[PATCH] D123515: [RISCV] Support '.option arch' directive

[luxufan via Phabricator via llvm-commits]

StephenFan added inline comments.


================
Comment at: llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp:2498
+          if (getSTI().hasFeature(Feature.Value) &&
+              Feature.Implies.test(Ext->Value))
+            return Error(Parser.getTok().getLoc(),
----------------
craig.topper wrote:
> I don't think the implies list is normalized to include transitive implications. For example if A implies B and B implies C. I don't think the C is A's implies list.
> 
> This also doesn't cover cases that can't be expressed in the .td file. At one point Zve32f required either F or Zfinx. But F and Zfinx are mutually exclusive so we could't have Zve32f imply either of them in the .td file. All we could do is check it in `RISCVISAInfo::checkDependency`.
> I don't think the implies list is normalized to include transitive implications. For example if A implies B and B implies C. I don't think the C is A's implies list.
> 
Can this be handled by RISCVISAInfo? When I parse RISCVIAInfo from featureBits, it always updates implication.




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  https://reviews.llvm.org/D123515/new/

https://reviews.llvm.org/D123515