diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index b434a9cd5681..8aaec41158b2 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2006-01-20  Alan Modra  <amodra@bigpond.net.au>
+
+	* libgcc2.c (__floatdisf, __floatdidf): Don't use IBM Extended
+	Double TFmode.
+	(__floatundisf, __floatundidf): Likewise.
+	* libgcc2.h (IS_IBM_EXTENDED): Define.
+
 2006-01-19  DJ Delorie  <dj@redhat.com>
 
 	* config/m32c/m32c.h (REG_ALLOC_ORDER): Define.
diff --git a/gcc/libgcc2.c b/gcc/libgcc2.c
index 03cc448cab3e..97717a428c92 100644
--- a/gcc/libgcc2.c
+++ b/gcc/libgcc2.c
@@ -1371,7 +1371,14 @@ __floatunditf (UDWtype u)
 #if (defined(L_floatdisf) && LIBGCC2_HAS_SF_MODE)	\
      || (defined(L_floatdidf) && LIBGCC2_HAS_DF_MODE)
 #define DI_SIZE (W_TYPE_SIZE * 2)
-#define F_MODE_OK(SIZE) (SIZE < DI_SIZE && SIZE > (DI_SIZE - SIZE + FSSIZE))
+#define F_MODE_OK(SIZE) \
+  (SIZE < DI_SIZE							\
+   && SIZE > (DI_SIZE - SIZE + FSSIZE)					\
+   /* Don't use IBM Extended Double TFmode for TI->SF calculations.	\
+      The conversion from long double to float suffers from double	\
+      rounding, because we convert via double.  In any case, the	\
+      fallback code is faster.  */					\
+   && !IS_IBM_EXTENDED (SIZE))
 #if defined(L_floatdisf)
 #define FUNC __floatdisf
 #define FSTYPE SFtype
@@ -1476,7 +1483,14 @@ FUNC (DWtype u)
 #if (defined(L_floatundisf) && LIBGCC2_HAS_SF_MODE)	\
      || (defined(L_floatundidf) && LIBGCC2_HAS_DF_MODE)
 #define DI_SIZE (W_TYPE_SIZE * 2)
-#define F_MODE_OK(SIZE) (SIZE < DI_SIZE && SIZE > (DI_SIZE - SIZE + FSSIZE))
+#define F_MODE_OK(SIZE) \
+  (SIZE < DI_SIZE							\
+   && SIZE > (DI_SIZE - SIZE + FSSIZE)					\
+   /* Don't use IBM Extended Double TFmode for TI->SF calculations.	\
+      The conversion from long double to float suffers from double	\
+      rounding, because we convert via double.  In any case, the	\
+      fallback code is faster.  */					\
+   && !IS_IBM_EXTENDED (SIZE))
 #if defined(L_floatundisf)
 #define FUNC __floatundisf
 #define FSTYPE SFtype
diff --git a/gcc/libgcc2.h b/gcc/libgcc2.h
index f8056d66e141..f24854f97ed5 100644
--- a/gcc/libgcc2.h
+++ b/gcc/libgcc2.h
@@ -117,6 +117,14 @@ extern short int __get_eh_table_version (struct exception_descriptor *);
 #endif
 #endif
 
+/* FIXME: This #ifdef probably should be removed, ie. enable the test
+   for mips too.  */
+#ifdef __powerpc__
+#define IS_IBM_EXTENDED(SIZE) (SIZE == 106)
+#else
+#define IS_IBM_EXTENDED(SIZE) 0
+#endif
+
 #ifndef MIN_UNITS_PER_WORD
 #define MIN_UNITS_PER_WORD UNITS_PER_WORD
 #endif