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Re: [RFC PATCH, i386]: Use %r15 for REAL_PIC_OFFSET_TABLE_REGNUM on x86_64

On Fri, Dec 28, 2012 at 9:27 PM, Richard Henderson <> wrote:
> On 12/27/2012 12:08 AM, Uros Bizjak wrote:
>> The alternative approach is changing cpuid definition in cpuid.h (as
>> in attached patch) to preserve %rbx, but we can't detect various code
>> model settings there. Since the change depends on the definition of
>> __PIC__, we unnecessary preserve %rbx also for -mcmodel=small.
> Certainly we can.  We also control the preprocessor defines.
> All that's needed is that we create one for the code model.

Something like attached?

I have also included all suggestions (earlyclobber and operand prefix
on temporary register).

2012-12-30  Uros Bizjak  <>

	PR target/55712
	* config/i386/i386-c.c (ix86_target_macros_internal): Depending on
	selected code model, define __code_mode_small__, __code_model_medium__,
	__code_model_large__, __code_model_32__ or __code_model_kernel__.
	* config/i386/cpuid.h (__cpuid, __cpuid_count) [__i386__]: Prefix
	xchg temporary register with %k.  Declare temporary register as
	early clobbered.
	[__x86_64__]: For medium and large code models, preserve %rbx register.

Tested on x86_64-pc-linux-gnu {,-m32}.


Attachment: p.diff.txt
Description: Text document

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