[PATCH] D130919: [MRI] isConstantPhysReg should also check if the register is clobbered by a RegMask

Tue Sep 20 08:01:14 PDT 2022

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In D130919#3802764 <https://reviews.llvm.org/D130919#3802764>, @arichardson wrote:

> In D130919#3802733 <https://reviews.llvm.org/D130919#3802733>, @arsenm wrote:
>
>> Can this be closed with D131958 <https://reviews.llvm.org/D131958>?
>
> I think so (about to commit that revision once I check tests still pass), but it's hard to say if it covers all cases this revision does since there are no tests.

No, a phyiscal register is not a target constant register, but if it is not modified inside a specific function, it can still be treated as a constant register by MachineRegisterInfo::isConstantPhysReg inside the specific function. The modification should include both defined register operand and regmask.

I will update this patch. But it still depends on D132987 <https://reviews.llvm.org/D132987> and D132561 <https://reviews.llvm.org/D132561> to prevent regressions. These are real problems exposed by this patch.

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https://reviews.llvm.org/D130919