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

gcc/ChangeLog

@@ -1,3 +1,9 @@
+2019-04-30  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/89475
+	* tree-ssa-ccp.c (evaluate_stmt): Handle BUILT_IN_BSWAP{16,32,64}
+	calls.
+
 2019-04-30  Martin Liska  <mliska@suse.cz>
 
 	PR translation/90274

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.  */
+     accepted by native_encode_expr or empty ctors.  */
-  if (native_encode_expr (expr, tmpbuf, byte_size - 1) == 0)
+  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);
 }

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2019-04-30  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/89475
+	* gcc.dg/tree-ssa/pr89475.c: New test.
+
 2019-04-30  Bin Cheng  <bin.cheng@linux.alibaba.com>
 
 	PR tree-optimization/90240

gcc/testsuite/gcc.dg/tree-ssa/pr89475.c

@@ -0,0 +1,104 @@
+/* PR tree-optimization/89475 */
+/* { dg-do compile { target { ilp32 || lp64 } } } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+/* { dg-final { scan-tree-dump-not "link_error " "optimized" } } */
+
+void link_error (void);
+
+unsigned short
+f0 (unsigned short x)
+{
+  x &= 0xaa55;
+  x = __builtin_bswap16 (x);
+  if (x & 0xaa55)
+    link_error ();
+  return x;
+}
+
+unsigned short
+f1 (unsigned short x)
+{
+  x &= 0x55aa;
+  x = __builtin_bswap16 (x);
+  if (x & 0x55aa)
+    link_error ();
+  return x;
+}
+
+unsigned int
+f2 (unsigned int x)
+{
+  x &= 0x55aa5aa5U;
+  x = __builtin_bswap32 (x);
+  if (x & 0x5aa555aaU)
+    link_error ();
+  return x;
+}
+
+unsigned long long int
+f3 (unsigned long long int x)
+{
+  x &= 0x55aa5aa544cc2211ULL;
+  x = __builtin_bswap64 (x);
+  if (x & 0xeedd33bb5aa555aaULL)
+    link_error ();
+  return x;
+}
+
+unsigned short
+f4 (unsigned short x)
+{
+  x = __builtin_bswap32 (x);
+  if (x != 0)
+    link_error ();
+  return x;
+}
+
+unsigned int
+f5 (unsigned int x)
+{
+  x = __builtin_bswap64 (x);
+  if (x != 0)
+    link_error ();
+  return x;
+}
+
+unsigned short
+f6 (unsigned short x)
+{
+  x |= 0xaa55;
+  x = __builtin_bswap16 (x);
+  if ((x | 0xaa55) != 0xffff)
+    link_error ();
+  return x;
+}
+
+unsigned short
+f7 (unsigned short x)
+{
+  x |= 0x55aa;
+  x = __builtin_bswap16 (x);
+  if ((x | 0x55aa) != 0xffff)
+    link_error ();
+  return x;
+}
+
+unsigned int
+f8 (unsigned int x)
+{
+  x |= 0x55aa5aa5U;
+  x = __builtin_bswap32 (x);
+  if ((x | 0x5aa555aaU) != 0xffffffffU)
+    link_error ();
+  return x;
+}
+
+unsigned long long int
+f9 (unsigned long long int x)
+{
+  x |= 0x55aa5aa544cc2211ULL;
+  x = __builtin_bswap64 (x);
+  if ((x | 0xeedd33bb5aa555aaULL) != 0xffffffffffffffffULL)
+    link_error ();
+  return x;
+}

gcc/tree-ssa-ccp.c

@@ -1960,6 +1960,35 @@ evaluate_stmt (gimple *stmt)
 		break;
 	      }
 
+	    case BUILT_IN_BSWAP16:
+	    case BUILT_IN_BSWAP32:
+	    case BUILT_IN_BSWAP64:
+	      val = get_value_for_expr (gimple_call_arg (stmt, 0), true);
+	      if (val.lattice_val == UNDEFINED)
+		break;
+	      else if (val.lattice_val == CONSTANT
+		       && val.value
+		       && TREE_CODE (val.value) == INTEGER_CST)
+		{
+		  tree type = TREE_TYPE (gimple_call_lhs (stmt));
+		  int prec = TYPE_PRECISION (type);
+		  wide_int wval = wi::to_wide (val.value);
+		  val.value
+		    = wide_int_to_tree (type,
+					wide_int::from (wval, prec,
+							UNSIGNED).bswap ());
+		  val.mask
+		    = widest_int::from (wide_int::from (val.mask, prec,
+							UNSIGNED).bswap (),
+					UNSIGNED);
+		  if (wi::sext (val.mask, prec) != -1)
+		    break;
+		}
+	      val.lattice_val = VARYING;
+	      val.value = NULL_TREE;
+	      val.mask = -1;
+	      break;
+
 	    default:;
 	    }
 	}