Change default optimisation level to O1 when exporting to uVision

[chrissnow]

Description

When exporting to uVision the default level is O0 which is wasteful as dead code and variables are included. O1 removes this without causing debugging issues.

From
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0472k/chr1359124221739.html

Although the debug view produced by -O0 corresponds most closely to the source code, users might prefer the debug view produced by -O1 because this improves the quality of the code without changing the fundamental structure.

Fixes #11068

Pull request type

[ ] Fix
[ ] Refactor
[ ] Target update
[x] Functionality change
[ ] Docs update
[ ] Test update
[ ] Breaking change

Reviewers

Release Notes

Default uVision optimisation level changed to O1. It matches the debug profile.

[ciarmcom]

@chrissnow, thank you for your changes.
@ARMmbed/mbed-os-tools @ARMmbed/mbed-os-maintainers please review.

[0xc0170]

Before I approve, I would like to make sure the other exporters are aligned or why they shouldn't !

[chrissnow]

I agree that it would be nice that they are all aligned,I think Os is used in some exports, O1 in others.
uVision has limited options,

Ideally the export should match debug profile which it now does?

mbed-os/tools/profiles/debug.json

Line 19 in 2e09a27

"common": ["-c", "--target=arm-arm-none-eabi", "-mthumb", "-g", "-O1",

It would be possible to output uVision projects that include all 3 profiles as different project targets
http://www.keil.com/support/man/docs/uv4/uv4_ca_projtargfilegr.htm

Or alternatively pass the profiles optimisation level to the exporter.

Sadly both are a bit beyond the time I can commit to this.

[0xc0170]

Matching debug profile

I've checked IAR it's set to High balanced, but that shall be fixed separately

[0xc0170]

CI started

[kjbracey]

How do exporters and profiles interact? Are the exporters supposed to export according to a specified profile, or create an export with all profiles?

I think it's got to be one of the above, and either way, it would be preferable to pick the optimisation level up from the profile, just like the language selection. I was messing with that mapping in #11225; I'm not familiar with how all the plumbing hangs together, but presumably that concept could easily be copied over for the optimisation and debug options.

[0xc0170]

My initial expectation were the same but I checked some and could not find optimization being exported.

They contain "non valid flag" checks:

IAR implementation:

        # Flag invalid if set in template
        # Optimizations are also set in template
        invalid_flag = lambda x: x in template or re.match("-O(\d|time|n|hz?)", x)

uvision

        def valid_flag(x):
            return (
                x not in in_template and
                not x.startswith("-O") and
                not x.startswith("-std") and
                not x.startswith("-D")
            )

This means exporters are using predefined optimization level in templates and even ignores some other flags as we can see.

I think it's got to be one of the above, and either way, it would be preferable to pick the optimisation level up from the profile, just like the language selection. I was messing with that mapping in #11225; I'm not familiar with how all the plumbing hangs together, but presumably that concept could easily be copied over for the optimisation and debug options.

Ideally yes (exporting profiles is not that simple but if we can use the profile then it would be as simple as export debug or export release. Having multiple profiles is supported by many tools, but might require bit more work to refactor templates). It might be worth creating a new ticket for this (to find out why there are these non valid options in each exporter).

cc @ARMmbed/mbed-os-tools

[mbed-ci]

Test run: SUCCESS

Summary: 11 of 11 test jobs passed
Build number : 1
Build artifacts

[0xc0170]

I'll merge this as it aligns with the default profile and create a new issue for profiles not being exported

[0xc0170]

created #11263