On Mon, Nov 22, 2021 at 3:40 PM Maxim Blinov <maxim.bli...@embecosm.com> wrote:
>
> Hi Richard,
>
> The purpose of this patch is to give more of the target code access to
> the cumulative_args_t structure in order to enable certain (otherwise
> currently impossible) stack layout constraints, specifically for
> parameters that are passed over the stack. For example, there are some
> targets (not yet in GCC trunk) which explicitly require the
> distinction between named and variadic parameters in order to enforce
> different alignment rules (when passing over the stack.) Such a
> constraint would be accommodated by this patch.
>
> The patch itself is very straightforward and simply adds the parameter
> to the two functions which we'd like to extend. The motivation of
> defining new target hooks was to minimize the patch size.
I would prefer to adjust the existing hooks if there's currently no way to
implement the aarch64 darwin ABI instead of optimizing for patch size.
I have no opinion on whether passing down cummulative args is the
proper thing to do design-wise. It might be that TARGET_FUNCTION_ARG_BOUNDARY
is only one part that cummulative args using code should look at
(given you don't show the other users of function_arg_boundary that do not
conveniently have a CA struct around).
Richard.
> A concrete user of this change that we have in mind is the AArch64
> Darwin parameter passing abi, which mandates that when passing on the
> stack, named parameters are to be naturally-aligned, however variadic
> ones are to be word-aligned. However this patch is completely generic
> in nature and should enable all targets to have more control over
> their parameter layout process.
>
> Best Regards,
> Maxim
>
> On Mon, 15 Nov 2021 at 07:11, Richard Biener <richard.guent...@gmail.com>
> wrote:
> >
> > On Sat, Nov 13, 2021 at 10:43 AM Maxim Blinov <maxim.bli...@embecosm.com>
> > wrote:
> > >
> > > The two target hooks responsible for informing GCC about stack
> > > parameter alignment are `TARGET_FUNCTION_ARG_BOUNDARY` and
> > > `TARGET_FUNCTION_ARG_ROUND_BOUNDARY`, which currently only consider
> > > the tree and machine_mode of a specific given argument.
> > >
> > > Create two new target hooks suffixed with '_CA', and pass in a third
> > > `cumulative_args_t` parameter. This enables the backend to make
> > > alignment decisions based on the context of the whole function rather
> > > than individual parameters.
> > >
> > > The orignal machine_mode/tree type macros are not removed - they are
> > > called by the default implementations of `TARGET_...BOUNDARY_CA` and
> > > `TARGET_...ROUND_BOUNDARY_CA`. This is done with the intetnion of
> > > avoiding large mechanical modifications of nearly every backend in
> > > GCC. There is also a new flag, -fstack-use-cumulative-args, which
> > > provides a way to completely bypass the new `..._CA` macros. This
> > > feature is intended for debugging GCC itself.
> >
> > Just two quick comments without looking at the patch.
> >
> > Please do not introduce options in the user namespace -f... which are
> > for debugging only. I think you should go without this part instead.
> >
> > Second, you fail to motivate the change. I cannot make sense of
> > "This enables the backend to make alignment decisions based on the
> > context of the whole function rather than individual parameters."
> >
> > Richard.
> >
> > >
> > > gcc/ChangeLog:
> > >
> > > * calls.c (initialize_argument_information): Pass `args_so_far`.
> > > * common.opt: New flag `-fstack-use-cumulative-args`.
> > > * config.gcc: No platforms currently use ..._CA-hooks: Set
> > > -fstack-use-cumulative-args to be off by default.
> > > * target.h (cumulative_args_t): Move declaration from here, to...
> > > * cumulative-args.h (cumulative_args_t): ...this new file. This is
> > > to permit backends to include the declaration of cumulative_args_t
> > > without dragging in circular dependencies.
> > > * function.c (assign_parm_find_entry_rtl): Provide
> > > cumulative_args_t to locate_and_pad_parm.
> > > (gimplify_parameters): Ditto.
> > > (locate_and_pad_parm): Conditionally call new hooks if we're
> > > invoked with -fstack-use-cumulative-args.
> > > * function.h: Include cumulative-args.h.
> > > (locate_and_pad_parm): Add cumulative_args_t parameter.
> > > * target.def (function_arg_boundary_ca): Add.
