Add the sources for an API test case to be written

Author: jasonmolenda

lldb/test/API/macosx/unwind-frameless-faulted/interrupt-and-trap-funcs.s

@@ -0,0 +1,92 @@
+#define DW_CFA_register 0x9
+#define ehframe_x22  22
+#define ehframe_x23  23
+#define ehframe_pc 32
+
+  .section  __TEXT,__text,regular,pure_instructions
+
+//--------------------------------------
+// to_be_interrupted() a frameless function that does a non-ABI
+// function call ("is interrupted/traps" simulated) to trap().
+// Before it branches to trap(), it puts its return address in
+// x23.  trap() knows to branch back to $x23 when it has finished.
+//--------------------------------------
+  .globl  _to_be_interrupted
+  .p2align  2
+_to_be_interrupted:
+  .cfi_startproc
+
+  // This is a garbage entry to ensure that eh_frame is emitted,
+  // it isn't used for anything.  If there's no eh_frame, lldb
+  // can do an assembly emulation scan and add a rule for $lr
+  // which won't expose the issue at hand.
+  .cfi_escape DW_CFA_register, ehframe_x22, ehframe_x23
+  mov x24, x0
+  add x24, x24, #1
+
+  adrp x23, L_.return@PAGE        ; put return address in x4
+  add x23, x23, L_.return@PAGEOFF
+
+  b _trap                     ; branch to trap handler, fake async interrupt
+
+L_.return:
+  mov x0, x24
+  ret
+  .cfi_endproc
+  
+
+
+//--------------------------------------
+// trap() trap handler function, sets up stack frame
+// with special unwind rule for the pc value of the
+// "interrupted" stack frame (it's in x23), then calls
+// break_to_debugger().
+//--------------------------------------
+  .globl  _trap
+  .p2align  2
+_trap:                                  
+  .cfi_startproc
+  .cfi_signal_frame
+
+  // The pc value when we were interrupted is in x23
+  .cfi_escape DW_CFA_register, ehframe_pc, ehframe_x23
+
+  // standard prologue save of fp & lr so we can call puts()
+  sub sp, sp, #32
+  stp x29, x30, [sp, #16]
+  add x29, sp, #16
+  .cfi_def_cfa w29, 16
+  .cfi_offset w30, -8
+  .cfi_offset w29, -16
+
+  bl _break_to_debugger
+
+  ldp x29, x30, [sp, #16]
+  add sp, sp, #32
+
+  // jump back to $x23 to resume execution of to_be_interrupted
+  br x23
+  .cfi_endproc
+
+//--------------------------------------
+// break_to_debugger() executes a BRK instruction
+//--------------------------------------
+  .globl _break_to_debugger
+  .p2align  2
+_break_to_debugger:                                  
+  .cfi_startproc
+
+  // standard prologue save of fp & lr so we can call puts()
+  sub sp, sp, #32
+  stp x29, x30, [sp, #16]
+  add x29, sp, #16
+  .cfi_def_cfa w29, 16
+  .cfi_offset w30, -8
+  .cfi_offset w29, -16
+
+  brk #0xf000   ;; __builtin_debugtrap aarch64 instruction
+
+  ldp x29, x30, [sp, #16]
+  add sp, sp, #32
+  ret
+  .cfi_endproc

lldb/test/API/macosx/unwind-frameless-faulted/main.c

@@ -0,0 +1,6 @@
+int to_be_interrupted(int);
+int main() {
+  int c = 10;
+  c = to_be_interrupted(c);
+  return c;
+}