• HotSpot

HotSpot

To build hotspot, get the sources, for example into /usr/src/hotspot

# To build a C2 compiler
/usr/src/hotspot/build/linux$ make debug ALT_BOOTDIR=/usr/lib/jvm/java-6-sun
# To build a C1 compiler
/usr/src/hotspot/build/linux$ make debug1 ALT_BOOTDIR=/usr/lib/jvm/java-6-sun

To use the newly built hotspot, use the following hotspot.sh script.

#!/bin/sh

build1=/usr/src/hotspot/build/linux/linux_i486_compiler1/debug
build2=/usr/src/hotspot/build/linux/linux_i486_compiler2/debug

build=$build1

export JAVA_HOME=/usr/lib/jvm/java-6-sun/
export LD_LIBRARY_PATH=$build
exec $build/gamma $*

I didn't find a way to get a list of the interesting -XX options, you can get them using the following script (but probably it can be done easier):

#!/bin/sh

hotspot_dir="$1"
exe=/tmp/hotspot_options

if [ -z "$hotspot_dir" ]; then
        echo Usage: $0 "<hotspot dir>" >&2
        exit 1
fi

cpp <<- EOF | grep BLAH | sed 's/BAZ/\n/g;s/BLAH//g' | gcc -x c - -o ${exe}
        #include "${hotspot_dir}/src/share/vm/runtime/globals.hpp"
        #include "${hotspot_dir}/src/share/vm/c1/c1_globals.hpp"
        #include "${hotspot_dir}/src/share/vm/opto/c2_globals.hpp"

        #define foo4(a, b, c, d) BLAH printf("%s (%s)\n\t%s\n\n", #b, #a, d); BAZ
        #define foo3(a, b, c) BLAH printf("%s (%s)\n\t%s\n\n", #b, #a, c); BAZ

        #define a(aa, bb, cc, dd) foo4(aa, bb, cc, dd)
        #define b(aa, bb, cc) foo3(aa, bb, cc)
        #define c(aa, bb, cc, dd) foo4(aa, bb, cc, dd)
        #define d(aa, bb, cc) foo3(aa, bb, cc)
        #define e(aa, bb, cc, dd) foo4(aa, bb, cc, dd)
        #define f(aa, bb, cc, dd) foo4(aa, bb, cc, dd)
        #define g(aa, bb, cc, dd) foo4(aa, bb, cc, dd)
        #define h(aa, bb, cc, dd) foo4(aa, bb, cc, dd)
        #define i(aa, bb, cc, dd) foo4(aa, bb, cc, dd)
        #define j(aa, bb, cc) foo3(aa, bb, cc)
        #define k(aa, bb, cc, dd) foo4(aa, bb, cc, dd)
        #define l(aa, bb, cc) foo3(aa, bb, cc)
        #define m(aa, bb, cc, dd) foo4(aa, bb, cc, dd)
        #define n(aa, bb, cc, dd) foo4(aa, bb, cc, dd)
        #define o(aa, bb, cc) foo3(aa, bb, cc)
        #define p(aa, bb, cc, dd) foo4(aa, bb, cc, dd)
        #define q(aa, bb, cc) foo3(aa, bb, cc)
        #define r(aa, bb, cc, dd) foo4(aa, bb, cc, dd)
        #define s(aa, bb, cc, dd) foo4(aa, bb, cc, dd)

        BLAH#include<stdio.h>

        BLAH int main() {

        BLAH printf("\n\n\n================== RUNTIME  ==================\n\n\n");

        RUNTIME_FLAGS(a, b, c, d, e, f, g, h)

        BLAH printf("\n\n\n================== C1  ==================\n\n\n");

        C1_FLAGS(i, j, k, l, m)

        BLAH printf("\n\n\n================== C2  ==================\n\n\n");

        C2_FLAGS(n, o, p, q, r, s)

        BLAH }

EOF

${exe}
rm ${exe}

If you want to use an disassembler, you must provide one in a shared library disassembler.so. Here is a simple binutils based disassebler for x86:

Makefile :

HOTSPOT_HOME = /usr/src/hotspot

disassembler.so: disass.cc
        g++ -I$(HOTSPOT_HOME) -fpic -shared -o $@ $< -lopcodes

disass.cc:

#include <dis-asm.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>

#include "src/share/vm/compiler/disassemblerEnv.hpp"

static void disass_printf(PTR p, const char *fmt, ...) {
        char buf[512];
        va_list ap;
        va_start(ap, fmt);
        buf[0] = '\0';
        vsprintf(buf, fmt, ap);
        ((DisassemblerEnv *)p)->print_raw(buf);
        va_end(ap);
}

static int disass_buffer_read_memory(bfd_vma memaddr, bfd_byte *myaddr, unsigned int length, struct disassemble_info *info)
{
        memcpy(myaddr, (void *) (intptr_t) memaddr, length);

        return 0;
}

extern "C" unsigned char *decode_instruction(unsigned char *code, DisassemblerEnv *env) {
        static int initialized = 0;
        static disassemble_info info;

        if (!initialized) {
                INIT_DISASSEMBLE_INFO(info, NULL, disass_printf);       
                info.mach             = bfd_mach_i386_i386;
                info.read_memory_func = &disass_buffer_read_memory;
                initialized = 1;
        }

        info.stream = env;

        return code + print_insn_i386((bfd_vma) (intptr_t) code, &info);
}