re PR debug/49831 (arm-linux-gnueabi bootstrap failures due to ICE in dwarf2cfi.c connect_traces)

PR debug/49831
        * dwarf2cfi.c (connect_traces): Allow unvisited traces.  Skip
        them entirely.

Constant pools are emitted in such a way as to be indistinguishable
from regular instructions, and these constant pools are, naturally,
not reachable as code.

From-SVN: r176730

gcc/ChangeLog

 2011-07-24  Richard Henderson  <rth@redhat.com>
 
+	PR debug/49831
+	* dwarf2cfi.c (connect_traces): Allow unvisited traces.  Skip
+	them entirely.
+
+2011-07-24  Richard Henderson  <rth@redhat.com>
+
 	PR debug/49825
 	* dwarf2cfi.c (dwarf2out_stack_adjust): Move A_O_A test earlier.
 	(dwarf2out_notice_stack_adjust): Use args_size from call_insn.

gcc/dwarf2cfi.c

@@ -2641,14 +2641,22 @@ connect_traces (void)
 
   prev_ti = VEC_index (dw_trace_info, trace_info, 0);
 
-  for (i = 1; i < n; ++i, prev_ti = ti)
+  for (i = 1; i < n; ++i)
     {
       dw_cfi_row *old_row;
 
       ti = VEC_index (dw_trace_info, trace_info, i);
 
-      /* We must have both queued and processed every trace.  */
-      gcc_assert (ti->beg_row && ti->end_row);
+      /* ??? Ideally, we should have both queued and processed.  However
+	 the current representation of constant pools on various targets
+	 is indistinguishable from unreachable code.  Assume for the 
+	 moment that we can simply skip over such traces.  */
+      /* ??? Consider creating a DATA_INSN rtx code to indicate that
+	 these are not "real" instructions, and should not be considered.
+	 This could be generically useful for tablejump data as well.  */
+      if (ti->beg_row == NULL)
+	continue;
+      gcc_assert (ti->end_row != NULL);
 
       /* In dwarf2out_switch_text_section, we'll begin a new FDE
 	 for the portion of the function in the alternate text
@@ -2677,6 +2685,8 @@ connect_traces (void)
 	    }
 	  while (note != add_cfi_insn);
 	}
+
+      prev_ti = ti;
     }
 }