[ Home | Articles | Account | People | Projects | FAQ ] Name: graydon hoare
Member since: 2000-02-06 05:06:58
Last Login: 2009-05-05 18:25:12
Homepage: www.pobox.com/~graydon
Notes: Currently at mozilla corporation. Formerly at red hat, zks, UofT, novare, and elsewhere.
Interested primarily in languages and software engineering automation (formal methods, automated debugging, version control, SCM, etc), with side interests in lots of other fiddly things.
17 Mar 2009 (updated 17 Mar 2009 at 19:40 UTC) »
What he wrote was this:
I’d like to pick my VM for its security, footprint, handling of parallelism and messaging, and run-time appropriateness. This would let me choose Lisp, Haskell, Python or C++, depending on the skillset of engineers available to me; and the JVM, .NET platform, or LLVM, depending on how I meant the code to be used.
To me this shows a pretty broad misunderstanding of the "VM" suffix shared by JVM and LLVM. They're different layers in the language implementation stack. There is no run-time component to LLVM to speak of; nothing on the scale of the services offered by a JVM. No "parallelism and messaging" system, no verifier, no security system, no reflection services, no dynamic loading services beyond the OS loader, no adaptive inlining or specializing by the JIT as the program's running, no complete GC, etc. etc. I'm not particularly keen on the JVMs flavours of all these services, but they're nontrivial. If you're writing a language that wants any of that stuff, and you want to "target LLVM", you're going to be writing a lot more of your own runtime services. Even getting GC working in an LLVM-targeted language involves nontrivial user-written parts.
About your example: GCJ does not compile Java "to the GCC runtime". The GCC runtime is roughly "libgcc and libc". GCJ compiles using GCC's infrastructure, sure, but its runtime library is quite substantial on its own.
(Appropriately enough, a moment of searching turns up the fact that there is also an LLVM sub-project to provide the JVM and .NET runtime services on top of LLVM. Heh.)
It's rather the same objection asm programmers make when choosing against C or C++. The comparison extends, in fact, to the counter-arguments made by the high-level system defenders: that the C compiler (or JVM runtime as the case may be) is capable of automatic optimizations far beyond the "intention and control" of the lower-level hacker.
Strangely, media codecs and arithmetic libraries still get some of their cores written in asm, and OS kernels, graphics libraries, network stacks, servers, games and desktop applications still get written in C. I think a bit of the "automatic-optimization better than any human" story is overreaching, doesn't happen as often as the defenders wish, or enough to make up the difference for the systemic taxes.
The OP's notion that he'll someday be able to "choose" between LLVM and a JVM as backend is meaningless, alas, apples-to-oranges. LLVM is a lower-level component (compiler backend); you could implement a JVM using LLVM, but the complexity of a JVM comes from the abstract semantics required by the Java language spec (which includes a VM spec), not any particular implementation substrate.
gij -Dgnu.java.awt.peer.gtk.Graphics=Graphics2D -jar jedit.jar
you should get something like this.
today jedit started working on free swing. it's a bit ugly and slow, but it's by far the largest free swing GUI we've constructed yet. that's rendering on cairo, which seems to be maturing nicely. I also taught the imageio system to use gdk-pixbuf, so now we can load and save most major image formats.
monotone
we've upgraded to sqlite 3.0, which does away with most real size restrictions. I put some of my ogg files and digital camera images in it. seems to work. also the current head supports "single file" diffs, commits, reverts, etc. many active development branches now; people are adding features faster than I can keep track. that's quite satisfying.
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