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--- rfc:jit [2019/02/13 09:07] – dmitry
+++ rfc:jit [2019/02/22 12:08] – Compatibility with C compilers without GCC explicit global register variables extension dmitry
@@ Line 402: / Line 402: @@
 ===== State and compatibility =====
-Currently we support only x86 and x86_64 non-ZTS builds on POSIX platforms (tested on Linux).
+Currently we only support x86 and x86_64 non-ZTS builds on POSIX platforms (tested on Linux).
-We support only "Hybrid VM" that requires C compiler with GCC extensions (labels as values and explicit global register variables). Unfortunately, LLVM doesn't support the second feature and MSVC - both.
+We support "Hybrid" and "Call" VM with and without GCC explicit global register variables extension.
+There is no any restriction on C compiler any more. LLVM build works fine. Anatol Belski is going to work on Windows support.
-ZTS support is not a big problem, but it should be implemented after ZTS improvement described at [[https://wiki.php.net/zts-improvement|https://wiki.php.net/zts-improvement]]
+ZTS support is doable and shouldn't be very difficult, but should be implemented once the ZTS improvements described at [[https://wiki.php.net/zts-improvement|https://wiki.php.net/zts-improvement]] are done.
-LLVM and MSVC are not supported yet. Without JIT, bench.php is about 2 times faster on PHP built with GCC, then with LLVM or MSVC. LLVM and MSVC reqiure support for "Call VM" (it's implemented, but wasn't tested for a while) and additional code for opcode handlers argument passing and FP/IP register reloading (to emulate register variables and reuse existing code-generator). Windows support might also require adoption to different calling convention.
+Windows is not currently supported. At least 64-bit Windows implementation requires adopting to a different calling convention.
-Alternative way to support all platforms and C compilers is generating low-level VM (using the same JIT framework). This VM won't depend on C compiler extensions, and going to be comptible with JIT out of the box. As a side effect, interpretation should also became faster. This approach is used in JVM template VM, low level WebKit interpreter, V8 ignition interpreter, LuaJIT interpreter. Low-level VM may be implemented in PHP-8, in addition to existing interpreter written in C.
 ===== Open Issues =====

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