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Re: [PATCH] Pass -mtune and -march options to assembler.


On Sat, 30 May 2009, Valdimir Volynsky wrote:

>  Mark Mitchell <mark@codesourcery.com> wrote:
> 
> > However you are solving this in the assembler, you can also solve it in the
> > compiler.  After all, the assembler has no information which the compiler
> > does not provide to it!
> > There are two parts to that recommendation: knowing what
> > opcodes start with 0xf7, and knowing the alignment of
> > instructions.  Both of those things are just as knowable in
> > the compiler as they are in the assembler.
> 
> But this information are knowable to assembler already, and not available
> in current GCC version. Do you suggest to add it to GCC? In this case
> assembler not required at all.

There is nothing wrong in principle with linking the assembler into the 
compiler when it becomes useful for the compiler to have information that 
is much more readily available with existing assembler code, including 
exact length information for inline asms.  (This would of course need to 
be optional while there are targets supported by GCC but not by the GNU 
assembler, such as Darwin and alpha*-dec-osf*, and would need to continue 
to support .s output with -save-temps.)  It might be hard to implement 
because so far the GNU assembler isn't designed for use as a library, but 
that's another matter, and linking the assembler into the compiler could 
also yield compile-time performance improvements.

-- 
Joseph S. Myers
joseph@codesourcery.com


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