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Fix JIT tier-up from within loops for already-JIT-compiled functions

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* libguile/jit.c (scm_jit_compute_mcode): If a caller wants mcode for a
  loop but the function already has mcode, instead of punting, just
  compile again.
This commit is contained in:
Andy Wingo 2019-12-08 21:44:47 +01:00
parent d14e8fabb3
commit a1e88ebc12
1 changed files with 32 additions and 28 deletions
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22
libguile/jit.c
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@ -4916,15 +4916,20 @@ scm_jit_compute_mcode (scm_thread *thread, struct scm_jit_function_data *data)
if (vcode_start == thread->vm.ip) if (vcode_start == thread->vm.ip)
return data->mcode; return data->mcode;
/* FIXME: The function has mcode, compiled via some other /* The function has mcode, compiled via some other activation
activation (possibly in another thread), but right now we're (possibly in another thread), but right now we're currently in
currently in an interpreted loop (not at the beginning of the an interpreted loop (not at the beginning of the function). It
function). We should re-compute the offset into the mcode. would be nice if we could jump into the already-compiled
For now though, just punt. */ function, but we don't know the offset. You'd think we could
return NULL; just compile again without writing bytes to find out the offset
into the old code, but we're not guaranteed to get the same
compiled code, for example due to variations on whether direct
callees have mcode at the time of the compile, or different
encodings for relative references. So oh well: we're just
going to compile another copy and update the mcode pointer,
hoping this is a rare occurence. */
} }
else
{
uint8_t *mcode = compute_mcode (thread, thread->vm.ip, data); uint8_t *mcode = compute_mcode (thread, thread->vm.ip, data);
if (!mcode) if (!mcode)
@ -4947,7 +4952,6 @@ scm_jit_compute_mcode (scm_thread *thread, struct scm_jit_function_data *data)
return mcode; return mcode;
} }
}
void void
scm_jit_enter_mcode (scm_thread *thread, const uint8_t *mcode) scm_jit_enter_mcode (scm_thread *thread, const uint8_t *mcode)