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Tweaked alt-tag encoding to match color/dir naming order

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This is mainly to avoid mistakes caused by names/encodings disagreeing:

  LFSR_TAG_ALT  0x4kkk  v1cd kkkk -kkk kkkk
                        ^ ^^ '------+-----'
                        '-||--------|------- valid bit
                          '|--------|------- color
                           '--------|------- dir
                                    '------- key

Notably, the LFSR_TAG_ALT() macro has already caused issues by being
both 1. ambiguous, and 2. not really type-checkable. It's easy to get
the order wrong and things not really break, just behave poorly, it's
really not great!

To be honest the exact order is a bit arbitrary, the color->dir naming
appeared by accident because I guess it felt more natural. Maybe because
of English's weird implicit adjective ordering? Maybe because of how
often conditions show up as the last part of the name in other
instruction sets?

At least one plus is that this moves the dir-bit next to the key. This
makes it so all of the condition information is encoding is the lowest
13-bits of the tag, which may lead to minor optimization tricks for
implementing flips and such.

Code changes:

           code          stack
  before: 34080           2864
  after:  34068 (-0.0%)   2864 (+0.0%)
This commit is contained in:
Christopher Haster
2024-04-23 03:19:07 -05:00
parent 884982987e
commit faf8c4b641
7 changed files with 29 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lfs.c
+15 -15
View File
@@ -758,10 +758,10 @@ enum lfsr_tag {
// alt pointers form the inner nodes of our rbyd trees
LFSR_TAG_ALT = 0x4000,
LFSR_TAG_LE = 0x0000,
LFSR_TAG_GT = 0x2000,
LFSR_TAG_B = 0x0000,
LFSR_TAG_R = 0x1000,
LFSR_TAG_R = 0x2000,
LFSR_TAG_LE = 0x0000,
LFSR_TAG_GT = 0x1000,
// checksum tags
LFSR_TAG_CKSUM = 0x3000,
@@ -783,10 +783,10 @@ enum lfsr_tag {
};
// some other tag encodings with their own subfields
#define LFSR_TAG_ALT(d, c, key) \
#define LFSR_TAG_ALT(c, d, key) \
(LFSR_TAG_ALT \
| (0x2000 & (d)) \
| (0x1000 & (c)) \
| (0x2000 & (c)) \
| (0x1000 & (d)) \
| (0x0fff & (lfsr_tag_t)(key)))
#define LFSR_TAG_UATTR(attr) \
@@ -874,11 +874,11 @@ static inline bool lfsr_tag_isgt(lfsr_tag_t tag) {
}
static inline bool lfsr_tag_isa(lfsr_tag_t tag) {
return (tag & 0x2fff) == (LFSR_TAG_GT | 0);
return (tag & 0x1fff) == (LFSR_TAG_GT | 0);
}
static inline bool lfsr_tag_isn(lfsr_tag_t tag) {
return (tag & 0x2fff) == (LFSR_TAG_LE | 0);
return (tag & 0x1fff) == (LFSR_TAG_LE | 0);
}
static inline lfsr_tag_t lfsr_tag_isparallel(lfsr_tag_t a, lfsr_tag_t b) {
@@ -3010,7 +3010,7 @@ trunk:;
// stitch together both trunks
err = lfsr_p_push(lfs, rbyd, p,
LFSR_TAG_ALT(LFSR_TAG_LE, LFSR_TAG_B, d_tag),
LFSR_TAG_ALT(LFSR_TAG_B, LFSR_TAG_LE, d_tag),
d_rid - (lower_rid - weight),
jump);
if (err) {
@@ -3105,7 +3105,7 @@ trunk:;
// .-'| .--'
// 3 4 3 4 x
} else {
alt = LFSR_TAG_ALT(LFSR_TAG_LE, LFSR_TAG_B, 0);
alt = LFSR_TAG_ALT(LFSR_TAG_B, LFSR_TAG_LE, 0);
weight = 0;
jump = 0;
}
@@ -3278,12 +3278,12 @@ stem:;
