[LLVMdev] clang build (Debug+Asserts) fails with Cygwin and Mingw (ASTContext.o: File too big)

[Liviu Gheorghisan]

Hi again,

After googling a little I noticed this patch: 
https://sourceware.org/ml/binutils/2014-03/msg00110.html

introduced in Binutils in March 2014 (GNU assembler (GNU Binutils) 
2.24.51.20140326), that extends GNU assembler for Cygwin and Mingw with 
this flag:

-mbig-obj               generate big object files

So, clang can be built with this flag by adding this to llvm/Makefile.rules:

ifeq ($(HOST_OS), $(filter $(HOST_OS), Cygwin MingW))
     CXX.Flags += -Xassembler -mbig-obj
endif

The problem is that, although ASTContext.o is built successfully with 
-mbig-obj, the build fails later on in clang/unittests, like this:

as: 
/cygdrive/d/Projects/Cpp/llvm/cfgCygDebugAsserts/tools/clang/unittests/Tooling/Debug+Asserts/RecursiveASTVisitorTest.o: 
section 
.debug_frame$_ZN5clang19RecursiveASTVisitorINS_17LambdaExprVisitorEE32WalkUpFromCXXTemporaryObjectExprEPNS_22CXXTemporaryObjectExprE: 
string table overflow at offset 10000096
/tmp/ccQCVRXf.s: Assembler messages:
/tmp/ccQCVRXf.s: Fatal error: can't close 
/cygdrive/d/Projects/Cpp/llvm/cfgCygDebugAsserts/tools/clang/unittests/Tooling/Debug+Asserts/RecursiveASTVisitorTest.o: 
File too big
/cygdrive/d/Projects/Cpp/llvm/Makefile.rules:1509: recipe for target 
'/cygdrive/d/Projects/Cpp/llvm/cfgCygDebugAsserts/tools/clang/unittests/Tooling/Debug+Asserts/RecursiveASTVisitorTest.o' 
failed


For this latter problem ("string table overflow"), I didn't yet find a 
solution, apart from building without debug info, and with optimizations 
enabled. See this also: 
http://stackoverflow.com/questions/14125007/gcc-string-table-overflow-error-during-compilation

I will switch back to Linux.

On 5/3/2014 12:42 AM, Liviu Gheorghisan wrote:
>
>
> On 5/2/2014 11:41 PM, David Blaikie wrote:
>> Any idea what all those sections are - comdat inline functions?
>>
> No idea, as I cannot run objdump -h on a object file that I couldn't
> build :)
>   Anyhow, I have an old, successful Debug+Asserts build of clang, made
> with Mingw also, for clang revision 206070. Apparently, the ASTContext.o
> file there contained 16453 sections, not 33066, as there are today.
>
>> Does the debug info in COFF do something weird and emit a section per
>> type or function?
>>
> I will do a release build tomorrow and check the sections. (in my
> timezone it's night) - I will let you know!
>
>> On Fri, May 2, 2014 at 1:11 PM, Liviu Gheorghisan <livghe at gmx.com> wrote:
>>> Hello,
>>>
>>> After switching from a Linux development host to Windows7 with Cygwin, I
>>> notice the following problem when building clang (trunk, HEAD):
>>> (also happens with Mingw)
>>>
>>> ...
>>>
>>> llvm[4]: Compiling ParseInit.cpp for Debug+Asserts build
>>> as:
>>> /cygdrive/d/Projects/Cpp/llvm/cfgCygwin/tools/clang/lib/AST/Debug+Asserts/ASTContext.o:
>>>
>>> too many sections (33066)
>>> /tmp/ccmtDH7w.s: Assembler messages:
>>> /tmp/ccmtDH7w.s: Fatal error: can't write
>>> /cygdrive/d/Projects/Cpp/llvm/cfgCygwin/tools/clang/lib/AST/Debug+Asserts/ASTContext.o:
>>>
>>> File too big
>>> as:
>>> /cygdrive/d/Projects/Cpp/llvm/cfgCygwin/tools/clang/lib/AST/Debug+Asserts/ASTContext.o:
>>>
>>> too many sections (33066)
>>> /tmp/ccmtDH7w.s: Fatal error: can't close
>>> /cygdrive/d/Projects/Cpp/llvm/cfgCygwin/tools/clang/lib/AST/Debug+Asserts/ASTContext.o:
>>>
>>> File too big
>>> /cygdrive/d/Projects/Cpp/llvm/Makefile.rules:1509: recipe for target
>>> '/cygdrive/d/Projects/Cpp/llvm/cfgCygwin/tools/clang/lib/AST/Debug+Asserts/ASTContext.o'
>>>
>>> failed
>>> make[4]: ***
>>> [/cygdrive/d/Projects/Cpp/llvm/cfgCygwin/tools/clang/lib/AST/Debug+Asserts/ASTContext.o]
>>>
>>> Error 1
>>> make[4]: Leaving directory
>>> '/cygdrive/d/Projects/Cpp/llvm/cfgCygwin/tools/clang/lib/AST'
>>> /cygdrive/d/Projects/Cpp/llvm/Makefile.rules:936: recipe for target
>>> 'AST/.makeall' failed
>>> make[3]: *** [AST/.makeall] Error 2
>>>
>>> ...
>>>
>>>
>>> The reason for this seems to be that the COFF object format in
>>> Windows only
>>> supports a maximum of 2^15 sections (32768) for obj files.
>>>
>>> To work around this issue, Microsoft's compiler cl has a flag called
>>> /bigobj
>>> that allocates 32 bits in order to store the number of sections
>>> (instead of
>>> 16 bits, as this standard specifies:
>>> http://msdn.microsoft.com/en-us/library/gg463119.aspx )
>>>
>>> Also check this for /bigobj:
>>> http://msdn.microsoft.com/en-us/library/ms173499.aspx
>>>
>>> Anybody else having this problem with Mingw/Cygwin? If yes, how did you
>>> overcome it?
>>>
>>> My Cygwin version is this:
>>> $ uname -a
>>> CYGWIN_NT-6.1 livghe-i5 1.7.29(0.272/5/3) 2014-04-07 13:46 x86_64 Cygwin
>>>
>>> The only option I currently see is to split the mammoth cpp file
>>> (ASTContext.cpp)  in 2 parts, or to get rid of the debug info (not
>>> desired).
>>>
>>>
>>> --
>>> Best Regards,
>>> -Liviu
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>

-- 
Best Regards,
-Liviu