Re: [PATCH v4] i386: Allow -mlarge-data-threshold with -mcmodel=large

[Fangrui Song <maskray@google.com>]

On Tue, Aug 1, 2023 at 12:51 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
>
> [...]

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