Change remove floating point libs from IRAM

[s-hadinger]

Description:

Changed linker script to move all floating point libs from libgcc.a out of IRAM. No interrupt handler is using float/double so we can safely move them back to IROM.

This is a quick and dirty patch, I'm sending a PR to Arduino Core in parallel to make it a compile flag.

IRAM size reduction:

• Tasmota (std): from 31660 to 30620 (-1040 bytes)
• Tasmota-sensors: from 31656 to 30616 (-1040 bytes)
• Tasmota-IR: from 29364 to 28324 (-1040 bytes)

The actual change is adding the following in eagle.app.v6.common.ld in section .irom0.text::

    *libgcc.a:*f2.o(.literal .text)
    *libgcc.a:*f3.o(.literal .text)
    *libgcc.a:*fsi.o(.literal .text)
    *libgcc.a:*fdi.o(.literal .text)
    *libgcc.a:*ifs.o(.literal .text)
    *libgcc.a:*idf.o(.literal .text)

Checklist:

• The pull request is done against the latest dev branch
• Only relevant files were touched
• Only one feature/fix was added per PR.
• The code change is tested and works on core Tasmota_core_stage
• The code change pass travis tests. Your PR cannot be merged unless tests pass
• I accept the CLA.

[Jason2866]

5 test devices with different sensors does work without a issue with this PR

[arendst]

I store my source on "Google Drive". This fails the compiler as the linker path contains a space in the path. Moving the source to a non spaced folder works fine.

Working on renaming "Google Drive" to "GoogleDrive"...

[s-hadinger]

This is probably not the best way to force a local linker script, but I didn't find a better way.

Anyways, I hope the PR esp8266/Arduino#7180 will be quickly merged in Arduino Core. After that it will only be a compilation flag.

[arendst]

Fixed it by removing and re-installing Google Drive pointing it to a renamed folder. Very (in)flexible this Google stuff.

[Jason2866]

Another way would be patching the file on the fly.
https://docs.platformio.org/en/latest/projectconf/advanced_scripting.html#override-package-files

EspEasy is doing this. Example PUYA patch

[s-hadinger]

That's very interesting, I didn't know this feature. I'm a bit reluctant to use patch files, they can very easily break whenever Arduino updates their files.