[gcc/devel/rust/master] Merge #1543

[gcc/devel/rust/master] Merge #1543

[Thomas Schwinge]

https://gcc.gnu.org/g:bef31ea273689021f0fc8168f417edf386060512

commit bef31ea273689021f0fc8168f417edf386060512
Merge: e623ee314fb bb5efc657ae
Author: bors[bot] <26634292+bors[bot]@users.noreply.github.com>
Date:   Fri Oct 7 11:03:59 2022 +0000

    Merge #1543
    
    1543: Reintroduce targetrustm hooks without the maze of macro definitions in target headers r=CohenArthur a=ibuclaw
    
    - Adds skeleton support and documentation for targetrustm hooks.
    - Re-adds previously reverted `TARGET_RUST_CPU_INFO` target hook.
    - Re-adds the previously reverted `TARGET_RUST_OS_INFO` target hook.
    - Implements `TARGET_RUST_CPU_INFO` hook for x86 (only a subset of the original i386-rust.cc was re-added)
    - Implements `TARGET_RUST_OS_INFO` hook for darwin (covers both x86 and powerpc).
    
    There's quite a bit to unpick from what was removed, but I hope this shows how firstly `rust-target.h` and `tm_rust.h` should be kept as empty as possible for the `default-rust.cc` source file that pulls in these headers; secondly all rust macros and declarations be put in rust-specific headers, then pulled into tm_rust.h as-needed. From every other `${target}-rust.cc` file, you can include as much as you like in order to pry out the information you need to get at.
    
    I've verified this does work as expected with the `-frust-dump-target_options` switch, e.g with `-mavx2`
    ```
    target_endian: "little"
    target_pointer_width: "64"
    target_feature: "fxsr"
    target_feature: "popcnt"
    target_feature: "avx2"
    target_feature: "ssse3"
    target_feature: "sse4.1"
    target_feature: "sse3"
    target_feature: "avx"
    target_feature: "sse"
    target_feature: "xsave"
    target_feature: "sse4.2"
    target_feature: "sse2"
    target_feature: "mmx"
    target_arch: "x86_64"
    ```
    
    I've also built a few darwin cross compilers with the following results on i686-darwin
    ```
    target_pointer_width: "32"
    target_env: ""
    target_vendor: "apple"
    target_endian: "little"
    target_os: "macos"
    target_family: "unix"
    target_feature: "sse3"
    target_feature: "sse"
    target_feature: "sse2"
    target_feature: "mmx"
    target_arch: "x86"
    ```
    and on powerpc64-darwin
    ```
    target_pointer_width: "64"
    target_env: ""
    target_vendor: "apple"
    target_endian: "big"
    target_os: "macos"
    target_family: "unix"
    ```
    
    Co-authored-by: Iain Buclaw <ibuclaw@gdcproject.org>

Diff:

 .github/bors_log_expected_warnings |   8 +--
 gcc/Makefile.in                    |  34 +++++++++-
 gcc/config.gcc                     |  27 ++++++++
 gcc/config/darwin-rust.cc          |  44 +++++++++++++
 gcc/config/default-rust.cc         |  29 +++++++++
 gcc/config/i386/i386-rust.cc       | 129 +++++++++++++++++++++++++++++++++++++
 gcc/config/i386/i386-rust.h        |  22 +++++++
 gcc/config/i386/t-i386             |   4 ++
 gcc/config/t-darwin                |   4 ++
 gcc/configure                      |  21 +++++-
 gcc/configure.ac                   |  14 ++++
 gcc/doc/tm.texi                    |  26 ++++++++
 gcc/doc/tm.texi.in                 |  17 +++++
 gcc/genhooks.cc                    |   1 +
 gcc/rust/rust-lang.cc              |   2 -
 gcc/rust/rust-session-manager.cc   |   8 ++-
 gcc/rust/rust-target-def.h         |  20 ++++++
 gcc/rust/rust-target.def           |  52 +++++++++++++++
 gcc/rust/rust-target.h             |  35 ++++++++++
 19 files changed, 487 insertions(+), 10 deletions(-)