Strange debug behavior with 4.4.3

[Steve Teale]

I just built 4.4.3 - very simply

mkdir obdir
cd objdir
../configure --enable-languages=c,c++
make

make finished without errors, so then with a file foo.c

void foo()
{
}

I debug

steve@Ubuntu:~/gcc-4.4.3/objdir$ gdb --args gcc/cc1 ~/scratch/foo.c
GNU gdb (GDB) 7.0-ubuntu
...
This GDB was configured as "i486-linux-gnu".
...
Reading symbols from /home/steve/gcc-4.4.3/objdir/gcc/cc1...done.
(gdb) b gimplify.c:6249
Breakpoint 1 at 0x81a520c: file ../../gcc/gimplify.c, line 6249.
(gdb) run
Starting
program: /home/steve/gcc-4.4.3/objdir/gcc/cc1 /home/steve/scratch/foo.c
 foo
Breakpoint 1, gimplify_expr (expr_p=0xb7f41758, pre_p=0xbffff1b8,
post_p=0x0, 
    gimple_test_f=0x819b000 <is_gimple_stmt>, fallback=fb_none)
    at ../../gcc/gimplify.c:6249
6249	  save_expr = *expr_p;
(gdb) n
6250	  if (save_expr == NULL_TREE)
(gdb) n
6254	  is_statement = gimple_test_f == is_gimple_stmt;
(gdb) n
6255	  if (is_statement)
(gdb) n
6256	    gcc_assert (pre_p);
(gdb) n
6259	  if (gimple_test_f == is_gimple_reg)
(gdb) n
6261	  else if (gimple_test_f == is_gimple_val
(gdb) n
6274	  else if (gimple_test_f == is_gimple_min_lval
(gdb) n
6277	  else if (gimple_test_f == is_gimple_addressable)
(gdb) n
6279	  else if (gimple_test_f == is_gimple_stmt)
(gdb) n
6280	    gcc_assert (fallback == fb_none);
(gdb) n
6293	  if (pre_p == NULL)
(gdb) n
6296	  if (post_p == NULL)
(gdb) n
6307	  pre_last_gsi = gsi_last (*pre_p);
(gdb) n
6308	  post_last_gsi = gsi_last (*post_p);
(gdb) n
6310	  saved_location = input_location;
(gdb) n
6311	  if (save_expr != error_mark_node
(gdb) n
6312	      && EXPR_HAS_LOCATION (*expr_p))
(gdb) n
6311	  if (save_expr != error_mark_node
(gdb) n
6313	    input_location = EXPR_LOCATION (*expr_p);
(gdb) n
6729				   post_p == &internal_post ? NULL : post_p,

Things go pear shaped after line 6312 - after that, next seems to get
you somewhere rather arbitrary.

I guess I'm doing something stupid - can anyone tell me what?

Thanks
Steve