fix Issue 21826 - MSCOFF output for Win32 should not use EBP for anyt…

[WalterBright]

…hing other than the frame pointer

This is causing problems with #12409 but is not the purpose of that PR, so I separated it out.

The 114-115 fix disables use of EBP for general register use for the Win32 mscoff model.

The 536 just fixes a bug where it might wrongly select EBP. No test case known to trigger it, very hard to devise a test case that does as it is hyper sensitive to how registers are allocated.

[dlang-bot]

Thanks for your pull request, @WalterBright!

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	21826	normal	MSCOFF output for Win32 should not use EBP for anything other than the frame pointer

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + dmd#12433"

[RazvanN7]

@WalterBright Are you suggesting we merge this without tests?

This is causing problems with #12409 but is not the purpose of that PR, so I separated it out.

Can't a test case be extracted from there?

[WalterBright]

Can't a test case be extracted from there?

No because it is dependent on the code generation strategy being changed in #12409

[RazvanN7]

IMHO this would be placed better as a separate commit in #12409 . That way it can be covered by a test. I see no point in separating ii out since it is so closely coupled with that fix.

[WalterBright]

It's a distinct bug. Distinct bugs shouldn't be combined into one PR.

It doesn't need a distinct test in #12409 because the test suite already fails if this is not corrected.