gbenson.net

I always plan to write about what I’ve been doing at the end of the day, but I never quite get round to it. Usually my head is too full of code, or something. So I end up with a piece of paper with scribble all over it to write about in the morning. Here’s yesterday’s notes.

1. There are two VMs, client and server. When you build the C++ interpreter it’s the server JIT it gets built into.
2. The templater that makes the stubs has some magic to support multi-model architectures. It works like this. To generate the stubs for ppc and ppc64 you run the templater like this:

   python porter/generate.py ppc

   Whether a ppc64-specific file is generated depends on a template’s filename. If it has CPU in it, you get ppc only; if it has CPUS you get ppc and ppc64. So from the template:

   porter/hotspot/src/cpu/CPU/vm/assembler_CPU.cpp

   you get:

   hotspot/src/cpu/ppc/vm/assembler_ppc.hpp

   but from the template:

   porter/hotspot/build/linux/makefiles/CPUS.make

   you get:

   hotspot/build/linux/makefiles/ppc.make
   hotspot/build/linux/makefiles/ppc64.make

   It’s clunky but it works.

3. This is possibly obvious, but sneaky too. Everything in a CPU template is evaluated once, for the main cpu (the one you specify on the command line). A consequence of this is that the templater function is64bit(cpu) will always return False if it’s in a CPU template. You need to use other methods to conditionalize this, #ifdef _LP64 for example.
4. My bootstrap environment is… interesting. XSLT with IcedTea’s gij/ecj combo produces mangled jvmti headers on ppc, but the IBM JDK from RHEL5 doesn’t understand version 50 class files. So I’m using the IBM JDK with IcedTea’s javac wrapper.