JIT: SIGFPE on $x % -1 with a constant -1 divisor when $x is PHP_INT_MIN (opcache.jit=function) #24390

With the JIT enabled, PHP_INT_MIN % -1 (literal -1 divisor) kills the process with SIGFPE instead of returning 0.

<?php
function f($x) { return $x % -1; }
var_dump(f(PHP_INT_MIN));

php -n -d opcache.enable_cli=1 -d opcache.file_update_protection=0 -d opcache.jit_buffer_size=64M -d opcache.jit=function input.php

On a release build the process exits with signal 8 (exit status 136) and prints nothing. On an ASan build:

AddressSanitizer:DEADLYSIGNAL
==2435==ERROR: AddressSanitizer: FPE on unknown address 0x000049aecd40 (pc 0x000049aecd40 bp 0x7ffc40bb7b80 sp 0x7ffc40bb78f0 T0)
    #0 0x49aecd40  (/dev/zero (deleted)+0x8000d40)
SUMMARY: AddressSanitizer: FPE (/dev/zero (deleted)+0x8000d40)

Expected int(0): that is what the interpreter prints, and mod_function in Zend/zend_operators.c special-cases a divisor of -1.

Reproduces on master at 5ccc56b with both an ASan build and a release build.

Looks like the constant-divisor branch for ZEND_MOD in zend_jit_long_math_helper (ext/opcache/jit/zend_jit_ir.c) emits a plain idiv by -1, which traps when the dividend is ZEND_LONG_MIN; the non-constant branch has a guard for this case.

The trigger came from a generated test, not from a real program. I can send a patch if that helps.

Found with an LLM-based testing tool; I used Claude to reduce it and look for the cause.