[M3commit] CVS Update: cm3
Tony Hosking
hosking at cs.purdue.edu
Thu Jan 6 22:56:48 CET 2011
You are confusing code emitted in the body of the loop with dynamic executions of that code.
CG calls are all compile-time generation of code.
On Jan 6, 2011, at 4:17 PM, Jay K wrote:
>
> If I have a try/finally or lock in a loop, those lines aren't going to guaranteeably store the same values each time?
>
> - Jay
>
> ----------------------------------------
>> Subject: Re: [M3commit] CVS Update: cm3
>> From: hosking at cs.purdue.edu
>> Date: Thu, 6 Jan 2011 16:00:08 -0500
>> CC: m3commit at elegosoft.com
>> To: jay.krell at cornell.edu
>>
>> In the code below there are no initializations.
>>
>> On Jan 6, 2011, at 3:51 PM, Jay K wrote:
>>
>>>
>>> ps: I think there other non-ideal initializations here.
>>> e.g.
>>>
>>>
>>> TryFinStmt.m3:Compile2
>>> (* declare and initialize the info record *)
>>> frame := CG.Declare_local (M3ID.NoID, M3RT.EF2_SIZE, Target.Address.align,
>>> CG.Type.Struct, 0, in_memory := TRUE,
>>> up_level := FALSE, f := CG.Never);
>>> CG.Load_procedure (p.handler.cg_proc);
>>> CG.Store_addr (frame, M3RT.EF2_handler);
>>> CG.Load_static_link (p.handler.cg_proc);
>>> CG.Store_addr (frame, M3RT.EF2_frame);
>>>
>>>
>>> Putting TRY/LOCK in loops probably repeatedly does the same initializations.
>>> Granted, this is non-stack-walker code.
>>>
>>> Seems all bit a suspicious to me, though I'm pretty ignorant of m3front still..
>>>
>>> - Jay
>>>
>>> ----------------------------------------
>>>> From: jay.krell at cornell.edu
>>>> To: hosking at cs.purdue.edu
>>>> CC: m3commit at elegosoft.com
>>>> Subject: RE: [M3commit] CVS Update: cm3
>>>> Date: Thu, 6 Jan 2011 20:48:56 +0000
>>>>
>>>>
>>>> The same way as before. I think this operates at too low a level to get any automatic initialization.
>>>>
>>>> TryStmt.m3 and TryFinStmt.m3:
>>>>
>>>> frame := CG.Declare_local (M3ID.NoID, M3RT.EF1_SIZE, Target.Address.align,
>>>> CG.Type.Struct, 0, in_memory := TRUE,
>>>> up_level := FALSE, f := CG.Never);
>>>>
>>>> I agree though, this might not be ideal.
>>>>
>>>> - Jay
>>>>
>>>>
>>>> ----------------------------------------
>>>>> Subject: Re: [M3commit] CVS Update: cm3
>>>>> From: hosking at cs.purdue.edu
>>>>> Date: Thu, 6 Jan 2011 15:42:33 -0500
>>>>> CC: m3commit at elegosoft.com
>>>>> To: jay.krell at cornell.edu
>>>>>
>>>>> I don't understand what you mean by "initializes to NIL".
>>>>> How are you creating the frame variable?
>>>>> If you do it properly the language semantics will cause it be initialized to NIL automatically.
>>>>>
>>>>> On Jan 6, 2011, at 3:33 PM, Jay K wrote:
>>>>>
>>>>>>
>>>>>> Ok.
>>>>>> Do you know where to initialize the jmpbuf to NIL?
>>>>>>
>>>>>> I have a diff that "works" (ie: doesn't crash) and is *close* to correct,
>>>>>> it checks for NIL and branches around the alloca for non-NIL, but it
>>>>>> also initializes to NIL repeatedly, so no change effectively.
