block
if (sb != &blocks) { if (sb != blocks) {
if (!(*sb)->statements && !(*sb)->labels) { if (!(*sb)->statements && !(*sb)->labels) {
// empty final block with no labels // empty final block with no labels
sblock = *sb; sblock = *sb;
@ -2378,7 +2380,7 @@ merge_blocks (sblock_t *blocks)
free_sblock (sblock); free_sblock (sblock);
} }
} }
return blocks; return did_something;
} }
static void static void
@ -2653,7 +2655,7 @@ make_statements (expr_t *e)
if (options.block_dot.thread) if (options.block_dot.thread)
dump_dot (va (0, "thread-%d", pass), sblock, dump_dot_sblock); dump_dot (va (0, "thread-%d", pass), sblock, dump_dot_sblock);
did_something |= remove_dead_blocks (sblock); did_something |= remove_dead_blocks (sblock);
sblock = merge_blocks (sblock); did_something |= merge_blocks (&sblock);
if (options.block_dot.dead) if (options.block_dot.dead)
dump_dot (va (0, "dead-%d", pass), sblock, dump_dot_sblock); dump_dot (va (0, "dead-%d", pass), sblock, dump_dot_sblock);
pass++; pass++;