> > > (function_arg_round_boundary_ca): Ditto.
> > > * targhooks.c (default_function_arg_boundary_ca): Implement.
> > > (default_function_arg_round_boundary_ca): Ditto.
> > > * targhooks.h (default_function_arg_boundary_ca): Declare.
> > > (default_function_arg_round_boundary_ca): Ditto.
> > > * doc/invoke.texi (-fstack-use-cumulative-args): Document.
> > > * doc/tm.texi: Regenerate.
> > > * doc/tm.texi.in: Ditto.
> > > ---
> > > gcc/calls.c | 3 +++
> > > gcc/common.opt | 4 ++++
> > > gcc/config.gcc | 7 +++++++
> > > gcc/cumulative-args.h | 20 ++++++++++++++++++++
> > > gcc/doc/invoke.texi | 12 ++++++++++++
> > > gcc/doc/tm.texi | 20 ++++++++++++++++++++
> > > gcc/doc/tm.texi.in | 4 ++++
> > > gcc/function.c | 25 +++++++++++++++++++++----
> > > gcc/function.h | 2 ++
> > > gcc/target.def | 24 ++++++++++++++++++++++++
> > > gcc/target.h | 17 +----------------
> > > gcc/targhooks.c | 16 ++++++++++++++++
> > > gcc/targhooks.h | 6 ++++++
> > > 13 files changed, 140 insertions(+), 20 deletions(-)
> > > create mode 100644 gcc/cumulative-args.h
> > >
> > > diff --git a/gcc/calls.c b/gcc/calls.c
> > > index 27b59f26ad3..cef612a6ef4 100644
> > > --- a/gcc/calls.c
> > > +++ b/gcc/calls.c
> > > @@ -1527,6 +1527,7 @@ initialize_argument_information (int num_actuals
> > > ATTRIBUTE_UNUSED,
> > > #endif
> > > reg_parm_stack_space,
> > > args[i].pass_on_stack ? 0 : args[i].partial,
> > > + args_so_far,
> > > fndecl, args_size, &args[i].locate);
> > > #ifdef BLOCK_REG_PADDING
> > > else
> > > @@ -4205,6 +4206,7 @@ emit_library_call_value_1 (int retval, rtx orgfun,
> > > rtx value,
> > > argvec[count].reg != 0,
> > > #endif
> > > reg_parm_stack_space, 0,
> > > + args_so_far,
> > > NULL_TREE, &args_size, &argvec[count].locate);
> > >
> > > if (argvec[count].reg == 0 || argvec[count].partial != 0
> > > @@ -4296,6 +4298,7 @@ emit_library_call_value_1 (int retval, rtx orgfun,
> > > rtx value,
> > > argvec[count].reg != 0,
> > > #endif
> > > reg_parm_stack_space,
> > > argvec[count].partial,
> > > + args_so_far,
> > > NULL_TREE, &args_size,
> > > &argvec[count].locate);
> > > args_size.constant += argvec[count].locate.size.constant;
> > > gcc_assert (!argvec[count].locate.size.var);
> > > diff --git a/gcc/common.opt b/gcc/common.opt
> > > index de9b848eda5..982417c1e39 100644
> > > --- a/gcc/common.opt
> > > +++ b/gcc/common.opt
> > > @@ -2705,6 +2705,10 @@ fstack-usage
> > > Common RejectNegative Var(flag_stack_usage)
> > > Output stack usage information on a per-function basis.
> > >
> > > +fstack-use-cumulative-args
> > > +Common RejectNegative Var(flag_stack_use_cumulative_args)
> > > Init(STACK_USE_CUMULATIVE_ARGS_INIT)
> > > +Use cumulative args-based stack layout hooks.
> > > +
> > > fstrength-reduce
> > > Common Ignore
> > > Does nothing. Preserved for backward compatibility.
> > > diff --git a/gcc/config.gcc b/gcc/config.gcc
> > > index edd12655c4a..046d691af56 100644
> > > --- a/gcc/config.gcc
> > > +++ b/gcc/config.gcc
> > > @@ -1070,6 +1070,13 @@ case ${target} in
> > > ;;
> > > esac
> > >
> > > +# Figure out if we need to enable -foff-stack-trampolines by default.
