No tail call optimization in Thumb mode?

[Kazu Hirata]

Hi,

Why is tail call optimization for Thumb disabled on GCC?  I am
wondering if this is a TODO item or something that we cannot do
intrinsically.

"The ARM-THUMB Procedure Call Standard" says "No tail continuation in
Thumb-state" several times in its figures and measurements, but the
document doesn't explicitly forbid tail call optimization for Thumb.

Thanks in advance,

Kazu Hirata