GNU Arm Embedded Toolchain

Change from 4.8q3 to 4.9q1

Asked by Martin Lang

Hello,

I updated my toolchain from 4.8q3 to 4.9q1 and was wondering why my bin file size
is increasing from 272kb(4.8q3) to 284kb(4.9q1). This is not a big deal, but I'm wondering
why that is the case.

(I compiled both with O1)

thanks for any help

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Tony Liu (mrtoniliu) said : 		#1

Hi,

Is that bin file is your programme or the one in toolchain? Generally, there will be some optimisations in each updates, some of them may increase the codesize a little bit but has a better performance. Also it may come from update of newlib.

BR,
Tony

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Tony Liu (mrtoniliu) said : 		#2

Hi,

It is also possibly related to the known issue described in the release.txt:

Thumb1 code size regression due to new register allocation:
  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61578
  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59535
  A workaround is to disable it by option -mno-lra.

BR,
Tony

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Martin Lang (mart-lang-in) said : 		#3

Thanks for that hint. I tried with -mno-lra but it doesn't change the size of my bin file.
Here are my compiling params I used:

 arm-none-eabi-gcc -mcpu=cortex-m4 -mfpu=fpv4-sp-d16 -mno-lra -mfloat-abi=hard -mthumb -Wall -ffunction-sections -g -O1 -c -D...

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Thomas Preud'homme (thomas-preudhomme) said : 		#4

Hi Martin,

One way to check where does this come from is to look at the size column in the output of "arm-none-eabi-readelf -s" command and compare between the two toolchain. The next step is to compare the objdump for the biggest offender and report here so we can examine.

Best regards.

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