[PATCH] D135693: [WIP][RegisterScavenger][RISCV] Don't search for FrameSetup instrs if we were searching from Non-FrameSetup instrs

[luxufan via Phabricator via llvm-commits]

StephenFan added a comment.

In D135693#3850538 <https://reviews.llvm.org/D135693#3850538>, @craig.topper wrote:

> In D135693#3850055 <https://reviews.llvm.org/D135693#3850055>, @craig.topper wrote:
>
>> If I understand correctly, the use of a vreg in the frame-setup allowed findSurvivorBackward to trigger this code
>>
>>   // Keep searching when we find a vreg since the spilled register will
>>   // be usefull for this other vreg as well later.
>>   bool FoundVReg = false;
>>   for (const MachineOperand &MO : MI.operands()) {
>>     if (MO.isReg() && Register::isVirtualRegister(MO.getReg())) {
>>       FoundVReg = true;
>>       break;
>>     }
>>   }
>>   if (FoundVReg) {
>>     InstrCountDown = InstrLimit;
>>     Pos = I;
>>   }
>>
>> which caused the search to stop above the frame-setup. So another option might be to use T1 as the scratch register in frame-setup as was once proposed in an earlier revision of https://reviews.llvm.org/D61884
>
> But we can't use T1 with shrink wrapping and I've confirmed the same bug exists with shrink wrapping.

Thanks for looking into shrink-wrapping! Do you mind sharing your shrink-wrapping test cases? So that I can pick them as CodeGen/RISCV test cases.


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