[llvm] [X86] Support EGPR (R16-R31) for APX (PR #67702)

[Shengchen Kan via llvm-commits]

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@@ -158,6 +158,10 @@ X86RegisterInfo::getLargestLegalSuperClass(const TargetRegisterClass *RC,
     case X86::GR16RegClassID:
     case X86::GR32RegClassID:
     case X86::GR64RegClassID:
+    case X86::GR8_NOREX2RegClassID:
+    case X86::GR16_NOREX2RegClassID:
+    case X86::GR32_NOREX2RegClassID:
+    case X86::GR64_NOREX2RegClassID:
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KanRobert wrote:

There is no `createVirtualRegister(&X86::GRxxRegClass)` for instructions that can not encode EGPR so far. If there is any in the future, we will directly use `createVirtualRegister(&X86::GRxx_NOREX2RegClass)` at those places.

https://github.com/llvm/llvm-project/pull/67702