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Speed up replace-region-contents memory allocation

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* src/editfns.c (Freplace_region_contents):
Coalesce three SAFE_ALLOCAs into one.
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Paul Eggert 2026-06-06 12:28:17 -07:00 committed by Pip Cet
parent 565639eb32
commit 09047cde59
1 changed files with 13 additions and 6 deletions
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19
src/editfns.c
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@ -2068,17 +2068,20 @@ a buffer or a string. But this is deprecated. */)
specpdl_ref count = SPECPDL_INDEX (); specpdl_ref count = SPECPDL_INDEX ();
ptrdiff_t diags = size_a + size_b + 3; ptrdiff_t diags = size_a + size_b + 3;
ptrdiff_t bytes_per_diag = 2 * sizeof (ptrdiff_t) + sizeof (int);
ptrdiff_t surplus_char_bytes = 3 * sizeof (int);
ptrdiff_t align_bytes = (alignof (ptrdiff_t) < alignof (int)
? alignof (int) - alignof (ptrdiff_t) : 0);
ptrdiff_t del_bytes = size_a / CHAR_BIT + 1; ptrdiff_t del_bytes = size_a / CHAR_BIT + 1;
ptrdiff_t ins_bytes = size_b / CHAR_BIT + 1; ptrdiff_t ins_bytes = size_b / CHAR_BIT + 1;
ptrdiff_t *buffer; ptrdiff_t *buffer;
ptrdiff_t bytes_needed; ptrdiff_t bytes_needed;
if (ckd_mul (&bytes_needed, diags, 2 * sizeof *buffer) if (ckd_mul (&bytes_needed, diags, bytes_per_diag)
|| ckd_add (&bytes_needed, bytes_needed, del_bytes + ins_bytes)) || ckd_add (&bytes_needed, bytes_needed,
align_bytes - surplus_char_bytes + del_bytes + ins_bytes))
memory_full_up (); memory_full_up ();
USE_SAFE_ALLOCA; USE_SAFE_ALLOCA;
buffer = SAFE_ALLOCA (bytes_needed); buffer = SAFE_ALLOCA (bytes_needed);
unsigned char *deletions_insertions = memset (buffer + 2 * diags, 0,
del_bytes + ins_bytes);
/* The rest of the code is not prepared to handle a string SOURCE. */ /* The rest of the code is not prepared to handle a string SOURCE. */
if (!b) if (!b)
@ -2094,16 +2097,20 @@ a buffer or a string. But this is deprecated. */)
/* Copy the characters to arrays of C integers. This speeds up /* Copy the characters to arrays of C integers. This speeds up
comparison dramatically in multibyte buffers. */ comparison dramatically in multibyte buffers. */
int *chars_a = SAFE_ALLOCA (sizeof (chars_a[0]) * size_a); int *chars_a = (int *) (((uintptr_t) (buffer + 2 * diags) + align_bytes)
& ~align_bytes);
for (ptrdiff_t p = min_a; p < min_a + size_a; p++) for (ptrdiff_t p = min_a; p < min_a + size_a; p++)
chars_a[p - min_a] chars_a[p - min_a]
= BUF_FETCH_CHAR_AS_MULTIBYTE (a, buf_charpos_to_bytepos (a, p)); = BUF_FETCH_CHAR_AS_MULTIBYTE (a, buf_charpos_to_bytepos (a, p));
int *chars_b = SAFE_ALLOCA (sizeof (chars_b[0]) * size_b); int *chars_b = chars_a + size_a;
for (ptrdiff_t p = min_b; p < min_b + size_b; p++) for (ptrdiff_t p = min_b; p < min_b + size_b; p++)
chars_b[p - min_b] chars_b[p - min_b]
= BUF_FETCH_CHAR_AS_MULTIBYTE (b, buf_charpos_to_bytepos (b, p)); = BUF_FETCH_CHAR_AS_MULTIBYTE (b, buf_charpos_to_bytepos (b, p));
unsigned char *deletions_insertions = memset (chars_b + size_b, 0,
del_bytes + ins_bytes);
/* FIXME: It is not documented how to initialize the contents of the /* FIXME: It is not documented how to initialize the contents of the
context structure. This code cargo-cults from the existing context structure. This code cargo-cults from the existing
caller in src/analyze.c of GNU Diffutils, which appears to caller in src/analyze.c of GNU Diffutils, which appears to