[LLVMdev] warnings in inline assembly with used labels and -Wunused-label

[Chris Lattner]

On Jul 23, 2010, at 2:20 AM, Alexandre Colucci wrote:

> Hi,
> 
> llvm-gcc 4.2 generates warnings when I compile inline assembly code that contains used labels with -Wunused-label. The generated code seems to work yet. gcc 4.2 doesn't generate those warnings. I haven't found any bugs regarding this issue in the llvm bug database.
> 
> Does anyone know if this is a known llvm issue? Is it a warning that I can ignore and does not affect the generated code? Is there a workaround to avoid these warnings (without turning off -Wunused-label)?

What version of llvm-gcc 4.2 are you using?  I think that Dale just fixed this issue, so you might try SVN head to see if it is gone now.

-Chris

> 
> 
> Here is a small sample code that exhibits the issue:
> 
> int main()
> {
> __asm__
> 	{
> MyLabel:
> 		sub	ebx,8
> 		jg MyLabel
> 	}
> 	
> 	return 0;
> }
> 
> 
> Compile with llvm-gcc 4.2 on MacOSX 10.6:
> 
> llvm-gcc-4.2 -arch i386 -Wunused-label -fasm-blocks -o inlineassembly_llvm inlineassembly.c
> inlineassembly.c: In function ‘main’:
> inlineassembly.c:7: warning: label ‘LASM$MyLabel’ defined but not used
> 
> Compile with gcc 4.2 on MacOSX 10.6:
> 
> gcc -arch i386 -Wunused-label -fasm-blocks -o inlineassembly inlineassembly.c
> no warnings
> 
> 
> Thanks,
> Alexandre
> 
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev