From: Uros Bizjak <ubizjak@gmail.com>
To: Fangrui Song <maskray@google.com>
Cc: gcc-patches@gcc.gnu.org, Florian Weimer <fweimer@redhat.com>,
"H.J. Lu" <hjl.tools@gmail.com>, Jan Beulich <jbeulich@suse.com>,
Jan Hubicka <hubicka@ucw.cz>, Michael Matz <matz@suse.de>
Subject: Re: [PATCH v5] i386: Allow -mlarge-data-threshold with -mcmodel=large
Date: Mon, 16 Oct 2023 21:10:24 +0200 [thread overview]
Message-ID: <CAFULd4aSWeFx93CK96oYTO5nfMZtKeHqXTpAY0cpHfdyc1EKNg@mail.gmail.com> (raw)
In-Reply-To: <20231016182447.bticawp4aps7tsso@google.com>
On Mon, Oct 16, 2023 at 8:24 PM Fangrui Song <maskray@google.com> wrote:
>
> On 2023-10-16, Uros Bizjak wrote:
> >On Tue, Aug 1, 2023 at 9:51 PM Fangrui Song <maskray@google.com> wrote:
> >>
> >> When using -mcmodel=medium, large data objects larger than the
> >> -mlarge-data-threshold threshold are placed into large data sections
> >> (.lrodata, .ldata, .lbss and some variants). GNU ld and ld.lld 17 place
> >> .l* sections into separate output sections. If small and medium code
> >> model object files are mixed, the .l* sections won't exert relocation
> >> overflow pressure on sections in object files built with -mcmodel=small.
> >>
> >> However, when using -mcmodel=large, -mlarge-data-threshold doesn't
> >> apply. This means that the .rodata/.data/.bss sections may exert
> >> relocation overflow pressure on sections in -mcmodel=small object files.
> >>
> >> This patch allows -mcmodel=large to generate .l* sections and drops an
> >> unneeded documentation restriction that the value must be the same.
> >>
> >> Link: https://groups.google.com/g/x86-64-abi/c/jnQdJeabxiU
> >> ("Large data sections for the large code model")
> >>
> >> Signed-off-by: Fangrui Song <maskray@google.com>
> >>
> >> ---
> >> Changes from v1 (https://gcc.gnu.org/pipermail/gcc-patches/2023-April/616947.html):
> >> * Clarify commit message. Add link to https://groups.google.com/g/x86-64-abi/c/jnQdJeabxiU
> >>
> >> Changes from v2
> >> * Drop an uneeded limitation in the documentation.
> >>
> >> Changes from v3
> >> * Change scan-assembler directives to use \. to match literal .
> >> ---
> >> gcc/config/i386/i386.cc | 15 +++++++++------
> >> gcc/config/i386/i386.opt | 2 +-
> >> gcc/doc/invoke.texi | 6 +++---
> >> gcc/testsuite/gcc.target/i386/large-data.c | 13 +++++++++++++
> >> 4 files changed, 26 insertions(+), 10 deletions(-)
> >> create mode 100644 gcc/testsuite/gcc.target/i386/large-data.c
> >>
> >> diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
> >> index eabc70011ea..37e810cc741 100644
> >> --- a/gcc/config/i386/i386.cc
> >> +++ b/gcc/config/i386/i386.cc
> >> @@ -647,7 +647,8 @@ ix86_can_inline_p (tree caller, tree callee)
> >> static bool
> >> ix86_in_large_data_p (tree exp)
> >> {
> >> - if (ix86_cmodel != CM_MEDIUM && ix86_cmodel != CM_MEDIUM_PIC)
> >> + if (ix86_cmodel != CM_MEDIUM && ix86_cmodel != CM_MEDIUM_PIC &&
> >> + ix86_cmodel != CM_LARGE && ix86_cmodel != CM_LARGE_PIC)
> >
> >Please split multi-line expression before the operator, not after it,
> >as instructed in GNU Coding Standards [1] ...
> >
> >[1] https://www.gnu.org/prep/standards/html_node/Formatting.html
> >
> >> return false;
> >>
> >> if (exp == NULL_TREE)
> >> @@ -858,8 +859,9 @@ x86_elf_aligned_decl_common (FILE *file, tree decl,
> >> const char *name, unsigned HOST_WIDE_INT size,
> >> unsigned align)
> >> {
> >> - if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC)
> >> - && size > (unsigned int)ix86_section_threshold)
> >> + if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC ||
> >> + ix86_cmodel == CM_LARGE || ix86_cmodel == CM_LARGE_PIC) &&
> >> + size > (unsigned int)ix86_section_threshold)
> >
> >... also here ...
> >
> >> {
> >> switch_to_section (get_named_section (decl, ".lbss", 0));
> >> fputs (LARGECOMM_SECTION_ASM_OP, file);
> >> @@ -879,9 +881,10 @@ void
> >> x86_output_aligned_bss (FILE *file, tree decl, const char *name,
> >> unsigned HOST_WIDE_INT size, unsigned align)
> >> {
> >> - if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC)
> >> - && size > (unsigned int)ix86_section_threshold)
> >> - switch_to_section (get_named_section (decl, ".lbss", 0));
> >> + if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC ||
> >> + ix86_cmodel == CM_LARGE || ix86_cmodel == CM_LARGE_PIC) &&
> >> + size > (unsigned int)ix86_section_threshold)
> >
> >... and here.
> >
> >OK with these formatting changes.
> >
> >Thanks,
> >Uros.
>
> Thank you for the review!
> Posted PATCH v5 https://gcc.gnu.org/pipermail/gcc-patches/2023-October/633153.html
> with the formatting.
>
> I don't have write access to the gcc repository:)
Please provide the ChangeLog entry (see [1,2]) and I'll commit the
patch for you.
[1] https://gcc.gnu.org/contribute.html
[2] https://gcc.gnu.org/codingconventions.html#ChangeLogs
Thanks,
Uros.
next prev parent reply other threads:[~2023-10-16 19:10 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-01 19:51 [PATCH v4] " Fangrui Song
2023-08-22 7:19 ` Fangrui Song
2023-09-13 18:19 ` Fangrui Song
2023-09-27 17:54 ` Fangrui Song
2023-10-16 17:12 ` Uros Bizjak
2023-10-16 18:24 ` [PATCH v5] " Fangrui Song
2023-10-16 19:10 ` Uros Bizjak [this message]
2023-10-16 19:58 ` Fangrui Song
2023-10-16 21:46 ` Uros Bizjak
2023-10-16 18:21 Fangrui Song
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