[PATCH] D92933: [ARM][MachineOutliner] Handle stack usage.

Thu Dec 10 02:27:54 PST 2020

yroux added inline comments.

================
Comment at: llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp:5823
+      // outline this by saving all of its bytes.
+      else
+        NumBytesNoStackCalls += SequenceSize;
----------------
samparker wrote:
> We were returning here previously, and now it's possible that there's a Candidate that hasn't been inserted into CandidatesWithoutStackFixups. When we update RepeatedSequences on line 5832, are we guaranteed to have not missed some candidates?
OK, in fact what I tried to do here is just to fix the costs given to the candidates which was wrongly set to Calldefault for all candidates when SP wasn't used and at least one of them was called with save/restore of LR into the stack.

We were returning here without outling these candidates, if the need of stack fixup was detected, but that wasn't necessary the instructions which migh need such a fixup were marked as illegal for outlining in the code lines 6055-6070

So, here we are just preparing the next step which will handle the fixups, it is the same logic which is used in the AArch64 implementation.

I'll renane and change the description of this revision

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D92933/new/

https://reviews.llvm.org/D92933