[PATCH] D98101: [RISCV] Enable the LocalStackSlotAllocation pass support

[luxufan via Phabricator via llvm-commits]

StephenFan added inline comments.


================
Comment at: llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp:291
+  // For RISC-V, The machine instructions that include a FrameIndex operand
+  // are load/store(exclude vector load/store), ADDI instructions.
+  if (!MI->mayLoad() && !MI->mayStore() && !(MI->getOpcode() == RISCV::ADDI))
----------------
craig.topper wrote:
> I think vector load/store can have a frameindex operand. There's no immediate field so it will get split out into an ADDI in eliminateFrameIndex, but I think that happens later.
In the RISCVIselDAGToDAG.cpp:
```
case ISD::FrameIndex: {
    SDValue Imm = CurDAG->getTargetConstant(0, DL, XLenVT);
    int FI = cast<FrameIndexSDNode>(Node)->getIndex();
    SDValue TFI = CurDAG->getTargetFrameIndex(FI, VT);
    ReplaceNode(Node, CurDAG->getMachineNode(RISCV::ADDI, DL, VT, TFI, Imm));
    return;
  }
```
So the llvm ir like this :
```
%addr = alloca i8
call void callee(i8* %addr)
```
the %addr will be selected to ADDI


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https://reviews.llvm.org/D98101