From patchwork Tue Nov 27 17:10:36 2012
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Subject: bit_field_ref of constructor of vectors
Date: Tue, 27 Nov 2012 07:10:36 -0000
From: Marc Glisse <marc.glisse@inria.fr>
X-Patchwork-Id: 202266
Message-Id: <alpine.DEB.2.02.1211271758300.332@stedding.saclay.inria.fr>
To: Richard Biener <richard.guenther@gmail.com>
Cc: gcc-patches@gcc.gnu.org

On Tue, 27 Nov 2012, Marc Glisse wrote:

> On Tue, 27 Nov 2012, Richard Biener wrote:
>
>>> It passes bootstrap+testsuite.
>
> ... on x86_64-linux-gnu, sorry for the lack of precision (default languages, 
> Xeon E5520, graphite enabled).
[...]
>> Boostrapped and tested on ... ?
>> 
>> Ok if bootstrap / testing passes.
>
> Thanks, I'll retest it to make sure it still works.

Duh, it uses VEC, of course it doesn't work anymore...
Here is what I tested instead (I copied the 2 vec lines from somewhere 
else in the file). I'll probably commit it later today.

>>> 2012-11-12  Marc Glisse  <marc.glisse@inria.fr>
>>>
>>>         * fold-const.c (fold_ternary_loc) [BIT_FIELD_REF]: Handle
>>>         CONSTRUCTOR with vector elements.
>>>         * tree-ssa-propagate.c (valid_gimple_rhs_p): Handle CONSTRUCTOR
>>>         and BIT_FIELD_REF.


Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c	(revision 193847)
+++ gcc/fold-const.c	(working copy)
@@ -14074,66 +14074,76 @@ fold_ternary_loc (location_t loc, enum t
 	  unsigned HOST_WIDE_INT n = tree_low_cst (arg1, 1);
 	  unsigned HOST_WIDE_INT idx = tree_low_cst (op2, 1);
 
