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Triple Yang

2012-Dec-02 17:06 UTC

[LLVMdev] Splitting a load with 2 consumers into 2 loads.

OK, I get it.

The essence of this problem is that a node can be covered exactly and
just once but its result can be referred multiple times for a tree
pattern matching isel. So to duplicate a load node (only if we can!)
is convenient to conquer that case.

The truth is, in pattern (add (load) (load)), source operands are
memory addresses, and thus it can be treated         as (addmm
address, address). Here is an alternative you can take into
consideration: defining new node (like addmm, similiar with movmm) to
specify matching patterns for isel.

Regards.

2012/12/2 Joseph Pusdesris <joe at pusdesris.com>:> I am writing a target for an odd cisc-like architecture which has no
support
> for keeping most values in registers.  As such, memory-memory operations
are
> needed, but for isel to generate a memory-memory the pattern must be of the
> form (store (op (load) (load))).
>
> Let's use a simple example to show how this can be problematic:
>   %0 = load i32* %a.addr, align 4
>   store i32 %0, i32* %other, align 4
>   %1 = load i32* %b.addr, align 4
>   %add = add i32 %0, %1
> ----
> In this example, the (store (load)) pair -- the first two lines -- will be
> matched by isel as a MOVmm.  This will be problematic for the add though,
> since the load SDNode will be gone, making that part of the DAG no longer
of
> the form (add (load) (load)).  To counteract this, I would create 2 load
> SDNodes so that both of these patterns can be satisfied.  Does this make
> sense?
> -Joe
>
>
>
>
> On Sat, Dec 1, 2012 at 11:44 PM, Triple Yang <triple.yang at
gmail.com> wrote:
>>
>> Hi, Joe.
>>
>> I am sorry I did not catch your point. Can you provide more details?
>>
>> Since SDValue/SDNode can be used multiple times, why would you want to
>> create two identical objects
>> instead of reference to the same one?
>>
>> 2012/12/2 Joseph Pusdesris <joe at pusdesris.com>:
>> > Yes, changing parameters will create a new Node, but is there some
way I
>> > can
>> > force a new node with the same parameters?
>> > -Joe
>> >
>> >
>> > On Sat, Dec 1, 2012 at 10:57 PM, Triple Yang <triple.yang at
gmail.com>
>> > wrote:
>> >>
>> >> Hi, Joseph, I guess getLoad() will either search an existed
SDValue
>> >> *OR* create a new one for a non-existed one depending on real
>> >> parameters.
>> >>
>> >> Since you use exactly the same attributes dupVal/dupNode have,
no
>> >> doubt getLoad() return the old one.
>> >>
>> >> I am not sure it's *volatile* that let you get a new
result, you might
>> >> want to try change some other parameters and check what it
turns out.
>> >>
>> >> Regards.
>> >>
>> >> 2012/12/2 Joseph Pusdesris <joe at pusdesris.com>
>> >> >
>> >> > So I think I have made some progress.
>> >> > SDValue dupVal  = consumer->getOperand(OpNo);
>> >> > LoadSDNode *dupNode = (LoadSDNode*) dupVal.getNode();
>> >> >
>> >> > SDValue newLoad =
CurDAG->getLoad(dupVal.getValueType(),
>> >> > dupVal.getDebugLoc(),
>> >> >                                dupVal.getOperand(0),
>> >> > dupVal.getOperand(1),
>> >> >                               
dupNode->getPointerInfo(),
>> >> >                                dupNode->isVolatile(),
>> >> > dupNode->isNonTemporal(),
>> >> >                                dupNode->isInvariant(),
>> >> > dupNode->getAlignment(),
>> >> >                                dupNode->getTBAAInfo(),
>> >> > dupNode->getRanges());
>> >> > However, my problem now is that it will re-use the same
load still.
>> >> > If
>> >> > I change something, like setting volatile to true for
example, it
>> >> > will
>> >> > create a new node, but otherwise it will not.  Any ideas?
>> >> > -Joe
>> >> >
>> >> >
>> >> > On Fri, Nov 30, 2012 at 9:55 PM, Joseph Pusdesris <joe
at pusdesris.com>
>> >> > wrote:
>> >> >>
>> >> >> Hi, I am writing an llvm target and I need both loads
for isel
>> >> >> reasons,
>> >> >> but I am struggling to find the right way.  I have
been trying to
>> >> >> use
>> >> >> DAG.getLoad() to make a copy, then just change the
operand in the
>> >> >> consumers,
>> >> >> but I cannot seem to get all of the arguments needed
for that
>> >> >> function in
>> >> >> order to make the copy.  Any help would be great,
thanks!
>> >> >> -Joe
>> >> >
>> >> >
>> >> >
>> >> > _______________________________________________
>> >> > LLVM Developers mailing list
>> >> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> >> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>> >> >
>> >>
>> >>
>> >>
>> >> --
>> >> 杨勇勇 (Yang Yongyong)
>> >
>> >
>>
>>
>>
>> --
>> 杨勇勇 (Yang Yongyong)
>
>


