re PR tree-optimization/89475 (Teach ccp about __builtin_bswap{16,32,64})

	PR tree-optimization/89475
	* tree-ssa-ccp.c (evaluate_stmt): Handle BUILT_IN_BSWAP{16,32,64}
	calls.

	* gcc.dg/tree-ssa/pr89475.c: New test.

From-SVN: r270680

1 files changed, 46 insertions, 7 deletions

diff --git a/gcc/gimple-ssa-store-merging.c b/gcc/gimple-ssa-store-merging.c
index 4a8cf6f..5fdff6e 100644
--- a/gcc/gimple-ssa-store-merging.c
+++ b/gcc/gimple-ssa-store-merging.c
@@ -1615,13 +1615,31 @@ encode_tree_to_bitpos (tree expr, unsigned char *ptr, int bitlen, int bitpos,
 		       unsigned int total_bytes)
 {
   unsigned int first_byte = bitpos / BITS_PER_UNIT;
-  tree tmp_int = expr;
   bool sub_byte_op_p = ((bitlen % BITS_PER_UNIT)
 			|| (bitpos % BITS_PER_UNIT)
 			|| !int_mode_for_size (bitlen, 0).exists ());
+  bool empty_ctor_p
+    = (TREE_CODE (expr) == CONSTRUCTOR
+       && CONSTRUCTOR_NELTS (expr) == 0
+       && TYPE_SIZE_UNIT (TREE_TYPE (expr))
+		       && tree_fits_uhwi_p (TYPE_SIZE_UNIT (TREE_TYPE (expr))));
 
   if (!sub_byte_op_p)
-    return native_encode_expr (tmp_int, ptr + first_byte, total_bytes) != 0;
+    {
+      if (first_byte >= total_bytes)
+	return false;
+      total_bytes -= first_byte;
+      if (empty_ctor_p)
+	{
+	  unsigned HOST_WIDE_INT rhs_bytes
+	    = tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (expr)));
+	  if (rhs_bytes > total_bytes)
+	    return false;
+	  memset (ptr + first_byte, '\0', rhs_bytes);
+	  return true;
+	}
+      return native_encode_expr (expr, ptr + first_byte, total_bytes) != 0;
+    }
 
   /* LITTLE-ENDIAN
      We are writing a non byte-sized quantity or at a position that is not
@@ -1667,14 +1685,29 @@ encode_tree_to_bitpos (tree expr, unsigned char *ptr, int bitlen, int bitpos,
 
   /* We must be dealing with fixed-size data at this point, since the
      total size is also fixed.  */
-  fixed_size_mode mode = as_a <fixed_size_mode> (TYPE_MODE (TREE_TYPE (expr)));
+  unsigned int byte_size;
+  if (empty_ctor_p)
+    {
+      unsigned HOST_WIDE_INT rhs_bytes
+	= tree_to_uhwi (TYPE_SIZE_UNIT (TREE_TYPE (expr)));
+      if (rhs_bytes > total_bytes)
+	return false;
+      byte_size = rhs_bytes;
+    }
+  else
+    {
+      fixed_size_mode mode
+	= as_a <fixed_size_mode> (TYPE_MODE (TREE_TYPE (expr)));
+      byte_size = GET_MODE_SIZE (mode);
+    }
   /* Allocate an extra byte so that we have space to shift into.  */
-  unsigned int byte_size = GET_MODE_SIZE (mode) + 1;
+  byte_size++;
   unsigned char *tmpbuf = XALLOCAVEC (unsigned char, byte_size);
   memset (tmpbuf, '\0', byte_size);
   /* The store detection code should only have allowed constants that are
-     accepted by native_encode_expr.  */
-  if (native_encode_expr (expr, tmpbuf, byte_size - 1) == 0)
+     accepted by native_encode_expr or empty ctors.  */
+  if (!empty_ctor_p
+      && native_encode_expr (expr, tmpbuf, byte_size - 1) == 0)
     gcc_unreachable ();
 
   /* The native_encode_expr machinery uses TYPE_MODE to determine how many
@@ -4164,7 +4197,8 @@ lhs_valid_for_store_merging_p (tree lhs)
   tree_code code = TREE_CODE (lhs);
 
   if (code == ARRAY_REF || code == ARRAY_RANGE_REF || code == MEM_REF
-      || code == COMPONENT_REF || code == BIT_FIELD_REF)
+      || code == COMPONENT_REF || code == BIT_FIELD_REF
+      || DECL_P (lhs))
     return true;
 
   return false;
@@ -4178,6 +4212,11 @@ static bool
 rhs_valid_for_store_merging_p (tree rhs)
 {
   unsigned HOST_WIDE_INT size;
+  if (TREE_CODE (rhs) == CONSTRUCTOR
+      && CONSTRUCTOR_NELTS (rhs) == 0
+      && TYPE_SIZE_UNIT (TREE_TYPE (rhs))
+      && tree_fits_uhwi_p (TYPE_SIZE_UNIT (TREE_TYPE (rhs))))
+    return true;
   return (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (rhs))).is_constant (&size)
 	  && native_encode_expr (rhs, NULL, size) != 0);
 }