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

Alexandre Colucci timac at timac.org
Fri Jul 23 02:20:18 PDT 2010


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)?

Here is a small sample code that exhibits the issue:

int main()
		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


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