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From: Alexandre Oliva <aoliva@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-3693] Support multilib-aware target lib flags self-specs overriding Date: Sat, 5 Nov 2022 09:25:25 +0000 (GMT) [thread overview] Message-ID: <20221105092525.C5D9F3858C2D@sourceware.org> (raw) https://gcc.gnu.org/g:6b1a2474f9e422ef746f7ea13014b288850bb68a commit r13-3693-g6b1a2474f9e422ef746f7ea13014b288850bb68a Author: Alexandre Oliva <oliva@adacore.com> Date: Sat Nov 5 03:14:33 2022 -0300 Support multilib-aware target lib flags self-specs overriding This patch introduces -fmultiflags, short for multilib TFLAGS, as an option that does nothing by default, but that can be added to TFLAGS and mapped to useful options by driver self-specs. for gcc/ChangeLog * common.opt (fmultiflags): New. * doc/invoke.texi: Document it. * gcc.cc (driver_self_specs): Discard it. * opts.cc (common_handle_option): Ignore it in the driver. Diff: --- gcc/common.opt | 4 ++++ gcc/doc/invoke.texi | 30 +++++++++++++++++++++++++++++- gcc/gcc.cc | 6 +++++- gcc/opts.cc | 4 ++++ 4 files changed, 42 insertions(+), 2 deletions(-) diff --git a/gcc/common.opt b/gcc/common.opt index bce3e514f65..26e9d1cc4e7 100644 --- a/gcc/common.opt +++ b/gcc/common.opt @@ -2174,6 +2174,10 @@ fmove-loop-stores Common Var(flag_move_loop_stores) Optimization Move stores out of loops. +fmultiflags +Common Driver +Building block for specs-based multilib-aware TFLAGS. + fdce Common Var(flag_dce) Init(1) Optimization Use the RTL dead code elimination pass. diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index e9207a3a255..5077cd7d242 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -738,7 +738,7 @@ Objective-C and Objective-C++ Dialects}. -flto-report -flto-report-wpa -fmem-report-wpa @gol -fmem-report -fpre-ipa-mem-report -fpost-ipa-mem-report @gol -fopt-info -fopt-info-@var{options}@r{[}=@var{file}@r{]} @gol --fprofile-report @gol +-fmultiflags -fprofile-report @gol -frandom-seed=@var{string} -fsched-verbose=@var{n} @gol -fsel-sched-verbose -fsel-sched-dump-cfg -fsel-sched-pipelining-verbose @gol -fstats -fstack-usage -ftime-report -ftime-report-details @gol @@ -19344,6 +19344,34 @@ allocation for the WPA phase only. Makes the compiler print some statistics about permanent memory allocation before or after interprocedural optimization. +@item -fmultiflags +@opindex fmultiflags +This option enables multilib-aware @code{TFLAGS} to be used to build +target libraries with options different from those the compiler is +configured to use by default, through the use of specs (@xref{Spec +Files}) set up by compiler internals, by the target, or by builders at +configure time. + +Like @code{TFLAGS}, this allows the target libraries to be built for +portable baseline environments, while the compiler defaults to more +demanding ones. That's useful because users can easily override the +defaults the compiler is configured to use to build their own programs, +if the defaults are not ideal for their target environment, whereas +rebuilding the runtime libraries is usually not as easy or desirable. + +Unlike @code{TFLAGS}, the use of specs enables different flags to be +selected for different multilibs. The way to accomplish that is to +build with @samp{make TFLAGS=-fmultiflags}, after configuring +@samp{--with-specs=%@{fmultiflags:...@}}. + +This option is discarded by the driver once it's done processing driver +self spec. + +It is also useful to check that @code{TFLAGS} are being used to build +all target libraries, by configuring a non-bootstrap compiler +@samp{--with-specs='%@{!fmultiflags:%emissing TFLAGS@}'} and building +the compiler and target libraries. + @item -fprofile-report @opindex fprofile-report Makes the compiler print some statistics about consistency of the diff --git a/gcc/gcc.cc b/gcc/gcc.cc index 98a239c8531..830ab88701f 100644 --- a/gcc/gcc.cc +++ b/gcc/gcc.cc @@ -1327,7 +1327,11 @@ static const char *const multilib_defaults_raw[] = MULTILIB_DEFAULTS; static const char *const driver_self_specs[] = { "%{fdump-final-insns:-fdump-final-insns=.} %<fdump-final-insns", - DRIVER_SELF_SPECS, CONFIGURE_SPECS, GOMP_SELF_SPECS, GTM_SELF_SPECS + DRIVER_SELF_SPECS, CONFIGURE_SPECS, GOMP_SELF_SPECS, GTM_SELF_SPECS, + /* This discards -fmultiflags at the end of self specs processing in the + driver, so that it is effectively Ignored, without actually marking it as + Ignored, which would get it discarded before self specs could remap it. */ + "%<fmultiflags" }; #ifndef OPTION_DEFAULT_SPECS diff --git a/gcc/opts.cc b/gcc/opts.cc index ae079fcd20e..3797784c865 100644 --- a/gcc/opts.cc +++ b/gcc/opts.cc @@ -3248,6 +3248,10 @@ common_handle_option (struct gcc_options *opts, dc->report_bug = value; break; + case OPT_fmultiflags: + gcc_checking_assert (lang_mask == CL_DRIVER); + break; + default: /* If the flag was handled in a standard way, assume the lack of processing here is intentional. */
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