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6902182: 4/4 Starting with jdwp agent should not incur performance penalty

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Rename can_post_exceptions support to can_post_on_exceptions. Add support for should_post_on_exceptions flag to permit per JavaThread optimizations.

Reviewed-by: never, kvn, dcubed
This commit is contained in:
Tom Deneau 2010-02-01 17:35:05 -07:00 • committed by Daniel D. Daugherty
parent 679f958f72
commit f23b68b367
19 changed files with 111 additions and 52 deletions
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42
hotspot/src/share/vm/opto/graphKit.cpp
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@ -1,5 +1,5 @@
/*
* Copyright 2001-2009 Sun Microsystems, Inc. All Rights Reserved.
* Copyright 2001-2010 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -455,16 +455,44 @@ Bytecodes::Code GraphKit::java_bc() const {
return Bytecodes::_illegal;
}
void GraphKit::uncommon_trap_if_should_post_on_exceptions(Deoptimization::DeoptReason reason,
bool must_throw) {
// if the exception capability is set, then we will generate code
// to check the JavaThread.should_post_on_exceptions flag to see
// if we actually need to report exception events (for this
// thread). If we don't need to report exception events, we will
// take the normal fast path provided by add_exception_events. If
// exception event reporting is enabled for this thread, we will
// take the uncommon_trap in the BuildCutout below.
// first must access the should_post_on_exceptions_flag in this thread's JavaThread
Node* jthread = _gvn.transform(new (C, 1) ThreadLocalNode());
Node* adr = basic_plus_adr(top(), jthread, in_bytes(JavaThread::should_post_on_exceptions_flag_offset()));
Node* should_post_flag = make_load(control(), adr, TypeInt::INT, T_INT, Compile::AliasIdxRaw, false);
// Test the should_post_on_exceptions_flag vs. 0
Node* chk = _gvn.transform( new (C, 3) CmpINode(should_post_flag, intcon(0)) );
Node* tst = _gvn.transform( new (C, 2) BoolNode(chk, BoolTest::eq) );
// Branch to slow_path if should_post_on_exceptions_flag was true
{ BuildCutout unless(this, tst, PROB_MAX);
// Do not try anything fancy if we're notifying the VM on every throw.
// Cf. case Bytecodes::_athrow in parse2.cpp.
uncommon_trap(reason, Deoptimization::Action_none,
(ciKlass*)NULL, (char*)NULL, must_throw);
}
}
//------------------------------builtin_throw----------------------------------
void GraphKit::builtin_throw(Deoptimization::DeoptReason reason, Node* arg) {
bool must_throw = true;
if (env()->jvmti_can_post_exceptions()) {
// Do not try anything fancy if we're notifying the VM on every throw.
// Cf. case Bytecodes::_athrow in parse2.cpp.
uncommon_trap(reason, Deoptimization::Action_none,
(ciKlass*)NULL, (char*)NULL, must_throw);
return;
if (env()->jvmti_can_post_on_exceptions()) {
// check if we must post exception events, take uncommon trap if so
uncommon_trap_if_should_post_on_exceptions(reason, must_throw);
// here if should_post_on_exceptions is false
// continue on with the normal codegen
}
// If this particular condition has not yet happened at this