[Bug target/15340] [3.3/3.4/3.5 Regression] GCC internal error in preprocessed C code

["roger at eyesopen dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From roger at eyesopen dot com  2004-06-22 12:47 -------
This looks to be a bug in reload, or a problem with the x86 backend's constraint
matching.

In .19.life, we have

(insn 38 33 39 2 (set (reg:QI 84)
        (mem/s:QI (plus:SI (reg/f:SI 93)
                (reg/f:SI 93)) [0 dir S1 A8])) 46 {*movqi_1} (nil)
    (nil))

(insn 39 38 42 2 (set (reg/v:SI 63 [ y ])
        (sign_extend:SI (reg:QI 84))) 86 {extendqisi2} (insn_list 38 (nil))
    (expr_list:REG_DEAD (reg:QI 84)
        (nil)))

These get smushed in combine, but I believe are stiil valid in .20.combine

(insn 39 38 42 2 (set (reg/v:SI 63 [ y ])
        (sign_extend:SI (mem/s:QI (mult:SI (reg/f:SI 93)
                    (const_int 2 [0x2])) [0 dir S1 A8]))) 86 {extendqisi2} (nil)
    (nil))

But everything goes to hell in reload, as we consider substituting pseduo 93
for "(plus (reg/f:SI bp) (const_int -13))", producing this monster in .26.greg

Reloads for insn # 39
Reload 0: reload_in (QI) = (mem/s:QI (mult:SI (plus:SI (reg/f:SI 6 bp)
  (const_int -13 [0xfffffff3])) (const_int 2 [0x2])) [0 dir S1 A8])
        Q_REGS, RELOAD_FOR_INPUT (opnum = 1), optional
        reload_in_reg: (mem/s:QI (mult:SI (plus:SI (reg/f:SI 6 bp)
  (const_int -13 [0xfffffff3])) (const_int 2 [0x2])) [0 dir S1 A8])


(insn:HI 39 38 42 2 (set (reg/v:SI 3 bx [orig:63 y ] [63])
        (sign_extend:SI (mem/s:QI (mult:SI (plus:SI (reg/f:SI 6 bp)
                        (const_int -13 [0xfffffff3]))
                    (const_int 2 [0x2])) [0 dir S1 A8]))) 86 {extendqisi2} (nil)
    (nil))


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15340