&& lfsr_tag_key(tag_) < lfsr_tag_key(tag)))))) {
if (lfsr_tag_isrm(tag) || !lfsr_tag_key(tag)) {
// if removed, make our tag unreachable
alt = LFSR_TAG_ALT(LFSR_TAG_GT, LFSR_TAG_B, lower_tag);
alt = LFSR_TAG_ALT(LFSR_TAG_B, LFSR_TAG_GT, lower_tag);
weight = upper_rid - lower_rid + delta;
upper_rid -= weight;
} else {
// split less than
alt = LFSR_TAG_ALT(LFSR_TAG_LE, LFSR_TAG_B, tag_);
alt = LFSR_TAG_ALT(LFSR_TAG_B, LFSR_TAG_LE, tag_);
weight = upper_rid - lower_rid;
lower_rid += weight;
}
@@ -3299,12 +3299,12 @@ stem:;
&& lfsr_tag_key(tag_) > lfsr_tag_key(tag)))))) {
if (lfsr_tag_isrm(tag) || !lfsr_tag_key(tag)) {
// if removed, make our tag unreachable
alt = LFSR_TAG_ALT(LFSR_TAG_GT, LFSR_TAG_B, lower_tag);
alt = LFSR_TAG_ALT(LFSR_TAG_B, LFSR_TAG_GT, lower_tag);
weight = upper_rid - lower_rid + delta;
upper_rid -= weight;
} else {
// split greater than
alt = LFSR_TAG_ALT(LFSR_TAG_GT, LFSR_TAG_B, tag);
alt = LFSR_TAG_ALT(LFSR_TAG_B, LFSR_TAG_GT, tag);
weight = upper_rid - (rid+1);
upper_rid -= weight;
}
@@ -3770,10 +3770,10 @@ static int lfsr_rbyd_appendcompaction(lfs_t *lfs, lfsr_rbyd_t *rbyd,
// connect with an altle
err = lfsr_rbyd_appendtag(lfs, rbyd,
LFSR_TAG_ALT(
LFSR_TAG_LE,
(i == 0 && off < layer_)
? LFSR_TAG_R
: LFSR_TAG_B,
LFSR_TAG_LE,
tag),
weight,
rbyd->eoff - trunk);
scripts/dbgbmap.py
+2 -2
View File
@@ -44,8 +44,8 @@ TAG_SHRUB = 0x1000
TAG_CKSUM = 0x3000
TAG_ECKSUM = 0x3100
TAG_ALT = 0x4000
TAG_GT = 0x2000
TAG_R = 0x1000
TAG_R = 0x2000
TAG_GT = 0x1000
CHARS = 'mbd-'
scripts/dbgbtree.py
+2 -2
View File
@@ -42,8 +42,8 @@ TAG_SHRUB = 0x1000
TAG_CKSUM = 0x3000
TAG_ECKSUM = 0x3100
TAG_ALT = 0x4000
TAG_GT = 0x2000
TAG_R = 0x1000
TAG_R = 0x2000
TAG_GT = 0x1000
# some ways of block geometry representations
scripts/dbglfs.py
+2 -2
View File
@@ -43,8 +43,8 @@ TAG_SHRUB = 0x1000
TAG_CKSUM = 0x3000
TAG_ECKSUM = 0x3100
TAG_ALT = 0x4000
TAG_GT = 0x2000
TAG_R = 0x1000
TAG_R = 0x2000
TAG_GT = 0x1000
# some ways of block geometry representations
scripts/dbgmtree.py
+2 -2
View File
@@ -42,8 +42,8 @@ TAG_SHRUB = 0x1000
TAG_CKSUM = 0x3000
TAG_ECKSUM = 0x3100
TAG_ALT = 0x4000
TAG_GT = 0x2000
TAG_R = 0x1000
TAG_R = 0x2000
TAG_GT = 0x1000
# some ways of block geometry representations
scripts/dbgrbyd.py
+4 -4
View File
@@ -51,8 +51,8 @@ TAG_SHRUB = 0x1000
TAG_CKSUM = 0x3000
TAG_ECKSUM = 0x3100
TAG_ALT = 0x4000
TAG_GT = 0x2000
TAG_R = 0x1000
TAG_R = 0x2000
TAG_GT = 0x1000
# some ways of block geometry representations
@@ -371,7 +371,7 @@ def dbg_log(data, block_size, rev, eoff, weight, *,
wastrunk = True
lower_, upper_ = 0, 0
if (tag & 0xf000) == TAG_ALT:
if tag & TAG_ALT and not tag & TAG_GT:
lower_ += w
else:
upper_ += w
@@ -548,7 +548,7 @@ def dbg_log(data, block_size, rev, eoff, weight, *,
wastrunk = True
lower_, upper_ = 0, 0
if (tag & 0xe000) == TAG_ALT:
if tag & TAG_ALT and not tag & TAG_GT:
lower_ += w
else:
upper_ += w
scripts/dbgtag.py
+2 -2
View File
@@ -40,8 +40,8 @@ TAG_SHRUB = 0x1000
TAG_CKSUM = 0x3000
TAG_ECKSUM = 0x3100
TAG_ALT = 0x4000
TAG_GT = 0x2000
TAG_R = 0x1000
TAG_R = 0x2000
TAG_GT = 0x1000
# some ways of block geometry representations