[PATCH v2, i386]: Fix PR 36079 [4.3/4.4 Regression] cld instruction is not emitted anymore.

[Paolo Bonzini]

> 2008-05-21  Uros Bizjak  <ubizjak@gmail.com>
> 	    Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR target/36079
> 	* configure.ac: Handle --enable-cld.
> 	* configure: Regenerated.
> 	* config.gcc: Add USE_IX86_CLD to tm_defines for x86 targets.
> 	* config/i386/i386.h (struct machine_function): Add needs_cld field.
> 	(ix86_current_function_needs_cld): New define.
> 	* config/i386/i386.md (UNSPEC_CLD): New unspec volatile constant.
> 	(cld): New isns pattern.
> 	(strmov_singleop, rep_mov, strset_singleop, rep_stos, cmpstrnqi_nz_1,
> 	cmpstrnqi_1, strlenqi_1): Set ix86_current_function_needs_cld flag.
> 	* config/i386/i386.opt (mcld): New option.
> 	* config/i386/i386.c (ix86_expand_prologue): Emit cld insn if
> 	TARGET_CLD and ix86_current_function_needs_cld.
> 	(override_options): Use -mcld by default for 32-bit code if
> 	USE_IX86_CLD.
> 
> OK for 4.3 branch?

Build parts are ok for 4.3 and trunk, except that you could merge the 
case statement you added with the one before it (yes, that involves a 
small duplication).  Those parts are preapproved with this change.

The rest, you can approve yourself (though IIUC you want a word from the 
branch RMs).

Paolo