[AArch64][Outliner] Don't outline BTI instructions

We can't outline BTI instructions, because they need to be the very first
instruction executed after an indirect call or branch. If we outline them, then
an indirect call might go to the branch to the outlined function, which will
fault.

Differential revision: https://reviews.llvm.org/D57753

llvm-svn: 353190

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
index 4996f1c1764..e2018ab7578 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -5330,6 +5330,14 @@ AArch64InstrInfo::getOutliningType(MachineBasicBlock::iterator &MIT,
       MI.modifiesRegister(AArch64::W30, &getRegisterInfo()))
     return outliner::InstrType::Illegal;
 
+  // Don't outline BTI instructions, because that will prevent the outlining
+  // site from being indirectly callable.
+  if (MI.getOpcode() == AArch64::HINT) {
+    int64_t Imm = MI.getOperand(0).getImm();
+    if (Imm == 32 || Imm == 34 || Imm == 36 || Imm == 38)
+      return outliner::InstrType::Illegal;
+  }
+
   return outliner::InstrType::Legal;
 }