* fold-const.c (fold <PLUS_EXPR>): Transform x+x into x*2.0.

	Optimize x*c+x and x+x*c into x*(c+1) and x*c1+x*c2 into x*(c1+c2)
	for floating point expressions with -ffast-math.
	(fold <MULT_EXPR>): Don't transform x*2.0 into x+x.
	* expmed.c (expand_mult): Wrap long line.  Expand x*2.0 as x+x.

	* gcc.dg/20030804-1.c: New test case.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@70158 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 24 insertions, 1 deletions

diff --git a/gcc/expmed.c b/gcc/expmed.c
index 68163e9ba2b..89ecd0c1982 100644
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -2300,7 +2300,8 @@ synth_mult (struct algorithm *alg_out, unsigned HOST_WIDE_INT t,
    you should swap the two operands if OP0 would be constant.  */
 
 rtx
-expand_mult (enum machine_mode mode, rtx op0, rtx op1, rtx target, int unsignedp)
+expand_mult (enum machine_mode mode, rtx op0, rtx op1, rtx target,
+	     int unsignedp)
 {
   rtx const_op1 = op1;
 
@@ -2514,6 +2515,28 @@ expand_mult (enum machine_mode mode, rtx op0, rtx op1, rtx target, int unsignedp
 	}
     }
 
+  if (GET_CODE (op0) == CONST_DOUBLE)
+    {
+      rtx temp = op0;
+      op0 = op1;
+      op1 = temp;
+    }
+
+  /* Expand x*2.0 as x+x.  */
+  if (GET_CODE (op1) == CONST_DOUBLE
+      && GET_MODE_CLASS (mode) == MODE_FLOAT)
+    {
+      REAL_VALUE_TYPE d;
+      REAL_VALUE_FROM_CONST_DOUBLE (d, op1);
+
+      if (REAL_VALUES_EQUAL (d, dconst2))
+	{
+	  op0 = force_reg (GET_MODE (op0), op0);
+	  return expand_binop (mode, add_optab, op0, op0,
+			       target, unsignedp, OPTAB_LIB_WIDEN);
+	}
+    }
+
   /* This used to use umul_optab if unsigned, but for non-widening multiply
      there is no difference between signed and unsigned.  */
   op0 = expand_binop (mode,