> > > +case ${target} in
> > > +*)
> > > + tm_defines="$tm_defines STACK_USE_CUMULATIVE_ARGS_INIT=0"
> > > + ;;
> > > +esac
> > > +
> > > case ${target} in
> > > aarch64*-*-elf | aarch64*-*-fuchsia* | aarch64*-*-rtems*)
> > > tm_file="${tm_file} dbxelf.h elfos.h newlib-stdint.h"
> > > diff --git a/gcc/cumulative-args.h b/gcc/cumulative-args.h
> > > new file mode 100644
> > > index 00000000000..b60928e37f9
> > > --- /dev/null
> > > +++ b/gcc/cumulative-args.h
> > > @@ -0,0 +1,20 @@
> > > +#ifndef GCC_CUMULATIVE_ARGS_H
> > > +#define GCC_CUMULATIVE_ARGS_H
> > > +
> > > +#if CHECKING_P
> > > +
> > > +struct cumulative_args_t { void *magic; void *p; };
> > > +
> > > +#else /* !CHECKING_P */
> > > +
> > > +/* When using a GCC build compiler, we could use
> > > + __attribute__((transparent_union)) to get cumulative_args_t function
> > > + arguments passed like scalars where the ABI would mandate a less
> > > + efficient way of argument passing otherwise. However, that would come
> > > + at the cost of less type-safe !CHECKING_P compilation. */
> > > +
> > > +union cumulative_args_t { void *p; };
> > > +
> > > +#endif /* !CHECKING_P */
> > > +
> > > +#endif /* GCC_CUMULATIVE_ARGS_H */
> > > diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> > > index 2aba4c70b44..7ffb2997c69 100644
> > > --- a/gcc/doc/invoke.texi
> > > +++ b/gcc/doc/invoke.texi
> > > @@ -670,6 +670,7 @@ Objective-C and Objective-C++ Dialects}.
> > > -fverbose-asm -fpack-struct[=@var{n}] @gol
> > > -fleading-underscore -ftls-model=@var{model} @gol
> > > -fstack-reuse=@var{reuse_level} @gol
> > > +-fstack-use-cumulative-args @gol
> > > -ftrampolines -ftrapv -fwrapv @gol
> > > -fvisibility=@r{[}default@r{|}internal@r{|}hidden@r{|}protected@r{]} @gol
> > > -fstrict-volatile-bitfields -fsync-libcalls}
> > > @@ -16625,6 +16626,17 @@ the behavior of older compilers in which
> > > temporaries' stack space is
> > > not reused, the aggressive stack reuse can lead to runtime errors. This
> > > option is used to control the temporary stack reuse optimization.
> > >
> > > +@item -fstack-use-cumulative-args
> > > +@opindex fstack_use_cumulative_args
> > > +This option instructs the compiler to use the
> > > +@code{cumulative_args_t}-based stack layout target hooks,
> > > +@code{TARGET_FUNCTION_ARG_BOUNDARY_CA} and
> > > +@code{TARGET_FUNCTION_ARG_ROUND_BOUNDARY_CA}. If a given target does
> > > +not define these hooks, the default behaviour is to fallback to using
> > > +the standard non-@code{_CA} variants instead. Certain targets (such as
> > > +AArch64 Darwin) require using the more advanced @code{_CA}-based
> > > +hooks: For these targets this option should be enabled by default.
> > > +
> > > @item -ftrapv
> > > @opindex ftrapv
> > > This option generates traps for signed overflow on addition, subtraction,
> > > diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
> > > index 78a1af1ad4d..261eaf46ef5 100644
> > > --- a/gcc/doc/tm.texi
> > > +++ b/gcc/doc/tm.texi
> > > @@ -4322,6 +4322,16 @@ with the specified mode and type. The default
> > > hook returns
> > > @code{PARM_BOUNDARY} for all arguments.
> > > @end deftypefn
> > >
> > > +@deftypefn {Target Hook} {unsigned int} TARGET_FUNCTION_ARG_BOUNDARY_CA
> > > (machine_mode @var{mode}, const_tree @var{type}, cumulative_args_t
> > > @var{ca})
> > > +This is the @code{cumulative_args_t}-based version of
> > > +@code{TARGET_FUNCTION_ARG_BOUNDARY}. Define this hook if you need more
> > > +fine-grained control over argument alignment, e.g. depending on whether
> > > +it is a named argument or not, or any other criteria that you choose to
> > > +place in the @var{ca} structure.
