llvm dev - Sep 2018 - Porting Pass to New PassManager

Hi all,

I'm attempting to move the AddressSanitizer pass from the legacy
PassManager to the new one because the new one has various benefits
over legacy and wanted to clarify on something. Does creating the
static RegisterPass struct register the pass with the new PassManager?

It seems that RegisterPass does the same things that the
INITIALIZE_PASS_* macros do but it registers the pass with
PassRegistry::getPassRegistry(). What I'm not sure of is if this uses
the new PassManager infrastructure. Exploring the code doesn't seem to
show that this PassRegistry touches anything in the legacy namespace,
but I wanted double confirmation on this.

Thanks,
Leonard

Leonard,

nope, the PassRegistry stuff is all about legacy pass manager.
legacy namespace has not been extensively used to mark all the 
legacy-related stuff
(say, even Pass class which is a base for legacy passes is not under 
legacy namespace).

Registration for new-pass-manager passes happens in 
lib/Passes/PassRegistry.def.

Usually, when porting from legacy to new the main difference is analysis 
handling,
so people factor out the worker code into a method that takes analyses 
and call
this function both in legacy and new-pm passes.
In many cases it takes just a handful lines of code.

Feel free to ask questions, if any.

regards,
   Fedor.

On 09/25/2018 02:54 AM, Leonard Chan via llvm-dev wrote:
 > Hi all,
 >
 > I'm attempting to move the AddressSanitizer pass from the legacy
 > PassManager to the new one because the new one has various benefits
 > over legacy and wanted to clarify on something. Does creating the
 > static RegisterPass struct register the pass with the new PassManager?
 >
 > It seems that RegisterPass does the same things that the
 > INITIALIZE_PASS_* macros do but it registers the pass with
 > PassRegistry::getPassRegistry(). What I'm not sure of is if this uses
 > the new PassManager infrastructure. Exploring the code doesn't seem to
 > show that this PassRegistry touches anything in the legacy namespace,
 > but I wanted double confirmation on this.
 >
 > Thanks,
 > Leonard
 > _______________________________________________
 > LLVM Developers mailing list
 > llvm-dev at lists.llvm.org
 > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

Hi Leonard, Fedor,

while it's true that RegisterPass is not applicable for new-pm passes,
PassRegistry.def is not the whole story. Passes in PassRegistry are
available for the opt tool. The sanitizers are passes that usually get
added to the pipeline by the frontend. There, you need to use PassBuilder's
callbacks mechanism to hook the sanitizer into the optimizer.

Assuming you're willing to contribute your changes, please share your
progress! Thank you for making a move on this!

Cheers,
Philip

On Tue, Sep 25, 2018 at 8:27 AM Fedor Sergeev via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Leonard,
>
> nope, the PassRegistry stuff is all about legacy pass manager.
> legacy namespace has not been extensively used to mark all the
> legacy-related stuff
> (say, even Pass class which is a base for legacy passes is not under
> legacy namespace).
>
> Registration for new-pass-manager passes happens in
> lib/Passes/PassRegistry.def.
>
> Usually, when porting from legacy to new the main difference is analysis
> handling,
> so people factor out the worker code into a method that takes analyses
> and call
> this function both in legacy and new-pm passes.
> In many cases it takes just a handful lines of code.
>
> Feel free to ask questions, if any.
>
> regards,
>    Fedor.
>
> On 09/25/2018 02:54 AM, Leonard Chan via llvm-dev wrote:
>  > Hi all,
>  >
>  > I'm attempting to move the AddressSanitizer pass from the legacy
>  > PassManager to the new one because the new one has various benefits
>  > over legacy and wanted to clarify on something. Does creating the
>  > static RegisterPass struct register the pass with the new
PassManager?
>  >
>  > It seems that RegisterPass does the same things that the
>  > INITIALIZE_PASS_* macros do but it registers the pass with
>  > PassRegistry::getPassRegistry(). What I'm not sure of is if this
uses
>  > the new PassManager infrastructure. Exploring the code doesn't
seem to
>  > show that this PassRegistry touches anything in the legacy namespace,
>  > but I wanted double confirmation on this.
>  >
>  > Thanks,
>  > Leonard
>  > _______________________________________________
>  > LLVM Developers mailing list
>  > llvm-dev at lists.llvm.org
>  > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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Hi Fedor,

Thanks for the starting point of looking through PassRegistry.def. Do
you happen to have any specific examples or knowledge of previous
patches of passes that were part of the legacy PM but moved to the new
PM? I'm not sure if historically when the new PM was proposed, people
actually did move passes from legacy or people just add new passes
onto the new one.

Thanks,
Leonard
On Mon, Sep 24, 2018 at 11:27 PM Fedor Sergeev <fedor.sergeev at azul.com>
wrote:
>
> Leonard,
>
> nope, the PassRegistry stuff is all about legacy pass manager.
> legacy namespace has not been extensively used to mark all the
> legacy-related stuff
> (say, even Pass class which is a base for legacy passes is not under
> legacy namespace).
>
> Registration for new-pass-manager passes happens in
> lib/Passes/PassRegistry.def.
>
> Usually, when porting from legacy to new the main difference is analysis
> handling,
> so people factor out the worker code into a method that takes analyses
> and call
> this function both in legacy and new-pm passes.
> In many cases it takes just a handful lines of code.
>
> Feel free to ask questions, if any.
>
> regards,
>    Fedor.
>
> On 09/25/2018 02:54 AM, Leonard Chan via llvm-dev wrote:
>  > Hi all,
>  >
>  > I'm attempting to move the AddressSanitizer pass from the legacy
>  > PassManager to the new one because the new one has various benefits
>  > over legacy and wanted to clarify on something. Does creating the
>  > static RegisterPass struct register the pass with the new
PassManager?
>  >
>  > It seems that RegisterPass does the same things that the
>  > INITIALIZE_PASS_* macros do but it registers the pass with
>  > PassRegistry::getPassRegistry(). What I'm not sure of is if this
uses
>  > the new PassManager infrastructure. Exploring the code doesn't
seem to
>  > show that this PassRegistry touches anything in the legacy namespace,
>  > but I wanted double confirmation on this.
>  >
>  > Thanks,
>  > Leonard
>  > _______________________________________________
>  > LLVM Developers mailing list
>  > llvm-dev at lists.llvm.org
>  > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>