re PR tree-optimization/70497 (Missed CSE of subregs on GIMPLE)

2016-05-10  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/70497
	PR tree-optimization/28367
	* tree-ssa-sccvn.c (vn_nary_build_or_lookup): New function
	split out from ...
	(visit_reference_op_load): ... here.
	(vn_reference_lookup_3): Use it to handle subreg-like accesses
	with simplified BIT_FIELD_REFs.
	* tree-ssa-pre.c (eliminate_insert): Handle inserting BIT_FIELD_REFs.
	* tree-complex.c (extract_component): Handle BIT_FIELD_REFs
	correctly.

	* gcc.dg/torture/20160404-1.c: New testcase.
	* gcc.dg/tree-ssa/ssa-fre-54.c: Likewise.
	* gcc.dg/tree-ssa/ssa-fre-55.c: Likewise.

From-SVN: r236066

gcc/ChangeLog

+2016-05-10  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/70497
+	PR tree-optimization/28367
+	* tree-ssa-sccvn.c (vn_nary_build_or_lookup): New function
+	split out from ...
+	(visit_reference_op_load): ... here.
+	(vn_reference_lookup_3): Use it to handle subreg-like accesses
+	with simplified BIT_FIELD_REFs.
+	* tree-ssa-pre.c (eliminate_insert): Handle inserting BIT_FIELD_REFs.
+	* tree-complex.c (extract_component): Handle BIT_FIELD_REFs
+	correctly.
+
 2016-05-10  Pierre-Marie de Rodat  <derodat@adacore.com>
 
 	* dwarf2out.c (add_abstract_origin_attribute): Adjust

gcc/testsuite/ChangeLog

+2016-05-10  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/70497
+	PR tree-optimization/28367
+	* gcc.dg/torture/20160404-1.c: New testcase.
+	* gcc.dg/tree-ssa/ssa-fre-54.c: Likewise.
+	* gcc.dg/tree-ssa/ssa-fre-55.c: Likewise.
+
 2016-05-10  Pierre-Marie de Rodat  <derodat@adacore.com>
 
 	* gcc.dg/debug/dwarf2/nested_fun.c: New testcase.

gcc/testsuite/gcc.dg/torture/20160404-1.c

+/* { dg-do compile } */
+
+typedef __UINT64_TYPE__ UINT64;
+typedef union {
+    struct {
+	unsigned short lo4;
+	unsigned short lo3;
+	unsigned short lo2;
+	unsigned short lo1;
+    } i;
+    long double f;
+} BID_BINARY80LDOUBLE;
+UINT64 __binary80_to_bid32 (long double x)
+{
+  BID_BINARY80LDOUBLE x_in;
+  x_in.f = x;
+  return (x_in.i.lo4
+	  + ((UINT64)x_in.i.lo3 << 16)
+	  + ((UINT64)x_in.i.lo2 << 32)
+	  + ((UINT64)x_in.i.lo1 << 48));
+}

gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-54.c

+/* { dg-do run } */
+/* { dg-require-effective-target int32plus } */
+/* { dg-options "-O -fdump-tree-fre1 -fdump-tree-dse1" } */
+
+extern void abort (void);
+
+union U { int i; char c[4]; short s[2]; };
+
+char __attribute__((noinline,noclone)) foo(int i)
+{
+  union U u;
+  u.i = i;
+  /* This should be equivalent to (char) i.  */
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+  return u.c[0];
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+  return u.c[3];
+#else
+  return 0x04;
+#endif
+}
+
+short __attribute__((noinline,noclone)) baz(int i)
+{
+  union U u;
+  u.i = i;
+  /* This should be equivalent to (char) i.  */
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+  return u.s[0];
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+  return u.s[1];
+#else
+  return 0x0304;
+#endif
+}
+
+char __attribute__((noinline,noclone)) bar(int j)
+{
+  union U u;
+  u.i = j;
+  /* This gets simplified to a BIT_FIELD_REF.  */
+  return u.c[2];
+}
+
+int main()
+{
+  if (foo (0x01020304) != 0x04)
+    abort ();
+  if (baz (0x01020304) != 0x0304)
+    abort ();
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump "\\(char\\) i_" "fre1" } } */
+/* { dg-final { scan-tree-dump "\\(short int\\) i_" "fre1" } } */
+/* { dg-final { scan-tree-dump-not "u.i =" "dse1" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-55.c

