[GlobalISel]: Target specific MIs like REG_SEQUENCE shouldn't be Regbank selected

[aditya_nandakumar]

Summary

Current version of isTargetSpecificOpcode only checks for opcodes > PRE_ISEL_GENERIC_OPCODE_END.
We'd need to check for those TargetOpcodes defined before PRE_ISEL_GENERIC_OPCODE_BEGIN.

[arsenm]

Why shouldn't they be?

[qcolombet]

Hi Aditya,

I don't think this is the right way to fix that.
We want to RegBankSelect COPYs and PHIs (and REG_SEQUENCEs at some point) and this patch breaks that.

The problem is that REG_SEQUENCE are not supported yet in RegBankSelect (we miss the logic to create appropriate mappings) and I believe a better work around is to explicitly by pass REG_SEQUENCE for now in RegBankSelect.

Cheers,
-Quentin

[aditya_nandakumar]

Thanks Quentin. That makes sense. I'll update the patch for that.

[qcolombet]

Actually, now, that I think about it, REG_SEQUENCE, if any, should be supported on AArch64.
Thus, we should need anything.

[qcolombet]

*shouldn't

include/llvm/Target/TargetOpcodes.h

 /// to appear after ISel.
 static inline bool isPreISelGenericOpcode(unsigned Opcode) {
   return Opcode >= TargetOpcode::PRE_ISEL_GENERIC_OPCODE_START &&
          Opcode <= TargetOpcode::PRE_ISEL_GENERIC_OPCODE_END;
 }
 
 /// Check whether the given Opcode is a target-specific opcode.
 static inline bool isTargetSpecificOpcode(unsigned Opcode) {
-  return Opcode > TargetOpcode::PRE_ISEL_GENERIC_OPCODE_END;
+  return !isPreISelGenericOpcode(Opcode);
 }
 } // end namespace llvm
 
 #endif