[LLVMdev] Linking strncpy

[Chris Lattner]

On Wed, 14 Apr 2004, Eric Zimmerman wrote:
> I'm working on a CS326 compiler project, and I'm having some problems
> using string functions.  Some LLVM programs produced are either
> aborting or giving incorrect results; however, if I disassemble the
> LLVM bytecode and recompile with GCC, everything works fine.
>
> I encountered the following error when running lli with
> '-force-interpreter' option:
> "Tried to execute an unknown external function: sbyte * (sbyte
> *, sbyte *, uint) * strncpy"

This is one of the "features" of the interpreter: it only supports
external functions that it "knows" about.  Why not use the JIT, without
-force-interpreter?  Are you on a machine that we don't support?  If so,
you can either add support for strncpy (to
lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp) or use the C
backend.

-Chris


> Strncpy is used as part of my compiler's run-time library, and it was
> compiled with the C-frontend for LLVM.  Looking at the assembly, the
> function is declared at the top of the file;
>
> declare sbyte* %strncpy(sbyte*,sbyte*,uint) ;; __builtin_strncpy
>
> And it is called like this:
> 	%tmp.12 = call sbyte* (sbyte*, sbyte*, uint)* %strncpy(sbyte*
> %tmp.15, sbyte* %tmp.23, uint %tmp.27)
>
> What am I forgetting to do?  What is the right way to link to the
> string functions?  Thanks,
>
> -Eric Zimmerman
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev
>

-Chris

-- 
http://llvm.cs.uiuc.edu/
http://www.nondot.org/~sabre/Projects/