re PR rtl-optimization/37489 (const_true_rtx returned for float compare)

gcc/

2008-09-13  H.J. Lu  <hongjiu.lu@intel.com>

	PR rtl-optimization/37489
	* cse.c (fold_rtx): Don't return const_true_rtx for float
	compare if FLOAT_STORE_FLAG_VALUE is undefined.

gcc/testsuite/

2008-09-13  Raksit Ashok <raksit@google.com>

	PR rtl-optimization/37489
	* g++.dg/opt/cse3.C: New.

From-SVN: r140344

gcc/ChangeLog

+2008-09-13  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR rtl-optimization/37489
+	* cse.c (fold_rtx): Don't return const_true_rtx for float
+	compare if FLOAT_STORE_FLAG_VALUE is undefined.
+
 2008-09-13  Jan Hubicka  <jh@suse.cz>
 
 	PR tree-optimization/37392

gcc/cse.c

@@ -3214,17 +3214,24 @@ fold_rtx (rtx x, rtx insn)
       if (const_arg0 == 0 || const_arg1 == 0)
 	{
 	  struct table_elt *p0, *p1;
-	  rtx true_rtx = const_true_rtx, false_rtx = const0_rtx;
+	  rtx true_rtx, false_rtx;
 	  enum machine_mode mode_arg1;
 
-#ifdef FLOAT_STORE_FLAG_VALUE
 	  if (SCALAR_FLOAT_MODE_P (mode))
 	    {
+#ifdef FLOAT_STORE_FLAG_VALUE
 	      true_rtx = (CONST_DOUBLE_FROM_REAL_VALUE
 			  (FLOAT_STORE_FLAG_VALUE (mode), mode));
+#else
+	      true_rtx = NULL_RTX;
+#endif
 	      false_rtx = CONST0_RTX (mode);
 	    }
-#endif
+	  else
+	    {
+	      true_rtx = const_true_rtx;
+	      false_rtx = const0_rtx;
+	    }
 
 	  code = find_comparison_args (code, &folded_arg0, &folded_arg1,
 				       &mode_arg0, &mode_arg1);
@@ -3332,8 +3339,17 @@ fold_rtx (rtx x, rtx insn)
 						  const_arg1))
 			      || (REG_P (folded_arg1)
 				  && (REG_QTY (REGNO (folded_arg1)) == ent->comparison_qty))))
-			return (comparison_dominates_p (ent->comparison_code, code)
-				? true_rtx : false_rtx);
+			{
+			  if (comparison_dominates_p (ent->comparison_code, code))
+			    {
+			      if (true_rtx)
+				return true_rtx;
+			      else
+				break;
+			    }
+			  else
+			    return false_rtx;
+			}
 		    }
 		}
 	    }

gcc/testsuite/ChangeLog

+2008-09-13  Raksit Ashok <raksit@google.com>
+
+	PR rtl-optimization/37489
+	* g++.dg/opt/cse3.C: New.
+
 2008-09-13  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR testsuite/37495

gcc/testsuite/g++.dg/opt/cse3.C

+// This testcase resulted in invalid code generation on x86_64 targets
+// due to a bug in fold_rtx. For a "true" value, fold_rtx represented it
+// as const_true_rtx in floating-point mode, if the FLOAT_STORE_FLAG_VALUE
+// macro is not defined.
+
+// { dg-do run }
+// { dg-options "-O1 -fno-guess-branch-probability -fcse-follow-jumps -fgcse -frerun-cse-after-loop" }
+
+class StatVal {
+
+ public:
+
+  StatVal(double ev, double va)
+    : m(ev),
+      v(va) {}
+
+  StatVal(const StatVal& other)
+    : m(other.m),
+      v(other.v) {}
+
+  StatVal& operator*=(const StatVal& other) {
+    double A = m == 0 ? 1.0 : v / (m * m);
+    double B = other.m == 0 ? 1.0 : other.v / (other.m * other.m);
+    m = m * other.m;
+    v = m * m * (A + B);
+    return *this;
+  }
+
+  double m;
+  double v;
+};
+
+extern "C" void abort (void);
+
+const StatVal two_dot_three(2, 0.3);
+
+int main(int argc, char **argv) {
+
+  StatVal product3(two_dot_three);
+
+  product3 *= two_dot_three;
+
+  if (product3.v > 2.5)
+  {
+    abort();
+  }
+  return 0;
+}