llvm dev - Mar 2016 - IRBuilder Assignment ( '=' ) operator?

However I need the standard assignment operator so I can assign the value of a
temporary to that of another temporary, or to create a new temporary from an
existing one.

- Paul

________________________________________
From: Tim Northover <t.p.northover at gmail.com>
Sent: 16 March 2016 13:11
To: Paul Hancock
Cc: llvm-dev at lists.llvm.org
Subject: Re: [llvm-dev] IRBuilder Assignment ( '=' ) operator?

Hi Paul,

On 15 March 2016 at 17:59, Paul Hancock via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> In my code assembly system I have the various LH-RH operators, ADD, ADDF,
> SUB, etc, using CreateAdd, CreateFAdd, etc, however I cant seem to locate
> the correct function/s for the assignment operator.
The assignment is automatic. The pointer you get back from CreateAdd
can be used directly in other instructions. When this is transcribed
to the textual IR, LLVM will put in the appropriate assignments (so it
won't try to assign a store to anything for example, because it
doesn't produce a value that can be used elsewhere).

The Name parameter you pass to CreateAdd determines what variable will
be assigned, otherwise an incrementing number will be used (%1, %2,
...).

Cheers.

Tim.

Usual rules: Look at the IR Clang produces for some C code you're curious
about

On Tue, Mar 15, 2016 at 7:34 PM, Paul Hancock via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> However I need the standard assignment operator so I can assign the value
> of a temporary to that of another temporary, or to create a new temporary
> from an existing one.
>
> - Paul
>
> ________________________________________
> From: Tim Northover <t.p.northover at gmail.com>
> Sent: 16 March 2016 13:11
> To: Paul Hancock
> Cc: llvm-dev at lists.llvm.org
> Subject: Re: [llvm-dev] IRBuilder Assignment ( '=' ) operator?
>
> Hi Paul,
>
> On 15 March 2016 at 17:59, Paul Hancock via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
> > In my code assembly system I have the various LH-RH operators, ADD,
ADDF,
> > SUB, etc, using CreateAdd, CreateFAdd, etc, however I cant seem to
locate
> > the correct function/s for the assignment operator.
>
> The assignment is automatic. The pointer you get back from CreateAdd
> can be used directly in other instructions. When this is transcribed
> to the textual IR, LLVM will put in the appropriate assignments (so it
> won't try to assign a store to anything for example, because it
> doesn't produce a value that can be used elsewhere).
>
> The Name parameter you pass to CreateAdd determines what variable will
> be assigned, otherwise an incrementing number will be used (%1, %2,
> ...).
>
> Cheers.
>
> Tim.
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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There is a store operation if you want the value on the stack or heap, but
there is no assignment operator in IR.
CreateAdd returns an Instruction which represents both the operation and
the result value. Value's are immutable and can be used as input arguments
to any Instruction further down the control flow.

The other thing you might need to research is the Phi Instruction. Which
gives you a way to specify how the value in this basic block will be
different based on how we reached this block in the control flow of the
function.

On Wed, Mar 16, 2016 at 1:04 PM, Paul Hancock via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> However I need the standard assignment operator so I can assign the value
> of a temporary to that of another temporary, or to create a new temporary
> from an existing one.
>
> - Paul
>
> ________________________________________
> From: Tim Northover <t.p.northover at gmail.com>
> Sent: 16 March 2016 13:11
> To: Paul Hancock
> Cc: llvm-dev at lists.llvm.org
> Subject: Re: [llvm-dev] IRBuilder Assignment ( '=' ) operator?
>
> Hi Paul,
>
> On 15 March 2016 at 17:59, Paul Hancock via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
> > In my code assembly system I have the various LH-RH operators, ADD,
ADDF,
> > SUB, etc, using CreateAdd, CreateFAdd, etc, however I cant seem to
locate
> > the correct function/s for the assignment operator.
>
> The assignment is automatic. The pointer you get back from CreateAdd
> can be used directly in other instructions. When this is transcribed
> to the textual IR, LLVM will put in the appropriate assignments (so it
> won't try to assign a store to anything for example, because it
> doesn't produce a value that can be used elsewhere).
>
> The Name parameter you pass to CreateAdd determines what variable will
> be assigned, otherwise an incrementing number will be used (%1, %2,
> ...).
>
> Cheers.
>
> Tim.
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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I partially worked out that to do an assign I will need to manually assign a
temporary first and then load data into it, which also means I'll need to
set up a temporaries list in my code assembler as allocations must be done
before anything else? or is it fine to allocate a variable mid-way through a
function and the compiler will manage it?

With that as well, if I had a function that loads a value from a pointer and
then stores this value to multiple destinations, would it be ideal to store the
value in an allocated temporary? would the load be called for each store if I
don't allocate a temporary or will the load be called only the one time?

- Paul


________________________________
From: jeremy at lakeman.me <jeremy at lakeman.me> on behalf of Jeremy
Lakeman <Jeremy.Lakeman at gmail.com>
Sent: 16 March 2016 14:24
To: Paul Hancock
Cc: llvm-dev at lists.llvm.org
Subject: Re: [llvm-dev] IRBuilder Assignment ( '=' ) operator?

There is a store operation if you want the value on the stack or heap, but there
is no assignment operator in IR.
CreateAdd returns an Instruction which represents both the operation and the
result value. Value's are immutable and can be used as input arguments to
any Instruction further down the control flow.

The other thing you might need to research is the Phi Instruction. Which gives
you a way to specify how the value in this basic block will be different based
on how we reached this block in the control flow of the function.

On Wed, Mar 16, 2016 at 1:04 PM, Paul Hancock via llvm-dev <llvm-dev at
lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:
However I need the standard assignment operator so I can assign the value of a
temporary to that of another temporary, or to create a new temporary from an
existing one.

- Paul

________________________________________
From: Tim Northover <t.p.northover at gmail.com<mailto:t.p.northover at
gmail.com>>
Sent: 16 March 2016 13:11
To: Paul Hancock
Cc: llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>
Subject: Re: [llvm-dev] IRBuilder Assignment ( '=' ) operator?

Hi Paul,

On 15 March 2016 at 17:59, Paul Hancock via llvm-dev
<llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>>
wrote:
> In my code assembly system I have the various LH-RH operators, ADD, ADDF,
> SUB, etc, using CreateAdd, CreateFAdd, etc, however I cant seem to locate
> the correct function/s for the assignment operator.
The assignment is automatic. The pointer you get back from CreateAdd
can be used directly in other instructions. When this is transcribed
to the textual IR, LLVM will put in the appropriate assignments (so it
won't try to assign a store to anything for example, because it
doesn't produce a value that can be used elsewhere).

The Name parameter you pass to CreateAdd determines what variable will
be assigned, otherwise an incrementing number will be used (%1, %2,
...).

Cheers.

Tim.
_______________________________________________
LLVM Developers mailing list
llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

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