[Bug target/23095] [4.1 Regression] ICE in regstack compensate_edge

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

------- Additional Comments From steven at gcc dot gnu dot org  2005-07-27 19:21 -------
I'm not sure why reg-stack wants to insert compensation code at all.  The 
reg-stack dump shows that st(0) is live-at-end in the source block of the 
edge, but not live-at-start for the target block: 
 
Analyzing compilation unitPerforming intraprocedural optimizations 
Assembling functions: 
 foo 
Breakpoint 1, fancy_abort (file=0xb92af8 "../../mainline/gcc/reg-stack.c", 
line=2686, 
    function=0xb93230 "compensate_edge") at diagnostic.c:590 
590       internal_error ("in %s, at %s:%d", function, trim_filename (file), 
line); 
(gdb) up 
#1  0x000000000081098f in compensate_edge (e=0x2a95a6ef80, file=0xe3f6e0) at 
reg-stack.c:2686 
2686      gcc_assert (! (e->flags & EDGE_ABNORMAL)); 
(gdb) p debug_bb (e->src) 
;; basic block 12, loop depth 1, count 0 
;; prev block 11, next block 13 
;; pred:       11 [100.0%]  (fallthru,dfs_back,can_fallthru) 7 [19.0%]  
(dfs_back,can_fallthru,irreducible) 6 [19.0%]  
(dfs_back,can_fallthru,irreducible) 3 [35.4%]  (can_fallthru) 
;; succ:       6 [25.0%]  (ab,irreducible) 14 [25.0%]  (ab,irreducible) 13 
[25.0%]  (ab,irreducible) 5 [25.0%]  (ab,irreducible) 
;; Registers live at start:  1 [dx] 3 [bx] 4 [si] 5 [di] 6 [bp] 7 [sp] 20 
[frame] 
(code_label:HI 29 126 30 12 9 "" [3 uses]) 
(note:HI 30 29 125 12 [bb 12] NOTE_INSN_BASIC_BLOCK) 
(insn:TI 125 30 139 12 (set (reg:DF 8 st) 
        (mem/i:DF (plus:SI (reg/f:SI 6 bp) 
                (const_int -32 [0xffffffffffffffe0])) [4 absx+0 S8 A32])) 93 
{*movdf_nointeger} (nil) 
    (nil)) 
(insn:TI 139 125 31 12 (set (mem:DF (plus:SI (reg/f:SI 6 bp) 
                (const_int -40 [0xffffffffffffffd8])) [11 S8 A8]) 
        (reg:DF 8 st)) 93 {*movdf_nointeger} (insn_list:REG_DEP_TRUE 125 
(nil)) 
    (nil)) 
(jump_insn:TI 31 139 32 12 (set (pc) 
        (reg/f:SI 1 dx [orig:59 gotovar.36 ] [59])) 525 {*indirect_jump} 
(insn_list:REG_DEP_ANTI 125 (insn_list:REG_DEP_TRUE 139 (nil))) 
    (expr_list:REG_DEAD (reg/f:SI 1 dx [orig:59 gotovar.36 ] [59]) 
        (nil))) 
;; Registers live at end:  3 [bx] 4 [si] 5 [di] 6 [bp] 7 [sp] 8 [st] 20 
[frame] 
$10 = void 
(gdb) p debug_bb (e->dest) 
;; basic block 6, loop depth 1, count 0 
;; prev block 5, next block 7 
;; pred:       12 [25.0%]  (ab,irreducible) 5 [100.0%]  
(fallthru,can_fallthru) 13 [50.0%]  (can_fallthru,irreducible) 14 [50.0%]  
(can_fallthru,irreducible) 15 [100.0%]  (can_fallthru,irreducible) 
;; succ:       12 [19.0%]  (dfs_back,can_fallthru,irreducible) 7 [81.0%]  
(fallthru,can_fallthru,irreducible) 
;; Registers live at start:  3 [bx] 4 [si] 5 [di] 6 [bp] 7 [sp] 20 [frame] 
(code_label/s:HI 71 51 72 6 13 ("__label_000040") [6 uses]) 
(note:HI 72 71 118 6 [bb 6] NOTE_INSN_BASIC_BLOCK) 
(insn:TI 118 72 75 6 (set (reg/f:SI 1 dx [orig:59 gotovar.36 ] [59]) 
        (label_ref:SI 49)) 40 {*movsi_1} (nil) 
    (insn_list:REG_LABEL 49 (expr_list:REG_EQUAL (label_ref:SI 49) 
            (nil)))) 
(insn:TI 75 118 76 6 (set (reg:CCZ 17 flags) 
        (compare:CCZ (reg/f:SI 3 bx [orig:62 next.1 ] [62]) 
            (reg:SI 1 dx))) 5 {*cmpsi_1_insn} (insn_list:REG_DEP_TRUE 118 
(nil)) 
    (nil)) 
(jump_insn:TI 76 75 78 6 (set (pc) 
        (if_then_else (eq (reg:CCZ 17 flags) 
                (const_int 0 [0x0])) 
            (label_ref 29) 
            (pc))) 509 {*jcc_1} (insn_list:REG_DEP_ANTI 118 
(insn_list:REG_DEP_TRUE 75 (nil))) 
    (expr_list:REG_DEAD (reg:CCZ 17 flags) 
        (expr_list:REG_BR_PROB (const_int 1900 [0x76c]) 
            (nil)))) 
;; Registers live at end:  1 [dx] 3 [bx] 4 [si] 5 [di] 6 [bp] 7 [sp] 20 
[frame] 
$11 = void 
(gdb)       

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23095