Re: GCC fails with -O2 for own Target

[Jens Mehler <jens dot mehler at mni dot thm dot de>]

After testing around I came up with a much easier example to reproduce 
my error:

static unsigned char sbox[256];

void
test(void)
{
    int n;
    for (n =  0; n < 256; n++)
        sbox[n] = (unsigned char) n;
}

This results in the same error massage:
test3.c: In function 'test':
test3.c:4:1: internal compiler error: in gen_lowpart_general, at 
rtlhooks.c:59

Via GDB I was able to print the RTX in question:
As you can see the code is SYMBOL_REF and therefore the error.
I am not really sure how to track that any futher.

With best regards
Jens
-----

Breakpoint 2, gen_lowpart_general (mode=QImode, x=0x140fd2f80) at 
../../gcc-4.5.3/gcc/rtlhooks.c:41
41    {
(gdb) p *x
$4 = {
  code = SYMBOL_REF,
  mode = SImode,
  jump = 0,
  call = 0,
  unchanging = 0,
  volatil = 0,
  in_struct = 0,
  used = 0,
  frame_related = 0,
  return_val = 0,
  u = {
    fld = {{
        rt_int = 1089498632,
        rt_uint = 1089498632,
        rt_str = 0x140f06e08 "sbox",
        rt_rtx = 0x140f06e08,
        rt_rtvec = 0x140f06e08,
        rt_type = 1089498632,
        rt_addr_diff_vec_flags = {
          min_align = 8,
          base_after_vec = 0,
          min_after_vec = 1,
          max_after_vec = 1,
          min_after_base = 1,
          max_after_base = 0,
          offset_unsigned = 1,
          scale = 240
        },
        rt_cselib = 0x140f06e08,
        rt_bit = 0x140f06e08,
        rt_tree = 0x140f06e08,
        rt_bb = 0x140f06e08,
        rt_mem = 0x140f06e08,
        rt_reg = 0x140f06e08,
        rt_constant = 0x140f06e08
      }},
    hwint = {5384465928},
    block_sym = {
      fld = {{
          rt_int = 1089498632,
          rt_uint = 1089498632,
          rt_str = 0x140f06e08 "sbox",
          rt_rtx = 0x140f06e08,
          rt_rtvec = 0x140f06e08,
          rt_type = 1089498632,
          rt_addr_diff_vec_flags = {
            min_align = 8,
            base_after_vec = 0,
            min_after_vec = 1,
            max_after_vec = 1,
            min_after_base = 1,
            max_after_base = 0,
            offset_unsigned = 1,
            scale = 240
          },
          rt_cselib = 0x140f06e08,
          rt_bit = 0x140f06e08,
          rt_tree = 0x140f06e08,
          rt_bb = 0x140f06e08,
          rt_mem = 0x140f06e08,
          rt_reg = 0x140f06e08,
          rt_constant = 0x140f06e08
        }, {
          rt_int = 2,
          rt_uint = 2,
          rt_str = 0x2 <Address 0x2 out of bounds>,
          rt_rtx = 0x2,
          rt_rtvec = 0x2,
          rt_type = CCmode,
          rt_addr_diff_vec_flags = {
            min_align = 2,
            base_after_vec = 0,
            min_after_vec = 0,
            max_after_vec = 0,
            min_after_base = 0,
            max_after_base = 0,
            offset_unsigned = 0,
            scale = 0
          },
          rt_cselib = 0x2,
          rt_bit = 0x2,
          rt_tree = 0x2,
          rt_bb = 0x2,
          rt_mem = 0x2,
          rt_reg = 0x2,
          rt_constant = 0x2
        }, {
          rt_int = 1090375680,
          rt_uint = 1090375680,
          rt_str = 0x140fdd000 " ",
          rt_rtx = 0x140fdd000,
          rt_rtvec = 0x140fdd000,
          rt_type = 1090375680,
          rt_addr_diff_vec_flags = {
            min_align = 0,
            base_after_vec = 0,
            min_after_vec = 0,
            max_after_vec = 0,
            min_after_base = 0,
            max_after_base = 1,
            offset_unsigned = 0,
            scale = 253
          },
          rt_cselib = 0x140fdd000,
          rt_bit = 0x140fdd000,
          rt_tree = 0x140fdd000,
          rt_bb = 0x140fdd000,
          rt_mem = 0x140fdd000,
          rt_reg = 0x140fdd000,
          rt_constant = 0x140fdd000
        }},
      block = 0x40025,
      offset = 81
    },
    rv = {
      cl = 0,
      decimal = 0,
      sign = 1,
      signalling = 0,
      canonical = 0,
      uexp = 17023416,
      sig = {2, 5385342976, 262181}
    },
    fv = {
      data = {
        low = 5384465928,
        high = 2
      },
      mode = 1090375680
    }
  }
}

Am 25.07.13 06:11, schrieb Ian Lance Taylor:
> On Wed, Jul 24, 2013 at 6:38 PM, Jens Mehler <jens.mehler@mni.thm.de> wrote:
> > I have ported the GCC (v4.5.3) to a new target (32-bit RISC processor).
> > So far everything went fine. I wrote my own little C-Lib with basic input
> > output and tested it worked.
> > Until today I never actually tried optimization passes (maybe that was the
> > mistake that lead to this)
> > Anyway:
> > During porting and building Newlib I ran into an error that I tracked down
> > to the following code:
> >
> > unsigned char hexdig[256];
> >
> > static void htinit ( unsigned char *h , unsigned char *s , int inc)
> > {
> >      int i, j;
> >      for(i = 0; (j = s[i]) !=0; i++)
> >          h[j] = i + inc;
> > }
> >
> > void
> > hexdig_init ()
> > {
> >      htinit(hexdig, (unsigned char *) "0123456789", 0x10);
> >      htinit(hexdig, (unsigned char *) "abcdef", 0x10 + 10);
> >      htinit(hexdig, (unsigned char *) "ABCDEF", 0x10 + 10);
> > }
> >
> > Compiling this code without optimization works like a charm, however
> > compiling it with -O2 leads to the following error:
> > test1.c: In function 'hexdig_init':
> > test1.c:11:1: internal compiler error: in gen_lowpart_general, at
> > rtlhooks.c:59
> >
> > Tried with:
> > eco32-gcc -O2 -S test1.c
> >
> > My question in short is:
> > Could this be a targe- backend-error or just some configuration I have
> > missed while building GCC?
> It is most likely an error in your backend.  The first step is to
> break out the debugger and find out why that function is being called
> with something that is not a MEM.  You may want to look at
> http://gcc.gnu.org/wiki/DebuggingGCC .
>
> Ian