[Bug target/32659] New: abort during reload on (subreg:PSI (reg:DI ...) 4)

["zackw at panix dot com" <gcc-bugzilla@gcc.gnu.org>]

The attached test case produces this RTL sequence after lreg, when compiled at
-O2 -mcpu=m32cm:

(insn 12 11 13 2 ba-bug.ii:24 (set (reg:DI 26 [ p.2 ])
        (mem/s:DI (reg/f:PSI 31) [3 S8 A8])) 176 {movdi_splittable}
(expr_list:R
EG_DEAD (reg/f:PSI 31)
        (nil)))

(insn 13 12 14 2 ba-bug.ii:24 (set (reg:PSI 25 [ p$second ])
        (subreg:PSI (reg:DI 26 [ p.2 ]) 4)) 172 {movpsi_op} (nil))

[For reference, in -mcpu=m32cm mode, this target uses PSImode for 24-bit
pointers, which appear to be being padded to 32 bits in memory.]

During processing of insn 13, reload demands a MODE_PARTIAL_INT mode with at
least 64 bits.  There is no such mode, and the compiler aborts in
smallest_mode_for_size.

The test case is simplified from libstdc++ bitmap_alloc.cc.  It is extremely
fragile; any further simplification and the problem RTL sequence will be
eliminated by earlier optimizers.


-- 
           Summary: abort during reload on (subreg:PSI (reg:DI ...) 4)
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: zackw at panix dot com
GCC target triplet: m32c-unknown-elf


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32659