On Thu, Apr 19, 2012 at 6:06 PM, Eliot Miranda <eliot.miranda@gmail.com>wrote:
On Thu, Apr 19, 2012 at 12:55 AM, Mariano Martinez Peck < marianopeck@gmail.com> wrote:
On Thu, Apr 19, 2012 at 6:08 AM, Eliot Miranda <eliot.miranda@gmail.com>wrote:
http://www.mirandabanda.org/files/Cog/VM/VM.r2550/
CogVM binaries as per VMMaker.oscog-eem.157/r2550.
Stack/CoInterpreter/Cogit: Implement proper bounds checking for byte access to compiled methods. Raise errors for accesses outside initialPC to size.
CoInterpreter: Provide a thorough flush primitive for CompiledMethods that discards all machine code and makes sure that any contexts using the method have bytecode pcs. Primitive #215 (same as 116 in the Stack VM). This is much slower than 116 (flushCache) since it has to enumerate over all heap contexts.
Excellent. Does it mean we should implement something like this:
CompiledMethod >> flushCache "Tell the interpreter to remove all references to this method from its method lookup cache, if it has one. In addition, it provides a thorough flush primitive for CompiledMethods that discards all machine code and makes sure that any contexts using the method have bytecode pcs. This primitive must be called whenever a method is redefined or removed." <primitive: 215> self simpleFlushCache
CompiledMethod >> simpleFlushCache "Tell the interpreter to remove all references to this method from its method lookup cache, if it has one. This primitive must be called whenever a method is redefined or removed."
<primitive: 116>\
No. 215 is extremely expensive, because it scans the entire heap looking for contexts using the method, and in the common case of redefining a method it is unnecessary. It is only necessary if you modify a method still in-use; read the comment of the attached method.
Further, I would prefer to update the Interpreter to implement primitive 215 using primitive 116, i.e. in the Interpreter's primitive table have both
(116 primitiveFlushCacheByMethod) ... (215 primitiveFlushCacheByMethod) "primitiveVoidVMStateForMethod in the CoInterpreter"
This is what I've done in the StackInterpreter. In fact, we need to put in time to bring the Interpreter's primitive set into agreement with Cog.
Ok, I understand. Now, primitive 215 #primitiveVoidVMStateForMethod receives a CompiledMethod so we implement #voidCogVMState there. However, I see there is also primitive 214 #primitiveVoidVMState. Should we ALSO add something like voidCogVMState "Void all internal VM state in the stack and machine code zones <primitive: 214> ^self primitiveFailed But implemented in SmallttalkImage/VirtualMachine ?? thanks!
So I'm expecting we will have
voidCogVMState "Tell the VM to remove all references to any machine code form of the method. This primitive must be called whenever a method is in use and modified. This is more aggressive (and *much* more costly) than flushCache since it must search through all context objects, making sure that none have a (hidden) machine code pc in the receiver. Since modifying a method will likely change the generated machine code, modifying a method (rather than redefining it) requires this more aggressive flush."
<primitive: 215> ^self primitiveFailed
flushCache "Tell the interpreter to remove all references to this method from its method lookup cache, if it has one. This primitive must be called whenever a method is defined or removed. NOTE: Only one of two selective flush methods needs to be used. Squeak 2.2 and earlier uses 119 (See Symbol flushCache). Squeak 2.3 and later uses 116 (See CompiledMethod flushCache)."
<primitive: 116>
or
voidCogVMState "Tell the VM to remove all references to any machine code form of the method. This primitive must be called whenever a method is in use and modified. This is more aggressive (and *much* more costly) than flushCache since it must search through all context objects, making sure that none have a (hidden) machine code pc in the receiver. Since modifying a method will likely change the generated machine code, modifying a method (rather than redefining it) requires this more aggressive flush."
<primitive: 215> ^self flushCache
flushCache "Tell the interpreter to remove all references to this method from its method lookup cache, if it has one. This primitive must be called whenever a method is defined or removed. NOTE: Only one of two selective flush methods needs to be used. Squeak 2.2 and earlier uses 119 (See Symbol flushCache). Squeak 2.3 and later uses 116 (See CompiledMethod flushCache)."
<primitive: 116>
If you have a better name for #simpleFlushCache please let me know. if you agree, I will open an issue for this.
Cheers
Provide an xray primitive for CompiledMethod that answers if a method has machine code, and if so if it's machine code is frameless, and/or refers to a young object. No primitive number. Used to test the above.
Make printOopShort: print Association keys. Useful for longPrintOop:, and hence printReferencesTo: etc.
Mac OS: add fflush to debug printing in sqMacUIEventsUniversal.c so output appears promptly.
Fix the annoying bogus error messages from the mprotect calls by getting the length arg to mprotect right.
Add version infor for the Cross/plugins tree. Add a -version switch to win32
--
best,
Eliot
-- Mariano http://marianopeck.wordpress.com
-- best, Eliot
-- Mariano http://marianopeck.wordpress.com