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utf8_to_uv_msgs: Avoid extra deref pointer writes
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This function is passed an address of where to write some values.
Instead of updating the derefernced pointer each time, do it once after
all the information is accumulated.

This allows for the values to be updated without updating the pointed to
variable, so makes some case in a switch() able to be more uniform.
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@khwilliamson
khwilliamson committed Dec 4, 2024
1 parent 8195a34 commit c2009f1
Showing 1 changed file with 15 additions and 25 deletions.
40 changes: 15 additions & 25 deletions utf8.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1603,8 +1603,6 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,
UV uv;
SSize_t expectlen; /* How long should this sequence be? */
SSize_t avail_len; /* When input is too short, gives what that is */
U32 discard_errors; /* Used to save branches when 'errors' is NULL; this
gets set and discarded */

dTHX;

Expand Down Expand Up @@ -1650,14 +1648,10 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,
possible_problems = 0;
expectlen = 0;
avail_len = 0;
discard_errors = 0;

if (errors) {
*errors = 0;
}
else {
errors = &discard_errors;
}

/* Accumulate the code point translation of the input byte sequence
* s0 .. e-1, looking for malformations.
Expand Down Expand Up @@ -1986,6 +1980,7 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,

bool disallowed = FALSE;
const U32 orig_problems = possible_problems;
U32 error_flags_return = 0;

/* The following macro returns 0 if no message needs to be generated
* for this problem even if everything else says to. Otherwise returns
Expand Down Expand Up @@ -2034,6 +2029,11 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,

U32 this_flag_bit = this_problem;

/* All cases but these two set this; it makes the cases simpler
* to do it here */
error_flags_return |= this_problem & ~( UTF8_GOT_PERL_EXTENDED
|UTF8_GOT_SUPER);

/* Turn off so next iteration doesn't retry this */
possible_problems &= ~this_problem;

Expand All @@ -2056,8 +2056,6 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,
break;

case UTF8_GOT_EMPTY:
*errors |= UTF8_GOT_EMPTY;

if (! (flags & UTF8_ALLOW_EMPTY)) {

/* This so-called malformation is now treated as a bug in
Expand All @@ -2075,8 +2073,6 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,
break;

case UTF8_GOT_CONTINUATION:
*errors |= UTF8_GOT_CONTINUATION;

if (! (flags & UTF8_ALLOW_CONTINUATION)) {
disallowed = TRUE;
if (NEED_MESSAGE(WARN_UTF8,,)) {
Expand All @@ -2091,7 +2087,6 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,
break;

case UTF8_GOT_SHORT:
*errors |= UTF8_GOT_SHORT;
uv = UNICODE_REPLACEMENT;

if (! (flags & UTF8_ALLOW_SHORT)) {
Expand All @@ -2110,7 +2105,6 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,
break;

case UTF8_GOT_NON_CONTINUATION:
*errors |= UTF8_GOT_NON_CONTINUATION;
uv = UNICODE_REPLACEMENT;

if (! (flags & UTF8_ALLOW_NON_CONTINUATION)) {
Expand Down Expand Up @@ -2140,8 +2134,6 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,
* this case are true */

if (flags & UTF8_WARN_SURROGATE) {
*errors |= UTF8_GOT_SURROGATE;

if (NEED_MESSAGE(WARN_SURROGATE,,)) {
pack_warn = packWARN(WARN_SURROGATE);

Expand All @@ -2161,7 +2153,6 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,

if (flags & UTF8_DISALLOW_SURROGATE) {
disallowed = TRUE;
*errors |= UTF8_GOT_SURROGATE;
}

break;
Expand All @@ -2173,8 +2164,6 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,
* this case are true */

if (flags & UTF8_WARN_NONCHAR) {
*errors |= UTF8_GOT_NONCHAR;

if (NEED_MESSAGE(WARN_NONCHAR,,)) {
/* The code above should have guaranteed that we don't
* get here with errors other than overlong */
Expand All @@ -2188,13 +2177,11 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,

if (flags & UTF8_DISALLOW_NONCHAR) {
disallowed = TRUE;
*errors |= UTF8_GOT_NONCHAR;
}

break;

case UTF8_GOT_LONG:
*errors |= UTF8_GOT_LONG;

if (! (flags & UTF8_ALLOW_LONG_AND_ITS_VALUE)) {
uv = UNICODE_REPLACEMENT;
Expand Down Expand Up @@ -2256,17 +2243,16 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,
/* Overflow means also got a super and are using Perl's
* extended UTF-8, but we handle all three cases here */
possible_problems &= ~(UTF8_GOT_SUPER|UTF8_GOT_PERL_EXTENDED);
*errors |= UTF8_GOT_OVERFLOW;
uv = UNICODE_REPLACEMENT;

/* But the API says we flag all errors found */
if (flags & (UTF8_WARN_SUPER|UTF8_DISALLOW_SUPER)) {
*errors |= UTF8_GOT_SUPER;
error_flags_return |= UTF8_GOT_SUPER;
}
if (flags
& (UTF8_WARN_PERL_EXTENDED|UTF8_DISALLOW_PERL_EXTENDED))
{
*errors |= UTF8_GOT_PERL_EXTENDED;
error_flags_return |= UTF8_GOT_PERL_EXTENDED;
}

/* Disallow if any of the three categories say to */
Expand Down Expand Up @@ -2312,7 +2298,7 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,
* warned about */

if (flags & UTF8_WARN_SUPER) {
*errors |= UTF8_GOT_SUPER;
error_flags_return |= UTF8_GOT_SUPER;

if (NEED_MESSAGE(WARN_NON_UNICODE,,)) {
pack_warn = packWARN(WARN_NON_UNICODE);
Expand Down Expand Up @@ -2365,7 +2351,7 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,
if (flags & ( UTF8_WARN_PERL_EXTENDED
|UTF8_DISALLOW_PERL_EXTENDED))
{
*errors |= UTF8_GOT_PERL_EXTENDED;
error_flags_return |= UTF8_GOT_PERL_EXTENDED;

if (flags & UTF8_DISALLOW_PERL_EXTENDED) {
disallowed = TRUE;
Expand All @@ -2374,7 +2360,7 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,
}

if (flags & UTF8_DISALLOW_SUPER) {
*errors |= UTF8_GOT_SUPER;
error_flags_return |= UTF8_GOT_SUPER;
disallowed = TRUE;
}

Expand Down Expand Up @@ -2409,6 +2395,10 @@ Perl_utf8_to_uv_msgs_helper_(const U8 * const s0,
*advance_p = curlen;
}

if (errors) {
*errors = error_flags_return;
}

if (disallowed) {
success = false;
uv = UNICODE_REPLACEMENT;
Expand Down

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