[PATCH] D100704: [Thumb1][MachineOutliner] Add Machine Outliner support for Thumb1

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

tTAILJMPdND isn't generally available in Thumb mode, only in Thumb2 or armv8m.base.

>   PUSH R4     ;; Free up an auxilary register
>   PUSH LR     ;; LR must go on the top of the stack
>   
>   ......      ;; Original sequence of instructions
>   
>   POP R4      ;; Pop LR off the stack into R4
>               ;; (Cannot be directly popped into LR)
>   MOV LR, R4  ;; Move LR into the correct register
>   POP R4      ;; Pop the original value of R4 into R4

Can we instead do something like:

  push lr
  .... ; Original sequence
  mov ip, r4
  pop r4
  mov lr, r4
  mov r4, ip



================
Comment at: llvm/lib/Target/ARM/Thumb1InstrInfo.cpp:257
+                                                LiveRegUnits UsedInSequence,
+                                                LiveRegUnits BeforeSequence) const {
+  const ARMBaseRegisterInfo *ARI = static_cast<const ARMBaseRegisterInfo *>(
----------------
BeforeSequence is unused here?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D100704/new/

https://reviews.llvm.org/D100704