[M3commit] CVS Update: cm3
Jay K
jay.krell at cornell.edu
Thu Jan 6 21:51:58 CET 2011
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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