Shark safepoint removal (part 1)
Gary Benson
gbenson at redhat.com
Fri May 29 02:20:47 PDT 2009
Hi all,
In HotSpot, whenever the garbage collector needs to run (and for
some other reasons) the VM must be brought to a safepoint, where
all the threads stop and wait for the GC (or whatever) to complete.
This means that running threads need to periodically check to see
if a safepoint is requested.
There are a couple of places where Java methods must check. Each
loop must have at least one safepoint, and a check must also be
performed when a method returns. There are also a couple of places
where a safepoint check implicitly happens -- when a Java method is
called, for example, or for certain calls to VM functions.
This commit allows Shark to keep track of these implicit safepoints
and use them to eliminate explicit ones.
Cheers,
Gary
--
http://gbenson.net/
-------------- next part --------------
diff -r 797d59eaba38 -r 1c47ca6df830 ChangeLog
--- a/ChangeLog Thu May 28 16:56:19 2009 +0100
+++ b/ChangeLog Fri May 29 10:12:01 2009 +0100
@@ -1,3 +1,34 @@
+2009-05-29 Gary Benson <gbenson at redhat.com>
+
+ * ports/hotspot/src/share/vm/shark/sharkState.hpp
+ (SharkState::_has_safepointed): New field.
+ (SharkState::has_safepointed): New method.
+ (SharkState::set_has_safepointed): Likewise.
+ * ports/hotspot/src/share/vm/shark/sharkState.cpp
+ (SharkState::SharkState): Initialize the above.
+ (SharkState::equal_to): Compare the above.
+ (SharkState::merge): Merge the above.
+
+ * ports/hotspot/src/share/vm/shark/sharkBlock.hpp
+ (SharkBlock::add_safepoint): Replaced with...
+ (SharkBlock::maybe_add_safepoint): New method.
+ * ports/hotspot/src/share/vm/shark/sharkBlock.cpp
+ (SharkBlock::add_safepoint): Replaced with...
+ (SharkBlock::maybe_add_safepoint): New method.
+ (SharkBlock::parse_bytecode): Updated for above.
+
+ * ports/hotspot/src/share/vm/shark/sharkTopLevelBlock.hpp
+ (SharkTopLevelBlock::add_safepoint): Replaced with...
+ (SharkTopLevelBlock::maybe_add_safepoint): New method.
+ (SharkTopLevelBlock::call_vm): Mark that a safepoint check
+ has occurred if a full VM call is made.
+ * ports/hotspot/src/share/vm/shark/sharkTopLevelBlock.cpp
+ (SharkTopLevelBlock::add_safepoint): Replaced with...
+ (SharkTopLevelBlock::maybe_add_safepoint): New method.
+ (SharkTopLevelBlock::do_return): Updated for above.
+ (SharkTopLevelBlock::do_call): Mark that a safepoint check
+ has occurred if a non-inlined Java call is made.
+
2009-05-28 Gary Benson <gbenson at redhat.com>
* ports/hotspot/src/share/vm/shark/sharkTopLevelBlock.hpp
diff -r 797d59eaba38 -r 1c47ca6df830 ports/hotspot/src/share/vm/shark/sharkBlock.cpp
--- a/ports/hotspot/src/share/vm/shark/sharkBlock.cpp Thu May 28 16:56:19 2009 +0100
+++ b/ports/hotspot/src/share/vm/shark/sharkBlock.cpp Fri May 29 10:12:01 2009 +0100
@@ -74,24 +74,24 @@
case Bytecodes::_if_icmpgt:
case Bytecodes::_if_icmpge:
if (iter()->get_dest() <= bci())
- add_safepoint();
+ maybe_add_safepoint();
break;
case Bytecodes::_goto_w:
if (iter()->get_far_dest() <= bci())
- add_safepoint();
+ maybe_add_safepoint();
break;
case Bytecodes::_tableswitch:
case Bytecodes::_lookupswitch:
if (switch_default_dest() <= bci()) {
- add_safepoint();
+ maybe_add_safepoint();
break;
}
int len = switch_table_length();
for (int i = 0; i < len; i++) {
if (switch_dest(i) <= bci()) {
- add_safepoint();
+ maybe_add_safepoint();
break;
}
}
@@ -1138,7 +1138,7 @@
ShouldNotCallThis();
}
-void SharkBlock::add_safepoint()
+void SharkBlock::maybe_add_safepoint()
{
ShouldNotCallThis();
}
diff -r 797d59eaba38 -r 1c47ca6df830 ports/hotspot/src/share/vm/shark/sharkBlock.hpp
--- a/ports/hotspot/src/share/vm/shark/sharkBlock.hpp Thu May 28 16:56:19 2009 +0100
+++ b/ports/hotspot/src/share/vm/shark/sharkBlock.hpp Fri May 29 10:12:01 2009 +0100
@@ -231,7 +231,7 @@
// Safepoints
protected:
- virtual void add_safepoint();
