[edk2] VS2013 build failures: unresolved external symbol __dtoui3

Subject: [edk2] VS2013 build failures: unresolved external symbol __dtoui3

From: "Scott Duplichan" <scott@notabs.org>

To: <edk2-devel@lists.sourceforge.net>

Date: 2014-09-05 07:40:53

Building AppPkg for IA32 using VS2013 fails with unresolved external symbol __dtoui3.
__dtoui3 is a helper function called by the generated code. It is analogous to the
__ftol2 helper function call generated by older Microsoft compilers. VS2013 calls
__dtoui3 instead of __ftol2. Apparently the new function converts double to integer
with reduced use of the x87 fpu.

The call to __ftol2 generated by older Microsoft compilers is resolved by binary
file StdLib\LibC\Main\Ia32\ftol2.obj, an object extracted from Microsoft libs. The
same approach could be used for VS2013's __dtoui3 by extracting ftol3.obj and adding
it to EDK2. But doing so causes unresolved external symbol __except1. This can be
fixed by extracting fpexcept.obj from VS2013 libs and adding it to EDK2. But once
that is done, 12 more unresolved externals are created.

Another approach is to use /arch:SSE when building LibGdtoa for IA32 with VS2013
(default is /arch:SSE2). This causes VS2013 to generate a call to __ftol2 instead
of __dtoui3 and resolves the build failure. I suppose this is the route to take.
Concerns are:
1) Is it OK to combine modules compiled with /arch:SSE2 and /arch:SSE?
2) Is the current EDK2 ftol2.obj binary compatible with all supported Microsoft
   compilers, including VS2013?
I will do some testing and submit a patch if it looks OK.

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