Zitat: But Nicolás Álvarez, who was also hanging out in the channel, asked whether PHP has a JIT engine. I answered that it doesn't (yet), and then the light bulb went off: Although PHP itself does not have a JIT, the PCRE regular expression engine that PHP uses does. After disabling PCRE's JIT with -dpcre.jit=0, the Valgrind output is now what I expect—with just the memory error that I thought was happening: