This change speeds up the indirect branches at return sites by taking
advantage of the CPU's return address stack.
* libguile/jit.c (emit_push_frame): Don't store the mra; we do that via
a trampoline.
(emit_handle_interrupts_trampoline): Take MRA from link register
instead of T0.
(compile_call, compile_call_label): Compute MRA via the new
jmpi_with_link lightening instruction.
(compile_return_values): Return to caller via ret instead of jmp.
(compile_handle_interrupts): Jump to handle-interrupts trampoline via
jmpi_with_link, to provide the MRA.
(initialize_jit): Bless the trampolines so that they are valid
operands to BX on ARM.
The existing calli / callr interface is for ABI calls. Sometimes though
you want to call some of your own code, just to get the current return
address. ARM's branch-and-link instructions are ideal for this but they
don't exist on x86; there we emulate them by adding corresponding
pop_link_register / push_link_register instructions that are no-ops on
ARM.
* lightening.h (FOR_EACH_INSTRUCTION): Add jit_jmpi_with_link,
pop_link_register, push_link_register.
* lightening/arm-cpu.c:
* lightening/x86-cpu.c:
* lightening/aarch64-cpu.c (jmpi_with_link, push_link_register)
(pop_link_register): Add implementations.
* lightening/arm.h:
* lightening/aarch64.h:
* lightening/x86.h (JIT_LR): New definition.
* tests/link-register.c: New test.
This patch is a bit unfortunate, in the sense that it exposes some of
the JIT guts to the rest of the VM. Code needs to treat "machine return
addresses" as valid if non-NULL (as before) and also not equal to a
tier-down trampoline. This is because tier-down at a return needs the
old frame pointer to load the "virtual return address", and the way this
patch works is that it passes the vra in a well-known register. It's a
custom calling convention for a certain kind of return.
* libguile/jit.h (scm_jit_return_to_interpreter_trampoline): New
internal global.
* libguile/jit.c: (scm_jit_clear_mcode_return_addresses): Move here,
from vm.c. Instead of zeroing return addresses, set them to the
return-to-interpreter trampoline.
* libguile/vm-engine.c (return-values): Don't enter mcode if the mra is
scm_jit_return_to_interpreter_trampoline.
* libguile/vm.c (capture_continuation): Treat the tier-down trampoline
as NULL.
* THANKS: Thank Christopher Allan Webber, Christopher Baines, and
Timothy Sample for contributions. Thank Andrea Azzarone, Михаил
Бахтерев, Jonathan Brielmaier, Josh Datko, Massimiliano Gubinelli, Arun
Isaac, Shea Levy, Chris Marusich, Jan Smydke, Tom de Vries, Jeffrey
Walton, and Zefram for fixes. Move Michael Talbot-Wilson and Michael
Tuexen to their proper place to fix the sorting.
* module/texinfo/html.scm (tag-replacements): Add support for @i
and @math. The tags used come from the texinfo documentation.
(rules): Convert @tie and @dots to the appropriate HTML entities.
* module/web/http.scm (spaces-and-tabs, space-or-tab?): New variables.
(read-header-line): After reading a header, if a space or tab follows,
read the continuation lines and join them.
* test-suite/tests/web-http.test: Add test.
* module/ice-9/suspendable-ports.scm (get-bytevector-n!): New procedure.
(get-bytevector-n): Rewrite in terms of 'get-bytevector-n!'.
(port-bindings): Add 'get-bytevector-n!'.
This is a followup to commit 91ba73b397.
* libguile/fports.c (fport_seek): Use 'lseek' instead of
'lseek_or_lseek64', and use 'scm_t_off' uniformly. That's the type used
in the function signature, and there's no benefit to using a wider type
internally. Remove the overflow check, which is no longer needed.
* doc/ref/r6rs.texi (rnrs io ports): Improve the descriptions of
'binary-port?' and 'textual-port?'.
* module/rnrs/io/ports.scm (binary-port?, textual-port?): Update the
docstrings.
Previously, in the case where OUT is 0, or ERR is 0 or 1,
e.g. when (current-error-port) points to STDOUT, the code in
'start_child' to relocate OUT/ERR out of the way to another file
descriptor had multiple bugs:
(1) It neglected to close the original file descriptor.
(2) It checked 'errno' without first checking the return value of
dup(2). This doesn't work because dup(2) leaves 'errno' unchanged
if there's no error.
(3) In case 'errno' contained EINTR, the retry code failed because
OUT (or ERR) was overwritten by the result of the previous failed
dup(2) call.
This commit fixes these problems, as well as another problem with
'execvp' error reporting.
* libguile/posix.c (renumber_file_descriptor): New static helper
function.
(start_child): Use 'renumber_file_descriptor'. If 'execvp' fails, write
the error message to file descriptor 2. Previously, we wrote the error
message to ERR, which was the old file descriptor before being relocated
to 2.
Reported by Massimiliano Gubinelli <m.gubinelli@gmail.com> in
<https://lists.gnu.org/archive/html/guile-user/2019-05/msg00070.html>.
* libguile/strings.c (scm_to_stringn): Check for (encoding == NULL)
before passing it to 'c_strcasecmp'. Eliminate redundant 'enc'
variable.
* libguile/bytevectors.c (INTEGER_ACCESSOR_PROLOGUE)
(scm_bytevector_copy_x, bytevector_large_set): Rewrite checks to reliably
detect overflows.
(make_bytevector): Constrain the bytevector length to avoid later
overflows during allocation.
(make_bytevector_from_buffer): Fix indentation.
(scm_bytevector_length): Use 'scm_from_size_t' to convert a 'size_t',
not 'scm_from_uint'.
* libguile/fports.c (fport_seek): Check for overflow before the implicit
conversion of the return value.
* libguile/guardians.c (guardian_print): Use 'scm_from_ulong' to convert
an 'unsigned long', not 'scm_from_uint'.
* libguile/ports.c (scm_unread_string): Change a variable to type 'size_t'.
(scm_seek, scm_truncate_file): Use 'scm_t_off' instead of
'off_t_or_off64_t' to avoid implicit type conversions that could
overflow, because 'ptob->seek' and 'ptob->truncate' use 'scm_t_off'.
* libguile/r6rs-ports.c (bytevector_input_port_seek)
(custom_binary_port_seek, bytevector_output_port_seek): Rewrite offset
calculations to reliably detect overflows. Use 'scm_from_off_t' to
convert a 'scm_t_off', not 'scm_from_long' nor 'scm_from_int'.
(scm_get_bytevector_n_x, scm_get_bytevector_all, scm_unget_bytevector)
(bytevector_output_port_write): Rewrite checks to reliably detect
overflows. Use 'size_t' where appropriate.
(bytevector_output_port_buffer_grow): Rewrite size calculations to
reliably detect overflows. Minor change in the calculation of the new
size: now it is max(min_size, 2*current_size), whereas previously it
would multiply current_size by the smallest power of 2 needed to surpass
min_size.
* libguile/strings.c (make_stringbuf): Constrain the stringbuf length to
avoid later overflows during allocation.
(scm_string_append): Change overflow check to use INT_ADD_OVERFLOW.
* libguile/strports.c (string_port_write): Rewrite size calculations to
reliably detect overflows.
(string_port_seek): Rewrite offset calculations to reliably detect
overflows. Use 'scm_from_off_t' to convert a 'scm_t_off', not
'scm_from_long'.
(string_port_truncate): Use 'scm_from_off_t' to convert a 'scm_t_off',
not 'scm_from_off_t_or_off64_t'.
* libguile/vectors.c (scm_c_make_vector): Change a variable to type
'size_t'.
* module/language/cps/closure-conversion.scm (compute-elidable-closures):
New function.
(convert-one, convert-closures): Add ability to set "self" variable of
$kfun to $f, hopefully avoiding passing that argument in some cases.
* module/language/cps/compile-bytecode.scm (compile-function): Pass the
has-closure? bit on through to the assembler.
* module/system/vm/assembler.scm (begin-standard-arity)
(begin-opt-arity, begin-kw-arity): Only reserve space for the closure
as appropriate.
* module/language/cps/slot-allocation.scm (allocate-args)
(compute-defs-and-uses, compute-needs-slot)
(compute-var-representations): Allow for closure slot allocation
differences.
* module/language/cps/cse.scm (compute-defs):
* module/language/cps/dce.scm (compute-live-code):
* module/language/cps/renumber.scm (renumber, compute-renaming):
(allocate-args):
* module/language/cps/specialize-numbers.scm (compute-significant-bits):
(compute-defs):
* module/language/cps/split-rec.scm (compute-free-vars):
* module/language/cps/types.scm (infer-types):
* module/language/cps/utils.scm (compute-max-label-and-var):
* module/language/cps/verify.scm (check-distinct-vars):
(compute-available-definitions): Allow closure to be #f.
* libguile/jit.c (compile_alloc_frame): Stop initializing locals.
(compile_bind_rest): Use emit_alloc_frame.
* libguile/vm-engine.c (assert_nargs_ee_locals, allocate_frame): Don't
initialize locals.
(bind_rest): Don't initialize locals, and assert that the locals count
has a minimum.
