diff --git a/gcc/config/mips/iris6.h b/gcc/config/mips/iris6.h
index 54d27aa6be4ed..1ecde02b3ebd7 100644
--- a/gcc/config/mips/iris6.h
+++ b/gcc/config/mips/iris6.h
@@ -62,6 +62,7 @@ extern const char *host_detect_local_cpu (int argc, const char **argv);
 
 /* MIPS specific debugging info */
 /* #define MIPS_DEBUGGING_INFO 1 */
+#define SGUG_DEBUGGING_INFO 1
 
 /* Force the generation of dwarf .debug_frame sections even if not
    compiling -g.  This guarantees that we can unwind the stack.  */
diff --git a/gcc/dwarf2cfi.c b/gcc/dwarf2cfi.c
index 07e6a5a2887f6..3c211453e95c2 100644
--- a/gcc/dwarf2cfi.c
+++ b/gcc/dwarf2cfi.c
@@ -797,6 +797,7 @@ def_cfa_0 (dw_cfa_location *old_cfa, dw_cfa_location *new_cfa)
 	cfi->dw_cfi_opc = DW_CFA_def_cfa_offset;
       cfi->dw_cfi_oprnd1.dw_cfi_offset = const_offset;
     }
+#ifndef SGUG_DEBUGGING_INFO /* SGI dbx thinks this means no offset. */
   else if (new_cfa->offset.is_constant ()
 	   && known_eq (new_cfa->offset, old_cfa->offset)
 	   && old_cfa->reg != INVALID_REGNUM
@@ -811,6 +812,7 @@ def_cfa_0 (dw_cfa_location *old_cfa, dw_cfa_location *new_cfa)
       cfi->dw_cfi_opc = DW_CFA_def_cfa_register;
       cfi->dw_cfi_oprnd1.dw_cfi_reg_num = new_cfa->reg;
     }
+#endif
   else if (new_cfa->indirect == 0
 	   && new_cfa->offset.is_constant (&const_offset))
     {
@@ -3488,6 +3490,10 @@ dwarf2out_do_cfi_asm (void)
 {
   int enc;
 
+#ifdef SGUG_DEBUGGING_INFO
+  return false;
+#endif
+
   if (saved_do_cfi_asm != 0)
     return saved_do_cfi_asm > 0;
 
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index d94cf7dc9285c..205a6d5fbdb7d 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -956,6 +956,11 @@ output_call_frame_info (int for_eh)
   if (for_eh && targetm.terminate_dw2_eh_frame_info)
     dw2_asm_output_data (4, 0, "End of Table");
 
+#ifdef SGUG_DEBUGGING_INFO
+  /* Work around Irix 6 assembler bug whereby labels at the end of a section
+     get a value of 0.  Putting .align 0 after the label fixes it.  */
+  ASM_OUTPUT_ALIGN (asm_out_file, 0);
+#endif
   /* Turn off app to make assembly quicker.  */
   if (flag_debug_asm)
     app_disable ();
@@ -19311,7 +19316,15 @@ add_data_member_location_attribute (dw_die_ref die,
 	  /* The DWARF2 standard says that we should assume that the structure
 	     address is already on the stack, so we can specify a structure
 	     field address by using DW_OP_plus_uconst.  */
+
+#ifdef SGUG_DEBUGGING_INFO
+	  /* ??? The SGI dwarf reader does not handle the DW_OP_plus_uconst
+	     operator correctly.  It works only if we leave the offset on the
+	     stack.  */
+	  op = DW_OP_constu;
+#else
 	  op = DW_OP_plus_uconst;
+#endif
 	  loc_descr = new_loc_descr (op, offset, 0);
 	}
     }
@@ -21698,6 +21711,17 @@ gen_array_type_die (tree type, dw_die_ref context_die)
       return;
     }
 
+  /* ??? The SGI dwarf reader fails for array of array of enum types
+     (e.g. const enum machine_mode insn_operand_mode[2][10]) unless the inner
+     array type comes before the outer array type.  We thus call gen_type_die
+     before we new_die and must prevent nested array types collapsing for this
+     target.  */
+
+#ifdef SGUG_DEBUGGING_INFO
+  gen_type_die (TREE_TYPE (type), context_die);
+  collapse_nested_arrays = false;
+#endif
+
   array_die = new_die (DW_TAG_array_type, scope_die, type);
   add_name_attribute (array_die, type_tag (type));
   equate_type_number_to_die (type, array_die);
@@ -21723,6 +21747,15 @@ gen_array_type_die (tree type, dw_die_ref context_die)
   add_AT_unsigned (array_die, DW_AT_ordering, DW_ORD_row_major);
 #endif
 
+#ifdef SGUG_DEBUGGING_INFO
+  /* The SGI compilers handle arrays of unknown bound by setting
+     AT_declaration and not emitting any subrange DIEs.  */
+  if (TREE_CODE (type) == ARRAY_TYPE
+      && ! TYPE_DOMAIN (type))
+    add_AT_flag (array_die, DW_AT_declaration, 1);
+  else
+#endif
+
   if (TREE_CODE (type) == VECTOR_TYPE)
     {
       /* For VECTOR_TYPEs we use an array die with appropriate bounds.  */
@@ -21745,6 +21778,10 @@ gen_array_type_die (tree type, dw_die_ref context_die)
 	element_type = TREE_TYPE (element_type);
       }
 
+#ifndef SGUG_DEBUGGING_INFO
+  gen_type_die (element_type, context_die);
+#endif
+
   add_type_attribute (array_die, element_type, TYPE_UNQUALIFIED,
 		      TREE_CODE (type) == ARRAY_TYPE
 		      && TYPE_REVERSE_STORAGE_ORDER (type),
@@ -23031,6 +23068,11 @@ gen_subprogram_die (tree decl, dw_die_ref context_die)
                                false);
 	}
 
+#ifdef SGUG_DEBUGGING_INFO
+      /* Add a reference to the FDE for this routine.  */
+      add_AT_fde_ref (subr_die, DW_AT_MIPS_fde, cfun->fde->fde_index);
+#endif
+
       cfa_fb_offset = CFA_FRAME_BASE_OFFSET (decl);
 
       /* We define the "frame base" as the function's CFA.  This is more
@@ -24272,6 +24314,24 @@ gen_producer_string (void)
   sprintf (tail, "%s %s", language_string, version_string);
   tail += plen;
 
+  if (!dwarf_record_gcc_switches)
+    {
+#ifdef SGUG_DEBUGGING_INFO
+      /* The MIPS/SGI compilers place the 'cc' command line options in the
+	 producer string.  The SGI debugger looks for -g, -g1, -g2, or -g3;
+	 if they do not appear in the producer string, the debugger reaches
+	 the conclusion that the object file is stripped and has no debugging
+	 information.  To get the MIPS/SGI debugger to believe that there is
+	 debugging information in the object file, we add a -g to the producer
+	 string.  */
+      if (debug_info_level > DINFO_LEVEL_TERSE)
+	{
+	  memcpy (tail, " -g", 3);
+	  tail += 3;
+	}
+#endif
+    }
+
   FOR_EACH_VEC_ELT (switches, j, p)
     {
       len = strlen (p);