>>>>>>
>>>>>>
>>>>>> Index: misc/Marker.m3
>>>>>> ===================================================================
>>>>>> RCS file: /usr/cvs/cm3/m3-sys/m3front/src/misc/Marker.m3,v
>>>>>> retrieving revision 1.7
>>>>>> diff -u -w -r1.7 Marker.m3
>>>>>> --- misc/Marker.m3 5 Jan 2011 14:34:54 -0000 1.7
>>>>>> +++ misc/Marker.m3 6 Jan 2011 20:32:00 -0000
>>>>>> @@ -233,6 +233,7 @@
>>>>>>
>>>>>> PROCEDURE CaptureState (frame: CG.Var; handler: CG.Label) =
>>>>>> VAR new: BOOLEAN;
>>>>>> + label := CG.Next_label ();
>>>>>> BEGIN
>>>>>> (* int setjmp(void* ); *)
>>>>>> IF (setjmp = NIL) THEN
>>>>>> @@ -263,18 +264,25 @@
>>>>>> Target.Word.cg_type, 0);
>>>>>> END;
>>>>>>
>>>>>> + (* IF frame.jmpbuf = NIL THEN *)
>>>>>> +
>>>>>> + CG.Load_nil ();
>>>>>> + CG.Load_addr (frame, M3RT.EF1_jmpbuf);
>>>>>> + CG.If_compare (Target.Address.cg_type, CG.Cmp.NE, label, CG.Maybe);
>>>>>> +
>>>>>> (* frame.jmpbuf = alloca(Csetjmp__Jumpbuf_size); *)
>>>>>> CG.Start_call_direct (alloca, 0, Target.Address.cg_type);
>>>>>> CG.Load_int (Target.Word.cg_type, Jumpbuf_size);
>>>>>> CG.Pop_param (Target.Word.cg_type);
>>>>>> CG.Call_direct (alloca, Target.Address.cg_type);
>>>>>> - CG.Store (frame, M3RT.EF1_jmpbuf, Target.Address.size, Target.Address.align,
>>>>>> - Target.Address.cg_type);
>>>>>> + CG.Store_addr (frame, M3RT.EF1_jmpbuf);
>>>>>> +
>>>>>> + (* END *)
>>>>>> + CG.Set_label (label);
>>>>>>
>>>>>> (* setmp(frame.jmpbuf) *)
>>>>>> CG.Start_call_direct (setjmp, 0, Target.Integer.cg_type);
>>>>>> - CG.Load (frame, M3RT.EF1_jmpbuf, Target.Address.size, Target.Address.align,
>>>>>> - Target.Address.cg_type);
>>>>>> + CG.Load_addr (frame, M3RT.EF1_jmpbuf);
>>>>>> CG.Pop_param (CG.Type.Addr);
>>>>>> CG.Call_direct (setjmp, Target.Integer.cg_type);
>>>>>> CG.If_true (handler, CG.Never);
>>>>>> cvs diff: Diffing stmts
>>>>>> Index: stmts/TryFinStmt.m3
>>>>>> ===================================================================
>>>>>> RCS file: /usr/cvs/cm3/m3-sys/m3front/src/stmts/TryFinStmt.m3,v
>>>>>> retrieving revision 1.6
>>>>>> diff -u -w -r1.6 TryFinStmt.m3
>>>>>> --- stmts/TryFinStmt.m3 5 Jan 2011 14:34:54 -0000 1.6
>>>>>> +++ stmts/TryFinStmt.m3 6 Jan 2011 20:32:00 -0000
>>>>>> @@ -299,6 +299,10 @@
>>>>>> CG.Load_nil ();
>>>>>> CG.Store_addr (frame, M3RT.EF1_info + M3RT.EA_exception);
>>>>>>
>>>>>> + (* no jmpbuf yet (avoid repeated alloca in try within loop) *)
>>>>>> + CG.Load_nil ();
>>>>>> + CG.Store_addr (frame, M3RT.EF1_jmpbuf);
>>>>>> +
>>>>>> l := CG.Next_label (3);
>>>>>> CG.Set_label (l, barrier := TRUE);
>>>>>> Marker.PushFrame (frame, M3RT.HandlerClass.Finally);
>>>>>> Index: stmts/TryStmt.m3
>>>>>> ===================================================================
>>>>>> RCS file: /usr/cvs/cm3/m3-sys/m3front/src/stmts/TryStmt.m3,v
>>>>>> retrieving revision 1.3
>>>>>> diff -u -w -r1.3 TryStmt.m3
>>>>>> --- stmts/TryStmt.m3 5 Jan 2011 14:34:54 -0000 1.3
>>>>>> +++ stmts/TryStmt.m3 6 Jan 2011 20:32:00 -0000
>>>>>> @@ -10,7 +10,7 @@
>>>>>>
>>>>>> IMPORT M3, M3ID, CG, Variable, Scope, Exceptionz, Value, Error, Marker;
>>>>>> IMPORT Type, Stmt, StmtRep, TryFinStmt, Token;
>>>>>> -IMPORT Scanner, ESet, Target, M3RT, Tracer;
>>>>>> +IMPORT Scanner, ESet, Target, M3RT, Tracer, IO;
>>>>>> FROM Scanner IMPORT Match, MatchID, GetToken, Fail, cur;
>>>>>>
>>>>>> TYPE
>>>>>> @@ -411,6 +411,10 @@
>>>>>> CG.Store_addr (frame, M3RT.EF1_exception);
>>>>>> ***********************************************)
>>>>>>
>>>>>> + (* no jmpbuf yet (avoid repeated alloca in try within loop) *)
>>>>>> + CG.Load_nil ();
>>>>>> + CG.Store_addr (frame, M3RT.EF1_jmpbuf);
>>>>>> +
>>>>>> IF (p.hasElse) THEN
>>>>>> Marker.PushTryElse (l, l+1, frame);
>>>>>> Marker.PushFrame (frame, M3RT.HandlerClass.ExceptElse);
>>>>>>
>>>>>>
>>>>>> The set_label before one of the PushEFrames could be moved down a bit,
>>>>>> to after the NIL initialization, and that'd fix some cases, but I think not all.
