[lto] fix types for enumerations

[lto] fix types for enumerations

[Nathan Froyd]

The compiler uses unsigned types for enumerations that have all
non-negative members.  We were not respecting this when reading in
enumeration types for LTO.  Fixed thusly.

176.gcc now compiles and runs correctly with -flto on
x86_64-unknown-linux-gnu.  This means all the C SPECint 2000 benchmarks
compile and run correctly with -flto.

...on that platform at least.  I believe Vlad said he was seeing issues
compiling/running with -flto on x86-unknown-linux-gnu; I will be looking
at that platform and powerpc over the next couple of days.

-Nathan

	* lto.c (lto_find_integral_type): Define as a macro.  Rename the
	original function to...
	(lto_find_integral_type_1): ...this.  Consult UNSIGNEDP if we
	don't have a base type.
	(lto_read_enumeration_type_DIE): Examine the values of the
	enumeration to determine whether we can use an unsigned type for
	the base type of the enumeration.

Index: lto.c
===================================================================
--- lto.c	(revision 131160)
+++ lto.c	(working copy)
@@ -1198,32 +1198,34 @@ lto_cache_lookup_DIE (lto_info_fd *fd, l
 
 /* Some DIEs (notably those for DW_TAG_subrange_type and
    DW_TAG_enumeration_type) may include either or both of base type and 
-   byte size attributes; the byte size is supposed modify the base
+   byte size attributes; the byte size is supposed to modify the base
    type.  Put them together and return the resulting type.
    Additionally enforce the restriction that the base type must be
    a complete integral type.
    If neither attribute is specified, then return integer_type as the default.
 */
 
+#define lto_find_integral_type(base,byte,got) lto_find_integral_type_1 (base, byte, got, false)
+
 static tree
-lto_find_integral_type (tree base_type, int byte_size, bool got_byte_size)
+lto_find_integral_type_1 (tree base_type, int byte_size, bool got_byte_size, bool unsignedp)
 {
   int nbits = byte_size * BITS_PER_UNIT;
 
   if (! base_type)
     {
       if (! got_byte_size)
-	base_type = integer_type_node;
+	base_type = unsignedp ? unsigned_type_node : integer_type_node;
       else if (nbits == INT_TYPE_SIZE)
-	base_type = integer_type_node;
+	base_type = unsignedp ? unsigned_type_node : integer_type_node;
       else if (nbits == CHAR_TYPE_SIZE)
-	base_type = char_type_node;
+	base_type = unsignedp ? unsigned_char_type_node : char_type_node;
       else if (nbits == SHORT_TYPE_SIZE)
-	base_type = short_integer_type_node;
+	base_type = unsignedp ? short_unsigned_type_node : short_integer_type_node;
       else if (nbits == LONG_TYPE_SIZE)
-	base_type = long_integer_type_node;
+	base_type = unsignedp ? long_unsigned_type_node : long_integer_type_node;
       else if (nbits == LONG_LONG_TYPE_SIZE)
-	base_type = long_long_integer_type_node;
+	base_type = unsignedp ? long_long_unsigned_type_node : long_long_integer_type_node;
       else
 	lto_abi_mismatch_error ();
     }
@@ -1833,6 +1835,7 @@ lto_read_enumeration_type_DIE (lto_info_
   bool got_byte_size = false;
   tree enumlist = NULL_TREE;
   tree parentdata;
+  bool use_unsigned = true;
 
   LTO_BEGIN_READ_ATTRS ()
     {
@@ -1862,20 +1865,10 @@ lto_read_enumeration_type_DIE (lto_info_
     }
   LTO_END_READ_ATTRS ();
 
-  /* Reconcile base type and byte size attributes.  */
-  base = lto_find_integral_type (base, byte_size, got_byte_size);
-
-  /* Build the (empty) enumeration type and fill in some attributes
-     copied from the base type.  */
+  /* Build the (empty) enumeration type.  */
   type = make_node (ENUMERAL_TYPE);
   if (name)
     TYPE_NAME (type) = name;
-  TYPE_MIN_VALUE (type) = TYPE_MIN_VALUE (base);
-  TYPE_MAX_VALUE (type) = TYPE_MAX_VALUE (base);
-  TYPE_UNSIGNED (type) = TYPE_UNSIGNED (base);
-  TYPE_SIZE (type) = 0;
-  TYPE_PRECISION (type) = TYPE_PRECISION (base);
-  layout_type (type);
 
   /* Process the enumerators.  */
   parentdata = context->parentdata;
@@ -1896,10 +1889,26 @@ lto_read_enumeration_type_DIE (lto_info_
 	  || ! TREE_PURPOSE (pair)
 	  || TREE_CODE (TREE_PURPOSE (pair)) != IDENTIFIER_NODE)
 	lto_abi_mismatch_error ();
+      /* Determine whether to use an unsigned type as the base.  */
+      if (INT_CST_LT (TREE_VALUE (pair), integer_zero_node))
+	use_unsigned = false;
       /* Link the enumerators together.  */
       TREE_CHAIN (pair) = enumlist;
       enumlist = pair;
     }
+
+  /* Reconcile base type and byte size attributes.  */
+  base = lto_find_integral_type_1 (base, byte_size, got_byte_size,
+				   use_unsigned);
+
+  /* Fill in various bits from the base type.  */
+  TYPE_MIN_VALUE (type) = TYPE_MIN_VALUE (base);
+  TYPE_MAX_VALUE (type) = TYPE_MAX_VALUE (base);
+  TYPE_UNSIGNED (type) = TYPE_UNSIGNED (base);
+  TYPE_SIZE (type) = 0;
+  TYPE_PRECISION (type) = TYPE_PRECISION (base);
+  layout_type (type);
+
   TYPE_VALUES (type) = enumlist;
   TYPE_STUB_DECL (type) = build_decl (TYPE_DECL, NULL_TREE, type);