[llvm] [RISCV][GlobalISel] Legalize and select G_ATOMICRMW_ADD instruction (PR #153791)

[Craig Topper via llvm-commits]

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@@ -1415,6 +1418,72 @@ void RISCVInstructionSelector::emitFence(AtomicOrdering FenceOrdering,
   MIB.buildInstr(RISCV::FENCE, {}, {}).addImm(Pred).addImm(Succ);
 }
 
+bool RISCVInstructionSelector::selectAtomicRMWAdd(MachineInstr &MI,
+                                                  MachineIRBuilder &MIB) const {
+  MachineBasicBlock &MBB = *MI.getParent();
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topperc wrote:

Isn't that GINodeEquiv already present in `llvm/include/llvm/Target/GlobalISel/SelectionDAGCompat.td`?

https://github.com/llvm/llvm-project/pull/153791