constexpr vector indexing

[Marc Glisse]

Hello,

it turns out there wasn't much missing here. I got side-tracked because 
fold_unary_loc doesn't call fold_indirect_ref_1, and fold_indirect_ref_1 
has a too strict comparison type == TREE_TYPE (optype) (should compare 
TYPE_MAIN_VARIANT instead?), but none of that was necessary so I'll leave 
it for another time. The new testcase is not that useful, but I didn't 
remember there was already one with dg-bogus.


Bootstrap+testsuite on x86_64-unknown-linux-gnu.

2013-07-07  Marc Glisse  <marc.gli...@inria.fr>

        PR c++/53094
gcc/cp/
        * semantics.c (cxx_eval_bit_field_ref): Handle VECTOR_CST.

gcc/testsuite/
        * g++.dg/cpp0x/constexpr-53094-1.C: Adjust.
        * g++.dg/ext/vector24.C: New testcase.

--
Marc GlisseIndex: testsuite/g++.dg/cpp0x/constexpr-53094-1.C
===================================================================
--- testsuite/g++.dg/cpp0x/constexpr-53094-1.C  (revision 200742)
+++ testsuite/g++.dg/cpp0x/constexpr-53094-1.C  (working copy)
@@ -1,6 +1,6 @@
 // { dg-do compile }
 // { dg-options "-std=gnu++11" }
 
 typedef float __attribute__ ((vector_size (4 * sizeof (float)))) V4;
 constexpr V4 v = { 1, 1, 1, 0 };
-constexpr V4 r = v[0] + v; // { dg-bogus "not a constant expression" "" { 
xfail *-*-* } }
+constexpr V4 r = v[0] + v;
Index: testsuite/g++.dg/ext/vector24.C
===================================================================
--- testsuite/g++.dg/ext/vector24.C     (revision 0)
+++ testsuite/g++.dg/ext/vector24.C     (revision 0)
@@ -0,0 +1,8 @@
+// { dg-do compile { target c++11 } }
+
+typedef long vec __attribute__((vector_size(2*sizeof(long))));
+constexpr vec v = { 33, 42 };
+constexpr auto l0 = v[0];
+constexpr auto l1 = v[1];
+static_assert(l0==33,"Fail");
+static_assert(l1==42,"Fail");

Property changes on: testsuite/g++.dg/ext/vector24.C
___________________________________________________________________
Added: svn:eol-style
   + native
Added: svn:keywords
   + Author Date Id Revision URL

Index: cp/semantics.c
===================================================================
--- cp/semantics.c      (revision 200742)
+++ cp/semantics.c      (working copy)
@@ -7179,29 +7179,35 @@ cxx_eval_bit_field_ref (const constexpr_
   tree whole = cxx_eval_constant_expression (call, orig_whole,
                                             allow_non_constant, addr,
                                             non_constant_p, overflow_p);
   tree start, field, value;
   unsigned HOST_WIDE_INT i;
 
   if (whole == orig_whole)
     return t;
   /* Don't VERIFY_CONSTANT here; we only want to check that we got a
      CONSTRUCTOR.  */
-  if (!*non_constant_p && TREE_CODE (whole) != CONSTRUCTOR)
+  if (!*non_constant_p
+      && TREE_CODE (whole) != VECTOR_CST
+      && TREE_CODE (whole) != CONSTRUCTOR)
     {
       if (!allow_non_constant)
        error ("%qE is not a constant expression", orig_whole);
       *non_constant_p = true;
     }
   if (*non_constant_p)
     return t;
 
+  if (TREE_CODE (whole) == VECTOR_CST)
+    return fold_ternary (BIT_FIELD_REF, TREE_TYPE (t), whole,
+                        TREE_OPERAND (t, 1), TREE_OPERAND (t, 2));
+
   start = TREE_OPERAND (t, 2);
   istart = tree_low_cst (start, 0);
   isize = tree_low_cst (TREE_OPERAND (t, 1), 0);
   utype = TREE_TYPE (t);
   if (!TYPE_UNSIGNED (utype))
     utype = build_nonstandard_integer_type (TYPE_PRECISION (utype), 1);
   retval = build_int_cst (utype, 0);
   FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (whole), i, field, value)
     {
       tree bitpos = bit_position (field);