Add a build_real_truncate helper function

...which simplifies the match.pd patterns I'm about to add.

Bootstrapped & regression-tested on x86_64-linux-gnu.

gcc/
	* real.h (build_real_truncate): Declare.
	* tree.c (build_real_truncate): New function.
	(strip_float_extensions): Use it.
	* builtins.c (fold_builtin_cabs, fold_builtin_sqrt, fold_builtin_cbrt)
	(fold_builtin_hypot, fold_builtin_pow): Likewise.
	* match.pd: Likewise.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@228483 138bc75d-0d04-0410-961f-82ee72b054a4

5 files changed, 37 insertions, 34 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index bd7626f5998..5c782900fd3 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2015-10-05  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* real.h (build_real_truncate): Declare.
+	* tree.c (build_real_truncate): New function.
+	(strip_float_extensions): Use it.
+	* builtins.c (fold_builtin_cabs, fold_builtin_sqrt, fold_builtin_cbrt)
+	(fold_builtin_hypot, fold_builtin_pow): Likewise.
+	* match.pd: Likewise.
+
 2015-10-05 James Greenhalgh <james.greenhalgh@arm.com>
 	   Jiong Wang  <jiong.wang@arm.com>
 
diff --git a/gcc/builtins.c b/gcc/builtins.c
index 9a81a182de4..89bea60a09d 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -7592,12 +7592,10 @@ fold_builtin_cabs (location_t loc, tree arg, tree type, tree fndecl)
       if (flag_unsafe_math_optimizations
 	  && operand_equal_p (real, imag, OEP_PURE_SAME))
         {
-	  const REAL_VALUE_TYPE sqrt2_trunc
-	    = real_value_truncate (TYPE_MODE (type), dconst_sqrt2 ());
 	  STRIP_NOPS (real);
 	  return fold_build2_loc (loc, MULT_EXPR, type,
-			      fold_build1_loc (loc, ABS_EXPR, type, real),
-			      build_real (type, sqrt2_trunc));
+				  fold_build1_loc (loc, ABS_EXPR, type, real),
+				  build_real_truncate (type, dconst_sqrt2 ()));
 	}
     }
 
@@ -7756,8 +7754,7 @@ fold_builtin_sqrt (location_t loc, tree arg, tree type)
 
 	  /* Adjust for the outer root.  */
 	  SET_REAL_EXP (&dconstroot, REAL_EXP (&dconstroot) - 1);
-	  dconstroot = real_value_truncate (TYPE_MODE (type), dconstroot);
-	  tree_root = build_real (type, dconstroot);
+	  tree_root = build_real_truncate (type, dconstroot);
 	  return build_call_expr_loc (loc, powfn, 2, arg0, tree_root);
 	}
     }
@@ -7804,11 +7801,9 @@ fold_builtin_cbrt (location_t loc, tree arg, tree type)
       if (BUILTIN_EXPONENT_P (fcode))
 	{
 	  tree expfn = TREE_OPERAND (CALL_EXPR_FN (arg), 0);
-	  const REAL_VALUE_TYPE third_trunc =
-	    real_value_truncate (TYPE_MODE (type), dconst_third ());
 	  arg = fold_build2_loc (loc, MULT_EXPR, type,
-			     CALL_EXPR_ARG (arg, 0),
-			     build_real (type, third_trunc));
+				 CALL_EXPR_ARG (arg, 0),
+				 build_real_truncate (type, dconst_third ()));
 	  return build_call_expr_loc (loc, expfn, 1, arg);
 	}
 
@@ -7824,8 +7819,7 @@ fold_builtin_cbrt (location_t loc, tree arg, tree type)
 	      REAL_VALUE_TYPE dconstroot = dconst_third ();
 
 	      SET_REAL_EXP (&dconstroot, REAL_EXP (&dconstroot) - 1);
-	      dconstroot = real_value_truncate (TYPE_MODE (type), dconstroot);
-	      tree_root = build_real (type, dconstroot);
+	      tree_root = build_real_truncate (type, dconstroot);
 	      return build_call_expr_loc (loc, powfn, 2, arg0, tree_root);
 	    }
 	}
@@ -7845,8 +7839,7 @@ fold_builtin_cbrt (location_t loc, tree arg, tree type)
 
