[all-commits] [llvm/llvm-project] d3864d: [Driver] Default -msmall-data-limit= to 0 and clea...

[Fangrui Song via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: d3864d946a178807bb5a87d3d1690e213c89e5be
      https://github.com/llvm/llvm-project/commit/d3864d946a178807bb5a87d3d1690e213c89e5be
  Author: Fangrui Song <i at maskray.me>
  Date:   2024-08-19 (Mon, 19 Aug 2024)

  Changed paths:
    M clang/include/clang/Basic/DiagnosticDriverKinds.td
    M clang/lib/Driver/ToolChains/Clang.cpp
    M clang/test/CodeGen/RISCV/riscv-sdata-module-flag.c
    R clang/test/Driver/riscv-sdata-warning.c
    A clang/test/Driver/riscv-sdata.c
    M llvm/lib/Target/RISCV/RISCVTargetObjectFile.h

  Log Message:
  -----------
  [Driver] Default -msmall-data-limit= to 0 and clean up code

D57497 added -msmall-data-limit= as an alias for -G and defaulted it to 8 for
-fno-pic/-fpie.

The behavior is already different from GCC in a few ways:

* GCC doesn't accept -G.
* GCC -fpie doesn't seem to use -msmall-data-limit=.
* GCC emits .srodata.cst* that we don't use (#82214). Writable contents
  caused confusion (https://bugs.chromium.org/p/llvm/issues/detail?id=61)

In addition,

* claiming `-shared` means we don't get a desired `-Wunused-command-line-argument` for `clang --target=riscv64-linux-gnu -fpic -c -shared a.c`.
* -mcmodel=large doesn't work for RISC-V yet, so the special case is strange.
* It's quite unusual to emit a warning when an option (unrelated to relocation model) is used with -fpic.
* We don't want future configurations (Android) to continue adding customization to `SetRISCVSmallDataLimit`.

I believe the extra code just doesn't pull its weight and should be
cleaned up. This patch also changes the default to 0. GP relaxation
users are encouraged to specify these customization options explicitly.

Pull Request: https://github.com/llvm/llvm-project/pull/83093



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