The motivation for this change is that SCM_MAKE_CHAR is sometimes passed
an expression that involves a procedure call that is not always trivial.
In other cases, the results are not guaranteed to be the same both
times, which could lead to the creation of invalid SCM objects.
* libguile/chars.h (SCM_MAKE_CHAR): Reimplement.
* libguile/scmsigs.c (signal_delivery_thread): Call scm_async_tick to
give any pending asyncs a chance to run before we block indefinitely
waiting for a signal to arrive.
Reported by Jeffrey Walton <noloader@gmail.com> in
<https://lists.gnu.org/archive/html/guile-devel/2019-03/msg00001.html>.
Note that C11 section 7.1.4 (Use of library functions) states that:
"unless explicitly stated otherwise in the detailed descriptions [of
library functions] that follow: If an argument to a function has an
invalid value (such as ... a null pointer ...) ..., the behavior is
undefined." Note that 'strxfrm' is an example of a standard C function
that explicitly states otherwise, allowing NULL to be passed in the
first argument if the size argument is zero, but no similar allowance is
specified for 'memcpy' or 'memcmp'.
* libguile/bytevectors.c (scm_uniform_array_to_bytevector): Call memcpy
only if 'byte_len' is non-zero.
* libguile/srfi-14.c (charsets_equal): Call memcmp only if the number of
ranges is non-zero.
* libguile/stime.c (setzone): Pass 1-character buffer to
'scm_to_locale_stringbuf', instead of NULL.
* libguile/strings.c (scm_to_locale_stringbuf): Call memcpy only if the
number of bytes to copy is non-zero.
* libguile/jit.c (compute_mcode): Move analysis outside the code
emitter, as it doesn't need to re-run on overflow.
(compile): Clear labels before emitting, as they may have changed if we
overflowed.
* libguile/jit.c (fp_scm_operand): Fix assertion about register state.
(compile_call_scm_sz_u32): Fix ABI declaration for immediate.
Some whitespace cleanups as well.
* libguile/jit.c (prepare_jit_state): Remove unused function.
(initialize_thread_jit_state): Since the lightening state is allocated
using GC memory, trace the JIT state.
(compute_mcode): Avoid double-compile.
* libguile/jit.c (struct scm_jit_state): Remove entry_mcode member.
(add_inter_instruction_patch): Fix off-by-one.
(compile): Reset reloc_idx when restarting a compile. All instructions
record their addresses.
This improves integration with other projects. Like for example Guile
already has files named jit.c and jit.h; it's easier to manage if
lightening uses its own file names.