-- 
杨勇勇 (Yang Yongyong)

Joseph Pusdesris

2012-Dec-02 17:34 UTC

head link

[LLVMdev] Splitting a load with 2 consumers into 2 loads.

I'll give that a shot, thanks!
-Joe


On Sun, Dec 2, 2012 at 12:06 PM, Triple Yang <triple.yang at gmail.com>
wrote:
> OK, I get it.
>
> The essence of this problem is that a node can be covered exactly and
> just once but its result can be referred multiple times for a tree
> pattern matching isel. So to duplicate a load node (only if we can!)
> is convenient to conquer that case.
>
> The truth is, in pattern (add (load) (load)), source operands are
> memory addresses, and thus it can be treated         as (addmm
> address, address). Here is an alternative you can take into
> consideration: defining new node (like addmm, similiar with movmm) to
> specify matching patterns for isel.
>
> Regards.
>
> 2012/12/2 Joseph Pusdesris <joe at pusdesris.com>:
> > I am writing a target for an odd cisc-like architecture which has no
> support
> > for keeping most values in registers.  As such, memory-memory
operations
> are
> > needed, but for isel to generate a memory-memory the pattern must be
of
> the
> > form (store (op (load) (load))).
> >
> > Let's use a simple example to show how this can be problematic:
> >   %0 = load i32* %a.addr, align 4
> >   store i32 %0, i32* %other, align 4
> >   %1 = load i32* %b.addr, align 4
> >   %add = add i32 %0, %1
> > ----
> > In this example, the (store (load)) pair -- the first two lines --
will
> be
> > matched by isel as a MOVmm.  This will be problematic for the add
though,
> > since the load SDNode will be gone, making that part of the DAG no
> longer of
> > the form (add (load) (load)).  To counteract this, I would create 2
load
> > SDNodes so that both of these patterns can be satisfied.  Does this
make
> > sense?
> > -Joe
> >
> >
> >
> >
> > On Sat, Dec 1, 2012 at 11:44 PM, Triple Yang <triple.yang at
gmail.com>
> wrote:
> >>
> >> Hi, Joe.
> >>
> >> I am sorry I did not catch your point. Can you provide more
details?
> >>
> >> Since SDValue/SDNode can be used multiple times, why would you
want to
> >> create two identical objects
> >> instead of reference to the same one?
> >>
> >> 2012/12/2 Joseph Pusdesris <joe at pusdesris.com>:
> >> > Yes, changing parameters will create a new Node, but is there
some
> way I
> >> > can
> >> > force a new node with the same parameters?
> >> > -Joe
> >> >
> >> >
> >> > On Sat, Dec 1, 2012 at 10:57 PM, Triple Yang <triple.yang
at gmail.com>
> >> > wrote:
> >> >>
> >> >> Hi, Joseph, I guess getLoad() will either search an
existed SDValue
> >> >> *OR* create a new one for a non-existed one depending on
real
> >> >> parameters.
> >> >>
> >> >> Since you use exactly the same attributes dupVal/dupNode
have, no
> >> >> doubt getLoad() return the old one.
> >> >>
> >> >> I am not sure it's *volatile* that let you get a new
result, you
> might
> >> >> want to try change some other parameters and check what
it turns out.
> >> >>
> >> >> Regards.
> >> >>
> >> >> 2012/12/2 Joseph Pusdesris <joe at pusdesris.com>
> >> >> >
> >> >> > So I think I have made some progress.
> >> >> > SDValue dupVal  = consumer->getOperand(OpNo);
> >> >> > LoadSDNode *dupNode = (LoadSDNode*)
dupVal.getNode();
> >> >> >
> >> >> > SDValue newLoad =
CurDAG->getLoad(dupVal.getValueType(),
> >> >> > dupVal.getDebugLoc(),
> >> >> >                                dupVal.getOperand(0),
> >> >> > dupVal.getOperand(1),
> >> >> >                               
dupNode->getPointerInfo(),
> >> >> >                               
dupNode->isVolatile(),
> >> >> > dupNode->isNonTemporal(),
> >> >> >                               
dupNode->isInvariant(),
> >> >> > dupNode->getAlignment(),
> >> >> >                               
dupNode->getTBAAInfo(),
> >> >> > dupNode->getRanges());
> >> >> > However, my problem now is that it will re-use the
same load still.
> >> >> > If
> >> >> > I change something, like setting volatile to true
for example, it
> >> >> > will
> >> >> > create a new node, but otherwise it will not.  Any
ideas?
> >> >> > -Joe
> >> >> >
> >> >> >
> >> >> > On Fri, Nov 30, 2012 at 9:55 PM, Joseph Pusdesris
<
> joe at pusdesris.com>
> >> >> > wrote:
> >> >> >>
> >> >> >> Hi, I am writing an llvm target and I need both
loads for isel
> >> >> >> reasons,
> >> >> >> but I am struggling to find the right way.  I
have been trying to
> >> >> >> use
> >> >> >> DAG.getLoad() to make a copy, then just change
the operand in the
> >> >> >> consumers,
> >> >> >> but I cannot seem to get all of the arguments
needed for that
> >> >> >> function in
> >> >> >> order to make the copy.  Any help would be
great, thanks!
> >> >> >> -Joe
> >> >> >
> >> >> >
> >> >> >
> >> >> > _______________________________________________
> >> >> > LLVM Developers mailing list
> >> >> > LLVMdev at cs.uiuc.edu        
http://llvm.cs.uiuc.edu
> >> >> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> >> >> >
> >> >>
> >> >>
> >> >>
> >> >> --
> >> >> 杨勇勇 (Yang Yongyong)
> >> >
> >> >
> >>
> >>
> >>
> >> --
> >> 杨勇勇 (Yang Yongyong)
> >
> >
>
>
>
> --
> 杨勇勇 (Yang Yongyong)
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Joseph Pusdesris

