Subject: Re: [PATCH 05/10] xdiff: use xdfenv_t in xdl_trim_ends() and xdl_cleanup_records()

From: Phillip Wood <[email-masked]>
Date: Tue, 20 Jan 2026 16:32:01 +0000

On 02/01/2026 18:52, Ezekiel Newren via GitGitGadget wrote:
> From: Ezekiel Newren <[email-masked]>
> 
> View with --color-words. Prepare these functions to use the fields:
> delta_start, delta_end. A future patch will add these fields to
> xdfenv_t.

I'm afraid this message doesn't make much sense to me. What are these 
new fields? I think it would help to explain what this up comming change 
is going to do and why.

Oh, having read patch 7 we're removing dstart and dend from xdfile_t and 
replacing them with delta_start and delta_end in xdfenv_t. It would be 
useful to say that here.
> -static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2) {
> +static int xdl_cleanup_records(xdlclassifier_t *cf, xdfenv_t *xe) {

Maybe we could add xdf1 and xdf2 as local variables to avoid having to 
change the code that accesses the members of xdfile_t that are not going 
to be moved to xdfenv_t.

Thanks

Phillip

>   	long i, nm, mlim;
>   	xrecord_t *recs;
>   	xdlclass_t *rcrec;
> @@ -273,11 +273,11 @@ static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xd
>   	 * Create temporary arrays that will help us decide if
>   	 * changed[i] should remain false, or become true.
>   	 */
> -	if (!XDL_CALLOC_ARRAY(action1, xdf1->nrec + 1)) {
> +	if (!XDL_CALLOC_ARRAY(action1, xe->xdf1.nrec + 1)) {
>   		ret = -1;
>   		goto cleanup;
>   	}
> -	if (!XDL_CALLOC_ARRAY(action2, xdf2->nrec + 1)) {
> +	if (!XDL_CALLOC_ARRAY(action2, xe->xdf2.nrec + 1)) {
>   		ret = -1;
>   		goto cleanup;
>   	}
> @@ -285,17 +285,17 @@ static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xd
>   	/*
>   	 * Initialize temporary arrays with DISCARD, KEEP, or INVESTIGATE.
>   	 */
> -	if ((mlim = xdl_bogosqrt((long)xdf1->nrec)) > XDL_MAX_EQLIMIT)
> +	if ((mlim = xdl_bogosqrt((long)xe->xdf1.nrec)) > XDL_MAX_EQLIMIT)
>   		mlim = XDL_MAX_EQLIMIT;
> -	for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
> +	for (i = xe->xdf1.dstart, recs = &xe->xdf1.recs[xe->xdf1.dstart]; i <= xe->xdf1.dend; i++, recs++) {
>   		rcrec = cf->rcrecs[recs->minimal_perfect_hash];
>   		nm = rcrec ? rcrec->len2 : 0;
>   		action1[i] = (nm == 0) ? DISCARD: (nm >= mlim && !need_min) ? INVESTIGATE: KEEP;
>   	}
>   
> -	if ((mlim = xdl_bogosqrt((long)xdf2->nrec)) > XDL_MAX_EQLIMIT)
> +	if ((mlim = xdl_bogosqrt((long)xe->xdf2.nrec)) > XDL_MAX_EQLIMIT)
>   		mlim = XDL_MAX_EQLIMIT;
> -	for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
> +	for (i = xe->xdf2.dstart, recs = &xe->xdf2.recs[xe->xdf2.dstart]; i <= xe->xdf2.dend; i++, recs++) {
>   		rcrec = cf->rcrecs[recs->minimal_perfect_hash];
>   		nm = rcrec ? rcrec->len1 : 0;
>   		action2[i] = (nm == 0) ? DISCARD: (nm >= mlim && !need_min) ? INVESTIGATE: KEEP;
> @@ -305,27 +305,27 @@ static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xd
>   	 * Use temporary arrays to decide if changed[i] should remain
>   	 * false, or become true.
>   	 */
> -	xdf1->nreff = 0;
> -	for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
> -	     i <= xdf1->dend; i++, recs++) {
