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Re: gcc miscompiles gcj @ -O2
Richard Henderson writes:
> Reason: exit_block modifies DECL_FUNCTION_BODY (current_function_decl).
Oh yeah that's right. For some reasons DECL_FUNCTION_BODY (mdecl) has
to have it's value set to the current block before we exit it.
> Therefore, if mdecl == current_function_decl, we have undefined
> behaviour, since there is no sequence point across the = in
>
> BLOCK_EXPR_BODY (DECL_FUNCTION_BODY (mdecl)) = exit_block ();
Thanks a bunch. I'm checking this patch in.
./A
2000-12-15 Alexandre Petit-Bianco <apbianco@cygnus.com>
* parse.y (end_artificial_method_body): Fixed undefined behavior.
Credits go to rth for finding it.
Index: parse.y
===================================================================
RCS file: /cvs/gcc/egcs/gcc/java/parse.y,v
retrieving revision 1.235
diff -u -p -r1.235 parse.y
--- parse.y 2000/12/14 04:28:50 1.235
+++ parse.y 2000/12/15 08:40:58
@@ -7200,7 +7200,11 @@ static void
end_artificial_method_body (mdecl)
tree mdecl;
{
- BLOCK_EXPR_BODY (DECL_FUNCTION_BODY (mdecl)) = exit_block ();
+ /* exit_block modifies DECL_FUNCTION_BODY (current_function_decl).
+ It has to be evaluated first. (if mdecl is current_function_decl,
+ we have an undefined behavior if no temporary variable is used.) */
+ tree b = exit_block ();
+ BLOCK_EXPR_BODY (DECL_FUNCTION_BODY (mdecl)) = b;
exit_block ();
}