2005-07-12 Dale Johannesen <dalej@apple.com>

        * expr.c (compress_float_constant):  Add cost check.
        * config/rs6000.c (rs6000_rtx_cost):  Adjust FLOAT_EXTEND cost.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@101938 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 19 insertions, 2 deletions

diff --git a/gcc/expr.c b/gcc/expr.c
index 01f890fa6a5..182ab2382be 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -3202,9 +3202,15 @@ compress_float_constant (rtx x, rtx y)
   enum machine_mode orig_srcmode = GET_MODE (y);
   enum machine_mode srcmode;
   REAL_VALUE_TYPE r;
+  int oldcost, newcost;
 
   REAL_VALUE_FROM_CONST_DOUBLE (r, y);
 
+  if (LEGITIMATE_CONSTANT_P (y))
+    oldcost = rtx_cost (y, SET);
+  else
+    oldcost = rtx_cost (force_const_mem (dstmode, y), SET);
+
   for (srcmode = GET_CLASS_NARROWEST_MODE (GET_MODE_CLASS (orig_srcmode));
        srcmode != orig_srcmode;
        srcmode = GET_MODE_WIDER_MODE (srcmode))
@@ -3229,12 +3235,23 @@ compress_float_constant (rtx x, rtx y)
 	     the extension.  */
 	  if (! (*insn_data[ic].operand[1].predicate) (trunc_y, srcmode))
 	    continue;
+	  /* This is valid, but may not be cheaper than the original. */
+	  newcost = rtx_cost (gen_rtx_FLOAT_EXTEND (dstmode, trunc_y), SET);
+	  if (oldcost < newcost)
+	    continue;
 	}
       else if (float_extend_from_mem[dstmode][srcmode])
-	trunc_y = validize_mem (force_const_mem (srcmode, trunc_y));
+	{
+	  trunc_y = force_const_mem (srcmode, trunc_y);
+	  /* This is valid, but may not be cheaper than the original. */
+	  newcost = rtx_cost (gen_rtx_FLOAT_EXTEND (dstmode, trunc_y), SET);
+	  if (oldcost < newcost)
+	    continue;
+	  trunc_y = validize_mem (trunc_y);
+	}
       else
 	continue;
-
+ 
       emit_unop_insn (ic, x, trunc_y, UNKNOWN);
       last_insn = get_last_insn ();