[clang] [llvm] [ARM, AArch64] Don't put BTI at asm goto branch targets (PR #141562)

[Peter Smith via cfe-commits]

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@@ -275,18 +275,33 @@ class MachineBasicBlock
   /// of a terminator, exception-handling target, or jump table. This is
   /// either the result of an IR-level "blockaddress", or some form
   /// of target-specific branch lowering.
+  ///
+  /// The name of this function `hasAddressTaken` implies that the address of
+  /// the block is known and used in a general sense, but not necessarily that
+  /// the address is used by an indirect branch instruction. So branch target
+  /// enforcement need not put a BTI instruction (or equivalent) at the start
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smithp35 wrote:

If we're looking for a more architecture neutral term than BTI instruction (or equivalent) the Wikipedia term "Branch Target" instruction could be useful.

https://en.wikipedia.org/wiki/Indirect_branch_tracking

As an Arm person I'm personally not in any hurry to change this :-) 

https://github.com/llvm/llvm-project/pull/141562