Re: [PATCH] Improve verification of loop->latch in verify_loop_structure

[Alan Lawrence]

Here's a reduced testcase (reduced to the point of generating lots of
warnings, I'm compiling with -O2 -w, on x86_64):

struct __jmp_buf_tag
  {
  };
typedef struct __jmp_buf_tag sigjmp_buf[1];
extern struct cmd_list_element *showlist;
struct internalvar
{
  struct internalvar *next;
};
static struct internalvar *internalvars;
struct internalvar *
create_internalvar (const char *name)
{
  struct internalvar *var = ((struct internalvar *) xmalloc (sizeof
(struct internalvar)));
  internalvars = var;
}

void
show_convenience (char *ignore, int from_tty)
{
  struct gdbarch *gdbarch = get_current_arch ();
  int varseen = 0;
  for (struct internalvar *var = internalvars; var; var = var->next)
    {
      if (!varseen)
        varseen = 1;
      sigjmp_buf *buf = exceptions_state_mc_init ();
      __sigsetjmp ();
      while (exceptions_state_mc_action_iter ())
        while (exceptions_state_mc_action_iter_1 ())
          ;
    }
  if (!varseen)
      printf_unfiltered ();
}

On 26 November 2015 at 11:33, Alan Lawrence <alan.lawre...@arm.com> wrote:
> This caused an ICE compiling value.c from gdb on
> aarch64-none-linux-gnu; the testcase, after preprocessing on aarch64,
> ICEs on both aarch64 and x86_64, but is about 1MB - I'm working on
> reducing that down to something small enough to post...
>
> $ ./gcc/xgcc -B ./gcc -O2 -g value.c
> ../../binutils-gdb/gdb/value.c: In function ‘show_convenience’:
> ../../binutils-gdb/gdb/value.c:2615:1: error: loop 3’s latch is missing
> ../../binutils-gdb/gdb/value.c:2615:1: internal compiler error: in
> verify_loop_structure, at cfgloop.c:1669
> 0x71e653 verify_loop_structure()
>         /work/alalaw01/src2/gcc/gcc/cfgloop.c:1669
> 0x97c6ae checking_verify_loop_structure
>         /work/alalaw01/src2/gcc/gcc/cfgloop.h:325
> 0x97c6ae loop_optimizer_init(unsigned int)
>         /work/alalaw01/src2/gcc/gcc/loop-init.c:106
> 0x97c78a rtl_loop_init
>         /work/alalaw01/src2/gcc/gcc/loop-init.c:398
> 0x97c78a execute
>         /work/alalaw01/src2/gcc/gcc/loop-init.c:425
>
> --Alan