[PATCH v4 0/6] Add ARM support for VS2017

[Pete Batard <pete@akeo.ie>]

(This v4 is the same as v3 from 2017-12-08, except to take into account Ard's
remarks and reuse the existing RVCT assembly for the MSFT compiler intrinsics)


The following series adds ARM compilation support for the VS2017 toolchain.
* PATCH 1 targets the disabling of VS Level 4 warnings. The disabled warnings
  for ARM are now aligned with IA32 and X64.
* PATCH 2 adds a NULL handler for the base stack check, since this is a GCC
  functionality.
* PATCH 3 updates MdePkg/Library/BaseLib so that the RVCT assembly sources
  are also used for MSFT.
* PATCH 4 adds the required compiler intrinsics replacements for division,
  shift, by reusing the RVCT code, as well as memset/memcpy.
* PATCH 5 adds variable argument handlers for print output. Note that this
  is done without relying on any external headers, with the VA_ARG macro
  having been reverse engineered from MSFT ARM assembly output.
* PATCH 6 enables the selection of ARM in the conf templates.

With these patches, VS2017 toolchain users should be able to compile
regular UEFI ARM applications using EDK2. Note that, unlike ARM64 support,
ARM support does not require a specific update of Visual Studio 2017, as
the ARM toolchain has been available from the very first release.

Additional notes:

We tested compiling and running the full UEFI Shell with this series, as
well as a small set of applications and drivers, and found no issues.
With an additional patch [1], it is also possible to use this proposal to
compile a complete QEMU ARM firmware. As the patch shows, the changes that
need to be applied to the EDK2 sources to achieve this are actually very
minimal.

However, the generated firmware does not currently boot, possibly because
of the following warnings being generated by the MS compiler:
- ArmCpuDxe.dll : warning LNK4072: section count 118 exceeds max (96); image may not run
- UiApp.dll : warning LNK4072: section count 113 exceeds max (96); image may not run

As far as I could see, the section count max is hardcoded so a workaround
would be needed to address those.

Also, because the VS2017 ARM compiler forces a section alignment of 4096
bytes (which in turn forces use to use /FILEALIGN:4096 as a linker option
for the firmware generation), the generated firmware exceeds 2MB and we
had to double its size to 4MB.

At this stage, since the goal of this series is to allow users to compile
regular ARM UEFI applications using the VS2017 toolchain, I have no plans
to spend more time on the QEMU firmware issues, especially as I suspect 
that reducing the firmware size back to 2 MB may not be achievable without
Microsoft altering their compiler. I am however hopeful that ARM
specialists can take this matter over eventually...

Regards,

/Pete

[1] https://github.com/pbatard/edk2/commit/c4ce41094a46f4f3dc7ccc64a90604813f037b13

Pete Batard (6):
  MdePkg: Disable some Level 4 warnings for VS2017/ARM
  MdePkg/Library/BaseStackCheckLib: Add Null handler for VS2017/ARM
  MdePkg/Library/BaseLib: Enable VS2017/ARM builds
  ArmPkg/Library/CompilerIntrinsicsLib: Enable VS2017/ARM builds
  MdePkg/Include: Add VA list support for VS2017/ARM
  BaseTools/Conf: Add VS2017/ARM support

 ArmPkg/Library/CompilerIntrinsicsLib/Arm/div.asm               | 43 +++++++--
 ArmPkg/Library/CompilerIntrinsicsLib/Arm/ldivmod.asm           | 40 ++++++--
 ArmPkg/Library/CompilerIntrinsicsLib/Arm/llsr.asm              | 22 +++--
 ArmPkg/Library/CompilerIntrinsicsLib/Arm/uldiv.asm             | 29 +++++-
 ArmPkg/Library/CompilerIntrinsicsLib/CompilerIntrinsicsLib.inf | 16 +++-
 ArmPkg/Library/CompilerIntrinsicsLib/memcpy_ms.c               | 34 +++++++
 ArmPkg/Library/CompilerIntrinsicsLib/memset_ms.c               | 33 +++++++
 BaseTools/Conf/build_rule.template                             | 31 ++++++-
 BaseTools/Conf/tools_def.template                              | 31 +++++++
 MdePkg/Include/Arm/ProcessorBind.h                             | 96 +++++++++++++++-----
 MdePkg/Include/Base.h                                          | 13 +++
 MdePkg/Library/BaseLib/Arm/CpuBreakpoint.asm                   |  5 +-
 MdePkg/Library/BaseLib/BaseLib.inf                             | 16 +++-
 MdePkg/Library/BaseStackCheckLib/BaseStackCheckLib.inf         |  5 +-
 MdePkg/Library/BaseStackCheckLib/BaseStackCheckNull.c          | 18 ++++
 15 files changed, 372 insertions(+), 60 deletions(-)
 create mode 100644 ArmPkg/Library/CompilerIntrinsicsLib/memcpy_ms.c
 create mode 100644 ArmPkg/Library/CompilerIntrinsicsLib/memset_ms.c
 create mode 100644 MdePkg/Library/BaseStackCheckLib/BaseStackCheckNull.c

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