* [Buildroot] [PATCH] Config.in: add -Ofast option
@ 2018-03-22 16:26 Joshua Henderson
2018-03-25 8:24 ` Yann E. MORIN
0 siblings, 1 reply; 4+ messages in thread
From: Joshua Henderson @ 2018-03-22 16:26 UTC (permalink / raw)
To: buildroot
-Ofast (introduced in GCC 4.6) It combines the existing optimization level -O3
with options that can affect standards compliance but result in better optimized
code. For example, -Ofast enables -ffast-math.
Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
---
Config.in | 9 +++++++++
package/Makefile.in | 3 +++
2 files changed, 12 insertions(+)
diff --git a/Config.in b/Config.in
index 0002df5..e83ce02 100644
--- a/Config.in
+++ b/Config.in
@@ -527,6 +527,15 @@ config BR2_OPTIMIZE_S
-ftree-vect-loop-version
This is the default.
+config BR2_OPTIMIZE_FAST
+ bool "optimize for fast"
+ help
+ Optimize for fast. Disregard strict standards compliance. -Ofast
+ enables all -O3 optimizations. It also enables optimizations that are
+ not valid for all standard-compliant programs. It turns on -ffast-math
+ and the Fortran-specific -fstack-arrays, unless -fmax-stack-var-size
+ is specified, and -fno-protect-parens.
+
endchoice
config BR2_GOOGLE_BREAKPAD_ENABLE
diff --git a/package/Makefile.in b/package/Makefile.in
index e387ce6..828e12e 100644
--- a/package/Makefile.in
+++ b/package/Makefile.in
@@ -128,6 +128,9 @@ endif
ifeq ($(BR2_OPTIMIZE_S),y)
TARGET_OPTIMIZATION = -Os
endif
+ifeq ($(BR2_OPTIMIZE_FAST),y)
+TARGET_OPTIMIZATION = -Ofast
+endif
ifeq ($(BR2_DEBUG_1),y)
TARGET_DEBUGGING = -g1
endif
--
2.7.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [Buildroot] [PATCH] Config.in: add -Ofast option
2018-03-22 16:26 [Buildroot] [PATCH] Config.in: add -Ofast option Joshua Henderson
@ 2018-03-25 8:24 ` Yann E. MORIN
2018-03-25 20:40 ` Thomas Petazzoni
0 siblings, 1 reply; 4+ messages in thread
From: Yann E. MORIN @ 2018-03-25 8:24 UTC (permalink / raw)
To: buildroot
Joshua, All,
On 2018-03-22 09:26 -0700, Joshua Henderson spake thusly:
> -Ofast (introduced in GCC 4.6) It combines the existing optimization level -O3
> with options that can affect standards compliance but result in better optimized
> code. For example, -Ofast enables -ffast-math.
>
> Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
> ---
> Config.in | 9 +++++++++
> package/Makefile.in | 3 +++
> 2 files changed, 12 insertions(+)
>
> diff --git a/Config.in b/Config.in
> index 0002df5..e83ce02 100644
> --- a/Config.in
> +++ b/Config.in
> @@ -527,6 +527,15 @@ config BR2_OPTIMIZE_S
> -ftree-vect-loop-version
> This is the default.
>
> +config BR2_OPTIMIZE_FAST
> + bool "optimize for fast"
-Ofast was introduced in gcc-4.6, so you need a dependency:
depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_6
Otherwise I'm fine with this.
Regards,
Yann E. MORIN.
> + help
> + Optimize for fast. Disregard strict standards compliance. -Ofast
> + enables all -O3 optimizations. It also enables optimizations that are
> + not valid for all standard-compliant programs. It turns on -ffast-math
> + and the Fortran-specific -fstack-arrays, unless -fmax-stack-var-size
> + is specified, and -fno-protect-parens.
