arm: offer 32-bit ARM at load, and fix `p` on carved code

Reported as "after c a few times and p at the entry point, Tab just flashes and
nothing decompiles". Three separate things, found by following it down:

**1. `p` failed on hand-carved code.** ida_funcs.add_func(ea) asks IDA to find
the function's end and on carved code it often can't — a run ending in a tail
call, or whose last instruction isn't recognised as a return, fails with no
reason given. add_func(ea, end) with an explicit end succeeds. define_func_run
tries IDA's way first, then falls back to the end of the contiguous instruction
run, and says which it used.

**2. The database was 64-bit, so Hex-Rays refused it regardless.** Bare `-parm`
gives an AArch64 database. Ask Hex-Rays for the failure object rather than
reading None as "dunno" and it says exactly what's wrong: "only 64-bit functions
can be decompiled in the current database". So the disassembly looked right and
F5 could never work.

That is decided at LOAD and cannot be corrected — inf_set_app_bitness(32)
afterwards makes the decompiler INTERR 50735. The fix is at the load dialog:
arm:ARMv7-A (most firmware), arm:ARMv7-M / arm:ARMv6-M (Cortex-M, Thumb only)
and arm:ARMv5TE now sit alongside 64-bit `arm`, labelled with their bitness.
With arm:ARMv7-A, experiments/fibonacci.bin decompiles:

  void __fastcall __noreturn sub_0(int a1) { int v2; v2 = sub_E3C(a1, 0); ... }

— and IDA's own auto-analysis finds 54 Thumb functions on load, versus none as
plain `arm`.

**3. `t` was silently building an undecompilable state.** It forced the SEGMENT
to 32-bit in a 64-bit database, which produces correct-looking disassembly that
F5 will never touch. It now says so and names the fix (Ctrl+L, arm:ARMv7-A)
rather than leaving you to discover it.

tools/verify_procs.py now reports each processor's resulting bitness, since that
is the reason the variants exist — and it compares against the base module name,
because a variant reports "ARM".

tests: test_thumb_ui.py +5 (13 total) — a 64-bit database warns and names the
fix, a 32-bit one finds functions by itself, Tab decompiles a Thumb function and
the result reads like C. test_formats.py +2 (34) pinning that a 32-bit variant is
offered and the ARM labels state their bitness. 209/0 scenarios, 26/0 blob, 30/0
project UI.

1 files changed, 10 insertions, 1 deletions

diff --git a/idatui/app.py b/idatui/app.py
index ff67eef..ec55911 100644
--- a/idatui/app.py
+++ b/idatui/app.py
@@ -5191,13 +5191,22 @@ class IdaTui(App):
                 verb = f"{mode} @ {ea:#x}"
                 if r.get("forced_32bit"):
                     verb += " (segment set to 32-bit; Thumb needs ARM32)"
+                if r.get("db_64bit"):
+                    # Disassembly will look right and F5 will never work.
+                    verb += ("  \u26a0 this database is 64-bit, so Hex-Rays "
+                             "won't decompile it \u2014 Ctrl+L and pick "
+                             "arm:ARMv7-A")
                 verb += (f" \u2014 {n} instruction{'s' if n != 1 else ''}"
                          if n else " \u2014 still doesn't decode")
                 # falls through to the shared reload: same cache bump, same
                 # anchor restore, same flash. That is the whole point of having
                 # one path.
             elif kind == "func":
-                self.program.define_func(ea)
+                r = self.program.define_func(ea)
+                if r.get("start") and r.get("end"):
+                    verb = (f"created function {r['start']}\u2013{r['end']}"
+                            + (" (end worked out from the code)"
+                               if r.get("how") == "explicit-end" else ""))
             elif kind == "string":
                 s = self.program.make_string(ea)
                 verb = f"made string ({s[:24]!r})" if s else verb