Re: [Patch][ARM]Don't put volatile memory access in IT block for cortex-m7

[Richard Earnshaw <Richard dot Earnshaw at foss dot arm dot com>]

On 25/02/15 10:42, Terry Guo wrote:
> > -----Original Message-----
> > From: gcc-patches-owner@gcc.gnu.org [mailto:gcc-patches-
> > owner@gcc.gnu.org] On Behalf Of Richard Earnshaw
> > Sent: Wednesday, February 18, 2015 2:45 AM
> > To: Terry Guo; gcc-patches@gcc.gnu.org
> > Cc: Richard Earnshaw; Ramana Radhakrishnan
> > Subject: Re: [Patch][ARM]Don't put volatile memory access in IT block for
> > cortex-m7
> >
> > On 12/02/15 11:12, Terry Guo wrote:
> > > Hi there,
> > >
> > > This patch intends to prevent gcc from putting volatile memory access
> > > into IT block for target like cortex-m7.
> > >
> > > gcc/ChangeLog:
> > >
> > > 2015-02-12  Terry Guo  <terry.guo@arm.com>
> > >
> > > 	* config/arm/arm.c (arm_tune_cortex_m7): New global variable.
> > > 	* config/arm/arm.h (TARGET_NO_VOLATILE_CE): New macro.
> > >                  (arm_tune_cortex_m7): Declare new global variable.
> > > 	* config/arm/arm.md (arm_comparison_operator): Disabled if not
> > allow
> > >                   volatile memory access in IT block.
> > >
> > > gcc/testsuite/ChangeLog:
> > >
> > > 2015-02-12  Terry Guo  <terry.guo@arm.com>
> > >
> > > 	* gcc.target/arm/cortex-m7-it-volatile.c: New test.
> >
> > Not ok.
> >
> > +/* Targets that don't support accessing volatile memory inside IT
> > block.  */
> > +#define TARGET_NO_VOLATILE_CE		(arm_tune_cortex_m7)
> >
> > Please don't create feature bits that explicitly test for a particular target.
> > Instead, define generic 'features' and then arrange for either the
> > architecture tables, or tuning tables (as appropriate) to enable that feature.
> >
> > See how arm_arch_arm_hwdiv is defined for how to do this.
> >
> > R.
>
> Thanks Richard.  Patch is updated per your suggestion. Is this one OK for current stage and 4.8/4.9?

This is OK for trunk. I suggest you let it gestate there for a few days 
before doing back-ports.

R.

> BR,
> Terry
>
> gcc/testsuite/ChangeLog:
>
> 2015-02-25  Terry Guo  <terry.guo@arm.com>
>
>      * gcc.target/arm/no-volatile-in-it.c: New test.
>
>
> gcc/ChangeLog:
>
> 2015-02-25  Terry Guo  <terry.guo@arm.com>
>
>      * config/arm/arm-cores.def (cortex-m7): Add flag FL_NO_VOLATILE_CE.
>      * config/arm/arm-protos.h (FL_NO_VOLATILE_CE): New flag.
>      (arm_arch_no_volatile_ce): Declare new global variable.
>      * config/arm/arm.c (arm_arch_no_volatile_ce): Define new global variable.
>      (arm_option_override): Assign value to arm_arch_no_volatile_ce.
>      * config/arm/arm.h (arm_arch_no_volatile_ce): Declare it.
>      (TARGET_NO_VOLATILE_CE): New macro.
>      * config/arm/arm.md (arm_comparison_operator): Disabled if not allow
>      volatile memory access in IT block