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gcc vs g++ and linking with as
- To: Chris Howard <choward at intellistor dot com>
- Subject: gcc vs g++ and linking with as
- From: "Robert J. Brown" <rj at eli dot elilabs dot com>
- Date: Fri, 26 Jun 1998 02:47:26 -0500
- Cc: c++-embedded at cygnus dot com, crossgcc at cygnus dot com
- References: <35926CEF.9F0E576F@intellistor.com>
>>>>> "Chris" == Chris Howard <choward@intellistor.com> writes:
Chris> binutils 2.9 gcc/g++ 2.8.0
Chris> Host Sun Sparc Solaris 2.5 Target Motorola Coldfire
Chris> (-m5200) a.out object format
Chris> ---
Chris> Not using stdlib (-nostdlib)
Chris> We have some code in assembler, and some in C. Compiling
Chris> with as,gcc and linking with ld works fine. Compiling with
Chris> as,g++ and linking with ld does not work, undefined symbols
Chris> for those things written in assembler.
You will have to declare the asm routines "extern 'C'" because the
assembler does not perform C++ name mangling for you.
Chris> The .o files output from g++ compilation have exported
Chris> symbols that end in '__Fv' whereas the assembler output .o
Chris> files don't have '__Fv' on the symbols. Is that the
Chris> problem? Is there some way to make it work? What is __Fv?
These are C++ mangled names. Use c++filt to de-mangle C++ mangled
names. The mangling encodes type information into the names so that
the linker can resolve functions with the same name but different
signatures.
Chris> An alternative might be to put the assembly code in C/C++
Chris> wrapper functions. Any hints/comments that would be
Chris> appreciated also.
This is not necessary -- just declare the asm functions extern 'C' and
the compiler will know not to mangle those names, so the linker will
be able to resolve them.
Chris> -- Chris Howard Fujitsu Computer Products of America
Chris> Longmont, Colorado
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