> > > +
> > > +The default hook will call @code{TARGET_FUNCTION_ARG_BOUNDARY}.
> > > +@end deftypefn
> > > +
> > > @deftypefn {Target Hook} {unsigned int}
> > > TARGET_FUNCTION_ARG_ROUND_BOUNDARY (machine_mode @var{mode}, const_tree
> > > @var{type})
> > > Normally, the size of an argument is rounded up to @code{PARM_BOUNDARY},
> > > which is the default value for this hook. You can define this hook to
> > > @@ -4329,6 +4339,16 @@ return a different value if an argument size must
> > > be rounded to a larger
> > > value.
> > > @end deftypefn
> > >
> > > +@deftypefn {Target Hook} {unsigned int}
> > > TARGET_FUNCTION_ARG_ROUND_BOUNDARY_CA (machine_mode @var{mode},
> > > const_tree @var{type}, cumulative_args_t @var{ca})
> > > +This is the @code{cumulative_args_t}-based version of
> > > +@code{TARGET_FUNCTION_ARG_ROUND_BOUNDARY}. Define this hook if you need
> > > more
> > > +fine-grained control over argument size rounding, e.g. depending on
> > > whether
> > > +it is a named argument or not, or any other criteria that you choose to
> > > +place in the @var{ca} structure.
> > > +
> > > +The default hook will call @code{TARGET_FUNCTION_ARG_ROUND_BOUNDARY}.
> > > +@end deftypefn
> > > +
> > > @defmac FUNCTION_ARG_REGNO_P (@var{regno})
> > > A C expression that is nonzero if @var{regno} is the number of a hard
> > > register in which function arguments are sometimes passed. This does
> > > diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
> > > index 4401550989e..933644dfa86 100644
> > > --- a/gcc/doc/tm.texi.in
> > > +++ b/gcc/doc/tm.texi.in
> > > @@ -3330,8 +3330,12 @@ required.
> > >
> > > @hook TARGET_FUNCTION_ARG_BOUNDARY
> > >
> > > +@hook TARGET_FUNCTION_ARG_BOUNDARY_CA
> > > +
> > > @hook TARGET_FUNCTION_ARG_ROUND_BOUNDARY
> > >
> > > +@hook TARGET_FUNCTION_ARG_ROUND_BOUNDARY_CA
> > > +
> > > @defmac FUNCTION_ARG_REGNO_P (@var{regno})
> > > A C expression that is nonzero if @var{regno} is the number of a hard
> > > register in which function arguments are sometimes passed. This does
> > > diff --git a/gcc/function.c b/gcc/function.c
> > > index 61b3bd036b8..1ebf3e0ffe5 100644
> > > --- a/gcc/function.c
> > > +++ b/gcc/function.c
> > > @@ -2610,7 +2610,9 @@ assign_parm_find_entry_rtl (struct
> > > assign_parm_data_all *all,
> > >
> > > locate_and_pad_parm (data->arg.mode, data->arg.type, in_regs,
> > > all->reg_parm_stack_space,
> > > - entry_parm ? data->partial : 0,
> > > current_function_decl,
> > > + entry_parm ? data->partial : 0,
> > > + all->args_so_far,
> > > + current_function_decl,
> > > &all->stack_args_size, &data->locate);
> > >
> > > /* Update parm_stack_boundary if this parameter is passed in the
> > > @@ -4027,6 +4029,7 @@ gimplify_parameters (gimple_seq *cleanup)
> > > void
> > > locate_and_pad_parm (machine_mode passed_mode, tree type, int in_regs,
> > > int reg_parm_stack_space, int partial,
> > > + cumulative_args_t ca,
> > > tree fndecl ATTRIBUTE_UNUSED,
> > > struct args_size *initial_offset_ptr,
> > > struct locate_and_pad_arg_data *locate)
> > > @@ -4064,9 +4067,23 @@ locate_and_pad_parm (machine_mode passed_mode,
> > > tree type, int in_regs,
> > > ? arg_size_in_bytes (type)
> > > : size_int (GET_MODE_SIZE (passed_mode)));
> > > where_pad = targetm.calls.function_arg_padding (passed_mode, type);
> > > - boundary = targetm.calls.function_arg_boundary (passed_mode, type);
