zend_compile: Add support for `%d` to `sprintf()` optimization (#14561)

* zend_compile: Rename `string_placeholder_count` to `placeholder_count` in `zend_compile_func_sprintf()`

Thi

zend_compile: Add support for `%d` to `sprintf()` optimization (#14561)

* zend_compile: Rename `string_placeholder_count` to `placeholder_count` in `zend_compile_func_sprintf()`

This is intended to make the diff of a follow-up commit smaller.

* zend_compile: Add support for `%d` to `sprintf()` optimization

This extends the existing `sprintf()` optimization by support for the `%d`
placeholder, which effectively equivalent to an `(int)` cast followed by a
`(string)` cast.

For a synthetic test using:

<?php

$a = 'foo';
$b = 42;

for ($i = 0; $i < 100_000_000; $i++) {
sprintf("%s-%d", $a, $b);
}

This optimization yields a 1.3× performance improvement:

$ hyperfine 'sapi/cli/php -d zend_extension=php-src/modules/opcache.so -d opcache.enable_cli=1 test.php' \
'/tmp/unoptimized -d zend_extension=php-src/modules/opcache.so -d opcache.enable_cli=1 test.php'
Benchmark 1: sapi/cli/php -d zend_extension=php-src/modules/opcache.so -d opcache.enable_cli=1 test.php
Time (mean ± σ): 3.296 s ± 0.094 s [User: 3.287 s, System: 0.005 s]
Range (min … max): 3.213 s … 3.527 s 10 runs

Benchmark 2: /tmp/unoptimized -d zend_extension=php-src/modules/opcache.so -d opcache.enable_cli=1 test.php
Time (mean ± σ): 4.300 s ± 0.025 s [User: 4.290 s, System: 0.007 s]
Range (min … max): 4.266 s … 4.334 s 10 runs

Summary
sapi/cli/php -d zend_extension=php-src/modules/opcache.so -d opcache.enable_cli=1 test.php ran
1.30 ± 0.04 times faster than /tmp/unoptimized -d zend_extension=php-src/modules/opcache.so -d opcache.enable_cli=1 test.php

* Fix sprintf_rope_optimization_003.phpt test expecation for 32-bit integers

* zend_compile: Indent switch-case labels in zend_compile_func_sprintf()

* Add GMP test to sprintf() rope optimization

* Add `%s` test case to sprintf() GMP test

show more ...