Move cabs simplifications to match.pd

The fold code also expanded cabs(x+yi) to fsqrt(x*x+y*y) when optimising
for speed.  tree-ssa-math-opts.c has this transformation too, but unlike
the fold code, it first checks whether the target implements the sqrt
optab.  The patch simply removes the fold code and keeps the
tree-ssa-math-opts.c logic the same.

gcc.dg/lto/20110201-1_0.c was relying on us replacing cabs
with fsqrt even on targets where fsqrt is itself a library call.
The discussion leading up to that patch suggested that we only
want to test the fold on targets with a square root instruction,
so it would be OK to skip the test on other targets:

        https://gcc.gnu.org/ml/gcc-patches/2011-07/msg01961.html
        https://gcc.gnu.org/ml/gcc-patches/2011-07/msg02036.html

The patch does that using the sqrt_insn effective target.

It's possible that removing the tree folds renders the LTO trick
unnecessary, but since the test was originally for an ICE, it seems
better to leave it as-is.

Tested on x86_64-linux-gnu, aarch64-linux-gnu and arm-linux-gnueabi.
20110201-1_0.c passes on all three.

gcc/
	* builtins.c (fold_builtin_cabs): Delete.
	(fold_builtin_1): Update accordingly.  Handle constant arguments here.
	* match.pd: Add rules previously handled by fold_builtin_cabs.

gcc/testsuite/
	* gcc.dg/lto/20110201-1_0.c: Restrict to sqrt_insn targets.
	Add associated options for arm*-*-*.
	(sqrt): Remove dummy definition.

From-SVN: r229141

1 files changed, 5 insertions, 77 deletions

diff --git a/gcc/builtins.c b/gcc/builtins.c
index fa02d26..2318b28 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -7538,82 +7538,6 @@ fold_fixed_mathfn (location_t loc, tree fndecl, tree arg)
   return NULL_TREE;
 }
 
-/* Fold call to builtin cabs, cabsf or cabsl with argument ARG.  TYPE is the
-   return type.  Return NULL_TREE if no simplification can be made.  */
-
-static tree
-fold_builtin_cabs (location_t loc, tree arg, tree type, tree fndecl)
-{
-  tree res;
-
-  if (!validate_arg (arg, COMPLEX_TYPE)
-      || TREE_CODE (TREE_TYPE (TREE_TYPE (arg))) != REAL_TYPE)
-    return NULL_TREE;
-
-  /* Calculate the result when the argument is a constant.  */
-  if (TREE_CODE (arg) == COMPLEX_CST
-      && (res = do_mpfr_arg2 (TREE_REALPART (arg), TREE_IMAGPART (arg),
-			      type, mpfr_hypot)))
-    return res;
-
-  if (TREE_CODE (arg) == COMPLEX_EXPR)
-    {
-      tree real = TREE_OPERAND (arg, 0);
-      tree imag = TREE_OPERAND (arg, 1);
-
-      /* If either part is zero, cabs is fabs of the other.  */
-      if (real_zerop (real))
-	return fold_build1_loc (loc, ABS_EXPR, type, imag);
-      if (real_zerop (imag))
-	return fold_build1_loc (loc, ABS_EXPR, type, real);
-
-      /* cabs(x+xi) -> fabs(x)*sqrt(2).  */
-      if (flag_unsafe_math_optimizations
-	  && operand_equal_p (real, imag, OEP_PURE_SAME))
-        {
-	  STRIP_NOPS (real);
-	  return fold_build2_loc (loc, MULT_EXPR, type,
-				  fold_build1_loc (loc, ABS_EXPR, type, real),
-				  build_real_truncate (type, dconst_sqrt2 ()));
-	}
-    }
-
-  /* Optimize cabs(-z) and cabs(conj(z)) as cabs(z).  */
-  if (TREE_CODE (arg) == NEGATE_EXPR
-      || TREE_CODE (arg) == CONJ_EXPR)
-    return build_call_expr_loc (loc, fndecl, 1, TREE_OPERAND (arg, 0));
-
-  /* Don't do this when optimizing for size.  */
-  if (flag_unsafe_math_optimizations
-      && optimize && optimize_function_for_speed_p (cfun))
-    {
-      tree sqrtfn = mathfn_built_in (type, BUILT_IN_SQRT);
-
-      if (sqrtfn != NULL_TREE)
-	{
-	  tree rpart, ipart, result;
-
-	  arg = builtin_save_expr (arg);
-
-	  rpart = fold_build1_loc (loc, REALPART_EXPR, type, arg);
-	  ipart = fold_build1_loc (loc, IMAGPART_EXPR, type, arg);
-
-	  rpart = builtin_save_expr (rpart);
-	  ipart = builtin_save_expr (ipart);
-
-	  result = fold_build2_loc (loc, PLUS_EXPR, type,
-				fold_build2_loc (loc, MULT_EXPR, type,
-					     rpart, rpart),
-				fold_build2_loc (loc, MULT_EXPR, type,
-					     ipart, ipart));
-
-	  return build_call_expr_loc (loc, sqrtfn, 1, result);
-	}
-    }
-
-  return NULL_TREE;
-}
-
 /* Build a complex (inf +- 0i) for the result of cproj.  TYPE is the
    complex tree type of the result.  If NEG is true, the imaginary
    zero is negative.  */
@@ -9655,7 +9579,11 @@ fold_builtin_1 (location_t loc, tree fndecl, tree arg0)
     break;
 
     CASE_FLT_FN (BUILT_IN_CABS):
-      return fold_builtin_cabs (loc, arg0, type, fndecl);
+      if (TREE_CODE (arg0) == COMPLEX_CST
+	  && TREE_CODE (TREE_TYPE (TREE_TYPE (arg0))) == REAL_TYPE)
+        return do_mpfr_arg2 (TREE_REALPART (arg0), TREE_IMAGPART (arg0),
+			     type, mpfr_hypot);
+      break;
 
     CASE_FLT_FN (BUILT_IN_CARG):
       return fold_builtin_carg (loc, arg0, type);