About compiler options when using NEON in i.MX6DL.

[keitanagashima]

Dear Sir or Madam,

Hello.

I have a question about compiler options when using NEON in i.MX6DL.

BSP:Yocto L3.10.17_1.0.0

We are executing the program which does an image processing at high speed with NEON.

But, it didn't perform well.

When compiling a program, we sets following compiler options.

[Compiler options]

arm-poky-linux-gnueabi-gcc -march=armv7-a -mthumb-interwork -mfloat-abi=hard -mfpu=neon -mcpu=cortex-a9 -mtune=cortex-a9 --sysroot=/opt/poky/1.5.1/sysroots/cortexa9hf-vfp-neon-poky-linux-gnueabi -c -O3 -flax-vector-conversions -I./../../test/header -I./../../test/header2 -I./ -I./../../../fsl-community-bsp/build/tmp/work/cortexa9hf-vfp-neon-poky-linux-gnueabi/opencv/2.4.6+gitAUTOINC+c5afaa4e8d-r0/packages-split/opencv-dev/usr/include test1.c test2.c

[Quesition]

Please give me your advice to implove the performance.

PS,

When changing "mfloat-abi=hard" to "soft" or "softfp", it became a build error.

Best Regards,

Keita

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[Yuri · Accepted solution]

1.
Please refer to the next VFP introduction on i.MX6 :

https://community.freescale.com/docs/DOC-100112

Also, the following may be helpful :

"Question, enabling NEON H/W"

https://community.freescale.com/message/380469#380469

2.

  Note, that under Linux we should use the same options for floating point support  and

the same interface for floating point parameters in fucntion calls (ABI) : hardware or software.

Therefore if Linux release is based on hardware options, it is needed to apply those ones

to all applications.

Have a great day,
Yuri

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