re PR rtl-optimization/41574 (Distribute floating point expressions causes bad code [4.4 only])

2009-10-05  Doug Kwan  <dougkwan@google.com>

	PR rtl-optimization/41574
	Index: combine.c (distribute_and_simplify_rtx): Quit if RTX mode is
	floating point and we are not doing unsafe math optimizations.

From-SVN: r152443

gcc/ChangeLog

+2009-10-05  Doug Kwan  <dougkwan@google.com>
+
+	PR rtl-optimization/41574
+	Index: combine.c (distribute_and_simplify_rtx): Quit if RTX mode is
+	floating point and we are not doing unsafe math optimizations.
+
 2009-10-03  Simon Baldwin  <simonb@google.com>
 	    Cary Coutant  <ccoutant@google.com>
 	    Rafael Espindola  <espindola@google.com>

gcc/combine.c

@@ -8811,6 +8811,12 @@ distribute_and_simplify_rtx (rtx x, int n)
   enum rtx_code outer_code, inner_code;
   rtx decomposed, distributed, inner_op0, inner_op1, new_op0, new_op1, tmp;
 
+  /* Distributivity is not true for floating point as it can change the
+     value.  So we don't do it unless -funsafe-math-optimizations.  */
+  if (FLOAT_MODE_P (GET_MODE (x))
+      && ! flag_unsafe_math_optimizations)
+    return NULL_RTX;
+
   decomposed = XEXP (x, n);
   if (!ARITHMETIC_P (decomposed))
     return NULL_RTX;