[Bug rtl-optimization/69447] [5/6 Regression] wrong code with -O2 -fno-schedule-insns and mixed 8/16/32/64bit arithmetics @ armv7a

[rth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69447

--- Comment #6 from Richard Henderson <rth at gcc dot gnu.org> ---
... except that's not the same set of live ranges
computed by IRA:

   Insn 55(l0): point = 9
   Insn 70(l0): point = 11
   ...
   Insn 50(l0): point = 19
   ...
   Insn 21(l0): point = 61
   Insn 19(l0): point = 65
   Insn 17(l0): point = 67

 a3(r111 [0]): [10..67]
 a3(r111 [1]): [62..67]

If we remat insn 21 into insn 50, we don't extend the lifetime
of r111[0], but we do extend the lifetime of r111[1].

The problem appears to be that IRA takes subregs into account
but LRA doesn't.  Vlad, am I on the right track here?