[PATCH] D101920: [AArch64][v8.3A] Avoid inserting implicit landing pads (PACI*SP)

Tue Jan 10 14:37:31 PST 2023

eugenis added a comment.
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This change claims that PACIASP has an implicit BTI JC. Is that correct? From my reading of the spec (and I have about 50% certainty that I'm right), the behavior is actually the same as of BTI C. At least this is true on Linux, where SCTRL_EL1.BT0 is set to 1.

I'm asking because `-mbranch-protection=standard` emits shorter code sequence with `-march=armv8.2-a` compared to `-march=armv8.3-a`. See

  0:   d503233f        paciasp

vs

  0:   d503245f        bti     c
  4:   dac103fe        pacia   x30, sp

Repository:
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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D101920/new/

https://reviews.llvm.org/D101920