[Bug rtl-optimization/42691] problematic REG_EQUAL note added to SUBREG

["jingyu at google dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #8 from jingyu at google dot com  2010-01-13 20:03 -------
Yes. This is a regression from 4.2.1. I have not tried 4.3.x. But at least,
gcc-4.2.1 works correctly.

The following assembly is compiled out of gcc-4.2.1 with -mthumb -Os.

        ldr     r3, .L14+8
        ldr     r1, [r3]        <--- load 0x0
        ldr     r2, [r3, #4]   <--- load 0x07ff00000
        ...
        str     r1, [sp]
        str     r2, [sp, #4]
.L2:
        ldr     r4, [r6]
        ldr     r5, [r6, #4]
        ldr     r2, [sp]    <--- r2 = 0x0
        ldr     r3, [sp, #4]   <--- r3 = 0x07ff00000
        mov     r0, r4
        mov     r1, r5
        bl      __aeabi_dcmpeq
...

.L14:
        .word   0
        .word   0
        .word   _ZZ3addPdS_E3C.0
        .word   _ZZ3addPdS_E3C.1
...
_ZZ3addPdS_E3C.0:
        .short  0
        .short  0
        .short  0
        .short  32752


-- 

jingyu at google dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jingyu at google dot com
                   |dot org                     |
             Status|NEW                         |ASSIGNED
      Known to work|                            |4.2.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42691