[LLVMdev] problems with single byte stores in the arm backend

Robert Muth robertm at google.com
Wed Jul 13 09:09:03 PDT 2011


I have been struggling with this for way too long now, so hopefully the
mighty list can help:

I am trying to generate a byte store  instruction storing the constant value
4 at some given address
in a new helper function inside ARMISelLowering.cpp

I tried:

  SDValue Val = DAG.getConstant(4, MVT::i8);
  SDValue Store = DAG.getStore(chain,
                                 dl,
                                 Val,
                                 Addr,
                                 MachinePointerInfo(),
                                 false, false, 0);


This gives me a a legalizer assert for MVT::i8.

If I change it to MVT::i32 the code works but instead of
a single byte store (STRB) I get a word store (STR).

How can I force the width of the store?

Thanks,
Robert
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