Subject: [PATCH v3 0/6] Xdiff cleanup part 3

From: "Ezekiel Newren via GitGitGadget" <[email-masked]>
Date: Fri, 27 Mar 2026 19:23:47 +0000

Changes in v3:

 * run make DEVELOPER=1 on each commit and fix all compiler issues

v2 is a radical departure from v1 Changes in v2:

 * make the flow of xdl_cleanup_records() easier to follow

There is no performance or behavioral change introduced in this patch
series.

=== original cover letter bellow ===

Patch series summary:

 * patch 1: Introduce the ivec type
 * patch 2: Create the function xdl_do_classic_diff()
 * patches 3-4: generic cleanup
 * patches 5-8: convert from dstart/dend (in xdfile_t) to
   delta_start/delta_end (in xdfenv_t)
 * patches 9-10: move xdl_cleanup_records(), and related, from xprepare.c to
   xdiffi.c

Things that will be addressed in future patch series:

 * Make xdl_cleanup_records() easier to read
 * convert recs/nrec into an ivec
 * convert changed to an ivec
 * remove reference_index/nreff from xdfile_t and turn it into an ivec
 * splitting minimal_perfect_hash out as its own ivec
 * improve the performance of the classifier and parsing/hashing lines

=== before this patch series typedef struct s_xdfile { xrecord_t *recs;
size_t nrec; ptrdiff_t dstart, dend; bool *changed; size_t *reference_index;
size_t nreff; } xdfile_t;

typedef struct s_xdfenv { xdfile_t xdf1, xdf2; } xdfenv_t;

=== after this patch series typedef struct s_xdfile { xrecord_t *recs;
size_t nrec; bool *changed; size_t *reference_index; size_t nreff; }
xdfile_t;

typedef struct s_xdfenv { xdfile_t xdf1, xdf2; size_t delta_start,
delta_end; size_t mph_size; } xdfenv_t;

Ezekiel Newren (6):
  xdiff/xdl_cleanup_records: delete local recs pointer
  xdiff: use unambiguous types in xdl_bogo_sqrt()
  xdiff/xdl_cleanup_records: use unambiguous types
  xdiff/xdl_cleanup_records: make limits more clear
  xdiff/xdl_cleanup_records: make setting action easier to follow
  xdiff/xdl_cleanup_records: simplify INVESTIGATE handling for clarity

 xdiff/xdiffi.c   |  2 +-
 xdiff/xprepare.c | 84 ++++++++++++++++++++++++++++++++----------------
 xdiff/xutils.c   |  4 +--
 xdiff/xutils.h   |  2 +-
 4 files changed, 60 insertions(+), 32 deletions(-)

base-commit: ca1db8a0f7dc0dbea892e99f5b37c5fe5861be71
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2156%2Fezekielnewren%2Fxdiff-cleanup-3-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2156/ezekielnewren/xdiff-cleanup-3-v3
Pull-Request: https://github.com/git/git/pull/2156

Range-diff vs v2:

 1:  8f9165d477 = 1:  da32a9747c xdiff/xdl_cleanup_records: delete local recs pointer
 -:  ---------- > 2:  86b0ad100c xdiff: use unambiguous types in xdl_bogo_sqrt()
 5:  a52787f019 ! 3:  39a35365ae xdiff/xdl_cleanup_records: use unambiguous types
     @@ Commit message
          xdiff/xdl_cleanup_records: use unambiguous types
      
          Change the parameters of xdl_clean_mmatch() and the local variables
     -    i, nm in xdl_cleanup_records() to use unambiguous types. Best viewed
     -    with --color-words.
     +    i, nm, mlim in xdl_cleanup_records() to use unambiguous types. Best
     +    viewed with --color-words.
      