>>>>>>
>>>>>> Thanks,
>>>>>> - Jay
>>>>>>
>>>>>>
>>>>>> ----------------------------------------
>>>>>>> Subject: Re: [M3commit] CVS Update: cm3
>>>>>>> From: hosking at cs.purdue.edu
>>>>>>> Date: Thu, 6 Jan 2011 14:11:04 -0500
>>>>>>> CC: m3commit at elegosoft.com
>>>>>>> To: jay.krell at cornell.edu
>>>>>>>
>>>>>>> At this point, we are trying to move away from the setjmp implementation to one that relies on unwind support, so I don't think the effort here is worthwhile.
>>>>>>>
>>>>>>> Antony Hosking | Associate Professor | Computer Science | Purdue University
>>>>>>> 305 N. University Street | West Lafayette | IN 47907 | USA
>>>>>>> Office +1 765 494 6001 | Mobile +1 765 427 5484
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Jan 6, 2011, at 2:00 PM, Jay K wrote:
>>>>>>>
>>>>>>>>
>>>>>>>> I believe you can, but it'd take significant work in the frontend.
>>>>>>>> The jmpbuf should identify merely which procedure/frame to return to.
>>>>>>>> There would also be a volatile local integer, that gets altered at certain points through the function.
>>>>>>>> When setjmp returns exceptionally, you'd switch on that integer to determine where to "really" go.
>>>>>>>> This is analogous to how other systems work -- NT/x86 has a highly optimized frame based exception
>>>>>>>> handling. Instead of a generic thread local, FS:0 is reserved to be the head of the linked list of frames.
>>>>>>>> Instead of setjmp, the compiler pessimizes appropriately.
>>>>>>>>
>>>>>>>>
>>>>>>>> So the result is that a function with one or more tries, or one or more locals with destructors,
>>>>>>>> puts one node on the FS:0 list, and then mucks with the volatile local integer to indicate
>>>>>>>> where in the function it is.
>>>>>>>>
>>>>>>>>
>>>>>>>> If NT/x86 were inefficient more analogous to current Modula-3, it'd link/unlink in FS:0 more often.
>>>>>>>>
>>>>>>>>
>>>>>>>> It is more work through, granted, I can understand that.
>>>>>>>> And given that we have a much better option for many platforms, the payoff would be reduced.
>>>>>>>>
>>>>>>>>
>>>>>>>> Anyway, I'm trying what you say, like for TRY within a loop.
>>>>>>>>
>>>>>>>>
>>>>>>>> I should point out that alloca has an extra inefficiency vs. the previous approach.
>>>>>>>> It aligns more. So it is using more stack than the other way.
>>>>>>>> And it might pessimize codegen in other ways.
>>>>>>>>
>>>>>>>>
>>>>>>>> The gcc code appears somewhat similar..I think the tables merely describe, again, which
>>>>>>>> function/frame to return to, and that within the frame there is a local integer to determine
>>>>>>>> more precisely what to do. I'm not sure. I saw mention of a switch.
