[PATCH] D79785: [ARM] Register pressure with -mthumb forces register reload before each call

[Prathamesh via Phabricator via llvm-commits]

prathamesh added a comment.

Hi,
It seems the issue comes from TargetInstrInfo::foldMemoryOperand, which adds the memory operands of LoadMI to newly created MI.
It calls foldMemoryOperandImpl:

else {

    // Ask the target to do the actual folding.
    NewMI = foldMemoryOperandImpl(MF, MI, Ops, MI, LoadMI, LIS);
  }

and then:

  // Copy the memoperands from the load to the folded instruction.
  if (MI.memoperands_empty()) {
    NewMI->setMemRefs(MF, LoadMI.memoperands())

If we return immediately after calling foldMemoryOperandImpl, then the test-case compiles succeesfully.
I guess for this specific folding we don't need to attach memory operands of LoadMI, but that might not be true in general case ?
Should there be some way for foldMemoryOperandImpl to signal to foldMemoryOperand not to add memory operands of LoadMI ?
Thanks.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D79785/new/

https://reviews.llvm.org/D79785