[Bug middle-end/41082] [4.5/4.6 Regression] FAIL: gfortran.fortran-torture/execute/where_2.f90 execution, -O3

["jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41082

--- Comment #61 from Jakub Jelinek <jakub at gcc dot gnu.org> 2010-12-07 22:07:59 UTC ---
I've managed to massage both -O3 -m64 -mtune={rs64,power4} darwin assembly into
ppc64-linux assembly.
Before DSE2 we have:
(insn 460 483 925 33 (set (reg:CC 75 cr7)
        (compare:CC (reg:SI 11 r11 [orig:866 reduce+32 ] [866])
            (const_int 6 [0x6]))) where_2.f90:11 451 {*cmpsi_internal1}
     (nil))

(insn 925 460 926 33 (set (reg:CC 0 r0)
        (reg:CC 75 cr7)) where_2.f90:11 358 {*movcc_internal1}
     (nil))

(insn 926 925 467 33 (set (mem/c:CC (plus:DI (reg/f:DI 1 r1)
                (const_int 272 [0x110])) [5 %sfp+272 S4 A32])
        (reg:CC 0 r0)) where_2.f90:11 358 {*movcc_internal1}
     (nil))

... # %sfp+272 not used anywhere here

(insn 931 415 932 33 (set (reg:CC 19 r19)
        (mem/c:CC (plus:DI (reg/f:DI 1 r1)
                (const_int 272 [0x110])) [5 %sfp+272 S4 A32])) where_2.f90:11
358 {*movcc_internal1}
     (nil))

(insn 932 931 461 33 (set (reg:CC 74 cr6)
        (reg:CC 19 r19)) where_2.f90:11 358 {*movcc_internal1}
     (nil))

(insn 461 932 422 33 (set (reg:SI 27 r27 [712])
        (gt:SI (reg:CC 74 cr6)
            (const_int 0 [0]))) where_2.f90:11 462 {*rs6000.md:13486}
     (nil))

and DSE2 somehow decides to nuke the insn 926 store.  The error could be also
that RA decides to share %sfp+272 not just for the CCmode stuff, but also
before that for a SImode value.

Looking into it...