+ virtual void maybe_add_safepoint();
// Traps
protected:
diff -r 797d59eaba38 -r 1c47ca6df830 ports/hotspot/src/share/vm/shark/sharkState.cpp
--- a/ports/hotspot/src/share/vm/shark/sharkState.cpp Thu May 28 16:56:19 2009 +0100
+++ b/ports/hotspot/src/share/vm/shark/sharkState.cpp Fri May 29 10:12:01 2009 +0100
@@ -33,7 +33,8 @@
_function(function),
_method(NULL),
_oop_tmp(NULL),
- _frame_cache(NULL)
+ _frame_cache(NULL),
+ _has_safepointed(false)
{
initialize(NULL);
}
@@ -43,7 +44,8 @@
_function(state->function()),
_method(state->method()),
_oop_tmp(state->oop_tmp()),
- _frame_cache(NULL)
+ _frame_cache(NULL),
+ _has_safepointed(state->has_safepointed())
{
initialize(state);
}
@@ -105,6 +107,9 @@
if (num_monitors() != other->num_monitors())
return false;
+ if (has_safepointed() != other->has_safepointed())
+ return false;
+
// Local variables
for (int i = 0; i < max_locals(); i++) {
SharkValue *value = local(i);
@@ -215,6 +220,9 @@
// Frame cache
frame_cache()->merge(other->frame_cache());
+
+ // Safepointed status
+ set_has_safepointed(this->has_safepointed() && other->has_safepointed());
}
void SharkState::decache_for_Java_call(ciMethod* callee)
diff -r 797d59eaba38 -r 1c47ca6df830 ports/hotspot/src/share/vm/shark/sharkState.hpp
--- a/ports/hotspot/src/share/vm/shark/sharkState.hpp Thu May 28 16:56:19 2009 +0100
+++ b/ports/hotspot/src/share/vm/shark/sharkState.hpp Fri May 29 10:12:01 2009 +0100
@@ -45,6 +45,7 @@
SharkValue** _sp;
int _num_monitors;
llvm::Value* _oop_tmp;
+ bool _has_safepointed;
public:
SharkBlock *block() const
@@ -161,6 +162,17 @@
_oop_tmp = oop_tmp;
}
+ // Safepointed status
+ public:
+ bool has_safepointed() const
+ {
+ return _has_safepointed;
+ }
+ void set_has_safepointed(bool has_safepointed)
+ {
+ _has_safepointed = has_safepointed;
+ }
+
// Comparison
public:
bool equal_to(SharkState* other);
diff -r 797d59eaba38 -r 1c47ca6df830 ports/hotspot/src/share/vm/shark/sharkTopLevelBlock.cpp
--- a/ports/hotspot/src/share/vm/shark/sharkTopLevelBlock.cpp Thu May 28 16:56:19 2009 +0100
+++ b/ports/hotspot/src/share/vm/shark/sharkTopLevelBlock.cpp Fri May 29 10:12:01 2009 +0100
@@ -435,8 +435,11 @@
handle_return(T_VOID, exception);
}
-void SharkTopLevelBlock::add_safepoint()
+void SharkTopLevelBlock::maybe_add_safepoint()
{
+ if (current_state()->has_safepointed())
+ return;
+
BasicBlock *orig_block = builder()->GetInsertBlock();
SharkState *orig_state = current_state()->copy();
@@ -462,6 +465,8 @@
builder()->SetInsertPoint(safepointed);
current_state()->merge(orig_state, orig_block, safepointed_block);
+
+ current_state()->set_has_safepointed(true);
}
void SharkTopLevelBlock::do_trap(int trap_request)
@@ -720,7 +725,7 @@
{
if (target()->intrinsic_id() == vmIntrinsics::_Object_init)
call_register_finalizer(local(0)->jobject_value());
- add_safepoint();
+ maybe_add_safepoint();
handle_return(type, NULL);
}
@@ -1142,6 +1147,9 @@
// Check for pending exceptions
check_pending_exception(EX_CHECK_FULL);
+
+ // Mark that a safepoint check has occurred
+ current_state()->set_has_safepointed(true);
}
void SharkTopLevelBlock::do_instance_check()
diff -r 797d59eaba38 -r 1c47ca6df830 ports/hotspot/src/share/vm/shark/sharkTopLevelBlock.hpp
--- a/ports/hotspot/src/share/vm/shark/sharkTopLevelBlock.hpp Thu May 28 16:56:19 2009 +0100
+++ b/ports/hotspot/src/share/vm/shark/sharkTopLevelBlock.hpp Fri May 29 10:12:01 2009 +0100
@@ -257,8 +257,10 @@
llvm::CallInst *res = builder()->CreateCall(callee, args_start, args_end);
function()->reset_last_Java_frame();
current_state()->cache_after_VM_call();
- if (ea != EX_CHECK_NONE)
+ if (ea != EX_CHECK_NONE) {
check_pending_exception(ea);
+ current_state()->set_has_safepointed(true);
+ }
return res;
}
@@ -308,7 +310,7 @@
// Safepoints
private:
- void add_safepoint();
+ void maybe_add_safepoint();
// Traps
private:
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