re PR middle-end/32279 (Fold 1.0/sqrt(x/y) to sqrt(y/x))

	PR middle-end/32279
	* fold-const (fold_binary) [RDIV_EXPR]: Optimize a/sqrt(b/c)
	into a*sqrt(c/b) if flag_unsafe_math_optimizations is set.

testsuite/ChangeLog:

	PR middle-end/32279
	* gcc.dg/builtins-11.c: Also check folding of a/sqrt(b/c).

From-SVN: r125614

gcc/ChangeLog

+2007-06-11  Uros Bizjak  <ubizjak@gmail.com>
+
+	PR middle-end/32279
+	* fold-const (fold_binary) [RDIV_EXPR]: Optimize a/sqrt(b/c)
+	into a*sqrt(c/b) if flag_unsafe_math_optimizations is set.
+
 2007-06-10  Jan Sjodin  <jan.sjodin@amd.com>
 	    Sebastian Pop  <sebpop@gmail.com>
 

gcc/fold-const.c

@@ -10555,6 +10555,24 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
 		}
 	    }
 
+	  /* Optimize a/sqrt(b/c) into a*sqrt(c/b).  */
+	  if (BUILTIN_SQRT_P (fcode1))
+	    {
+	      tree rootarg = CALL_EXPR_ARG (arg1, 0);
+
+	      if (TREE_CODE (rootarg) == RDIV_EXPR)
+		{
+		  tree rootfn = TREE_OPERAND (CALL_EXPR_FN (arg1), 0);
+		  tree b = TREE_OPERAND (rootarg, 0);
+		  tree c = TREE_OPERAND (rootarg, 1);
+
+		  tree tmp = fold_build2 (RDIV_EXPR, type, c, b);
+
+		  tmp = build_call_expr (rootfn, 1, tmp);
+		  return fold_build2 (MULT_EXPR, type, arg0, tmp);
+		}
+	    }
+
 	  /* Optimize x/expN(y) into x*expN(-y).  */
 	  if (BUILTIN_EXPONENT_P (fcode1))
 	    {

gcc/testsuite/ChangeLog

+2007-06-11  Uros Bizjak  <ubizjak@gmail.com>
+
+	PR middle-end/32279
+	* gcc.dg/builtins-11.c: Also check folding of a/sqrt(b/c).
+
 2007-06-10  Jerry DeLisle  <jvdelisle@gcc.gnu.org>
 
 	PR libgfortran/32235

gcc/testsuite/gcc.dg/builtins-11.c

-/* Copyright (C) 2003 Free Software Foundation.
+/* Copyright (C) 2003,2007 Free Software Foundation.
 
    Check that constant folding of built-in math functions doesn't
    break anything and produces the expected results.
@@ -36,6 +36,9 @@ void test(double x, double y, double z)
 
   if (x/pow(y,z) != x*pow(y,-z))
     link_error ();
+
+  if (x/sqrt(y/z) != x*sqrt(z/y))
+    link_error ();
 }
 
 int main()