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Fix replace-region-contents performance bug

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* src/editfns.c (rbc_quitcounter): Remove; the quitcounter
is now part of the context.
(EXTRA_CONTEXT_FIELDS): Remove unused member early_abort_tests.
Add jmp, quitcounter.
(Freplace_buffer_contents): Use setjmp/longjmp to recover from
a compareseq that runs too long.  Omit unnecessary rarely_quit
call.
(buffer_chars_equal): Occasionally check for early abort and
longjmp out if so (Bug#43016).
This commit is contained in:
Paul Eggert 2020-08-24 13:12:51 -07:00
parent 519fc10f12
commit 08a6d14e41
1 changed files with 15 additions and 16 deletions
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31
src/editfns.c
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@ -1877,9 +1877,6 @@ determines whether case is significant or ignored. */)
#undef EQUAL
#define USE_HEURISTIC
/* Counter used to rarely_quit in replace-buffer-contents. */
static unsigned short rbc_quitcounter;
#define XVECREF_YVECREF_EQUAL(ctx, xoff, yoff) \
buffer_chars_equal ((ctx), (xoff), (yoff))
@ -1900,7 +1897,8 @@ static unsigned short rbc_quitcounter;
unsigned char *deletions; \
unsigned char *insertions; \
struct timespec time_limit; \
unsigned int early_abort_tests;
sys_jmp_buf jmp; \
unsigned short quitcounter;
#define NOTE_DELETE(ctx, xoff) set_bit ((ctx)->deletions, (xoff))
#define NOTE_INSERT(ctx, yoff) set_bit ((ctx)->insertions, (yoff))
@ -2029,14 +2027,17 @@ nil. */)
.heuristic = true,
.too_expensive = XFIXNUM (max_costs),
.time_limit = time_limit,
.early_abort_tests = 0
};
memclear (ctx.deletions, del_bytes);
memclear (ctx.insertions, ins_bytes);
/* compareseq requires indices to be zero-based. We add BEGV back
later. */
bool early_abort = compareseq (0, size_a, 0, size_b, false, &ctx);
bool early_abort;
if (! sys_setjmp (ctx.jmp))
early_abort = compareseq (0, size_a, 0, size_b, false, &ctx);
else
early_abort = true;
if (early_abort)
{
@ -2046,8 +2047,6 @@ nil. */)
return Qnil;
}
rbc_quitcounter = 0;
Fundo_boundary ();
bool modification_hooks_inhibited = false;
record_unwind_protect_excursion ();
@ -2071,8 +2070,7 @@ nil. */)
walk backwards, we don’t have to keep the positions in sync. */
while (i >= 0 || j >= 0)
{
/* Allow the user to quit if this gets too slow. */
rarely_quit (++rbc_quitcounter);
rarely_quit (++ctx.quitcounter);
/* Check whether there is a change (insertion or deletion)
before the current position. */
@ -2087,8 +2085,6 @@ nil. */)
while (j > 0 && bit_is_set (ctx.insertions, j - 1))
--j;
rarely_quit (rbc_quitcounter++);
ptrdiff_t beg_a = min_a + i;
ptrdiff_t beg_b = min_b + j;
eassert (beg_a <= end_a);
@ -2108,7 +2104,6 @@ nil. */)
}
SAFE_FREE_UNBIND_TO (count, Qnil);
rbc_quitcounter = 0;
if (modification_hooks_inhibited)
{
@ -2155,12 +2150,16 @@ static bool
buffer_chars_equal (struct context *ctx,
ptrdiff_t pos_a, ptrdiff_t pos_b)
{
if (!++ctx->quitcounter)
{
maybe_quit ();
if (compareseq_early_abort (ctx))
sys_longjmp (ctx->jmp, 1);
}
pos_a += ctx->beg_a;
pos_b += ctx->beg_b;
/* Allow the user to escape out of a slow compareseq call. */
rarely_quit (++rbc_quitcounter);
ptrdiff_t bpos_a =
ctx->a_unibyte ? pos_a : buf_charpos_to_bytepos (ctx->buffer_a, pos_a);
ptrdiff_t bpos_b =