llvm dev - Jan 2018 - How to use stack maps

Is there an explanation anywhere of what code that uses a stack map looks
like? I'm interested in writing a garbage collector, but it's not clear
to
me how my code should make use of the stack map format to actually locate
roots in memory.
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> Is there an explanation anywhere of what code that uses a stack map looks
> like? I'm interested in writing a garbage collector, but it's not
clear to
> me how my code should make use of the stack map format to actually locate
> roots in memory.
>
Quoted from ​[1],

The intrinsics documented here are currently used by the JavaScript
compiler within the open source WebKit project, see the FTL JIT, but they
are designed to be used whenever stack maps or code patching are needed.


Maybe you can look FTL JIT for example?

​[1] https://llvm.org/docs/StackMaps.html
​
HTH,
chenwj​

-- 
Wei-Ren Chen (陳韋任)
Homepage: https://people.cs.nctu.edu.tw/~chenwj
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Hi,
  I implemented a garbage collector for a language I wrote in college using
the llvm gc statepoint infrastructure.

Information for statepoints:
https://llvm.org/docs/Statepoints.html

Example usage of parsing the llvm stackmap can be found at:
 https://github.com/dotnet/llilc/blob/master/lib/GcInfo/GcInfo.cpp
 https://llvm.org/docs/StackMaps.html#stackmap-format

https://github.com/llvm-mirror/llvm/blob/4604874612fa292ab4c49f96aedefdf8be1ff27e/include/llvm/Object/StackMapParser.h

Thanks,
 River Riddle


On Sat, Jan 13, 2018 at 10:02 AM, benzrf via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Is there an explanation anywhere of what code that uses a stack map looks
> like? I'm interested in writing a garbage collector, but it's not
clear to
> me how my code should make use of the stack map format to actually locate
> roots in memory.
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
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p.s. the stackmap format is intended to be transcoded into whatever 
internal format you might want.  It's not expected to be a long lived 
data structure.  Given that, the format prioritizes simplicity over size 
and efficiency of access.

The format itself is documented here:

https://llvm.org/docs/StackMaps.html#stack-map-format


On 01/13/2018 05:48 PM, River Riddle via llvm-dev wrote:
> Hi,
>   I implemented a garbage collector for a language I wrote in college 
> using the llvm gc statepoint infrastructure.
>
> Information for statepoints:
> https://llvm.org/docs/Statepoints.html
>
> Example usage of parsing the llvm stackmap can be found at:
> https://github.com/dotnet/llilc/blob/master/lib/GcInfo/GcInfo.cpp
> https://llvm.org/docs/StackMaps.html#stackmap-format
>
https://github.com/llvm-mirror/llvm/blob/4604874612fa292ab4c49f96aedefdf8be1ff27e/include/llvm/Object/StackMapParser.h
>
> Thanks,
>  River Riddle
>
>
> On Sat, Jan 13, 2018 at 10:02 AM, benzrf via llvm-dev 
> <llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>> wrote:
>
>     Is there an explanation anywhere of what code that uses a stack
>     map looks like? I'm interested in writing a garbage collector, but
>     it's not clear to me how my code should make use of the stack map
>     format to actually locate roots in memory.
>
>     _______________________________________________
>     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
>     <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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