diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index aeb9d19f81b..c81598c1d43 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2006-12-14  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/30172
+	* fold-const.c (fold_binary): Fold __complex__ ( x, 0 )
+	+ __complex__ ( 0, y ) to __complex__ ( x, y ).
+	Fold __complex__ (x, y) * +-I to __complex__ (-+y, +-x).
+
 2006-12-14  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/30198
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 751ef2e6157..18746096b5a 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -8755,6 +8755,41 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
 				    fold_convert (type, tem));
 	    }
 
+	  /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
+	     to __complex__ ( x, y ).  This is not the same for SNaNs or
+	     if singed zeros are involved.  */
+	  if (!HONOR_SNANS (TYPE_MODE (TREE_TYPE (arg0)))
+              && !HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg0)))
+	      && COMPLEX_FLOAT_TYPE_P (TREE_TYPE (arg0)))
+	    {
+	      tree rtype = TREE_TYPE (TREE_TYPE (arg0));
+	      tree arg0r = fold_unary (REALPART_EXPR, rtype, arg0);
+	      tree arg0i = fold_unary (IMAGPART_EXPR, rtype, arg0);
+	      bool arg0rz = false, arg0iz = false;
+	      if ((arg0r && (arg0rz = real_zerop (arg0r)))
+		  || (arg0i && (arg0iz = real_zerop (arg0i))))
+		{
+		  tree arg1r = fold_unary (REALPART_EXPR, rtype, arg1);
+		  tree arg1i = fold_unary (IMAGPART_EXPR, rtype, arg1);
+		  if (arg0rz && arg1i && real_zerop (arg1i))
+		    {
+		      tree rp = arg1r ? arg1r
+				  : build1 (REALPART_EXPR, rtype, arg1);
+		      tree ip = arg0i ? arg0i
+				  : build1 (IMAGPART_EXPR, rtype, arg0);
+		      return fold_build2 (COMPLEX_EXPR, type, rp, ip);
+		    }
+		  else if (arg0iz && arg1r && real_zerop (arg1r))
+		    {
+		      tree rp = arg0r ? arg0r
+				  : build1 (REALPART_EXPR, rtype, arg0);
+		      tree ip = arg1i ? arg1i
+				  : build1 (IMAGPART_EXPR, rtype, arg1);
+		      return fold_build2 (COMPLEX_EXPR, type, rp, ip);
+		    }
+		}
+	    }
+
           if (flag_unsafe_math_optimizations
 	      && (TREE_CODE (arg0) == RDIV_EXPR || TREE_CODE (arg0) == MULT_EXPR)
 	      && (TREE_CODE (arg1) == RDIV_EXPR || TREE_CODE (arg1) == MULT_EXPR)
@@ -9207,6 +9242,28 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
 		}
 	    }
 
+	  /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
+	     This is not the same for NaNs or if singed zeros are
+	     involved.  */
+	  if (!HONOR_NANS (TYPE_MODE (TREE_TYPE (arg0)))
+              && !HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg0)))
+	      && COMPLEX_FLOAT_TYPE_P (TREE_TYPE (arg0))
+	      && TREE_CODE (arg1) == COMPLEX_CST
+	      && real_zerop (TREE_REALPART (arg1)))
+	    {
+	      tree rtype = TREE_TYPE (TREE_TYPE (arg0));
+	      if (real_onep (TREE_IMAGPART (arg1)))
+		return fold_build2 (COMPLEX_EXPR, type,
+				    negate_expr (fold_build1 (IMAGPART_EXPR,
+							      rtype, arg0)),
+				    fold_build1 (REALPART_EXPR, rtype, arg0));
+	      else if (real_minus_onep (TREE_IMAGPART (arg1)))
+		return fold_build2 (COMPLEX_EXPR, type,
+				    fold_build1 (IMAGPART_EXPR, rtype, arg0),
+				    negate_expr (fold_build1 (REALPART_EXPR,
+							      rtype, arg0)));
+	    }
+
 	  /* Optimize z * conj(z) for floating point complex numbers.
 	     Guarded by flag_unsafe_math_optimizations as non-finite
 	     imaginary components don't produce scalar results.  */
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b99415c9d8c..296a34ca7c3 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2006-12-14  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/30172
+	* gcc.dg/pr30172-1.c: New testcase.
+
 2006-12-14  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/30198
diff --git a/gcc/testsuite/gcc.dg/pr30172-1.c b/gcc/testsuite/gcc.dg/pr30172-1.c
new file mode 100644
index 00000000000..14b5fa515f6
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr30172-1.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-funsafe-math-optimizations -ffinite-math-only -fdump-tree-gimple" } */
+
+_Complex double test1 (double x) { return x + 1.i; }
+_Complex double test2 (double x) { return 1 + x * 1.i; }
+_Complex double test3 (double x, double y) { return x + y * 1.i; }
+_Complex double test4 (double x, double y) { return (x + y * 1.i) * 1.i; }
+_Complex double test5 (double x, double y) { return (x + y * 1.i) * -1.i; }
+
+/* { dg-final { scan-tree-dump "COMPLEX_EXPR <x, 1.0e\\+0>" "gimple" } } */
+/* { dg-final { scan-tree-dump "COMPLEX_EXPR <1.0e\\+0, x>" "gimple" } } */
+/* { dg-final { scan-tree-dump "COMPLEX_EXPR <x, y>" "gimple" } } */
+/* { dg-final { scan-tree-dump "D.* = -y;\n.*COMPLEX_EXPR <D.*, x>" "gimple" } } */
+/* { dg-final { scan-tree-dump "D.* = -x;\n.*COMPLEX_EXPR <y, D.*>" "gimple" } } */
+/* { dg-final { cleanup-tree-dump "original" } } */