[all-commits] [llvm/llvm-project] 6a0c44: [Driver, sanitizer] Remove RequiresPIE and msan's N...

[Fangrui Song via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 6a0c440159aa2b2e895fe6e04af39c91e54733ce
      https://github.com/llvm/llvm-project/commit/6a0c440159aa2b2e895fe6e04af39c91e54733ce
  Author: Fangrui Song <i at maskray.me>
  Date:   2024-01-11 (Thu, 11 Jan 2024)

  Changed paths:
    M clang/lib/Driver/SanitizerArgs.cpp

  Log Message:
  -----------
  [Driver,sanitizer] Remove RequiresPIE and msan's NeedPIE setting (#77689)

The two variables cause clang to default to -fPIE when no PIC/PIC option
is
specified.

msan used to require PIE because many `kMemoryLayout` made the low
address (used by ET_EXEC executables) invalid. Current msan.h no longer
does so, rendering this PIE requirement unneeded. The same argument
applies to -fsanitize=dataflow.

On Linux, most builds set CLANG_DEFAULT_PIE_ON_LINUX to 1, making
`RequiresPIE/NeedPIE` redundant on Linux.

(`NeedPIE` is not removed for now due to the -fsanitize-cfi-cross-dso
comment. If it's indeed incompatible with explicit -fno-pic, a warning
is probably better.)