[LLVMdev] Linking strncpy

[Reid Spencer]

The only thing I can think of is that string.h is being #included and
has different signatures for memcpy and strncpy. Possibly "char" is not
signed on your machine (very unusual) or some of the parameters are
declared as "const".

Reid.

On Wed, 2004-04-14 at 18:19, Eric Zimmerman wrote:
> Chris,
> 
> I'm fine with using JIT, but I'm trying to understand this problem:
> 1. My LLVM program does not produce correct results
> 2. Using llvm-dis, I disassemble the bytecode to C
> 3. I recompile using GCC and the program _works correctly_.
> 
> The only odd thing is when I recompile with GCC, I see these messages:
> 
> pal3.c:195: warning: conflicting types for built-in function `strcmp'
> pal3.c:200: warning: conflicting types for built-in function `memcpy'
> pal3.c:202: warning: conflicting types for built-in function `strncpy'
> 
> The lines referenced are:
> int strcmp(signed char *, signed char *);
> signed char *memcpy(signed char *, signed char *, unsigned );
> signed char *strncpy(signed char *, signed char *, unsigned );
> 
> Do you have any insight into what's happening?  Thanks,
> -Eric
> 
> ----- Forwarded message from Chris Lattner <sabre at nondot.org> -----
> 
> Date: Wed, 14 Apr 2004 19:25:45 -0500 (CDT)
> From: Chris Lattner <sabre at nondot.org>
> To: llvmdev at cs.uiuc.edu
> Subject: Re: [LLVMdev] Linking strncpy
> Reply-To: llvmdev at cs.uiuc.edu
> 
> 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
> >
> 
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_______________________
Reid Spencer
President & CTO
eXtensible Systems, Inc.
rspencer at x10sys.com
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