[Bug rtl-optimization/82683] Combine: GCC generates bad code with -tune=thunderx2t99

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82683

--- Comment #5 from Segher Boessenkool <segher at gcc dot gnu.org> ---
Oh, it does show the intermediate results:

Trying 18 -> 19:
Successfully matched this instruction:
(set (reg/f:DI 78 [ _7 ])
    (plus:DI (ashift:DI (reg:DI 83 [ _26 ])
            (const_int 2 [0x2]))
        (reg/f:DI 76 [ _4 ])))
allowing combination of insns 18 and 19
original costs 4 + 4 = 8
replacement cost 8
deferring deletion of insn with uid = 18.
modifying insn i3    19: r78:DI=r83:DI<<0x2+r76:DI
      REG_DEAD r83:DI
      REG_DEAD r76:DI
deferring rescan insn with uid = 19.

(How do you dump things?  You forgot a -all?)