>>>>>>>>
>>>>>>>>
>>>>>>>> - Jay
>>>>>>>>
>>>>>>>> ________________________________
>>>>>>>>> Subject: Re: [M3commit] CVS Update: cm3
>>>>>>>>> From: hosking at cs.purdue.edu
>>>>>>>>> Date: Thu, 6 Jan 2011 13:52:42 -0500
>>>>>>>>> CC: m3commit at elegosoft.com
>>>>>>>>> To: jay.krell at cornell.edu
>>>>>>>>>
>>>>>>>>> You can't have one jmpbuf per procedure. You need one per TRY scope,
>>>>>>>>> since they can be nested.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Jan 6, 2011, at 11:35 AM, Jay K wrote:
>>>>>>>>>
>>>>>>>>> Hm. How do I single instance the "EF1"? The current code allocates a
>>>>>>>>> local "EF1" for each try.
>>>>>>>>> I guess, really, it is EF1, EF2, etc.
>>>>>>>>> So there should be a separate local for the jmpbuf pointer, and store
>>>>>>>>> it in each EF* block?
>>>>>>>>> How do I make just one jmpbuf pointer? I couldn't easily figure out how
>>>>>>>>> to in the front end, I need to read it more.
>>>>>>>>>
>>>>>>>>> something like:
>>>>>>>>>
>>>>>>>>> PROCEDURE F1() = BEGIN TRY1 do stuff1 TRY2 do stuff 2 TRY3 do stuff 3
>>>>>>>>> END END END END F1;
>>>>>>>>> =>
>>>>>>>>>
>>>>>>>>> void F1()
>>>>>>>>> {
>>>>>>>>> jmp_buf* jb = 0;
>>>>>>>>> EF1 a,b,c;
>>>>>>>>> setjmp(a.jmpbuf = jb ? jb : (jb = alloca(sizeof(jmp_buf))); // TRY1
>>>>>>>>> do stuff 1...
>>>>>>>>> setjmp(b.jmpbuf = jb ? jb : (jb = alloca(sizeof(jmp_buf))); // TRY2
>>>>>>>>> do stuff 2...
>>>>>>>>> setjmp(c.jmpbuf = jb ? jb : (jb = alloca(sizeof(jmp_buf))); // TRY3
>>>>>>>>> do stuff 3...
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> (The actual syntactic and semantic correctness of this code -- the
>>>>>>>>> existance of the ternary operator, and that it only evaluates one side
>>>>>>>>> or the other, and that assignment is expression..I quite like those
>>>>>>>>> features....)
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Still, something I can't pin down strikes me as too simple here.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> If there is just one setjmp, and no integer(s) to keep track of
>>>>>>>>> additional progress, you only ever know the last place you were in a
>>>>>>>>> function.
>>>>>>>>> That doesn't seem adequate.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> What if a function raises an exception, catches it within itself, and
>>>>>>>>> then raises something else, and then wants to catch that?
>>>>>>>>> It won't know where to resume, right? It's just keep longjmping to the
>>>>>>>>> same place.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> In the Visual C++ runtime, there is "local unwind" and "global unwind".
>>>>>>>>> "local unwind" is like, "within the same functin", "global unwind" is
>>>>>>>>> across functions.
>>>>>>>>> I think somehow that is related here.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> e.g. how would you ensure forward progress in this:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> EXCEPTION E1;
>>>>>>>>> EXCEPTION E2;
>>>>>>>>> EXCEPTION E3;
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> PROCEDURE F4() RAISES ANY =
>>>>>>>>> CONST Function = "F4 ";
>>>>>>>>> BEGIN
>>>>>>>>> Put(Function & Int(Line())); NL();
>>>>>>>>> TRY
>>>>>>>>> Put(Function & Int(Line())); NL();
>>>>>>>>> TRY
>>>>>>>>> Put(Function & Int(Line())); NL();
>>>>>>>>> TRY
>>>>>>>>> Put(Function & Int(Line())); NL();
>>>>>>>>> RAISE E1;
>>>>>>>>> EXCEPT ELSE
>>>>>>>>> RAISE E2;
>>>>>>>>> END;
>>>>>>>>> EXCEPT ELSE
>>>>>>>>> RAISE E3;
>>>>>>>>> END;
>>>>>>>>> EXCEPT ELSE
>>>>>>>>> END;
>>>>>>>>> END F4;
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Oddly in my test p251, the stack depth is not increased by TRY.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> - Jay
>>>>>>>>>
>>>>>>>>> ________________________________
>>>>>>>>> Subject: Re: [M3commit] CVS Update: cm3
>>>>>>>>> From: hosking at cs.purdue.edu
>>>>>>>>> Date: Thu, 6 Jan 2011 09:22:09 -0500
>>>>>>>>> CC: m3commit at elegosoft.com
>>>>>>>>> To: jay.krell at cornell.edu
>>>>>>>>>
>>>>>>>>> I am OK with what you have currently:
>>>>>>>>>
>>>>>>>>> At each TRY:
>>>>>>>>>
>>>>>>>>> 1. Check if a corresponding alloca block has been allocated by checking
>>>>>>>>> if the corresponding local variable is NIL.