> +	xe->xdf1.nreff = 0;
> +	for (i = xe->xdf1.dstart, recs = &xe->xdf1.recs[xe->xdf1.dstart];
> +	     i <= xe->xdf1.dend; i++, recs++) {
>   		if (action1[i] == KEEP ||
> -		    (action1[i] == INVESTIGATE && !xdl_clean_mmatch(action1, i, xdf1->dstart, xdf1->dend))) {
> -			xdf1->reference_index[xdf1->nreff++] = i;
> +		    (action1[i] == INVESTIGATE && !xdl_clean_mmatch(action1, i, xe->xdf1.dstart, xe->xdf1.dend))) {
> +			xe->xdf1.reference_index[xe->xdf1.nreff++] = i;
>   			/* changed[i] remains false, i.e. keep */
>   		} else
> -			xdf1->changed[i] = true;
> +			xe->xdf1.changed[i] = true;
>   			/* i.e. discard */
>   	}
>   
> -	xdf2->nreff = 0;
> -	for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];
> -	     i <= xdf2->dend; i++, recs++) {
> +	xe->xdf2.nreff = 0;
> +	for (i = xe->xdf2.dstart, recs = &xe->xdf2.recs[xe->xdf2.dstart];
> +	     i <= xe->xdf2.dend; i++, recs++) {
>   		if (action2[i] == KEEP ||
> -		    (action2[i] == INVESTIGATE && !xdl_clean_mmatch(action2, i, xdf2->dstart, xdf2->dend))) {
> -			xdf2->reference_index[xdf2->nreff++] = i;
> +		    (action2[i] == INVESTIGATE && !xdl_clean_mmatch(action2, i, xe->xdf2.dstart, xe->xdf2.dend))) {
> +			xe->xdf2.reference_index[xe->xdf2.nreff++] = i;
>   			/* changed[i] remains false, i.e. keep */
>   		} else
> -			xdf2->changed[i] = true;
> +			xe->xdf2.changed[i] = true;
>   			/* i.e. discard */
>   	}
>   
> @@ -340,27 +340,27 @@ cleanup:
>   /*
>    * Early trim initial and terminal matching records.
>    */
> -static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2) {
> +static int xdl_trim_ends(xdfenv_t *xe) {
>   	long i, lim;
>   	xrecord_t *recs1, *recs2;
>   
> -	recs1 = xdf1->recs;
> -	recs2 = xdf2->recs;
> -	for (i = 0, lim = (long)XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;
> +	recs1 = xe->xdf1.recs;
> +	recs2 = xe->xdf2.recs;
> +	for (i = 0, lim = (long)XDL_MIN(xe->xdf1.nrec, xe->xdf2.nrec); i < lim;
>   	     i++, recs1++, recs2++)
>   		if (recs1->minimal_perfect_hash != recs2->minimal_perfect_hash)
>   			break;
>   
> -	xdf1->dstart = xdf2->dstart = i;
> +	xe->xdf1.dstart = xe->xdf2.dstart = i;
>   
> -	recs1 = xdf1->recs + xdf1->nrec - 1;
> -	recs2 = xdf2->recs + xdf2->nrec - 1;
> +	recs1 = xe->xdf1.recs + xe->xdf1.nrec - 1;
> +	recs2 = xe->xdf2.recs + xe->xdf2.nrec - 1;
>   	for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)
>   		if (recs1->minimal_perfect_hash != recs2->minimal_perfect_hash)
>   			break;
>   
> -	xdf1->dend = (long)xdf1->nrec - i - 1;
> -	xdf2->dend = (long)xdf2->nrec - i - 1;
> +	xe->xdf1.dend = (long)xe->xdf1.nrec - i - 1;
> +	xe->xdf2.dend = (long)xe->xdf2.nrec - i - 1;
>   
>   	return 0;
>   }
> @@ -393,10 +393,10 @@ int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
>   		xdl_classify_record(2, &cf, rec);
>   	}
>   
> -	xdl_trim_ends(&xe->xdf1, &xe->xdf2);
> +	xdl_trim_ends(xe);
>   	if ((XDF_DIFF_ALG(xpp->flags) != XDF_PATIENCE_DIFF) &&
>   	    (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF) &&
> -	    xdl_cleanup_records(&cf, &xe->xdf1, &xe->xdf2) < 0) {
> +	    xdl_cleanup_records(&cf, xe) < 0) {
>   
>   		xdl_free_ctx(&xe->xdf2);
>   		xdl_free_ctx(&xe->xdf1);