Re: [PATCH v3 05/10] xdiff: delete struct diffdata_t
- From
- Phillip Wood <phillip.wood123@gmail.com>
- Date
- Sep 21, 2025, 13:06 UTC
- Message-ID
- <7979d8f5-1e97-4429-891a-678adb3ba54f@gmail.com>
- In-Reply-To
- <807ce3e5aae0253dd58c7a4d0bd04ca341b070c8.1758294992.git.gitgitgadget@gmail.com>
Hi Ezekiel
On 19/09/2025 16:16, Ezekiel Newren via GitGitGadget wrote:
Show 8 quoted lines
> From: Ezekiel Newren <ezekielnewren@gmail.com> > > Every field in this struct is an alias for a certain field in xdfile_t. > > diffdata_t.nrec -> xdfile_t.nreff > diffdata_t.ha -> xdfile_t.ha > diffdata_t.rindex -> xdfile_t.rindex > diffdata_t.rchg -> xdfile_t.rchg
That explains some of the changes here (so long as one assumes the aliasing is a bad thing) but it does not explain why it is a good idea to remove the local variables rchg[12] and rindex[12] and instead dereference xdf[12] inside the loops
Thanks
Phillip
Show 111 quoted lines
> Signed-off-by: Ezekiel Newren <ezekielnewren@gmail.com>
> ---
> xdiff/xdiffi.c | 32 ++++++++------------------------
> xdiff/xdiffi.h | 11 ++---------
> 2 files changed, 10 insertions(+), 33 deletions(-)
>
> diff --git a/xdiff/xdiffi.c b/xdiff/xdiffi.c
> index 5a96e36dfb..bbf0161f84 100644
> --- a/xdiff/xdiffi.c
> +++ b/xdiff/xdiffi.c
> @@ -257,10 +257,10 @@ static long xdl_split(unsigned long const *ha1, long off1, long lim1,
> * sub-boxes by calling the box splitting function. Note that the real job
> * (marking changed lines) is done in the two boundary reaching checks.
> */
> -int xdl_recs_cmp(diffdata_t *dd1, long off1, long lim1,
> - diffdata_t *dd2, long off2, long lim2,
> +int xdl_recs_cmp(xdfile_t *xdf1, long off1, long lim1,
> + xdfile_t *xdf2, long off2, long lim2,
> long *kvdf, long *kvdb, int need_min, xdalgoenv_t *xenv) {
> - unsigned long const *ha1 = dd1->ha, *ha2 = dd2->ha;
> + unsigned long const *ha1 = xdf1->ha, *ha2 = xdf2->ha;
>
> /*
> * Shrink the box by walking through each diagonal snake (SW and NE).
> @@ -273,17 +273,11 @@ int xdl_recs_cmp(diffdata_t *dd1, long off1, long lim1,
> * be obviously changed.
> */
> if (off1 == lim1) {
> - char *rchg2 = dd2->rchg;
> - long *rindex2 = dd2->rindex;
> -
> for (; off2 < lim2; off2++)
> - rchg2[rindex2[off2]] = 1;
> + xdf2->rchg[xdf2->rindex[off2]] = 1;
> } else if (off2 == lim2) {
> - char *rchg1 = dd1->rchg;
> - long *rindex1 = dd1->rindex;
> -
> for (; off1 < lim1; off1++)
> - rchg1[rindex1[off1]] = 1;
> + xdf1->rchg[xdf1->rindex[off1]] = 1;
> } else {
> xdpsplit_t spl;
> spl.i1 = spl.i2 = 0;
> @@ -300,9 +294,9 @@ int xdl_recs_cmp(diffdata_t *dd1, long off1, long lim1,
> /*
> * ... et Impera.
> */
> - if (xdl_recs_cmp(dd1, off1, spl.i1, dd2, off2, spl.i2,
> + if (xdl_recs_cmp(xdf1, off1, spl.i1, xdf2, off2, spl.i2,
> kvdf, kvdb, spl.min_lo, xenv) < 0 ||
> - xdl_recs_cmp(dd1, spl.i1, lim1, dd2, spl.i2, lim2,
> + xdl_recs_cmp(xdf1, spl.i1, lim1, xdf2, spl.i2, lim2,
> kvdf, kvdb, spl.min_hi, xenv) < 0) {
>
> return -1;
> @@ -318,7 +312,6 @@ int xdl_do_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
> long ndiags;
> long *kvd, *kvdf, *kvdb;
> xdalgoenv_t xenv;
> - diffdata_t dd1, dd2;
> int res;
>
> if (xdl_prepare_env(mf1, mf2, xpp, xe) < 0)
> @@ -357,16 +350,7 @@ int xdl_do_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
> xenv.snake_cnt = XDL_SNAKE_CNT;
> xenv.heur_min = XDL_HEUR_MIN_COST;
>
> - dd1.nrec = xe->xdf1.nreff;
> - dd1.ha = xe->xdf1.ha;
> - dd1.rchg = xe->xdf1.rchg;
> - dd1.rindex = xe->xdf1.rindex;
> - dd2.nrec = xe->xdf2.nreff;
> - dd2.ha = xe->xdf2.ha;
> - dd2.rchg = xe->xdf2.rchg;
> - dd2.rindex = xe->xdf2.rindex;
> -
> - res = xdl_recs_cmp(&dd1, 0, dd1.nrec, &dd2, 0, dd2.nrec,
> + res = xdl_recs_cmp(&xe->xdf1, 0, xe->xdf1.nreff, &xe->xdf2, 0, xe->xdf2.nreff,
> kvdf, kvdb, (xpp->flags & XDF_NEED_MINIMAL) != 0,
> &xenv);
> xdl_free(kvd);
> diff --git a/xdiff/xdiffi.h b/xdiff/xdiffi.h
> index 126c9d8ff4..49e52c67f9 100644
> --- a/xdiff/xdiffi.h
> +++ b/xdiff/xdiffi.h
> @@ -24,13 +24,6 @@
> #define XDIFFI_H
>
>
> -typedef struct s_diffdata {
> - long nrec;
> - unsigned long const *ha;
> - long *rindex;
> - char *rchg;
> -} diffdata_t;
> -
> typedef struct s_xdalgoenv {
> long mxcost;
> long snake_cnt;
> @@ -46,8 +39,8 @@ typedef struct s_xdchange {
>
>
>
> -int xdl_recs_cmp(diffdata_t *dd1, long off1, long lim1,
> - diffdata_t *dd2, long off2, long lim2,
> +int xdl_recs_cmp(xdfile_t *xdf1, long off1, long lim1,
> + xdfile_t *xdf2, long off2, long lim2,
> long *kvdf, long *kvdb, int need_min, xdalgoenv_t *xenv);
> int xdl_do_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
> xdfenv_t *xe);