Segmentation fault when compiling GCC with new RTL pass

[Tomasz Jankowski <tomcioj at gmail dot com>]

Hello,

I'm implementing new RTL pass in GCC. I attached current C source with
my RTL pass. I have to use GCC v4.5.1 port for OpenRISC project.

Basically I want to discover all "SET" insns which moves constant
immediate to register. Then I want to insert additional instruction
call right after this move instruction (for now I just want to insert
a copy of found "SET" insn). When I compile this pass with commented
"add_insn_after(...)" (line 70 in attachment) GCC compiles fine and
after installation it discovers SET insn properly. When I uncomment
this "add_insn_after(...)" compilation fails with message:

(...)
../../gcc-4.5.1/gcc/crtstuff.c: In function â__do_global_dtors_auxâ:
../../gcc-4.5.1/gcc/crtstuff.c:332:1: internal compiler error:
Segmentation fault
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.
(...)

I run my pass just after "expand" pass. This is first time I'm trying
to modify GCC. What am I doing wrong?

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"

#include "rtl.h"
#include "regs.h"
#include "flags.h"
#include "insn-config.h"
#include "recog.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#include "expr.h"
#include "toplev.h"
#include "target.h"
#include "timevar.h"
#include "tree-pass.h"

#include "insn-flags.h"

static bool gate_handle_rns (void);

static unsigned int rest_of_handle_rns (void);

struct rtl_opt_pass pass_rtl_rns =
{
    {
        RTL_PASS,
        "rtl-rns",                            /* name */
        gate_handle_rns,                      /* gate */
        rest_of_handle_rns,                   /* execute */
        NULL,                                 /* sub */
        NULL,                                 /* next */
        0,                                    /* static_pass_number */
        TV_DBR_SCHED,                         /* tv_id */
        0,                                    /* properties_required */
        0,                                    /* properties_provided */
        0,                                    /* properties_destroyed */
        0,                                    /* todo_flags_start */
        TODO_dump_func                        /* todo_flags_finish */
    }
};

static bool gate_handle_rns (void)
{
    return true;
}

static unsigned int rest_of_handle_rns (void)
{
    basic_block block;
    rtx         destination;
    rtx         source;
    rtx         set;
    rtx         instruction;
    
    FOR_EACH_BB (block)
    {
        FOR_BB_INSNS (block, instruction)
        {
            set = single_set (instruction);
            
            if (set != NULL_RTX)
            {
                destination = SET_DEST (set);
                source = SET_SRC (set);
                
                if (REG_P (destination) && CONST_INT_P (source))
                {                              
                    add_insn_after (copy_rtx (set), set, block);
                    
                    printf ("***** HIT *****\n");
                    print_rtl (stdout, set);
                }
            }
        }
    }
    
    return 0;
}