> > > - round_boundary = targetm.calls.function_arg_round_boundary
> > > (passed_mode,
> > > - type);
> > > +
> > > + if (flag_stack_use_cumulative_args)
> > > + {
> > > + boundary = targetm.calls.function_arg_boundary_ca (passed_mode,
> > > + type,
> > > + ca);
> > > + round_boundary = targetm.calls.function_arg_round_boundary_ca
> > > + (passed_mode, type, ca);
> > > + }
> > > + else
> > > + {
> > > + boundary = targetm.calls.function_arg_boundary (passed_mode,
> > > + type);
> > > + round_boundary = targetm.calls.function_arg_round_boundary
> > > + (passed_mode, type);
> > > + }
> > > +
> > > locate->where_pad = where_pad;
> > >
> > > /* Alignment can't exceed MAX_SUPPORTED_STACK_ALIGNMENT. */
> > > diff --git a/gcc/function.h b/gcc/function.h
> > > index 899430833ce..26f342caba3 100644
> > > --- a/gcc/function.h
> > > +++ b/gcc/function.h
> > > @@ -20,6 +20,7 @@ along with GCC; see the file COPYING3. If not see
> > > #ifndef GCC_FUNCTION_H
> > > #define GCC_FUNCTION_H
> > >
> > > +#include "cumulative-args.h"
> > >
> > > /* Stack of pending (incomplete) sequences saved by `start_sequence'.
> > > Each element describes one pending sequence.
> > > @@ -661,6 +662,7 @@ extern int aggregate_value_p (const_tree, const_tree);
> > > extern bool use_register_for_decl (const_tree);
> > > extern gimple_seq gimplify_parameters (gimple_seq *);
> > > extern void locate_and_pad_parm (machine_mode, tree, int, int, int,
> > > + cumulative_args_t,
> > > tree, struct args_size *,
> > > struct locate_and_pad_arg_data *);
> > > extern void generate_setjmp_warnings (void);
> > > diff --git a/gcc/target.def b/gcc/target.def
> > > index 51ea167172b..bb56afab539 100644
> > > --- a/gcc/target.def
> > > +++ b/gcc/target.def
> > > @@ -4959,6 +4959,18 @@ with the specified mode and type. The default
> > > hook returns\n\
> > > unsigned int, (machine_mode mode, const_tree type),
> > > default_function_arg_boundary)
> > >
> > > +DEFHOOK
> > > +(function_arg_boundary_ca,
> > > + "This is the @code{cumulative_args_t}-based version of\n\
> > > +@code{TARGET_FUNCTION_ARG_BOUNDARY}. Define this hook if you need more\n\
> > > +fine-grained control over argument alignment, e.g. depending on
> > > whether\n\
> > > +it is a named argument or not, or any other criteria that you choose
> > > to\n\
> > > +place in the @var{ca} structure.\n\
> > > +\n\
> > > +The default hook will call @code{TARGET_FUNCTION_ARG_BOUNDARY}.",
> > > + unsigned int, (machine_mode mode, const_tree type, cumulative_args_t
> > > ca),
> > > + default_function_arg_boundary_ca)
> > > +
> > > DEFHOOK
> > > (function_arg_round_boundary,
> > > "Normally, the size of an argument is rounded up to
> > > @code{PARM_BOUNDARY},\n\
> > > @@ -4968,6 +4980,18 @@ value.",
> > > unsigned int, (machine_mode mode, const_tree type),
> > > default_function_arg_round_boundary)
> > >
> > > +DEFHOOK
> > > +(function_arg_round_boundary_ca,
> > > + "This is the @code{cumulative_args_t}-based version of\n\
> > > +@code{TARGET_FUNCTION_ARG_ROUND_BOUNDARY}. Define this hook if you need
> > > more\n\
> > > +fine-grained control over argument size rounding, e.g. depending on
> > > whether\n\
> > > +it is a named argument or not, or any other criteria that you choose
> > > to\n\
> > > +place in the @var{ca} structure.\n\
> > > +\n\
> > > +The default hook will call @code{TARGET_FUNCTION_ARG_ROUND_BOUNDARY}.",
> > > + unsigned int, (machine_mode mode, const_tree type, cumulative_args_t