2012-Dec-03 19:58 UTC

head link

[LLVMdev] Splitting a load with 2 consumers into 2 loads.

This worked perfectly.  Thankyou.
-Joe


On Sun, Dec 2, 2012 at 12:34 PM, Joseph Pusdesris <joe at pusdesris.com>
wrote:
> I'll give that a shot, thanks!
> -Joe
>
>
> On Sun, Dec 2, 2012 at 12:06 PM, Triple Yang <triple.yang at
gmail.com>wrote:
>
>> OK, I get it.
>>
>> The essence of this problem is that a node can be covered exactly and
>> just once but its result can be referred multiple times for a tree
>> pattern matching isel. So to duplicate a load node (only if we can!)
>> is convenient to conquer that case.
>>
>> The truth is, in pattern (add (load) (load)), source operands are
>> memory addresses, and thus it can be treated         as (addmm
>> address, address). Here is an alternative you can take into
>> consideration: defining new node (like addmm, similiar with movmm) to
>> specify matching patterns for isel.
>>
>> Regards.
>>
>> 2012/12/2 Joseph Pusdesris <joe at pusdesris.com>:
>> > I am writing a target for an odd cisc-like architecture which has
no
>> support
>> > for keeping most values in registers.  As such, memory-memory
>> operations are
>> > needed, but for isel to generate a memory-memory the pattern must
be of
>> the
>> > form (store (op (load) (load))).
>> >
>> > Let's use a simple example to show how this can be
problematic:
>> >   %0 = load i32* %a.addr, align 4
>> >   store i32 %0, i32* %other, align 4
>> >   %1 = load i32* %b.addr, align 4
>> >   %add = add i32 %0, %1
>> > ----
>> > In this example, the (store (load)) pair -- the first two lines --
will
>> be
>> > matched by isel as a MOVmm.  This will be problematic for the add
>> though,
>> > since the load SDNode will be gone, making that part of the DAG no
>> longer of
>> > the form (add (load) (load)).  To counteract this, I would create
2 load
>> > SDNodes so that both of these patterns can be satisfied.  Does
this make
>> > sense?
>> > -Joe
>> >
>> >
>> >
>> >
>> > On Sat, Dec 1, 2012 at 11:44 PM, Triple Yang <triple.yang at
gmail.com>
>> wrote:
>> >>
>> >> Hi, Joe.
>> >>
>> >> I am sorry I did not catch your point. Can you provide more
details?
>> >>
>> >> Since SDValue/SDNode can be used multiple times, why would you
want to
>> >> create two identical objects
>> >> instead of reference to the same one?
>> >>
>> >> 2012/12/2 Joseph Pusdesris <joe at pusdesris.com>:
>> >> > Yes, changing parameters will create a new Node, but is
there some
>> way I
>> >> > can
>> >> > force a new node with the same parameters?
>> >> > -Joe
>> >> >
>> >> >
>> >> > On Sat, Dec 1, 2012 at 10:57 PM, Triple Yang
<triple.yang at gmail.com>
>> >> > wrote:
>> >> >>
>> >> >> Hi, Joseph, I guess getLoad() will either search an
