Re: [PATCH 2/2] arm: Add support for interrupt routines to reg_needs_saving_p

[Christophe Lyon via Gcc-patches]

On Fri, 15 May 2020 at 11:38, Ramana Radhakrishnan
 wrote:
>
> On Fri, May 15, 2020 at 7:36 AM Christophe Lyon
>  wrote:
> >
> > On Thu, 14 May 2020 at 17:58, Ramana Radhakrishnan
> >  wrote:
> > >
> > > >  static bool reg_needs_saving_p (unsigned reg)
> > > >  {
> > > >unsigned long func_type = arm_current_func_type ();
> > >
> > > Ah ok , you needed it here.
> >
> > Yes sorry.
> > Is this patch (2/2) OK?
> >
>
> This looks ok to me as long as there are no regressions and you rejig
> the hunks between 1/2 and 2/2
>
Ok, thanks!

> regards
> Ramana
>
> > Thanks,
> >
> > Christophe
> >
> > >
> > > Ramana

Re: [PATCH 2/2] arm: Add support for interrupt routines to reg_needs_saving_p

[Ramana Radhakrishnan via Gcc-patches]

On Fri, May 15, 2020 at 7:36 AM Christophe Lyon
 wrote:
>
> On Thu, 14 May 2020 at 17:58, Ramana Radhakrishnan
>  wrote:
> >
> > >  static bool reg_needs_saving_p (unsigned reg)
> > >  {
> > >unsigned long func_type = arm_current_func_type ();
> >
> > Ah ok , you needed it here.
>
> Yes sorry.
> Is this patch (2/2) OK?
>

This looks ok to me as long as there are no regressions and you rejig
the hunks between 1/2 and 2/2

regards
Ramana

> Thanks,
>
> Christophe
>
> >
> > Ramana

Re: [PATCH 2/2] arm: Add support for interrupt routines to reg_needs_saving_p

[Christophe Lyon via Gcc-patches]

On Thu, 14 May 2020 at 17:58, Ramana Radhakrishnan
 wrote:
>
> >  static bool reg_needs_saving_p (unsigned reg)
> >  {
> >unsigned long func_type = arm_current_func_type ();
>
> Ah ok , you needed it here.

Yes sorry.
Is this patch (2/2) OK?

Thanks,

Christophe

>
> Ramana

Re: [PATCH 2/2] arm: Add support for interrupt routines to reg_needs_saving_p

[Ramana Radhakrishnan via Gcc-patches]

>  static bool reg_needs_saving_p (unsigned reg)
>  {
>unsigned long func_type = arm_current_func_type ();

Ah ok , you needed it here.

Ramana

[PATCH 2/2] arm: Add support for interrupt routines to reg_needs_saving_p

[Christophe Lyon via Gcc-patches]

reg_needs_saving_p is only used when dealing with non-interrupt
routines, but it makes sense to extend it to support that context too,
and make arm_compute_save_reg0_reg12_mask use it.

Save only live registers for non-leaf functions, but assume a callee
could clobber any register.

2020-05-14  Christophe Lyon  

gcc/
* config/arm/arm.c (reg_needs_saving_p): Add support for interrupt
routines.
(arm_compute_save_reg0_reg12_mask): Use reg_needs_saving_p.
---
 gcc/config/arm/arm.c | 26 +++---
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 694c1bb..0107f50 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -4188,16 +4188,29 @@ arm_trampoline_adjust_address (rtx addr)
   return addr;
 }
 
-/* Return 1 if REG needs to be saved.   */
+/* Return 1 if REG needs to be saved. For interrupt handlers, this
+   includes call-clobbered registers too.  If this is a leaf function
+   we can just examine the registers used by the RTL, but otherwise we
+   have to assume that whatever function is called might clobber
+   anything, and so we have to save all the call-clobbered registers
+   as well.  */
 static bool reg_needs_saving_p (unsigned reg)
 {
   unsigned long func_type = arm_current_func_type ();
 
-  if (!df_regs_ever_live_p (reg)
-  || call_used_or_fixed_reg_p (reg))
-return false;
+  if (IS_INTERRUPT (func_type))
+if (df_regs_ever_live_p (reg)
+   /* Save call-clobbered core registers.  */
+   || (! crtl->is_leaf && call_used_or_fixed_reg_p (reg) && reg < 
FIRST_VFP_REGNUM))
+  return true;
+else
+  return false;
   else
-return true;
+if (!df_regs_ever_live_p (reg)
+   || call_used_or_fixed_reg_p (reg))
+  return false;
+else
+  return true;
 }
 
 /* Return 1 if it is possible to return using a single instruction.
@@ -20685,8 +20698,7 @@ arm_compute_save_reg0_reg12_mask (void)
max_reg = 12;
 
   for (reg = 0; reg <= max_reg; reg++)
-   if (df_regs_ever_live_p (reg)
-   || (! crtl->is_leaf && call_used_or_fixed_reg_p (reg)))
+   if (reg_needs_saving_p (reg))
  save_reg_mask |= (1 << reg);
 
   /* Also save the pic base register if necessary.  */
-- 
2.7.4