>>>>>>>>> 2. If not, then alloca and save its pointer in the local variable
>>>>>>>>> 3. Execute the try block.
>>>>>>>>>
>>>>>>>>> As you say, alloca should turn into an inline operation using the
>>>>>>>>> compiler's builtin implementation of alloca.
>>>>>>>>>
>>>>>>>>> On Jan 6, 2011, at 1:02 AM, Jay K wrote:
>>>>>>>>>
>>>>>>>>>> Code size will suffer.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Indeed. Unoptimized code size does suffer a lot, in functions that use try.
>>>>>>>>> Calling alloca, unoptimized, isn't small, and this adds n calls for n trys.
>>>>>>>>> I thought it'd only be one call. I didn't realize our implementation
>>>>>>>>> is as poor as it is, since a better but still
>>>>>>>>> portable implementation doesn't seem too too difficult.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Can we maybe do the optimizations I indicate -- no more than one
>>>>>>>>> setjmp/alloca/pushframe per function?
>>>>>>>>> Using a local integer to record the position within the function?
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Or just give me a week or few to get stack walking working and then
>>>>>>>>> live the regression on other targets?
>>>>>>>>> (NT386 isn't likely to get stack walking, though it *is* certainly
>>>>>>>>> possible; NT does have a decent runtime here..)
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> It *is* nice to not have have the frontend know about jmpbuf size.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> I looked into the "builtin_setjmp" stuff, but it can't be used so easily.
>>>>>>>>> It doesn't work for intra-function jumps, only inter-function.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> - Jay
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> ________________________________
>>>>>>>>> From: jay.krell at cornell.edu
>>>>>>>>> To: hosking at cs.purdue.edu
>>>>>>>>> CC: m3commit at elegosoft.com
>>>>>>>>> Subject: RE: [M3commit] CVS Update: cm3
>>>>>>>>> Date: Thu, 6 Jan 2011 04:52:33 +0000
>>>>>>>>>
>>>>>>>>> Ah..I'm doing more comparisons of release vs. head...but..I guess your
>>>>>>>>> point is, you'd rather have n locals, which the backend automatically
>>>>>>>>> merges, than n calls to alloca?
>>>>>>>>> It's not a huge difference -- there are still going to be n calls to
>>>>>>>>> setjmp and n calls to pthread_getspecific.
>>>>>>>>> The alloca calls will be dwarfed.
>>>>>>>>> Code size will suffer.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> And, even so, there are plenty of optimizations to be had, even if
>>>>>>>>> setjmp/pthread_getspecific is used.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> - It could make a maximum of one call to setjmp/pthread_getspecific
>>>>>>>>> per function
>>>>>>>>> - The calls to alloca could be merged. The frontend could keep track
>>>>>>>>> of how many calls it makes per function,
>>>>>>>>> issue a multiplication, and offset each jmpbuf. It is a tradeoff.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> So, yes, given my current understanding, it is progress.
>>>>>>>>> The target-dependence is not worth it, imho.
>>>>>>>>> I'll still do some comparisons to release.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> I'll still be looking into using the gcc unwinder relatively soon.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> - Jay
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> ________________________________
>>>>>>>>> Subject: Re: [M3commit] CVS Update: cm3
>>>>>>>>> From: hosking at cs.purdue.edu
>>>>>>>>> Date: Wed, 5 Jan 2011 21:14:17 -0500
>>>>>>>>> CC: m3commit at elegosoft.com
>>>>>>>>> To: jay.krell at cornell.edu
>>>>>>>>>
>>>>>>>>> On Jan 5, 2011, at 9:08 PM, Jay K wrote:
>>>>>>>>>
>>>>>>>>> Tony, um..well, um.. first, isn't that how it already worked maybe?
>>>>>>>>> Declaring a new local EF1 for each TRY? It looks like it.
>>>>>>>>> I'll do more testing.