> +
> endchoice
>
> config BR2_GOOGLE_BREAKPAD_ENABLE
> diff --git a/package/Makefile.in b/package/Makefile.in
> index e387ce6..828e12e 100644
> --- a/package/Makefile.in
> +++ b/package/Makefile.in
> @@ -128,6 +128,9 @@ endif
> ifeq ($(BR2_OPTIMIZE_S),y)
> TARGET_OPTIMIZATION = -Os
> endif
> +ifeq ($(BR2_OPTIMIZE_FAST),y)
> +TARGET_OPTIMIZATION = -Ofast
> +endif
> ifeq ($(BR2_DEBUG_1),y)
> TARGET_DEBUGGING = -g1
> endif
> --
> 2.7.4
>
> _______________________________________________
> buildroot mailing list
> buildroot at busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot
--
.-----------------.--------------------.------------------.--------------------.
| Yann E. MORIN | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software Designer | \ / CAMPAIGN | ___ |
| +33 223 225 172 `------------.-------: X AGAINST | \e/ There is no |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL | v conspiracy. |
'------------------------------^-------^------------------^--------------------'
^ permalink raw reply [flat|nested] 4+ messages in thread* [Buildroot] [PATCH] Config.in: add -Ofast option
2018-03-25 8:24 ` Yann E. MORIN
@ 2018-03-25 20:40 ` Thomas Petazzoni
2018-03-26 16:12 ` Yann E. MORIN
0 siblings, 1 reply; 4+ messages in thread
From: Thomas Petazzoni @ 2018-03-25 20:40 UTC (permalink / raw)
To: buildroot
Hello,
On Sun, 25 Mar 2018 10:24:34 +0200, Yann E. MORIN wrote:
> > +config BR2_OPTIMIZE_FAST
> > + bool "optimize for fast"
>
> -Ofast was introduced in gcc-4.6, so you need a dependency:
> depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_6
The "odd" thing being that menuconfig is organized as follows:
Target options --->
Build options --->
Toolchain --->
The optimization level is selected in "Build options" and the compiler
version is basically decided in "Toolchain".
So if you select -Ofast in Build options, and then go in Toolchain
chose a < 4.6 compiler, your -Ofast selection would disappear.
But there's no good way around this, and using gcc < 4.6 is anyway very
rare these days, so I also agree that the "depends on" you suggest is
what makes the most sense.
Thomas
--
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Buildroot] [PATCH] Config.in: add -Ofast option
2018-03-25 20:40 ` Thomas Petazzoni
@ 2018-03-26 16:12 ` Yann E. MORIN
0 siblings, 0 replies; 4+ messages in thread
From: Yann E. MORIN @ 2018-03-26 16:12 UTC (permalink / raw)
To: buildroot
Thomas, All,
On 2018-03-25 22:40 +0200, Thomas Petazzoni spake thusly:
> On Sun, 25 Mar 2018 10:24:34 +0200, Yann E. MORIN wrote:
> > > +config BR2_OPTIMIZE_FAST
> > > + bool "optimize for fast"
> >
> > -Ofast was introduced in gcc-4.6, so you need a dependency:
> > depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_6
>
> The "odd" thing being that menuconfig is organized as follows:
>
> Target options --->
> Build options --->
> Toolchain --->
>
> The optimization level is selected in "Build options" and the compiler
> version is basically decided in "Toolchain".
>
> So if you select -Ofast in Build options, and then go in Toolchain
> chose a < 4.6 compiler, your -Ofast selection would disappear.
Yeah, I know. But, as you ssay:
> But there's no good way around this, and using gcc < 4.6 is anyway very
... there's no good solution around this issue, and the case for gcc
before 4.6 is rare enough that we don't care abot those poor souls
anymore... :-/
> rare these days, so I also agree that the "depends on" you suggest is
> what makes the most sense.
Was that an Acked-by or a Reviewed-by? ;-)
Regards,
Yann E. MORIN.
--
.-----------------.--------------------.------------------.--------------------.
| Yann E. MORIN | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software Designer | \ / CAMPAIGN | ___ |
| +33 223 225 172 `------------.-------: X AGAINST | \e/ There is no |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL | v conspiracy. |
'------------------------------^-------^------------------^--------------------'
^ permalink raw reply [flat|nested] 4+ messages in thread
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2018-03-22 16:26 [Buildroot] [PATCH] Config.in: add -Ofast option Joshua Henderson
2018-03-25 8:24 ` Yann E. MORIN
2018-03-25 20:40 ` Thomas Petazzoni
2018-03-26 16:12 ` Yann E. MORIN
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