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Generalized lfsr_file_crystallize_ for future write strategies

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This function is actually pretty much the same in both the lazy and
eager crystallization write strategies. The main difference being the
nuances around the crystal_size parameter:

- lazy:  crystal_size => rough upper bound on crystal
- eager: crystal_size => strict lower bound on crystal

If we change these to an explicit crystal_min and crystal_max, we can
use lfsr_file_crystallize_ in both write strategies without changing the
logic.

It's out of scope right now, but this will help supporting both write
strategies in the future.

---

Unfortunately this added more code/stack that I was expecting:

           code          stack          ctx
  before: 36428           2248          636
  after:  36460 (+0.1%)   2280 (+1.4%)  636 (+0.0%)

I'm not exactly sure why, I guess the crystal_limit calculation is too
complex to const propagate the crystal_max=-1?

Maybe the LFS_NOINLINE is disabling certain cross-function
optimizations...
This commit is contained in:
Christopher Haster 2025-05-23 11:54:54 -05:00
parent 22c43124de
commit 9d6a94aa07
1 changed files with 9 additions and 5 deletions
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14
lfs.c
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@ -12093,11 +12093,15 @@ static int lfsr_file_graft(lfs_t *lfs, lfsr_file_t *file,
// hot-path
LFS_NOINLINE
static int lfsr_file_crystallize_(lfs_t *lfs, lfsr_file_t *file,
lfs_off_t block_pos, lfs_soff_t crystal_size,
lfs_off_t block_pos, lfs_soff_t crystal_min, lfs_soff_t crystal_max,
lfs_off_t pos, const uint8_t *buffer, lfs_size_t size) {
// limit to block_size and theoretical file size
// align to prog_size, limit to block_size and theoretical file size
lfs_off_t crystal_limit = lfs_min(
block_pos + lfs->cfg->block_size,
block_pos + lfs_min(
lfs_aligndown(
(lfs_off_t)crystal_max,
lfs->cfg->prog_size),
lfs->cfg->block_size),
lfs_max(
pos + size,
file->b.shrub.weight));
@ -12207,7 +12211,7 @@ static int lfsr_file_crystallize_(lfs_t *lfs, lfsr_file_t *file,
// but make sure to include all of the requested
// crystal if explicit, otherwise above loops
// may never terminate
&& (lfs_soff_t)(pos_ - block_pos) >= crystal_size) {
&& (lfs_soff_t)(pos_ - block_pos) >= crystal_min) {
break;
}
@ -12319,7 +12323,7 @@ static int lfsr_file_crystallize(lfs_t *lfs, lfsr_file_t *file,
// crystallize
int err = lfsr_file_crystallize_(lfs, file,
block_pos, crystal_size,
block_pos, crystal_size, -1,
pos, buffer, size);
if (err) {
return err;