PR c/52023

c-family:
	* c-common.c (c_sizeof_or_alignof_type): Add parameter min_alignof
	and check field alignment if set.
	* c-common.h (c_sizeof_or_alignof_type): Update prototype.
	(c_sizeof, c_alignof): Update calls to c_sizeof_or_alignof_type.

c:
	* c-parser.c (c_parser_alignas_specifier): Use
	c_sizeof_or_alignof_type instead of c_alignof.
	(c_parser_alignof_expression): Likewise, with min_alignof
	parameter depending on alignof spelling used.

cp:
	* typeck.c (cxx_sizeof_or_alignof_type): Update call to
	c_sizeof_or_alignof_type.

objc:
	* objc-act.c (objc_synthesize_getter): Update calls to
	c_sizeof_or_alignof_type.

testsuite:
	* gcc.dg/c11-align-6.c: New test.


git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@205685 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 22 insertions, 3 deletions

diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index e652802fde1..a06dea8b7f3 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -4921,14 +4921,17 @@ c_common_get_alias_set (tree t)
 }
 
 /* Compute the value of 'sizeof (TYPE)' or '__alignof__ (TYPE)', where
-   the second parameter indicates which OPERATOR is being applied.
+   the IS_SIZEOF parameter indicates which operator is being applied.
    The COMPLAIN flag controls whether we should diagnose possibly
    ill-formed constructs or not.  LOC is the location of the SIZEOF or
-   TYPEOF operator.  */
+   TYPEOF operator.  If MIN_ALIGNOF, the least alignment required for
+   a type in any context should be returned, rather than the normal
+   alignment for that type.  */
 
 tree
 c_sizeof_or_alignof_type (location_t loc,
-			  tree type, bool is_sizeof, int complain)
+			  tree type, bool is_sizeof, bool min_alignof,
+			  int complain)
 {
   const char *op_name;
   tree value = NULL;
@@ -4994,6 +4997,22 @@ c_sizeof_or_alignof_type (location_t loc,
 	value = size_binop_loc (loc, CEIL_DIV_EXPR, TYPE_SIZE_UNIT (type),
 				size_int (TYPE_PRECISION (char_type_node)
 					  / BITS_PER_UNIT));
+      else if (min_alignof)
+	{
+	  unsigned int align = TYPE_ALIGN (type);
+	  align = MIN (align, BIGGEST_ALIGNMENT);
+#ifdef BIGGEST_FIELD_ALIGNMENT
+	  align = MIN (align, BIGGEST_FIELD_ALIGNMENT);
+#endif
+	  tree field = build_decl (UNKNOWN_LOCATION, FIELD_DECL, NULL_TREE,
+				   type);
+	  unsigned int field_align = align;
+#ifdef ADJUST_FIELD_ALIGN
+	  field_align = ADJUST_FIELD_ALIGN (field, field_align);
+#endif
+	  align = MIN (align, field_align);
+	  value = size_int (align / BITS_PER_UNIT);
+	}
       else
 	value = size_int (TYPE_ALIGN_UNIT (type));
     }