          Signed-off-by: Ezekiel Newren <[email-masked]>
      
     @@ xdiff/xprepare.c: static bool xdl_clean_mmatch(uint8_t const *action, long i, lo
        * might be potentially discarded if they appear in a run of discardable.
        */
       static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2) {
     --	long i, nm;
     --	size_t mlim1, mlim2;
     -+	ptrdiff_t i;
     -+	size_t nm, mlim1, mlim2;
     +-	long i, nm, mlim;
     ++	ptrdiff_t i, nm, mlim;
       	xdlclass_t *rcrec;
       	uint8_t *action1 = NULL, *action2 = NULL;
       	bool need_min = !!(cf->flags & XDF_NEED_MINIMAL);
     -@@ xdiff/xprepare.c: static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xd
     - 	for (i = xdf1->dstart; i <= xdf1->dend; i++) {
     - 		size_t mph1 = xdf1->recs[i].minimal_perfect_hash;
     - 		rcrec = cf->rcrecs[mph1];
     --		nm = rcrec ? rcrec->len2 : 0;
     -+		nm = rcrec ? (size_t)rcrec->len2 : 0;
     - 		if (nm == 0)
     - 			action1[i] = DISCARD;
     - 		else if (nm < mlim1)
     -@@ xdiff/xprepare.c: static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xd
     - 	for (i = xdf2->dstart; i <= xdf2->dend; i++) {
     - 		size_t mph2 = xdf2->recs[i].minimal_perfect_hash;
     - 		rcrec = cf->rcrecs[mph2];
     --		nm = rcrec ? rcrec->len1 : 0;
     -+		nm = rcrec ? (size_t)rcrec->len1 : 0;
     - 		if (nm == 0)
     - 			action2[i] = DISCARD;
     - 		else if (nm < mlim2)
 2:  62adaa8e5a ! 4:  86dd98db9b xdiff/xdl_cleanup_records: make limits more clear
     @@ Commit message
          Signed-off-by: Ezekiel Newren <[email-masked]>
      
       ## xdiff/xprepare.c ##
     -@@ xdiff/xprepare.c: static bool xdl_clean_mmatch(uint8_t const *action, long i, long s, long e) {
     +@@ xdiff/xprepare.c: static bool xdl_clean_mmatch(uint8_t const *action, ptrdiff_t i, ptrdiff_t s, pt
        * might be potentially discarded if they appear in a run of discardable.
        */
       static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2) {
     --	long i, nm, mlim;
     -+	long i, nm;
     -+	size_t mlim1, mlim2;
     +-	ptrdiff_t i, nm, mlim;
     ++	ptrdiff_t i, nm, mlim1, mlim2;
       	xdlclass_t *rcrec;
       	uint8_t *action1 = NULL, *action2 = NULL;
       	bool need_min = !!(cf->flags & XDF_NEED_MINIMAL);
     @@ xdiff/xprepare.c: static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *
       	/*
       	 * Initialize temporary arrays with DISCARD, KEEP, or INVESTIGATE.
       	 */
     --	if ((mlim = xdl_bogosqrt((long)xdf1->nrec)) > XDL_MAX_EQLIMIT)
     +-	if ((mlim = (long)xdl_bogosqrt((uint64_t)xdf1->nrec)) > XDL_MAX_EQLIMIT)
      -		mlim = XDL_MAX_EQLIMIT;
       	for (i = xdf1->dstart; i <= xdf1->dend; i++) {
       		size_t mph1 = xdf1->recs[i].minimal_perfect_hash;
     @@ xdiff/xprepare.c: static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *
      +		action1[i] = (nm == 0) ? DISCARD: nm >= mlim1 ? INVESTIGATE: KEEP;
       	}
       
     --	if ((mlim = xdl_bogosqrt((long)xdf2->nrec)) > XDL_MAX_EQLIMIT)
     +-	if ((mlim = (long)xdl_bogosqrt((uint64_t)xdf2->nrec)) > XDL_MAX_EQLIMIT)
      -		mlim = XDL_MAX_EQLIMIT;
       	for (i = xdf2->dstart; i <= xdf2->dend; i++) {
       		size_t mph2 = xdf2->recs[i].minimal_perfect_hash;
 3:  8be7e4781a = 5:  ecc25be32f xdiff/xdl_cleanup_records: make setting action easier to follow
 4:  6abd052c34 = 6:  8f4def8814 xdiff/xdl_cleanup_records: simplify INVESTIGATE handling for clarity

-- 
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