existed SDValue
>> >> >> *OR* create a new one for a non-existed one depending
on real
>> >> >> parameters.
>> >> >>
>> >> >> Since you use exactly the same attributes
dupVal/dupNode have, no
>> >> >> doubt getLoad() return the old one.
>> >> >>
>> >> >> I am not sure it's *volatile* that let you get a
new result, you
>> might
>> >> >> want to try change some other parameters and check
what it turns
>> out.
>> >> >>
>> >> >> Regards.
>> >> >>
>> >> >> 2012/12/2 Joseph Pusdesris <joe at
pusdesris.com>
>> >> >> >
>> >> >> > So I think I have made some progress.
>> >> >> > SDValue dupVal  = consumer->getOperand(OpNo);
>> >> >> > LoadSDNode *dupNode = (LoadSDNode*)
dupVal.getNode();
>> >> >> >
>> >> >> > SDValue newLoad =
CurDAG->getLoad(dupVal.getValueType(),
>> >> >> > dupVal.getDebugLoc(),
>> >> >> >                               
dupVal.getOperand(0),
>> >> >> > dupVal.getOperand(1),
>> >> >> >                               
dupNode->getPointerInfo(),
>> >> >> >                               
dupNode->isVolatile(),
>> >> >> > dupNode->isNonTemporal(),
>> >> >> >                               
dupNode->isInvariant(),
>> >> >> > dupNode->getAlignment(),
>> >> >> >                               
dupNode->getTBAAInfo(),
>> >> >> > dupNode->getRanges());
>> >> >> > However, my problem now is that it will re-use
the same load
>> still.
>> >> >> > If
>> >> >> > I change something, like setting volatile to
true for example, it
>> >> >> > will
>> >> >> > create a new node, but otherwise it will not. 
Any ideas?
>> >> >> > -Joe
>> >> >> >
>> >> >> >
>> >> >> > On Fri, Nov 30, 2012 at 9:55 PM, Joseph
Pusdesris <
>> joe at pusdesris.com>
>> >> >> > wrote:
>> >> >> >>
>> >> >> >> Hi, I am writing an llvm target and I need
both loads for isel
>> >> >> >> reasons,
>> >> >> >> but I am struggling to find the right way. 
I have been trying to
>> >> >> >> use
>> >> >> >> DAG.getLoad() to make a copy, then just
change the operand in the
>> >> >> >> consumers,
>> >> >> >> but I cannot seem to get all of the
arguments needed for that
>> >> >> >> function in
>> >> >> >> order to make the copy.  Any help would be
great, thanks!
>> >> >> >> -Joe
>> >> >> >
>> >> >> >
>> >> >> >
>> >> >> > _______________________________________________
>> >> >> > LLVM Developers mailing list
>> >> >> > LLVMdev at cs.uiuc.edu        
http://llvm.cs.uiuc.edu
>> >> >> >
http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>> >> >> >
>> >> >>
>> >> >>
>> >> >>
>> >> >> --
>> >> >> 杨勇勇 (Yang Yongyong)
>> >> >
>> >> >
>> >>
>> >>
>> >>
>> >> --
>> >> 杨勇勇 (Yang Yongyong)
>> >
>> >
>>
>>
>>
>> --
>> 杨勇勇 (Yang Yongyong)
>>
>
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