Bug #19267: Compile fails when enabling YJIT on x64-mingw-ucrt

• Status: Feedback
• Assignee: -
• Target version: -
• ruby -v: ruby 3.1.3p185 (2022-11-24 revision 1a6b16756e) [x64-mingw-ucrt]
• Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN

[cfis (Charlie Savage)]

Ruby fails to compile with msys2/ucrt64 when enabling yjit.

Error:

In file included from ./include/ruby/defines.h:72,
                 from ./include/ruby/ruby.h:25,
                 from eval_intern.h:4,
                 from vm.c:13:
vm.c: In function 'mjit_check_iseq':
vm.c:393:12: warning: implicit declaration of function 'MJIT_FUNC_STATE_P' [-Wimplicit-function-declaration]
  393 |     ASSUME(MJIT_FUNC_STATE_P(mjit_state));
      |            ^~~~~~~~~~~~~~~~~
./include/ruby/backward/2/assume.h:43:46: note: in definition of macro 'RB_LIKELY'
   43 | # define RB_LIKELY(x)   (__builtin_expect(!!(x), 1))
      |                                              ^
./include/ruby/backward/2/assume.h:27:28: note: in expansion of macro 'RBIMPL_ASSUME'
   27 | #define ASSUME             RBIMPL_ASSUME             /**< @old{RBIMPL_ASSUME} */
      |                            ^~~~~~~~~~~~~
vm.c:393:5: note: in expansion of macro 'ASSUME'
  393 |     ASSUME(MJIT_FUNC_STATE_P(mjit_state));
      |     ^~~~~~
vm.c:394:19: error: conversion to incomplete type
  394 |     switch ((enum rb_mjit_func_state)mjit_state) {
      |                   ^~~~~~~~~~~~~~~~~~
vm.c:395:12: error: 'MJIT_FUNC_NOT_COMPILED' undeclared (first use in this function)
  395 |       case MJIT_FUNC_NOT_COMPILED:

The problem:

In ruby-3.2.0.ext\include\x64-mingw-ucrt\ruby\config.h

#define USE_MJIT 0
#define USE_YJIT 1

But in mjit.h:

# if USE_MJIT
...
// Return true if jit_func is part of enum rb_mjit_func_state
#define MJIT_FUNC_STATE_P(jit_func) ((uintptr_t)(jit_func) <= (uintptr_t)MJIT_FUNC_FAILED)
...
# end

So MJIT_FUNC_STATE_P is never defined.

Then in vm.c:

#if USE_MJIT || USE_YJIT
# ifdef MJIT_HEADER
NOINLINE(static COLDFUNC VALUE mjit_check_iseq(rb_execution_context_t *ec, const rb_iseq_t *iseq, struct rb_iseq_constant_body *body));
# else
static inline VALUE mjit_check_iseq(rb_execution_context_t *ec, const rb_iseq_t *iseq, struct rb_iseq_constant_body *body);
# endif
static VALUE
mjit_check_iseq(rb_execution_context_t *ec, const rb_iseq_t *iseq, struct rb_iseq_constant_body *body)
{
    uintptr_t mjit_state = (uintptr_t)(body->jit_func);
    ASSUME(MJIT_FUNC_STATE_P(mjit_state));
 etc

Note that MJIT_HEADER is not defined.

Note this is just the first of many errors that you will encounter.

To get Ruby 3.2.0 to compile, I had to do a significant rearrangement of mjit.h which I have attached.

However, when yjit.c then compiles:

yjit.c: In function 'rb_yjit_mark_unused':
yjit.c:93:5: warning: implicit declaration of function 'madvise'; did you mean 'raise'? [-Wimplicit-function-declaratio
]
   93 |     madvise(mem_block, mem_size, MADV_DONTNEED);
      |     ^~~~~~~
      |     raise
yjit.c:93:34: error: 'MADV_DONTNEED' undeclared (first use in this function)
   93 |     madvise(mem_block, mem_size, MADV_DONTNEED);

This is because the check in yjit.c (line 32) is:

// For mmapp(), sysconf()
#if defined _WIN32
#include <unistd.h>
#include <sys/mman.h>
#endif

UCRT doesn't define _WIN32, it defines _WIN64

However, then the next issue - there is no sys/mman.h header with mingw.

So enabling yjit on mingw breaks the compile and is apparently unsupported.

[k0kubun (Takashi Kokubun)]

• Status changed from Open to Feedback

https://github.com/ruby/ruby/blob/master/doc/yjit/yjit.md
It currently only supports macOS and Linux on x86-64 and arm64/aarch64 CPUs.

I'm not sure if YJIT supports msys2/ucrt64. If you manually passed --enable-yjit to ./configure (./configure does that automatically for supported platforms when rustc 1.58.0+ is available), you might want to stop doing so until the platform gets supported.

[cfis (Charlie Savage)]

Yes, I will disable yjit.