expanding i16 operations in presence of an i16 regclass.

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1

Reframing and Reposting my earlier query:

My target has 16-bit registers for indirect address of data.
All other registers are 8-bit.

Therefore I have added regclasses for i8 and i16 types.

All arithmetic operations (including pointer arithmetic ) are 8-bit operations.

The problem is that LLVM does not expand i16 operations to i8 operations in presence of i16 regclass.

What is the best way to tackle this?

Do I need to custom lower arithmetic operations during Legalize using LowerOperation ( )?

  • Sanjiv
2

Reframing and Reposting my earlier query:

My target has 16-bit registers for indirect address of data.
All other registers are 8-bit.

Therefore I have added regclasses for i8 and i16 types.

All arithmetic operations (including pointer arithmetic ) are 8-bit operations.

The problem is that LLVM does not expand i16 operations to i8 operations in presence of i16 regclass.

What is the best way to tackle this?

Do I need to custom lower arithmetic operations during Legalize using LowerOperation ( )?

What happens if you mark i16 arithmetic operations expand? i.e. setOperationAction(ISD::ADD, MVT::i16, Expand);

Evan