Documenting Cygnus and gcc compiler problems

Martin Buchholz
Tue Dec 7 15:29:00 GMT 1999

This ChangeLog intentionally left blank.

gcc maintainers: This is a patch to XEmacs, not gcc; but you might
want to document these problems yourself.

--- PROBLEMS	1999/09/22 23:43:39
+++ PROBLEMS	1999/12/07 23:24:32
@@ -41,14 +41,33 @@
 There have been reports of egcs-1.1 not compiling XEmacs correctly on
 Alpha Linux.  There have also been reports that egcs-1.0.3a is O.K.
-*** Don't use -O2 with gcc 2.7.2 under Intel/XXX without also using
+*** Don't use -O2 or -O3 with Cygwin 1.0, CodeFusion-99070 or gcc 2.7.2 on x86
+without also using `-fno-strength-reduce'.
 gcc will generate incorrect code otherwise.  This bug is present in at
 least 2.6.x and 2.7.[0-2].  This bug has been fixed in GCC and
 later.  This bug is O/S independent, but is limited to x86 architectures.
 This problem is known to be fixed in egcs (or pgcc) 1.0 or later.
+Unfortunately, later releases of Cygnus-released compilers (not the
+Net-released ones) have a bug with the same `problem signature'.
+If you're lucky, you'll get an error while compiling that looks like:
+event-stream.c:3189: internal error--unrecognizable insn:
+(insn 256 14 15 (set (reg/v:SI 24)
+        (minus:SI (reg/v:SI 25)
+            (const_int 2))) -1 (insn_list 11 (nil))
+    (nil))
+    0       0 [main]
+If you're unlucky, your code will simply execute incorrectly.
+*** Don't use gcc-2.95.2 with -mcpu=ultrasparc on Solaris 2.6.
+gcc will assume a 64-bit operating system, even though you've
+merely told it to assume a 64-bit instruction set.
 *** Don't use -O2 with gcc 2.7.2 under Intel architectures without also
 using `-fno-caller-saves'.

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