RE: [PATCH, ARM] Fix PR64453: live high register not saved in function prolog with -Os

["Thomas Preud'homme" <thomas.preudhomme@arm.com>]

Hi Ramana,

> From: Ramana Radhakrishnan [mailto:ramana.gcc@googlemail.com]
> Sent: Wednesday, January 14, 2015 7:21 PM
> On Wed, Jan 14, 2015 at 10:20 AM, Thomas Preud'homme
> <thomas.preudhomme@arm.com> wrote:
> > When compiling for size, live high registers are not saved in function
> prolog in ARM backend in Thumb mode. The problem comes from
> arm_conditional_register_usage setting call_used_regs for all high
> register to avoid them being allocated. However, this cause prolog to not
> save these register even if they are used. This patch marks high registers
> as really needing to be saved in prolog if live, no matter what is the
> content of call_used_regs.
> >
> > ChangeLog entries are as follows:
> >
> > gcc/ChangeLog
> >
> > 2015-01-12 Thomas Preud'homme thomas.preudhomme@arm.com
> >
> >     PR target/64453
> >     * config/arm/arm.c (callee_saved_reg_p): Define.
> >     (arm_compute_save_reg0_reg12_mask): Use callee_saved_reg_p
> to check if
> >     register is callee saved instead of !call_used_regs[reg].
> >     (thumb1_compute_save_reg_mask): Likewise.
> >
> >
> > gcc/testsuite/ChangeLog
> >
> > 2014-12-31 Thomas Preud'homme thomas.preudhomme@arm.com
> >
> >     * gcc.target/arm/pr64453.c: New.
> >
> >
> >
> 
> OK.
> 
> Ramana

The patch applies cleanly on GCC 4.8 and 4.9 branches when omitting the cosmetic change
in arm_conditional_register_usage () which was unintended. I compiled an arm-none-eabi
GCC cross compiler and ran the testsuite for both backport without any regression.

Is this ok for the 4.8 and 4.9 branches?

Best regards,

Thomas