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Finger crossed then that Azule can get a proper moving GC to work with LLVM then, until then a CL on LLVM (even Julia) are stuck with kinda bad GC. I wonder wh

Finger crossed then that Azule can get a proper moving GC to work with LLVM then, until then a CL on LLVM (even Julia) are stuck with kinda bad GC. I wonder why start from scratch for an LLVM backend, can't SBCL be used to generate LLVM code?

aidenn0 12y ago
It wasn't from scratch, it was from ECL. And did you mean Azul?
drmeister 12y ago
SBCL doesn't generate LLVM code. My primary goal was Common Lisp with C++ interoperation. It seemed easier at the time to start from the ECL Common Lisp code base and write a new C++ core and a Common Lisp interpreter that always interoperated with C++. As I wrote the compiler and expanded the system I maintained C++ interoperation all the time. There were a hundred problems that I had to discover and solve along the way to maintain a Common Lisp that interoperated with C++. You can get some level of interoperation between ECL and C++ up in a weekend but it won't work with C++ exceptions and RAII and there are dozens of other problems. In retrospect I don't think I would have gotten here starting from ECL because I never really understood the ECL code.
ioddly 12y ago
Is the compacting garbage collector mentioned in the article not a proper moving GC? I am not familiar with it.
- drmeister 12y ago
  Yes, the Memory Pool System by Ravenbrook (https://www.ravenbrook.com/project/mps/ https://www.ravenbrook.com/project/mps/) is a proper, moving garbage collector. It uses precise GC on the heap and conservative GC on the stack, as does the garbage collector in Steel Bank Common Lisp on x86 chips. I need it because I need my code to run on 100,000 CPU supercomputers with a controlled memory footprint to develop organic nano machines (seriously).
  - ioddly 12y ago
    To be honest I was just kind of thinking "oh great another language implementation," before I read what you're actually doing and why you needed to create clasp. I appreciate the difficulty of writing precisely GC'd C/C++. It's pretty awesome that you were able to use clang to (I assume this is mainly what the analyzer does) track roots in C & C++ code. Best of luck.
    - drmeister 12y ago
      Thanks - yes the analyzer tracks roots through about 300 C++ classes. It also finds global variables and builds C++ code to interface with the MPS library. I exposed the Clang libraries to search the AST and describe the AST in Common Lisp and then wrote the static analyzer in Lisp. I shudder at the thought of doing this all in C++ and I write a lot of complicated stuff like Common Lisp implementations in C++ :-). Common Lisp is the language of trees and pattern recognition. Common Lisp is the perfect tool for this job.

aidenn0 12y ago

It wasn't from scratch, it was from ECL. And did you mean Azul?

drmeister 12y ago

SBCL doesn't generate LLVM code. My primary goal was Common Lisp with C++ interoperation. It seemed easier at the time to start from the ECL Common Lisp code base and write a new C++ core and a Common Lisp interpreter that always interoperated with C++. As I wrote the compiler and expanded the system I maintained C++ interoperation all the time. There were a hundred problems that I had to discover and solve along the way to maintain a Common Lisp that interoperated with C++. You can get some level of interoperation between ECL and C++ up in a weekend but it won't work with C++ exceptions and RAII and there are dozens of other problems. In retrospect I don't think I would have gotten here starting from ECL because I never really understood the ECL code.

ioddly 12y ago

Is the compacting garbage collector mentioned in the article not a proper moving GC? I am not familiar with it.

drmeister 12y ago
Yes, the Memory Pool System by Ravenbrook (https://www.ravenbrook.com/project/mps/ https://www.ravenbrook.com/project/mps/) is a proper, moving garbage collector. It uses precise GC on the heap and conservative GC on the stack, as does the garbage collector in Steel Bank Common Lisp on x86 chips. I need it because I need my code to run on 100,000 CPU supercomputers with a controlled memory footprint to develop organic nano machines (seriously).
- ioddly 12y ago
  To be honest I was just kind of thinking "oh great another language implementation," before I read what you're actually doing and why you needed to create clasp. I appreciate the difficulty of writing precisely GC'd C/C++. It's pretty awesome that you were able to use clang to (I assume this is mainly what the analyzer does) track roots in C & C++ code. Best of luck.
  - drmeister 12y ago
    Thanks - yes the analyzer tracks roots through about 300 C++ classes. It also finds global variables and builds C++ code to interface with the MPS library. I exposed the Clang libraries to search the AST and describe the AST in Common Lisp and then wrote the static analyzer in Lisp. I shudder at the thought of doing this all in C++ and I write a lot of complicated stuff like Common Lisp implementations in C++ :-). Common Lisp is the language of trees and pattern recognition. Common Lisp is the perfect tool for this job.