>>>>>>>>>
>>>>>>>>> Yes, it did. I assume you simply have a local variable for each TRY
>>>>>>>>> block that is a pointer now instead of a jmp_buf. Should be OK.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> So the additional inefficiency is multiplied the same as the rest of
>>>>>>>>> the preexisting inefficiency.
>>>>>>>>> And the preexisting inefficiency is way more than the increase.
>>>>>>>>>
>>>>>>>>> And second, either way, it could be better.
>>>>>>>>>
>>>>>>>>> Basically, the model should be, that if a function has any try or lock,
>>>>>>>>> it calls setjmp once.
>>>>>>>>> And then, it should have one volatile integer, that in a sense
>>>>>>>>> represents the line number.
>>>>>>>>> But not really. It's like, every time you cross a TRY, the integer is
>>>>>>>>> incremented, every time you
>>>>>>>>> cross a finally or unlock, the integer is decremented. Or rather, the
>>>>>>>>> value can be stored.
>>>>>>>>> And then there is a maximum of one one handler per function, it
>>>>>>>>> switches on the integer
>>>>>>>>> to decide where it got into the function and what it should do.
>>>>>>>>>
>>>>>>>>> This is how other compilers work and it is a fairly simple sensible approach.
>>>>>>>>>
>>>>>>>>> - Jay
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> ________________________________
>>>>>>>>> Subject: Re: [M3commit] CVS Update: cm3
>>>>>>>>> From: hosking at cs.purdue.edu
>>>>>>>>> Date: Wed, 5 Jan 2011 20:49:24 -0500
>>>>>>>>> CC: m3commit at elegosoft.com
>>>>>>>>> To: jay.krell at cornell.edu
>>>>>>>>>
>>>>>>>>> Note that you need a different jmpbuf for each nested TRY!
>>>>>>>>>
>>>>>>>>> Antony Hosking | Associate Professor | Computer Science | Purdue University
>>>>>>>>> 305 N. University Street | West Lafayette | IN 47907 | USA
>>>>>>>>> Office +1 765 494 6001 | Mobile +1 765 427 5484
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Jan 5, 2011, at 8:33 PM, Jay K wrote:
>>>>>>>>>
>>>>>>>>> oops, that's not how I thought it worked. I'll do more testing and fix
>>>>>>>>> it -- check for NIL.
>>>>>>>>>
>>>>>>>>> - Jay
>>>>>>>>>
>>>>>>>>> ________________________________
>>>>>>>>> Subject: Re: [M3commit] CVS Update: cm3
>>>>>>>>> From: hosking at cs.purdue.edu
>>>>>>>>> Date: Wed, 5 Jan 2011 20:23:09 -0500
>>>>>>>>> CC: m3commit at elegosoft.com
>>>>>>>>> To: jay.krell at cornell.edu
>>>>>>>>>
>>>>>>>>> Ah, yes, I guess you need a different jmpbuf for each TRY. But now you
>>>>>>>>> are allocating on every TRY where previously the storage was statically
>>>>>>>>> allocated. Do you really think this is progress?
>>>>>>>>>
>>>>>>>>> On Jan 5, 2011, at 5:40 PM, Jay K wrote:
>>>>>>>>>
>>>>>>>>> I've back with full keyboard if more explanation needed. The diff is
>>>>>>>>> actually fairly small to read.
>>>>>>>>> I understand it is definitely less efficient, a few more instructions
>>>>>>>>> for every try/lock.
>>>>>>>>> No extra function call, at least with gcc backend.
>>>>>>>>> I haven't tested NT386 yet. Odds are so/so that it works -- the change
>>>>>>>>> is written so that it should work
>>>>>>>>> but I have to test it to be sure, will to roughly tonight. And there
>>>>>>>>> probably is a function call there.