 		  real_arithmetic (&dconstroot, MULT_EXPR,
                                    dconst_third_ptr (), dconst_third_ptr ());
-		  dconstroot = real_value_truncate (TYPE_MODE (type), dconstroot);
-		  tree_root = build_real (type, dconstroot);
+		  tree_root = build_real_truncate (type, dconstroot);
 		  return build_call_expr_loc (loc, powfn, 2, arg0, tree_root);
 		}
 	    }
@@ -7862,10 +7855,8 @@ fold_builtin_cbrt (location_t loc, tree arg, tree type)
 	  if (tree_expr_nonnegative_p (arg00))
 	    {
 	      tree powfn = TREE_OPERAND (CALL_EXPR_FN (arg), 0);
-	      const REAL_VALUE_TYPE dconstroot
-		= real_value_truncate (TYPE_MODE (type), dconst_third ());
-	      tree narg01 = fold_build2_loc (loc, MULT_EXPR, type, arg01,
-					 build_real (type, dconstroot));
+	      tree c = build_real_truncate (type, dconst_third ());
+	      tree narg01 = fold_build2_loc (loc, MULT_EXPR, type, arg01, c);
 	      return build_call_expr_loc (loc, powfn, 2, arg00, narg01);
 	    }
 	}
@@ -8391,13 +8382,9 @@ fold_builtin_hypot (location_t loc, tree fndecl,
   /* hypot(x,x) -> fabs(x)*sqrt(2).  */
   if (flag_unsafe_math_optimizations
       && operand_equal_p (arg0, arg1, OEP_PURE_SAME))
-    {
-      const REAL_VALUE_TYPE sqrt2_trunc
-	= real_value_truncate (TYPE_MODE (type), dconst_sqrt2 ());
-      return fold_build2_loc (loc, MULT_EXPR, type,
-			  fold_build1_loc (loc, ABS_EXPR, type, arg0),
-			  build_real (type, sqrt2_trunc));
-    }
+    return fold_build2_loc (loc, MULT_EXPR, type,
+			    fold_build1_loc (loc, ABS_EXPR, type, arg0),
+			    build_real_truncate (type, dconst_sqrt2 ()));
 
   return NULL_TREE;
 }
@@ -8529,10 +8516,8 @@ fold_builtin_pow (location_t loc, tree fndecl, tree arg0, tree arg1, tree type)
 	  tree arg = CALL_EXPR_ARG (arg0, 0);
 	  if (tree_expr_nonnegative_p (arg))
 	    {
-	      const REAL_VALUE_TYPE dconstroot
-		= real_value_truncate (TYPE_MODE (type), dconst_third ());
-	      tree narg1 = fold_build2_loc (loc, MULT_EXPR, type, arg1,
-					build_real (type, dconstroot));
+	      tree c = build_real_truncate (type, dconst_third ());
+	      tree narg1 = fold_build2_loc (loc, MULT_EXPR, type, arg1, c);
 	      return build_call_expr_loc (loc, fndecl, 2, arg, narg1);
 	    }
 	}
diff --git a/gcc/match.pd b/gcc/match.pd
index 8842e047d50..9962b0ae355 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -2189,8 +2189,7 @@ along with GCC; see the file COPYING3.  If not see
        {
        CASE_FLT_FN (BUILT_IN_EXP):
          /* Prepare to do logN(exp(exponent) -> exponent*logN(e).  */
-	 x = build_real (type, real_value_truncate (TYPE_MODE (type),
-						    dconst_e ()));
+	 x = build_real_truncate (type, dconst_e ());
          break;
        CASE_FLT_FN (BUILT_IN_EXP2):
          /* Prepare to do logN(exp2(exponent) -> exponent*logN(2).  */
@@ -2226,8 +2225,7 @@ along with GCC; see the file COPYING3.  If not see
          break;
        CASE_FLT_FN (BUILT_IN_CBRT):
 	 /* Prepare to do logN(cbrt(x) -> (1/3)*logN(x).  */
-         x = build_real (type, real_value_truncate (TYPE_MODE (type),
-						    dconst_third ()));
+         x = build_real_truncate (type, dconst_third ());
          break;
        default:
 	 gcc_unreachable ();
diff --git a/gcc/real.h b/gcc/real.h
index ecbe563abd6..149727953de 100644
--- a/gcc/real.h
+++ b/gcc/real.h
@@ -440,6 +440,9 @@ bool real_can_shorten_arithmetic (machine_mode, machine_mode);
 /* In tree.c: wrap up a REAL_VALUE_TYPE in a tree node.  */
 extern tree build_real (tree, REAL_VALUE_TYPE);
 
+/* Likewise, but first truncate the value to the type.  */
+extern tree build_real_truncate (tree, REAL_VALUE_TYPE);
+
 /* Calculate R as X raised to the integer exponent N in mode MODE.  */
 extern bool real_powi (REAL_VALUE_TYPE *, machine_mode,
 		       const REAL_VALUE_TYPE *, HOST_WIDE_INT);
diff --git a/gcc/tree.c b/gcc/tree.c
index bfcf3746da2..f78a2c26cd7 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -1877,6 +1877,14 @@ build_real (tree type, REAL_VALUE_TYPE d)
   return v;
 }
 
+/* Like build_real, but first truncate D to the type.  */
+
+tree
+build_real_truncate (tree type, REAL_VALUE_TYPE d)
+{
+  return build_real (type, real_value_truncate (TYPE_MODE (type), d));
+}
+
 /* Return a new REAL_CST node whose type is TYPE
    and whose value is the integer value of the INTEGER_CST node I.  */
 
@@ -12093,7 +12101,7 @@ strip_float_extensions (tree exp)
 	       && exact_real_truncate (TYPE_MODE (double_type_node), &orig))
 	type = double_type_node;
       if (type)
-	return build_real (type, real_value_truncate (TYPE_MODE (type), orig));
+	return build_real_truncate (type, orig);
     }
 
   if (!CONVERT_EXPR_P (exp))