> > > ca),
> > > + default_function_arg_round_boundary_ca)
> > > +
> > > /* Return the diagnostic message string if function without a prototype
> > > is not allowed for this 'val' argument; NULL otherwise. */
> > > DEFHOOK
> > > diff --git a/gcc/target.h b/gcc/target.h
> > > index d8f45fb99c3..5b28ece7e1c 100644
> > > --- a/gcc/target.h
> > > +++ b/gcc/target.h
> > > @@ -51,22 +51,7 @@
> > > #include "insn-codes.h"
> > > #include "tm.h"
> > > #include "hard-reg-set.h"
> > > -
> > > -#if CHECKING_P
> > > -
> > > -struct cumulative_args_t { void *magic; void *p; };
> > > -
> > > -#else /* !CHECKING_P */
> > > -
> > > -/* When using a GCC build compiler, we could use
> > > - __attribute__((transparent_union)) to get cumulative_args_t function
> > > - arguments passed like scalars where the ABI would mandate a less
> > > - efficient way of argument passing otherwise. However, that would come
> > > - at the cost of less type-safe !CHECKING_P compilation. */
> > > -
> > > -union cumulative_args_t { void *p; };
> > > -
> > > -#endif /* !CHECKING_P */
> > > +#include "cumulative-args.h"
> > >
> > > /* Types of memory operation understood by the "by_pieces"
> > > infrastructure.
> > > Used by the TARGET_USE_BY_PIECES_INFRASTRUCTURE_P target hook and
> > > diff --git a/gcc/targhooks.c b/gcc/targhooks.c
> > > index 6f071f80231..d83f362a5ae 100644
> > > --- a/gcc/targhooks.c
> > > +++ b/gcc/targhooks.c
> > > @@ -850,6 +850,14 @@ default_function_arg_boundary (machine_mode mode
> > > ATTRIBUTE_UNUSED,
> > > return PARM_BOUNDARY;
> > > }
> > >
> > > +unsigned int
> > > +default_function_arg_boundary_ca (machine_mode mode ATTRIBUTE_UNUSED,
> > > + const_tree type ATTRIBUTE_UNUSED,
> > > + cumulative_args_t ca ATTRIBUTE_UNUSED)
> > > +{
> > > + return default_function_arg_boundary (mode, type);
> > > +}
> > > +
> > > unsigned int
> > > default_function_arg_round_boundary (machine_mode mode ATTRIBUTE_UNUSED,
> > > const_tree type ATTRIBUTE_UNUSED)
> > > @@ -857,6 +865,14 @@ default_function_arg_round_boundary (machine_mode
> > > mode ATTRIBUTE_UNUSED,
> > > return PARM_BOUNDARY;
> > > }
> > >
> > > +unsigned int
> > > +default_function_arg_round_boundary_ca (machine_mode mode
> > > ATTRIBUTE_UNUSED,
> > > + const_tree type ATTRIBUTE_UNUSED,
> > > + cumulative_args_t ca
> > > ATTRIBUTE_UNUSED)
> > > +{
> > > + return default_function_arg_round_boundary (mode, type);
> > > +}
> > > +
> > > void
> > > hook_void_bitmap (bitmap regs ATTRIBUTE_UNUSED)
> > > {
> > > diff --git a/gcc/targhooks.h b/gcc/targhooks.h
> > > index 11e9d7dd1a8..f33374ef073 100644
> > > --- a/gcc/targhooks.h
> > > +++ b/gcc/targhooks.h
> > > @@ -154,6 +154,12 @@ extern unsigned int default_function_arg_boundary
> > > (machine_mode,
> > > const_tree);
> > > extern unsigned int default_function_arg_round_boundary (machine_mode,
> > > const_tree);
> > > +extern unsigned int default_function_arg_boundary_ca (machine_mode,
> > > + const_tree,
> > > + cumulative_args_t
> > > ca);
> > > +extern unsigned int default_function_arg_round_boundary_ca (machine_mode,
> > > + const_tree,
> > > +
> > > cumulative_args_t ca);
> > > extern bool hook_bool_const_rtx_commutative_p (const_rtx, int);
> > > extern rtx default_function_value (const_tree, const_tree, bool);
> > > extern HARD_REG_SET default_zero_call_used_regs (HARD_REG_SET);
> > > --
> > > 2.30.1 (Apple Git-130)
> > >
