diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b738ffb6eece564bd23a5341522bced8c93e00cb..87d86d7217d5ce27624a8426439b93c55b2f8aa0 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2003-06-12  Roger Sayle  <roger@eyesopen.com>
+
+	* fold-const.c (tree_expr_nonnegative_p): Add support for
+	floating point constants, addition and multiplication.
+
 2003-06-12  J"orn Rennecke <joern.rennecke@superh.com>
 
 	* sh.md (adddi3_compact, subdi3_compact): Add earlyclobber
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 927b4d7410c5ddf0e3b33caa80f0152d838e60e8..b3271a2c6dadc33e4547738961e1ca913d2dcfdc 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -8014,9 +8014,29 @@ tree_expr_nonnegative_p (t)
 	 C[LT]Z_DEFINED_VALUE_AT_ZERO is set, since what we're
 	 computing here is a user-visible property.  */
       return 0;
-      
+
     case INTEGER_CST:
       return tree_int_cst_sgn (t) >= 0;
+
+    case REAL_CST:
+      return ! REAL_VALUE_NEGATIVE (TREE_REAL_CST (t));
+
+    case PLUS_EXPR:
+      return FLOAT_TYPE_P (TREE_TYPE (t))
+	     && tree_expr_nonnegative_p (TREE_OPERAND (t, 0))
+	     && tree_expr_nonnegative_p (TREE_OPERAND (t, 1));
+
+    case MULT_EXPR:
+      if (FLOAT_TYPE_P (TREE_TYPE (t)))
+	{
+	  /* x * x for floating point x is always non-negative.  */
+	  if (operand_equal_p (TREE_OPERAND (t, 0), TREE_OPERAND (t, 1), 0))
+	    return 1;
+	  return tree_expr_nonnegative_p (TREE_OPERAND (t, 0))
+		 && tree_expr_nonnegative_p (TREE_OPERAND (t, 1));
+	}
+      return 0;
+
     case TRUNC_DIV_EXPR:
     case CEIL_DIV_EXPR:
     case FLOOR_DIV_EXPR:
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index acd4e47aab1eec8b28b9ed76e377368b29b60fc0..704694ab33c69e16400192e07d17ccc1d44b067b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2003-06-12  Roger Sayle  <roger@eyesopen.com>
+
+	* gcc.dg/builtins-21.c: New test case.
+
 2003-06-11  Kelley Cook  <kelleycook@wideopenwest.com>
 
 	* lib/gcc.exp (gcc_target_compile): Put TOOL_OPTIONS at front of
diff --git a/gcc/testsuite/gcc.dg/builtins-21.c b/gcc/testsuite/gcc.dg/builtins-21.c
new file mode 100644
index 0000000000000000000000000000000000000000..38d0c4f3114675589033c70b5ba8a992b82e90fe
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/builtins-21.c
@@ -0,0 +1,55 @@
+/* Copyright (C) 2003  Free Software Foundation.
+
+   Verify that built-in math function constant folding doesn't
+   cause any problems for the compiler.
+
+   Written by Roger Sayle, 7th June 2003.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O2 -ffast-math" } */
+
+double test1(double x)
+{
+  return fabs(x*x);
+}
+
+double test2(double x)
+{
+  return fabs(sqrt(x)+2.0);
+}
+
+double test3(double x)
+{
+  return fabs(3.0*exp(x));
+}
+
+float test1f(float x)
+{
+  return fabsf(x*x);
+}
+
+float test2f(float x)
+{
+  return fabsf(sqrtf(x)+2.0f);
+}
+
+float test3f(float x)
+{
+  return fabsf(3.0f*expf(x));
+}
+
+long double test1l(long double x)
+{
+  return fabsl(x*x);
+}
+
+long double test2l(long double x)
+{
+  return fabsl(sqrtl(x)+2.0l);
+}
+
+long double test3l(long double x)
+{
+  return fabsl(3.0l*expl(x));
+}
+