fix Issue 21490 - Optimizer can add SSE integer multiply for machines…

[WalterBright]

… less than SSE4.1 which do not have it

The test case is adding -O to dmd/test/runnable/testxmm.d, but both this PR and #12035 are necessary for that to work. So they are mutually blocking each other. One has to be pulled first. I suggest this one.

[dlang-bot]

Thanks for your pull request, @WalterBright!

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	21490	normal	Optimizer can add SSE integer multiply for machines less than SSE4.1 which do not have it

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#12038"

[ibuclaw]

I see nothing wrong here, maybe you are just building the compiler with the default CPU set too high?

[ibuclaw]

Or cpuid is mis-detecting the native CPU.

dmd/src/dmd/mars.d

Lines 1420 to 1423 in b475122

	import core.cpuid;
	params.cpu = core.cpuid.avx2 ? CPU.avx2 :
	core.cpuid.avx ? CPU.avx :
	CPU.sse2;

[WalterBright]

The detection in the front end is correct. The problem is the optimizer does not check the SSE support level before inserting a multiply.

[PetarKirov]

I don't like merging bug fixes without corresponding tests, but #12039 should fill the gap once this is merged.

I will merge this PR first and then I will cherry-pick #12039 in #12035 and rebase on master.

[WalterBright]

@PetarKirov thanks!

[PetarKirov]

@WalterBright you're most welcome, thanks for fixing this bug so quickly!