[Bug middle-end/23090] [4.0/4.1 Regression] gcc.c-torture/execute/20050713-1.c -Os fails

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

------- Additional Comments From dje at gcc dot gnu dot org  2005-07-27 22:22 -------
This looks wrong in the initial argument passing RTL.  (virtual-incoming-args is
r1+24):

(insn 13 11 14 1 (set (reg:SI 122)
        (mem/s:SI (plus:SI (reg/f:SI 114 virtual-incoming-args)
                (const_int 8 [0x8])) [3 x+8 S4 A32])) -1 (nil)
    (nil))

(insn 14 13 15 1 (set (mem:SI (plus:SI (reg/f:SI 114 virtual-incoming-args)
                (const_int 32 [0x20])) [0 S4 A32])
        (reg:SI 122)) -1 (nil)
    (nil))

corresponds to

        lwz r0,32(r1)
        stw r0,56(r1)

(insn 19 18 20 1 (set (reg:SI 124)
        (plus:SI (reg/f:SI 114 virtual-incoming-args)
            (const_int 24 [0x18]))) -1 (nil)
    (nil))

(insn 20 19 21 1 (parallel [
            (set (reg:SI 6 r6)
                (mem/s:SI (reg:SI 124) [3 z+0 S4 A32]))
            (set (reg:SI 7 r7)
                (mem/s:SI (plus:SI (reg:SI 124)
                        (const_int 4 [0x4])) [3 z+4 S4 A32]))
            (set (reg:SI 8 r8)
                (mem/s:SI (plus:SI (reg:SI 124)
                        (const_int 8 [0x8])) [3 z+8 S4 A32]))
        ]) -1 (nil)
    (nil))

corresponds to

        addi r2,r1,48
        lswi r6,r2,12

Whoops!  We just generated RTL that writes a new value to
virtual-incoming-args+32 before reading the old value from it.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23090