[PATCH] Fix PR lto/49302 (corrected)

["William J. Schmidt" <wschmidt@linux.vnet.ibm.com>]

Richard, thanks for the comments.  Here's the revised patch for
expanding cabs in gimple.

Given the direction this pass is taking, should it eventually be renamed
from cse_sincos to something more general?

Thanks,
Bill


2011-06-09  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR lto/49302
	* tree-ssa-math-opts.c (build_and_insert_ref): New.
	(gimple_expand_builtin_pow): Minor cleanup.
	(gimple_expand_builtin_cabs): New.
	(execute_cse_sincos): Add case for BUILT_IN_CABS.
	

Index: gcc/tree-ssa-math-opts.c
===================================================================
--- gcc/tree-ssa-math-opts.c	(revision 174845)
+++ gcc/tree-ssa-math-opts.c	(working copy)
@@ -1070,6 +1070,22 @@ build_and_insert_binop (gimple_stmt_iterator *gsi,
   return result;
 }
 
+/* Build a gimple reference operation with the given CODE and argument
+   ARG, assigning the result to a new SSA name for variable TARGET.  
+   Insert the statement prior to GSI's current position, and return
+   the fresh SSA name.  */
+
+static inline tree
+build_and_insert_ref (gimple_stmt_iterator *gsi, location_t loc, tree type,
+		      tree target, enum tree_code code, tree arg0)
+{
+  tree result = make_ssa_name (target, NULL);
+  gimple stmt = gimple_build_assign (result, build1 (code, type, arg0));
+  gimple_set_location (stmt, loc);
+  gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
+  return result;
+}
+
 /* ARG0 and ARG1 are the two arguments to a pow builtin call in GSI
    with location info LOC.  If possible, create an equivalent and
    less expensive sequence of statements prior to GSI, and return an
@@ -1124,7 +1140,7 @@ gimple_expand_builtin_pow (gimple_stmt_iterator *g
      if we don't have a hardware sqrt insn.  */
   dconst1_4 = dconst1;
   SET_REAL_EXP (&dconst1_4, REAL_EXP (&dconst1_4) - 2);
-  hw_sqrt_exists = optab_handler(sqrt_optab, mode) != CODE_FOR_nothing;
+  hw_sqrt_exists = optab_handler (sqrt_optab, mode) != CODE_FOR_nothing;
 
   if (flag_unsafe_math_optimizations
       && sqrtfn
@@ -1306,6 +1322,42 @@ gimple_expand_builtin_pow (gimple_stmt_iterator *g
   return NULL_TREE;
 }
 
+/* ARG is the argument to a cabs builtin call in GSI with location info
+   LOC.  Create a sequence of statements prior to GSI that calculates
+   sqrt(R*R + I*I), where R and I are the real and imaginary components
+   of ARG, respectively.  Return an expression holding the result.  */
+
+static tree
+gimple_expand_builtin_cabs (gimple_stmt_iterator *gsi, location_t loc, tree arg)
+{
+  tree target, real_part, imag_part, addend1, addend2, sum, result;
+  tree type = TREE_TYPE (TREE_TYPE (arg));
+  tree sqrtfn = mathfn_built_in (type, BUILT_IN_SQRT);
+  enum machine_mode mode = TYPE_MODE (type);
+
+  if (!flag_unsafe_math_optimizations
+      || !optimize_bb_for_speed_p (gimple_bb (gsi_stmt (*gsi)))
+      || !sqrtfn
+      || optab_handler (sqrt_optab, mode) == CODE_FOR_nothing)
+    return NULL_TREE;
+
+  target = create_tmp_var (type, "cabs");
+  add_referenced_var (target);
+
+  real_part = build_and_insert_ref (gsi, loc, type, target,
+				    REALPART_EXPR, arg);
+  addend1 = build_and_insert_binop (gsi, loc, target, MULT_EXPR,
+				    real_part, real_part);
+  imag_part = build_and_insert_ref (gsi, loc, type, target, 
+				    IMAGPART_EXPR, arg);
+  addend2 = build_and_insert_binop (gsi, loc, target, MULT_EXPR,
+				    imag_part, imag_part);
+  sum = build_and_insert_binop (gsi, loc, target, PLUS_EXPR, addend1, addend2);
+  result = build_and_insert_call (gsi, loc, &target, sqrtfn, sum);
+
+  return result;
+}
+
 /* Go through all calls to sin, cos and cexpi and call execute_cse_sincos_1
    on the SSA_NAME argument of each of them.  Also expand powi(x,n) into
    an optimal number of multiplies, when n is a constant.  */
@@ -1388,6 +1440,21 @@ execute_cse_sincos (void)
 		    }
 		  break;
 
+		CASE_FLT_FN (BUILT_IN_CABS):
+		  arg0 = gimple_call_arg (stmt, 0);
+		  loc = gimple_location (stmt);
+		  result = gimple_expand_builtin_cabs (&gsi, loc, arg0);
+
+		  if (result)
+		    {
+		      tree lhs = gimple_get_lhs (stmt);
+		      gimple new_stmt = gimple_build_assign (lhs, result);
+		      gimple_set_location (new_stmt, loc);
+		      unlink_stmt_vdef (stmt);
+		      gsi_replace (&gsi, new_stmt, true);
+		    }
+		  break;
+
 		default:;
 		}
 	    }