gcj performance on Solaris 2.6

Thu Jul 26 12:19:00 GMT 2001

On 26 Jul 2001, Tom Tromey wrote:
> If you are running performance tests, always use at least -O1.
> -O2 is probably better. Often, -O3 can give worse results than -O2,
> though, because (I hear) it inlines too aggressively (perhaps not a
> problem for Java, where inlining is still not quite there).

True. Gcj has a different problem: every private/static/final method is
declared DECL_INLINE. That may not always do what you want.
I built one application library at -O0, -O2 and -O3 with the patch below,
and at -O2 unpatched for comparison.
 text data bss dec hex filename
1659369 247180 704 1907253 1d1a35 libjacl-O0.so
2474525 243612 704 2718841 297c79 libjacl-O2-unpatched.so
1354881 237836 704 1593421 18504d libjacl-O2.so
1418826 236272 704 1655802 1943fa libjacl-O3.so
With the patch -O2 yields the smallest binary, and -O3 slightly larger.
That's what I expect. But the unpatched gcj nearly doubles the text size
at -O2. The library built with -O3 executes fastest on my tests.
I'd be inclined to omit DECL_INLINE in the frontend and let the integrator
use its best judgement, at least until we have tree inlining with decent
heuristics. Of course one application on one platform isn't a good
data set. Comments?
Index: class.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/java/class.c,v
retrieving revision 1.100
diff -u -r1.100 class.c

--- class.c 2001年06月27日 20:38:20 1.100
+++ class.c 2001年07月26日 19:15:45
@@ -674,16 +674,16 @@
 if (access_flags & ACC_PUBLIC) METHOD_PUBLIC (fndecl) = 1;
 if (access_flags & ACC_PROTECTED) METHOD_PROTECTED (fndecl) = 1;
 if (access_flags & ACC_PRIVATE)
- METHOD_PRIVATE (fndecl) = DECL_INLINE (fndecl) = 1;
+ METHOD_PRIVATE (fndecl) = 1;
 if (access_flags & ACC_NATIVE)
 {
 METHOD_NATIVE (fndecl) = 1;
 DECL_EXTERNAL (fndecl) = 1;
 }
 if (access_flags & ACC_STATIC) 
- METHOD_STATIC (fndecl) = DECL_INLINE (fndecl) = 1;
+ METHOD_STATIC (fndecl) = 1;
 if (access_flags & ACC_FINAL) 
- METHOD_FINAL (fndecl) = DECL_INLINE (fndecl) = 1;
+ METHOD_FINAL (fndecl) = 1;
 if (access_flags & ACC_SYNCHRONIZED) METHOD_SYNCHRONIZED (fndecl) = 1;
 if (access_flags & ACC_ABSTRACT) METHOD_ABSTRACT (fndecl) = 1;
 if (access_flags & ACC_TRANSIENT) METHOD_TRANSIENT (fndecl) = 1;
