[PATCH] aarch64: Do not alter force_reg returned rtx expanding pauth builtins

[PATCH] aarch64: Do not alter force_reg returned rtx expanding pauth builtins

[Andrea Corallo]

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Hi all,

having a look for force_reg returned rtx later on modified I've found
this other case in `aarch64_general_expand_builtin` while expanding 
pointer authentication builtins.

Regtested and bootsraped on aarch64-linux-gnu.

Okay for trunk?

  Andrea


[-- Attachment #2: 0001-aarch64-Do-not-alter-force_reg-returned-rtx-expandin.patch --]
[-- Type: text/plain, Size: 1169 bytes --]

From 8869ee04e3788fdec86aa7e5a13e2eb477091d0e Mon Sep 17 00:00:00 2001
From: Andrea Corallo <andrea.corallo@arm.com>
Date: Mon, 21 Sep 2020 13:52:45 +0100
Subject: [PATCH] aarch64: Do not alter force_reg returned rtx expanding pauth
 builtins

2020-09-21  Andrea Corallo  <andrea.corallo@arm.com>

	* config/aarch64/aarch64-builtins.c
	(aarch64_general_expand_builtin): Do not alter value on a
	force_reg returned rtx.
---
 gcc/config/aarch64/aarch64-builtins.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/gcc/config/aarch64/aarch64-builtins.c b/gcc/config/aarch64/aarch64-builtins.c
index b787719cf5e..a77718ccfac 100644
--- a/gcc/config/aarch64/aarch64-builtins.c
+++ b/gcc/config/aarch64/aarch64-builtins.c
@@ -2079,10 +2079,10 @@ aarch64_general_expand_builtin (unsigned int fcode, tree exp, rtx target,
       arg0 = CALL_EXPR_ARG (exp, 0);
       op0 = force_reg (Pmode, expand_normal (arg0));
 
-      if (!target)
+      if (!(target
+	    && REG_P (target)
+	    && GET_MODE (target) == Pmode))
 	target = gen_reg_rtx (Pmode);
-      else
-	target = force_reg (Pmode, target);
 
       emit_move_insn (target, op0);
 
-- 
2.17.1

Re: [PATCH] aarch64: Do not alter force_reg returned rtx expanding pauth builtins

[Richard Sandiford]

Andrea Corallo <andrea.corallo@arm.com> writes:
> Hi all,
>
> having a look for force_reg returned rtx later on modified I've found
> this other case in `aarch64_general_expand_builtin` while expanding 
> pointer authentication builtins.
>
> Regtested and bootsraped on aarch64-linux-gnu.
>
> Okay for trunk?
>
>   Andrea
>
> From 8869ee04e3788fdec86aa7e5a13e2eb477091d0e Mon Sep 17 00:00:00 2001
> From: Andrea Corallo <andrea.corallo@arm.com>
> Date: Mon, 21 Sep 2020 13:52:45 +0100
> Subject: [PATCH] aarch64: Do not alter force_reg returned rtx expanding pauth
>  builtins
>
> 2020-09-21  Andrea Corallo  <andrea.corallo@arm.com>
>
> 	* config/aarch64/aarch64-builtins.c
> 	(aarch64_general_expand_builtin): Do not alter value on a
> 	force_reg returned rtx.
> ---
>  gcc/config/aarch64/aarch64-builtins.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/gcc/config/aarch64/aarch64-builtins.c b/gcc/config/aarch64/aarch64-builtins.c
> index b787719cf5e..a77718ccfac 100644
> --- a/gcc/config/aarch64/aarch64-builtins.c
> +++ b/gcc/config/aarch64/aarch64-builtins.c
> @@ -2079,10 +2079,10 @@ aarch64_general_expand_builtin (unsigned int fcode, tree exp, rtx target,
>        arg0 = CALL_EXPR_ARG (exp, 0);
>        op0 = force_reg (Pmode, expand_normal (arg0));
>  
> -      if (!target)
> +      if (!(target
> +	    && REG_P (target)
> +	    && GET_MODE (target) == Pmode))
>  	target = gen_reg_rtx (Pmode);
> -      else
> -	target = force_reg (Pmode, target);
>  
>        emit_move_insn (target, op0);

Do we actually use the result of this move?  It looked like we always
use op0 rather than target (good) and overwrite target with a later move.

If so, I think we should delete the move and convert the later code
to use expand_insn.