 	  if (n != 0
 	      && (idx % width) == 0
 	      && (n % width) == 0
 	      && ((idx + n) / width) <= TYPE_VECTOR_SUBPARTS (TREE_TYPE (arg0)))
 	    {
 	      idx = idx / width;
 	      n = n / width;
-	      if (TREE_CODE (type) == VECTOR_TYPE)
+
+	      if (TREE_CODE (arg0) == VECTOR_CST)
 		{
-		  if (TREE_CODE (arg0) == VECTOR_CST)
-		    {
-		      tree *vals = XALLOCAVEC (tree, n);
-		      unsigned i;
-		      for (i = 0; i < n; ++i)
-			vals[i] = VECTOR_CST_ELT (arg0, idx + i);
-		      return build_vector (type, vals);
-		    }
-		  else
-		    {
-		      vec<constructor_elt, va_gc> *vals;
-		      unsigned i;
-		      if (CONSTRUCTOR_NELTS (arg0) == 0)
-			return build_constructor (type,
-					      NULL);
-		      if (TREE_CODE (TREE_TYPE (CONSTRUCTOR_ELT (arg0,
-								 0)->value))
-			  != VECTOR_TYPE)
-			{
-			  vec_alloc (vals, n);
-			  for (i = 0;
-			       i < n && idx + i < CONSTRUCTOR_NELTS (arg0);
-			       ++i)
-			    CONSTRUCTOR_APPEND_ELT (vals, NULL_TREE,
-						    CONSTRUCTOR_ELT
-						      (arg0, idx + i)->value);
-			  return build_constructor (type, vals);
-			}
-		    }
+		  if (n == 1)
+		    return VECTOR_CST_ELT (arg0, idx);
+
+		  tree *vals = XALLOCAVEC (tree, n);
+		  for (unsigned i = 0; i < n; ++i)
+		    vals[i] = VECTOR_CST_ELT (arg0, idx + i);
+		  return build_vector (type, vals);
 		}
-	      else if (n == 1)
+
+	      /* Constructor elements can be subvectors.  */
+	      unsigned HOST_WIDE_INT k = 1;
+	      if (CONSTRUCTOR_NELTS (arg0) != 0)
 		{
-		  if (TREE_CODE (arg0) == VECTOR_CST)
-		    return VECTOR_CST_ELT (arg0, idx);
-		  else if (CONSTRUCTOR_NELTS (arg0) == 0)
-		    return build_zero_cst (type);
-		  else if (TREE_CODE (TREE_TYPE (CONSTRUCTOR_ELT (arg0,
-								  0)->value))
-			   != VECTOR_TYPE)
+		  tree cons_elem = TREE_TYPE (CONSTRUCTOR_ELT (arg0, 0)->value);
+		  if (TREE_CODE (cons_elem) == VECTOR_TYPE)
+		    k = TYPE_VECTOR_SUBPARTS (cons_elem);
+		}
+
+	      /* We keep an exact subset of the constructor elements.  */
+	      if ((idx % k) == 0 && (n % k) == 0)
+		{
+		  if (CONSTRUCTOR_NELTS (arg0) == 0)
+		    return build_constructor (type, NULL);
+		  idx /= k;
+		  n /= k;
+		  if (n == 1)
 		    {
 		      if (idx < CONSTRUCTOR_NELTS (arg0))
 			return CONSTRUCTOR_ELT (arg0, idx)->value;
 		      return build_zero_cst (type);
 		    }
+
+		  vec<constructor_elt, va_gc> *vals;
+		  vec_alloc (vals, n);
+		  for (unsigned i = 0;
+		       i < n && idx + i < CONSTRUCTOR_NELTS (arg0);
+		       ++i)
+		    CONSTRUCTOR_APPEND_ELT (vals, NULL_TREE,
+					    CONSTRUCTOR_ELT
+					      (arg0, idx + i)->value);
+		  return build_constructor (type, vals);
+		}
+	      /* The bitfield references a single constructor element.  */
+	      else if (idx + n <= (idx / k + 1) * k)
+		{
+		  if (CONSTRUCTOR_NELTS (arg0) <= idx / k)
+		    return build_zero_cst (type);
+		  else if (n == k)
+		    return CONSTRUCTOR_ELT (arg0, idx / k)->value;
+		  else
+		    return fold_build3_loc (loc, code, type,
+		      CONSTRUCTOR_ELT (arg0, idx / k)->value, op1,
+		      build_int_cst (TREE_TYPE (op2), (idx % k) * width));
 		}
 	    }
 	}
 
       /* A bit-field-ref that referenced the full argument can be stripped.  */
       if (INTEGRAL_TYPE_P (TREE_TYPE (arg0))
 	  && TYPE_PRECISION (TREE_TYPE (arg0)) == tree_low_cst (arg1, 1)
 	  && integer_zerop (op2))
 	return fold_convert_loc (loc, type, arg0);
 
Index: gcc/tree-ssa-propagate.c
===================================================================
--- gcc/tree-ssa-propagate.c	(revision 193847)
+++ gcc/tree-ssa-propagate.c	(working copy)
@@ -604,24 +604,38 @@ valid_gimple_rhs_p (tree expr)
 	      break;
 	    }
 	  return false;
 	}
       break;
 
     case tcc_vl_exp:
       return false;
 
     case tcc_exceptional:
+      if (code == CONSTRUCTOR)
+	{
+	  unsigned i;
+	  tree elt;
+	  FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (expr), i, elt)
+	    if (!is_gimple_val (elt))
+	      return false;
+	  return true;
+	}
       if (code != SSA_NAME)
         return false;
       break;
 
+    case tcc_reference:
+      if (code == BIT_FIELD_REF)
+	return is_gimple_val (TREE_OPERAND (expr, 0));
+      return false;
+
     default:
       return false;
     }
 
   return true;
 }
 
 
 /* Return true if EXPR is a CALL_EXPR suitable for representation
    as a single GIMPLE_CALL statement.  If the arguments require