[PATCH v5 0/8] BaseTools: add support for GCC5 in LTO mode

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

This v5 to introduce GCC5 is now a 8 piece series, including some
preparatory cleanup patches that allow all GCC4x and CLANG35 toolchains
to switch to using 'gcc' as the linker. This allows us to get rid of
the wrapper script to marshall ld arguments in order to make them
understandable by gcc, which is fragile and likely to cause problems in
the future.

Since there appears to be a natural split between the 'legacy' GCC
toolchains UNIXGCC, ELFGCC, and CYGGCC[xASL], both in term of supported
architectures [IA32, X64, IPF] vs [IA32, X64, ARM, AARCH64], and in
terms of maintenance, these toolchains are not moved to using 'gcc' as
the linker, and instead, a new BUILDRULEFAMILY is introduced called GCCLD
that will retain the old behavior.

The result is that GCC5 can align much more closely with its predecessors,
making the expected maintenance burden of supporting GCC back to v4.4
much lower.

Changes since v4:
- added patch to use 'protected' visibility only for the libraries that
  define the module entry points (_ModuleEntryPoint), to prevent them from
  being optimized away by the LTO routines
- added Jordan's ack/RBs
- add some extra comments to tools_def.template (#8)

Changes since v3:
- like Steven does in his GCC5LTO patch, add -fno-builtin to IA32 and X64
  CC_FLAGS; this addresses a build issue reported by Liming
- add -Os the the linker flags as well, for AARCH64 this does not seem to make
  a difference, but it is arguably correct since the LTO processing at link
  time involves code generation as well
- add Laszlo's ack to #2
- new patch #6 to omit the autogenerated build-id from the PE/COFF binary

Changes since v2:
- add license headers to LTO glue files for ARM and AARCH64 (#5)
- get rid of lto-ld-wrapper script

Ard Biesheuvel (8):
  BaseTools CLANG35: drop problematic use-movt and save-temps options
  ArmVirtPkg/ArmVirtPrePiUniCoreRelocatable: ignore .hash and .note
    sections
  BaseTools UNIXGCC ELFGCC CYGGCC: clone GCC build rule family into
    GCCLD
  BaseTools GCC: use 'gcc' as the linker command for GCC44 and later
  ArmPkg: add prebuilt glue binaries for GCC5 LTO support
  BaseTools GCC: drop GNU notes section from EFI image
  MdePkg GCC/X64: avoid 'hidden' visibility for module entry points
  BaseTools GCC: introduce GCC5 toolchain to support GCC v5.x in LTO
    mode

 ArmPkg/GccLto/liblto-aarch64.a                                         | Bin 0 -> 1016 bytes
 ArmPkg/GccLto/liblto-aarch64.s                                         |  27 ++
 ArmPkg/GccLto/liblto-arm.a                                             | Bin 0 -> 2096 bytes
 ArmPkg/GccLto/liblto-arm.s                                             |  61 ++++
 ArmVirtPkg/PrePi/ArmVirtPrePiUniCoreRelocatable.inf                    |   2 +-
 ArmVirtPkg/PrePi/Scripts/PrePi-PIE.lds                                 |   3 +
 BaseTools/Conf/build_rule.template                                     |  31 +-
 BaseTools/Conf/tools_def.template                                      | 350 +++++++++++++++-----
 BaseTools/Scripts/GccBase.lds                                          |   6 +
 EmulatorPkg/Unix/Host/Host.inf                                         |   6 +-
 MdePkg/Include/X64/ProcessorBind.h                                     |   9 +-
 MdePkg/Library/DxeCoreEntryPoint/DxeCoreEntryPoint.inf                 |   2 +
 MdePkg/Library/PeiCoreEntryPoint/PeiCoreEntryPoint.inf                 |   2 +
 MdePkg/Library/PeimEntryPoint/PeimEntryPoint.inf                       |   2 +
 MdePkg/Library/UefiApplicationEntryPoint/UefiApplicationEntryPoint.inf |   2 +
 MdePkg/Library/UefiDriverEntryPoint/UefiDriverEntryPoint.inf           |   2 +
 16 files changed, 396 insertions(+), 109 deletions(-)
 create mode 100644 ArmPkg/GccLto/liblto-aarch64.a
 create mode 100644 ArmPkg/GccLto/liblto-aarch64.s
 create mode 100644 ArmPkg/GccLto/liblto-arm.a
 create mode 100644 ArmPkg/GccLto/liblto-arm.s

-- 
2.7.4