[Bug rtl-optimization/70222] Test miscompiled with -O1

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70222

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Yeah, it is combine.
First of all, the -1ULL >> (... * 15) is properly optimized into
(insn 12 11 13 2 (set (reg:DI 102)
        (const_int 8589934591 [0x1ffffffff])) pr70222.c:9 85 {*movdi_internal}
     (nil))
but the
(insn 13 12 14 2 (parallel [
            (set (reg:SI 104 [ e ])
                (lshiftrt:SI (subreg:SI (reg:DI 102) 0)
                    (const_int 31 [0x1f])))
            (clobber (reg:CC 17 flags))
        ]) pr70222.c:9 562 {*lshrsi3_1}
     (expr_list:REG_DEAD (reg:DI 102)
        (expr_list:REG_UNUSED (reg:CC 17 flags)
            (nil))))
which is supposed to yield 1 or 0 (in this case 1) is mis-simplified into:
(insn 13 12 14 2 (parallel [
            (set (subreg:DI (reg:SI 104 [ e ]) 0)
                (lshiftrt:DI (reg:DI 102)
                    (subreg:QI (reg:SI 101) 0)))
            (clobber (reg:CC 17 flags))
        ]) pr70222.c:9 564 {*lshrdi3_1}
     (expr_list:REG_DEAD (reg:SI 101)
        (expr_list:REG_UNUSED (reg:CC 17 flags)
            (expr_list:REG_DEAD (reg:DI 102)
                (nil)))))