[all-commits] [llvm/llvm-project] 320fd3: [ARM] Implement harden-sls-retbr for Thumb mode

[Kristof Beyls via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 320fd3314e378ae6242a2dde97250a8a94d68e27
      https://github.com/llvm/llvm-project/commit/320fd3314e378ae6242a2dde97250a8a94d68e27
  Author: Kristof Beyls <kristof.beyls at arm.com>
  Date:   2020-12-19 (Sat, 19 Dec 2020)

  Changed paths:
    M llvm/lib/Target/ARM/ARMAsmPrinter.cpp
    M llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
    M llvm/lib/Target/ARM/ARMBaseInstrInfo.h
    M llvm/lib/Target/ARM/ARMConstantIslandPass.cpp
    M llvm/lib/Target/ARM/ARMInstrThumb2.td
    M llvm/lib/Target/ARM/ARMSLSHardening.cpp
    M llvm/test/CodeGen/ARM/speculation-hardening-sls.ll

  Log Message:
  -----------
  [ARM] Implement harden-sls-retbr for Thumb mode

The only non-trivial consideration in this patch is that the formation
of TBB/TBH instructions, which is done in the constant island pass, does
not understand the speculation barriers inserted by the SLSHardening
pass. As such, when harden-sls-retbr is enabled for a function, the
formation of TBB/TBH instructions in the constant island pass is
disabled.

Differential Revision: https://reviews.llvm.org/D92396