>>>>>>>>>
>>>>>>>>> - Jay
>>>>>>>>>
>>>>>>>>> ________________________________
>>>>>>>>> From: jay.krell at cornell.edu
>>>>>>>>> To: hosking at cs.purdue.edu
>>>>>>>>> Date: Wed, 5 Jan 2011 20:44:08 +0000
>>>>>>>>> CC: m3commit at elegosoft.com
>>>>>>>>> Subject: Re: [M3commit] CVS Update: cm3
>>>>>>>>>
>>>>>>>>> I only have phone right now. I think it is fairly clear: the jumpbuf in
>>>>>>>>> EF1 is now allocated with alloca, and a pointer stored. It is
>>>>>>>>> definitely a bit less efficient, but the significant advantage is
>>>>>>>>> frontend no longer needs to know the size or alignment of a jumpbuf.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> As well, there is no longer the problem regarding jumpbuf aligned to
>>>>>>>>> more than 64 bits. I at least checked on Linux/PowerPC and alloca seems
>>>>>>>>> to align to 16 bytes. I don't have an HPUX machine currently to see if
>>>>>>>>> the problem is addressed there.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> The inefficiency of course can be dramatically mitigated via a stack
>>>>>>>>> walker. I wanted to do this first though, while more targets using
>>>>>>>>> setjmp.
>>>>>>>>>
>>>>>>>>> - Jay/phone
>>>>>>>>>
>>>>>>>>> ________________________________
>>>>>>>>> Subject: Re: [M3commit] CVS Update: cm3
>>>>>>>>> From: hosking at cs.purdue.edu
>>>>>>>>> Date: Wed, 5 Jan 2011 13:35:59 -0500
>>>>>>>>> CC: jkrell at elego.de; m3commit at elegosoft.com
>>>>>>>>> To: jay.krell at cornell.edu
>>>>>>>>>
>>>>>>>>> Can you provide a more descriptive checkin comment? I don't know what
>>>>>>>>> has been done here without diving into the diff.
>>>>>>>>>
>>>>>>>>> Antony Hosking | Associate Professor | Computer Science | Purdue University
>>>>>>>>> 305 N. University Street | West Lafayette | IN 47907 | USA
>>>>>>>>> Office +1 765 494 6001 | Mobile +1 765 427 5484
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Jan 5, 2011, at 9:37 AM, Jay K wrote:
>>>>>>>>>
>>>>>>>>> diff attached
>>>>>>>>>
>>>>>>>>>> Date: Wed, 5 Jan 2011 15:34:55 +0000
>>>>>>>>>> To: m3commit at elegosoft.com
>>>>>>>>>> From: jkrell at elego.de
>>>>>>>>>> Subject: [M3commit] CVS Update: cm3
>>>>>>>>>>
>>>>>>>>>> CVSROOT: /usr/cvs
>>>>>>>>>> Changes by: jkrell at birch. 11/01/05 15:34:55
>>>>>>>>>>
>>>>>>>>>> Modified files:
>>>>>>>>>> cm3/m3-libs/m3core/src/C/Common/: Csetjmp.i3
>>>>>>>>>> cm3/m3-libs/m3core/src/C/I386_CYGWIN/: Csetjmp.i3
>>>>>>>>>> cm3/m3-libs/m3core/src/C/I386_MINGW/: Csetjmp.i3
>>>>>>>>>> cm3/m3-libs/m3core/src/C/I386_NT/: Csetjmp.i3
>>>>>>>>>> cm3/m3-libs/m3core/src/C/NT386/: Csetjmp.i3
>>>>>>>>>> cm3/m3-libs/m3core/src/runtime/ex_frame/: RTExFrame.m3
>>>>>>>>>> cm3/m3-libs/m3core/src/unix/Common/: Uconstants.c
>>>>>>>>>> cm3/m3-sys/m3cc/gcc/gcc/m3cg/: parse.c
>>>>>>>>>> cm3/m3-sys/m3front/src/misc/: Marker.m3
>>>>>>>>>> cm3/m3-sys/m3front/src/stmts/: TryFinStmt.m3 TryStmt.m3
>>>>>>>>>> cm3/m3-sys/m3middle/src/: M3RT.i3 M3RT.m3 Target.i3 Target.m3
>>>>>>>>>>
>>>>>>>>>> Log message:
>>>>>>>>>> use: extern INTEGER Csetjmp__Jumpbuf_size /* = sizeof(jmp_buf);
>>>>>>>>>> alloca(Csetjmp__Jumpbuf_size)
>>>>>>>>>>
>>>>>>>>>> to allocate jmp_buf
>>>>>>>>>>
>>>>>>>>>> - eliminates a large swath of target-dependent code
>>>>>>>>>> - allows for covering up the inability to declare
>>>>>>>>>> types with alignment > 64 bits
>>>>>>>>>>
>>>>>>>>>> It is, granted, a little bit slower, in an already prety slow path.
>>>>>>>>>> Note that alloca isn't actually a function call, at least with gcc backend.
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
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