view ASSEMBLY_EXCEPTION @ 11825:463f51256c86

AMD64HotSpot: emit jump to IC miss handler directly instead of emitting it inside verfied_entry for empty methods we emitted something like this if a inline cache is needed: prefix: 00: < IC check > ... 0b: jne <ic_miss_call> 11: nop ... verified_entry: 20: ret ic_miss_call: 21: jmp <entry of runtime function> when a method is deoptimized, HotSpot patches the verified_entry (0x20) with a jump to a stub that handles call-sites that has been made non-entrant. since this jump is 5 bytes long, it will overwrite ic_miss_call and blow up every caller that calls this method via the unverified entry (prefix). the fix is to emit the jump to the runtime function inside the unverfied entry: prefix: 00: < IC check > ... 0b: je <verified_entry> 11: jeq <entry of runtime function> 16: nop ... verified_entry: 20: ret
author Bernhard Urban <bernhard.urban@jku.at>
date Mon, 30 Sep 2013 09:32:18 +0200
parents c18cbe5936b8
children
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OPENJDK ASSEMBLY EXCEPTION

The OpenJDK source code made available by Oracle at openjdk.java.net and
openjdk.dev.java.net ("OpenJDK Code") is distributed under the terms of the
GNU General Public License <http://www.gnu.org/copyleft/gpl.html> version 2
only ("GPL2"), with the following clarification and special exception.

    Linking this OpenJDK Code statically or dynamically with other code
    is making a combined work based on this library.  Thus, the terms
    and conditions of GPL2 cover the whole combination.

    As a special exception, Oracle gives you permission to link this
    OpenJDK Code with certain code licensed by Oracle as indicated at
    http://openjdk.java.net/legal/exception-modules-2007-05-08.html
    ("Designated Exception Modules") to produce an executable,
    regardless of the license terms of the Designated Exception Modules,
    and to copy and distribute the resulting executable under GPL2,
    provided that the Designated Exception Modules continue to be
    governed by the licenses under which they were offered by Oracle.

As such, it allows licensees and sublicensees of Oracle's GPL2 OpenJDK Code to
build an executable that includes those portions of necessary code that Oracle
could not provide under GPL2 (or that Oracle has provided under GPL2 with the
Classpath exception).  If you modify or add to the OpenJDK code, that new
GPL2 code may still be combined with Designated Exception Modules if the
new code is made subject to this exception by its copyright holder.