The way this test is structured right now, I set a breakpoint on
the instruction before the __builtin_trap. It hits the breakpoint,
disables the breakpoint, and instruction steps. This hits the
builtin_trap instruction which debugserver (on arm64) now advances
to the next instruction and reports that address to lldb. lldb
doesn't recognize this as a proper response to the instruction
step and continues executing until the next trap, and the test fails.
On x86_64, when you hit a __builtin_debugtrap instruction, you
can continue past this in the debugger. This patch has debugserver
recognize the specific instruction used for __builtin_debugtrap
and advance the pc past it, so that the user can continue execution
once they've hit one of these.
In the patch discussion, we were in agreement that it would be better
to have this knowledge up in lldb instead of depending on each
stub rewriting the pc behind the debugger's back, but that's a
larger scale change for another day.
<rdar://problem/65521634>
Differential revision: https://reviews.llvm.org/D91238
Jason Molenda