Thanks,
Richard

Re: [PATCH] aarch64: Do not alter force_reg returned rtx expanding pauth builtins

[Andrea Corallo]

Hi Richard,

thanks for reviewing

Richard Sandiford <richard.sandiford@arm.com> writes:

> Andrea Corallo <andrea.corallo@arm.com> writes:
>> Hi all,
>>
>> having a look for force_reg returned rtx later on modified I've found
>> this other case in `aarch64_general_expand_builtin` while expanding 
>> pointer authentication builtins.
>>
>> Regtested and bootsraped on aarch64-linux-gnu.
>>
>> Okay for trunk?
>>
>>   Andrea
>>
>> From 8869ee04e3788fdec86aa7e5a13e2eb477091d0e Mon Sep 17 00:00:00 2001
>> From: Andrea Corallo <andrea.corallo@arm.com>
>> Date: Mon, 21 Sep 2020 13:52:45 +0100
>> Subject: [PATCH] aarch64: Do not alter force_reg returned rtx expanding pauth
>>  builtins
>>
>> 2020-09-21  Andrea Corallo  <andrea.corallo@arm.com>
>>
>> 	* config/aarch64/aarch64-builtins.c
>> 	(aarch64_general_expand_builtin): Do not alter value on a
>> 	force_reg returned rtx.
>> ---
>>  gcc/config/aarch64/aarch64-builtins.c | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/gcc/config/aarch64/aarch64-builtins.c b/gcc/config/aarch64/aarch64-builtins.c
>> index b787719cf5e..a77718ccfac 100644
>> --- a/gcc/config/aarch64/aarch64-builtins.c
>> +++ b/gcc/config/aarch64/aarch64-builtins.c
>> @@ -2079,10 +2079,10 @@ aarch64_general_expand_builtin (unsigned int fcode, tree exp, rtx target,
>>        arg0 = CALL_EXPR_ARG (exp, 0);
>>        op0 = force_reg (Pmode, expand_normal (arg0));
>>  
>> -      if (!target)
>> +      if (!(target
>> +	    && REG_P (target)
>> +	    && GET_MODE (target) == Pmode))
>>  	target = gen_reg_rtx (Pmode);
>> -      else
>> -	target = force_reg (Pmode, target);
>>  
>>        emit_move_insn (target, op0);
>
> Do we actually use the result of this move?  It looked like we always
> use op0 rather than target (good) and overwrite target with a later move.
>
> If so, I think we should delete the move

Good point agree.

> and convert the later code to use expand_insn.

I'm not sure I understand the suggestion right, xpaclri&friends patterns
are written with hardcoded in/out regs, is the suggestion to just use like
'expand_insn (CODE_FOR_xpaclri, 0, NULL)' in place of GEN_FCN+emit_insn?

Thanks!

  Andrea

Re: [PATCH] aarch64: Do not alter force_reg returned rtx expanding pauth builtins

[Richard Sandiford]

Andrea Corallo <andrea.corallo@arm.com> writes:
> Hi Richard,
>
> thanks for reviewing
>
> Richard Sandiford <richard.sandiford@arm.com> writes:
>
>> Andrea Corallo <andrea.corallo@arm.com> writes:
>>> Hi all,
>>>
>>> having a look for force_reg returned rtx later on modified I've found
>>> this other case in `aarch64_general_expand_builtin` while expanding 
>>> pointer authentication builtins.
>>>
>>> Regtested and bootsraped on aarch64-linux-gnu.
>>>
>>> Okay for trunk?
>>>
>>>   Andrea
>>>
>>> From 8869ee04e3788fdec86aa7e5a13e2eb477091d0e Mon Sep 17 00:00:00 2001
>>> From: Andrea Corallo <andrea.corallo@arm.com>
>>> Date: Mon, 21 Sep 2020 13:52:45 +0100
>>> Subject: [PATCH] aarch64: Do not alter force_reg returned rtx expanding pauth
>>>  builtins
>>>
>>> 2020-09-21  Andrea Corallo  <andrea.corallo@arm.com>
>>>
>>> 	* config/aarch64/aarch64-builtins.c
>>> 	(aarch64_general_expand_builtin): Do not alter value on a
>>> 	force_reg returned rtx.
>>> ---
>>>  gcc/config/aarch64/aarch64-builtins.c | 6 +++---
>>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/gcc/config/aarch64/aarch64-builtins.c b/gcc/config/aarch64/aarch64-builtins.c
>>> index b787719cf5e..a77718ccfac 100644
>>> --- a/gcc/config/aarch64/aarch64-builtins.c
>>> +++ b/gcc/config/aarch64/aarch64-builtins.c
>>> @@ -2079,10 +2079,10 @@ aarch64_general_expand_builtin (unsigned int fcode, tree exp, rtx target,
>>>        arg0 = CALL_EXPR_ARG (exp, 0);
>>>        op0 = force_reg (Pmode, expand_normal (arg0));
>>>  
>>> -      if (!target)
>>> +      if (!(target
>>> +	    && REG_P (target)
>>> +	    && GET_MODE (target) == Pmode))
>>>  	target = gen_reg_rtx (Pmode);
>>> -      else
>>> -	target = force_reg (Pmode, target);
>>>  
>>>        emit_move_insn (target, op0);
>>
>> Do we actually use the result of this move?  It looked like we always
>> use op0 rather than target (good) and overwrite target with a later move.
>>
>> If so, I think we should delete the move
>
> Good point agree.
>
>> and convert the later code to use expand_insn.
>
> I'm not sure I understand the suggestion right, xpaclri&friends patterns
> are written with hardcoded in/out regs, is the suggestion to just use like
> 'expand_insn (CODE_FOR_xpaclri, 0, NULL)' in place of GEN_FCN+emit_insn?

