[llvm] [LLVM] treat `@llvm.ssub.sat` the same as `@llvm.aarch64.neon.sqsub` (PR #140454)

[David Green via llvm-commits]

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@@ -1795,6 +1795,34 @@ bool AArch64LegalizerInfo::legalizeIntrinsic(LegalizerHelper &Helper,
     MI.eraseFromParent();
     return true;
   }
+  case Intrinsic::aarch64_neon_sqadd: {
+    MachineIRBuilder MIB(MI);
+    if (MIB.getMRI()->getType(MI.getOperand(0).getReg()).isVector())
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davemgreen wrote:

Can you create a `MachineRegisterInfo &MRI = *MIB.getMRI();` at the top of this function?

https://github.com/llvm/llvm-project/pull/140454