[Bug rtl-optimization/23943] [4.1 Regression] segv in side_effects_p()

[steven at gcc dot gnu dot org]

------- Additional Comments From steven at gcc dot gnu dot org  2005-09-18 14:13 -------
The problematic RTL is produced in cse.c:find_best_addr(), 
 
Breakpoint 12, find_best_addr (insn=0x2a95a5d820, loc=0x2a95a64ac8, 
mode=QImode) at cse.c:3004 
3004                    rtx new = simplify_gen_binary (GET_CODE (*loc), Pmode, 
(gdb) ll 
Undefined command: "ll".  Try "help". 
(gdb) l 
2999                   p = p->next_same_value, count++) 
3000                if (! p->flag 
3001                    && (REG_P (p->exp) 
3002                        || exp_equiv_p (p->exp, p->exp, 1, false))) 
3003                  { 
3004                    rtx new = simplify_gen_binary (GET_CODE (*loc), Pmode, 
3005                                                   p->exp, op1); 
3006                    int new_cost; 
3007 
3008                    /* Get the canonical version of the address so we can 
accept 
(gdb) p debug_rtx (*loc) 
(plus:DI (reg:DI 62) 
    (const:DI (plus:DI (symbol_ref:DI ("savecallsin") [flags 0x2] <var_decl 
0x2a95a3cdc0 savecallsin>) 
            (const_int -1 [0xffffffffffffffff])))) 
$60 = void 
(gdb) p p->exp 
$61 = 0x2a95a5efe0 
(gdb) p debug_rtx (p->exp) 
(expr_list:REG_DEP_TRUE (use (mem:BLK (scratch) [0 A8])) 
    (expr_list:REG_DEP_TRUE (symbol_ref:DI ("strlen") [flags 0x41] 
<function_decl 0x2a9590d500 strlen>) 
        (expr_list:REG_DEP_TRUE (symbol_ref:DI ("savecallsin") [flags 0x2] 
<var_decl 0x2a95a3cdc0 savecallsin>) 
            (nil)))) 
$62 = void 
(gdb) next 
3010                    new = canon_for_address (new); 
(gdb) p debug_rtx (new) 
(plus:DI (expr_list:REG_DEP_TRUE (use (mem:BLK (scratch) [0 A8])) 
        (expr_list:REG_DEP_TRUE (symbol_ref:DI ("strlen") [flags 0x41] 
<function_decl 0x2a9590d500 strlen>) 
            (expr_list:REG_DEP_TRUE (symbol_ref:DI ("savecallsin") [flags 0x2] 
<var_decl 0x2a95a3cdc0 savecallsin>) 
                (nil)))) 
    (const:DI (plus:DI (symbol_ref:DI ("savecallsin") [flags 0x2] <var_decl 
0x2a95a3cdc0 savecallsin>) 
            (const_int -1 [0xffffffffffffffff])))) 
$63 = void 
(gdb)  
 
My first question here was, why do we record EXPR_LISTs here?  But apparently 
we need to do so for libcalls.  Maybe we should not substitute EXPR_LISTs 
here, or make them rediculously expensive. 

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23943