Introduce fortran loop preheader

	* predict.def: Add fortran loop preheader predictor.
	* gimple-fold.c (gimple_fold_stmt_to_constant_1): Properly
	fold IFN_BUILTIN_EXPECT with a known constant argument.
	* trans-stmt.c (gfc_trans_simple_do): Predict the edge.
	* gfortran.dg/predict-1.f90: New test.

From-SVN: r237533

gcc/ChangeLog

 2016-06-16  Martin Liska  <mliska@suse.cz>
 
+	* predict.def: Add fortran loop preheader predictor.
+	* gimple-fold.c (gimple_fold_stmt_to_constant_1): Properly
+	fold IFN_BUILTIN_EXPECT with a known constant argument.
+
+2016-06-16  Martin Liska  <mliska@suse.cz>
+
 	* predict.def: Add 'Fortran' to display text of all
 	PRED_FORTRAN_* predictors.
 

gcc/fortran/ChangeLog

 2016-06-16  Martin Liska  <mliska@suse.cz>
 
+	* trans-stmt.c (gfc_trans_simple_do): Predict the edge.
+
+2016-06-16  Martin Liska  <mliska@suse.cz>
+
 	* trans-array.c (gfc_array_allocate): Do not generate expect
 	stmt.
 	* trans.c (gfc_allocate_using_malloc): Properly set FAIL_ALLOC

gcc/fortran/trans-stmt.c

@@ -1938,7 +1938,9 @@ gfc_trans_simple_do (gfc_code * code, stmtblock_t *pblock, tree dovar,
   else
     cond = fold_build2_loc (loc, GE_EXPR, boolean_type_node, dovar,
 			    to);
-  tmp = fold_build3_loc (loc, COND_EXPR, void_type_node, cond, tmp,
+
+  tmp = fold_build3_loc (loc, COND_EXPR, void_type_node,
+			 gfc_likely (cond, PRED_FORTRAN_LOOP_PREHEADER), tmp,
 			 build_empty_stmt (loc));
   gfc_add_expr_to_block (pblock, tmp);
 

gcc/gimple-fold.c

@@ -5250,6 +5250,14 @@ gimple_fold_stmt_to_constant_1 (gimple *stmt, tree (*valueize) (tree),
 	      case IFN_UBSAN_CHECK_MUL:
 		subcode = MULT_EXPR;
 		break;
+	      case IFN_BUILTIN_EXPECT:
+		  {
+		    tree arg0 = gimple_call_arg (stmt, 0);
+		    tree op0 = (*valueize) (arg0);
+		    if (TREE_CODE (op0) == INTEGER_CST)
+		      return op0;
+		    return NULL_TREE;
+		  }
 	      default:
 		return NULL_TREE;
 	      }

gcc/predict.def

@@ -199,3 +199,9 @@ DEF_PREDICTOR (PRED_FORTRAN_INVALID_BOUND, "Fortran invalid bound", \
    which in turn has an optional argument.  */
 DEF_PREDICTOR (PRED_FORTRAN_ABSENT_DUMMY, "Fortran absent dummy", \
 	       HITRATE (60), 0)
+
+/* Fortran DO statement generates a pre-header guard:
+   empty = (step > 0 ? to < from : to > from), which can be predicted
+   to be very likely.  */
+DEF_PREDICTOR (PRED_FORTRAN_LOOP_PREHEADER, "Fortran loop preheader", \
+	       HITRATE (99), 0)

gcc/testsuite/ChangeLog

+2016-06-16  Martin Liska  <mliska@suse.cz>
+
+	* gfortran.dg/predict-1.f90: New test.
+
 2016-06-16  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/71242

gcc/testsuite/gfortran.dg/predict-1.f90

+! { dg-do compile }
+! { dg-options "-O2 -fdump-tree-profile_estimate" }
+
+subroutine test(block, array)
+integer :: i, block(9), array(2)
+
+do i = array(1), array(2)
+    block(i) = i
+end do
+end subroutine test
+
+! { dg-final { scan-tree-dump-times "Fortran loop preheader heuristics of edge\[^:\]*: 99.0%" 1 "profile_estimate" } }