131b862ac0
Commit a21195650e added a TSRM destructor, but that destructor
will get called by tsrm_shutdown(), which is after opcache.so has
already been unloaded, resulting in a shutdown crash, e.g.:
#0 0x00007fad01737500 in ?? ()
#1 0x000055ac54e723c4 in tsrm_shutdown () at TSRM/TSRM.c:194
#2 0x000055ac54c42180 in main (argc=80, argv=0x55ac57bc14d0) at sapi/cli/php_cli.c:1388
By calling ts_free_id() before opcache.so gets unloaded, we can easily
fix this crash bug.
Opcache JIT
This is the implementation of Opcache's JIT (Just-In-Time compiler), This converts the PHP Virtual Machine's opcodes into x64/x86 assembly, on POSIX platforms and Windows.
It generates native code directly from PHP byte-code and information collected by the SSA static analysis framework (a part of the opcache optimizer). Code is usually generated separately for each PHP byte-code instruction. Only a few combinations are considered together (e.g. compare + conditional jump).
See the JIT RFC for more details.
DynAsm
This uses DynAsm (developed for LuaJIT project) for the generation of native code. It's a very lightweight and advanced tool, but does assume good, and very low-level development knowledge of target assembler languages. In the past we tried LLVM, but its code generation speed was almost 100 times slower, making it prohibitively expensive to use.
The unofficial DynASM Documentation has a tutorial, reference, and instruction listing.
zend_jit_x86.dasc gets automatically converted to zend_jit_x86.c by the bundled
dynasm during make.