+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-optimized" } */
+
+typedef int v4si __attribute__((vector_size(16)));
+
+int f(v4si t)
+{
+  union {
+      v4si t1;
+      int t2[4];
+  } u;
+  u.t1 = t;
+  return u.t2[1];
+}
+
+/* { dg-final { scan-tree-dump-not "u;" "optimized" } } */
+/* { dg-final { scan-tree-dump-times "BIT_FIELD_REF" 1 "optimized" } } */

gcc/tree-complex.c

@@ -604,6 +604,21 @@ extract_component (gimple_stmt_iterator *gsi, tree t, bool imagpart_p,
     case COMPLEX_EXPR:
       gcc_unreachable ();
 
+    case BIT_FIELD_REF:
+      {
+	tree inner_type = TREE_TYPE (TREE_TYPE (t));
+	t = unshare_expr (t);
+	TREE_TYPE (t) = inner_type;
+	TREE_OPERAND (t, 1) = TYPE_SIZE (inner_type);
+	if (imagpart_p)
+	  TREE_OPERAND (t, 2) = size_binop (PLUS_EXPR, TREE_OPERAND (t, 2),
+					    TYPE_SIZE (inner_type));
+	if (gimple_p)
+	  t = force_gimple_operand_gsi (gsi, t, true, NULL, true,
+					GSI_SAME_STMT);
+	return t;
+      }
+
     case VAR_DECL:
     case RESULT_DECL:
     case PARM_DECL:

gcc/tree-ssa-pre.c

@@ -3855,19 +3855,28 @@ eliminate_insert (gimple_stmt_iterator *gsi, tree val)
   gimple *stmt = gimple_seq_first_stmt (VN_INFO (val)->expr);
   if (!is_gimple_assign (stmt)
       || (!CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (stmt))
-	  && gimple_assign_rhs_code (stmt) != VIEW_CONVERT_EXPR))
+	  && gimple_assign_rhs_code (stmt) != VIEW_CONVERT_EXPR
+	  && gimple_assign_rhs_code (stmt) != BIT_FIELD_REF))
     return NULL_TREE;
 
   tree op = gimple_assign_rhs1 (stmt);
-  if (gimple_assign_rhs_code (stmt) == VIEW_CONVERT_EXPR)
+  if (gimple_assign_rhs_code (stmt) == VIEW_CONVERT_EXPR
+      || gimple_assign_rhs_code (stmt) == BIT_FIELD_REF)
     op = TREE_OPERAND (op, 0);
   tree leader = TREE_CODE (op) == SSA_NAME ? eliminate_avail (op) : op;
   if (!leader)
     return NULL_TREE;
 
   gimple_seq stmts = NULL;
-  tree res = gimple_build (&stmts, gimple_assign_rhs_code (stmt),
-			   TREE_TYPE (val), leader);
+  tree res;
+  if (gimple_assign_rhs_code (stmt) == BIT_FIELD_REF)
+    res = gimple_build (&stmts, BIT_FIELD_REF,
+			TREE_TYPE (val), leader,
+			TREE_OPERAND (gimple_assign_rhs1 (stmt), 1),
+			TREE_OPERAND (gimple_assign_rhs1 (stmt), 2));
+  else
+    res = gimple_build (&stmts, gimple_assign_rhs_code (stmt),
+			TREE_TYPE (val), leader);
   gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
   VN_INFO_GET (res)->valnum = val;