Oops, sorry for the bogus comment, didn't look closely enough.

So yeah, no need to use expand_insn.  Rather than generate a new target,
it should be OK to return lr and x17_reg directly.  (Hope I'm right
this time. ;-))

Thanks,
Richard

[PATCH V2] aarch64: Do not alter force_reg returned rtx expanding pauth builtins

[Andrea Corallo]

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Hi all,

here the reworked patch addressing Richard's suggestions.

Regtested and bootsraped on aarch64-linux-gnu.

Okay for trunk?

Thanks!

  Andrea


[-- Attachment #2: 0001-aarch64-Do-not-alter-force_reg-returned-rtx-expandin.patch --]
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From 946d22aa247f2d1bb0c6b10a6e6db415b34feff2 Mon Sep 17 00:00:00 2001
From: Andrea Corallo <andrea.corallo@arm.com>
Date: Mon, 21 Sep 2020 13:52:45 +0100
Subject: [PATCH] aarch64: Do not alter force_reg returned rtx expanding pauth
 builtins

2020-09-21  Andrea Corallo  <andrea.corallo@arm.com>

	* config/aarch64/aarch64-builtins.c
	(aarch64_general_expand_builtin): Do not alter value on a
	force_reg returned rtx.
---
 gcc/config/aarch64/aarch64-builtins.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/gcc/config/aarch64/aarch64-builtins.c b/gcc/config/aarch64/aarch64-builtins.c
index b787719cf5e..d7eb8772b14 100644
--- a/gcc/config/aarch64/aarch64-builtins.c
+++ b/gcc/config/aarch64/aarch64-builtins.c
@@ -2079,20 +2079,13 @@ aarch64_general_expand_builtin (unsigned int fcode, tree exp, rtx target,
       arg0 = CALL_EXPR_ARG (exp, 0);
       op0 = force_reg (Pmode, expand_normal (arg0));
 
-      if (!target)
-	target = gen_reg_rtx (Pmode);
-      else
-	target = force_reg (Pmode, target);
-
-      emit_move_insn (target, op0);
-
       if (fcode == AARCH64_PAUTH_BUILTIN_XPACLRI)
 	{
 	  rtx lr = gen_rtx_REG (Pmode, R30_REGNUM);
 	  icode = CODE_FOR_xpaclri;
 	  emit_move_insn (lr, op0);
 	  emit_insn (GEN_FCN (icode) ());
-	  emit_move_insn (target, lr);
+	  return lr;
 	}
       else
 	{
@@ -2122,11 +2115,9 @@ aarch64_general_expand_builtin (unsigned int fcode, tree exp, rtx target,
 	  emit_move_insn (x17_reg, op0);
 	  emit_move_insn (x16_reg, op1);
 	  emit_insn (GEN_FCN (icode) ());
-	  emit_move_insn (target, x17_reg);
+	  return x17_reg;
 	}
 
-      return target;
-
     case AARCH64_JSCVT:
       {
 	expand_operand ops[2];
-- 
2.17.1

Re: [PATCH V2] aarch64: Do not alter force_reg returned rtx expanding pauth builtins

[Richard Sandiford]

Andrea Corallo <andrea.corallo@arm.com> writes:
> Hi all,
>
> here the reworked patch addressing Richard's suggestions.
>
> Regtested and bootsraped on aarch64-linux-gnu.
>
> Okay for trunk?

OK, thanks.

Richard

Re: [PATCH V2] aarch64: Do not alter force_reg returned rtx expanding pauth builtins

[Andrea Corallo]

Richard Sandiford <richard.sandiford@arm.com> writes:

> Andrea Corallo <andrea.corallo@arm.com> writes:
>> Hi all,
>>
>> here the reworked patch addressing Richard's suggestions.
>>
>> Regtested and bootsraped on aarch64-linux-gnu.
>>
>> Okay for trunk?
>
> OK, thanks.
>
> Richard

Into trunk as 92f0d3d03a7.

Thanks!

  Andrea