A Race of Two Compilers: GraalVM JIT versus HotSpot JIT C2 [video]
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Re: A Race of Two Compilers: GraalVM JIT versus HotSpot JIT C2 [video]
#2Here is the same speaker comparing C2 and clang: https://youtu.be/0yrBuPiGk8I
Re: A Race of Two Compilers: GraalVM JIT versus HotSpot JIT C2 [video]
#3Just in time compilation, I think it should be called “continuous profile guided compilation” instead, describes better the awesomeness that happens...
Re: A Race of Two Compilers: GraalVM JIT versus HotSpot JIT C2 [video]
#4Just in time compilation, I think it should be called “continuous profile guided compilation” instead, describes better the awesomeness that happens...
Some people differentiate between just-in-time compilation, which is what for example .NET does (or did, last time I checked), where it just literally compiles it as it would ahead-of-time, but at the last second before executing it for the first time, and dynamic compilation, which is for example what Graal does - compiling based on runtime conditions, possibly multiple times with different results as the program executes.
Re: A Race of Two Compilers: GraalVM JIT versus HotSpot JIT C2 [video]
#5Just in time compilation, I think it should be called “continuous profile guided compilation” instead, describes better the awesomeness that happens...
JITs do more than just profile-guided optimizations. Their secret weapon is speculative optimizations that mean they don't need to work hard (and often fail) to prove the soundness of certain optimizations. They're allowed to guess and be wrong.
Re: A Race of Two Compilers: GraalVM JIT versus HotSpot JIT C2 [video]
#6I'm curious if GraalVM can do the same rockstar party tricks on Java 11? He uses Java 12, but doesn't go into huge detail why he chose that rather than the LTS.
Re: A Race of Two Compilers: GraalVM JIT versus HotSpot JIT C2 [video]
#7I'm curious if GraalVM can do the same rockstar party tricks on Java 11? He uses Java 12, but doesn't go into huge detail why he chose that rather than the LTS.
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Re: A Race of Two Compilers: GraalVM JIT versus HotSpot JIT C2 [video]
#8From what I know, GraalVM EE (Enterprise Edition) does do loop vectorisation.
This will lead to an interesting problem if they want to replace C2 with Graal. Are they willing to regress performance for some open-source-only users, even if it's a performance win for others?
Re: A Race of Two Compilers: GraalVM JIT versus HotSpot JIT C2 [video]
#9From what I know, GraalVM EE (Enterprise Edition) does do loop vectorisation. This will lead to an interesting problem if they want to replace C2 with Graal. Are they willing to regress performance for some open-source-only users, even if it's a performance win for others?
Yes, this will be very interesting. Also, since GraalVM is pretty modular. Will someone provide a free/open source version with loop vectorisation and other goodies.
Re: A Race of Two Compilers: GraalVM JIT versus HotSpot JIT C2 [video]
#10Just in time compilation, I think it should be called “continuous profile guided compilation” instead, describes better the awesomeness that happens...
JITs do more than just profile-guided optimizations. Their secret weapon is speculative optimizations that mean they don't need to work hard (and often fail) to prove the soundness of certain optimizations. They're allowed to guess and be wrong.
Another advantage they have is that they can focus the spent optimization cycles on hot code.
AOT compilers can't afford running optimization passes in a loop (inline, optimize, inline, optimize, ...) until they reach a fixed point because that would blow up compile times if that were applied to the whole program.