[5/7,ARC] Enable indexed loads for elf targers.

gcc/
2017-02-28  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/arc/arc.opt (mindexed-loads): Use initial value
	TARGET_INDEXED_LOADS_DEFAULT.
	(mauto-modify-reg): Use initial value
	TARGET_AUTO_MODIFY_REG_DEFAULT.
	* config/arc/elf.h (TARGET_INDEXED_LOADS_DEFAULT): Define.
	(TARGET_AUTO_MODIFY_REG_DEFAULT): Likewise.
	* config/arc/linux.h (TARGET_INDEXED_LOADS_DEFAULT): Define.
	(TARGET_AUTO_MODIFY_REG_DEFAULT): Likewise.
---
 gcc/config/arc/arc.opt | 4 ++--
 gcc/config/arc/elf.h   | 8 ++++++++
 gcc/config/arc/linux.h | 8 ++++++++
 3 files changed, 18 insertions(+), 2 deletions(-)

* Claudiu Zissulescu <Claudiu.Zissulescu@synopsys.com> [2017-06-01 15:34:55 +0200]:

> gcc/
> 2017-02-28  Claudiu Zissulescu  <claziss@synopsys.com>
> 
> 	* config/arc/arc.opt (mindexed-loads): Use initial value
> 	TARGET_INDEXED_LOADS_DEFAULT.
> 	(mauto-modify-reg): Use initial value
> 	TARGET_AUTO_MODIFY_REG_DEFAULT.
> 	* config/arc/elf.h (TARGET_INDEXED_LOADS_DEFAULT): Define.
> 	(TARGET_AUTO_MODIFY_REG_DEFAULT): Likewise.
> 	* config/arc/linux.h (TARGET_INDEXED_LOADS_DEFAULT): Define.
> 	(TARGET_AUTO_MODIFY_REG_DEFAULT): Likewise.

The change looks fine, but it would be nice if the commit message
explained _why_ we are default off for Linux and on for Elf, I think
more text in the commit message on this sort of thing will help future
developers understand why things are the way they are.

Thanks,
Andrew



> ---
>  gcc/config/arc/arc.opt | 4 ++--
>  gcc/config/arc/elf.h   | 8 ++++++++
>  gcc/config/arc/linux.h | 8 ++++++++
>  3 files changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/gcc/config/arc/arc.opt b/gcc/config/arc/arc.opt
> index f01a2ff..ed2b827 100644
> --- a/gcc/config/arc/arc.opt
> +++ b/gcc/config/arc/arc.opt
> @@ -270,11 +270,11 @@ Target RejectNegative Var(arc_tune, TUNE_ARC700_4_2_XMAC)
>  Tune for ARC700 R4.2 Cpu with XMAC block.
>  
>  mindexed-loads
> -Target Var(TARGET_INDEXED_LOADS)
> +Target Var(TARGET_INDEXED_LOADS) Init(TARGET_INDEXED_LOADS_DEFAULT)
>  Enable the use of indexed loads.
>  
>  mauto-modify-reg
> -Target Var(TARGET_AUTO_MODIFY_REG)
> +Target Var(TARGET_AUTO_MODIFY_REG) Init(TARGET_AUTO_MODIFY_REG_DEFAULT)
>  Enable the use of pre/post modify with register displacement.
>  
>  mmul32x16
> diff --git a/gcc/config/arc/elf.h b/gcc/config/arc/elf.h
> index c5794f8..43f3408 100644
> --- a/gcc/config/arc/elf.h
> +++ b/gcc/config/arc/elf.h
> @@ -58,3 +58,11 @@ along with GCC; see the file COPYING3.  If not see
>  /* Bare-metal toolchains do not need a thread pointer register.  */
>  #undef TARGET_ARC_TP_REGNO_DEFAULT
>  #define TARGET_ARC_TP_REGNO_DEFAULT -1
> +
> +/* Indexed loads are default.  */
> +#undef TARGET_INDEXED_LOADS_DEFAULT
> +#define TARGET_INDEXED_LOADS_DEFAULT 1
> +
> +/* Pre/post modify with register displacement are default.  */
> +#undef TARGET_AUTO_MODIFY_REG_DEFAULT
> +#define TARGET_AUTO_MODIFY_REG_DEFAULT 1
> diff --git a/gcc/config/arc/linux.h b/gcc/config/arc/linux.h
> index 83e5a1d..d8e0063 100644
> --- a/gcc/config/arc/linux.h
> +++ b/gcc/config/arc/linux.h
> @@ -83,3 +83,11 @@ along with GCC; see the file COPYING3.  If not see
>  #define SUBTARGET_CPP_SPEC "\
>     %{pthread:-D_REENTRANT} \
>  "
> +
> +/* Indexed loads are default off.  */
> +#undef TARGET_INDEXED_LOADS_DEFAULT
> +#define TARGET_INDEXED_LOADS_DEFAULT 0
> +
> +/* Pre/post modify with register displacement are default off.  */
> +#undef TARGET_AUTO_MODIFY_REG_DEFAULT
> +#define TARGET_AUTO_MODIFY_REG_DEFAULT 0
> -- 
> 1.9.1
>

> The change looks fine, but it would be nice if the commit message
> explained _why_ we are default off for Linux and on for Elf, I think
> more text in the commit message on this sort of thing will help future
> developers understand why things are the way they are.
> 

This explanation is quite simple,  we haven't fully validated Linux with those options on. As it may take a while until I am getting a more complete image on this enhancement for Linux, I've enabled this option for elf, where I've got very good feedback from our gnu users.

Normally, it should be no problem to enable them for Linux as well, but I would like to have more testing data on this subject from various gnu users.

Thanks,
Claudiu

> The change looks fine, but it would be nice if the commit message
> explained _why_ we are default off for Linux and on for Elf, I think
> more text in the commit message on this sort of thing will help future
> developers understand why things are the way they are.
> 

Committed with suggested annotations. Thank you for your review,
Claudiu