NPE in IRDumper.print_ir on JRuby 9.3

[kalenp]

I'm getting an NPE when trying to dump the IR. Per suggestion from @headius, I added this code snippet immediately after a class definition (sample MyClass):

class MyClass
  def get
    ...
  end
end

def dump_ir
  m = MyClass.instance_method(:get)
  jm = JRuby.ref(m)
  scope = jm.get_method.get_ir_scope
  printed_ir = org.jruby.ir.persistence.IRDumper.print_ir(scope, true)
  bytes = printed_ir.to_byte_array
  puts String.from_java_bytes(bytes)
end

dump_ir()

This fails at the IRDumper.print_ir line with the error:

LoadError: load error: <file> -- java.lang.NullPointerException: null
require at org/jruby/RubyKernel.java:1017
<main> at <file>.rb
...

I also tried it with another method on a module with the same result, eg

module MyModule
  module_function def get
    ...
  end
end

m = MyModule.method(:get)

Environment Information

• jruby 9.3.13.0 (2.6.8) 2023-11-02 09b6f22 OpenJDK 64-Bit Server VM 11.0.15+0-adhoc..source on 11.0.15+0-adhoc..source +jit [x86_64-linux]
• Linux localhost 6.5.13-1rodete2-amd64 break script engine #1 SMP PREEMPT_DYNAMIC Debian 6.5.13-1rodete2 (2024-01-11) x86_64 GNU/Linux

[enebo]

If I try:

require 'jruby'

class MyClass
  def get
    1 + 1
  end
end

def dump_ir
  m = MyClass.instance_method(:get)
  jm = JRuby.ref(m)
  scope = jm.get_method.get_ir_scope
  printed_ir = org.jruby.ir.persistence.IRDumper.print_ir(scope, true)
  bytes = printed_ir.to_byte_array
  puts String.from_java_bytes(bytes)
end

dump_ir

I get:

system ~/work/jruby-9.5 9.5-dev * 5543% ~/releases/9.3.14.0/jruby-9.3.14.0/bin/jruby -v ../snippets/ir_dump.rb
jruby 9.3.14.0 (2.6.8) 2024-02-20 0db23ddd14 OpenJDK 64-Bit Server VM 20.0.1+9-29 on 20.0.1+9-29 +jit [x86_64-linux]
begin INSTANCE_METHOD<get>
flags: [FLAGS_COMPUTED]
signature(pre=0,opt=0,post=0,rest=NONE,kwargs=0,kwreq=0,kwrest=-1)

block #1 (out: 3,2): LBL_0:-1

block #2 (out: 3): LBL_1:-1
  0:         check_arity(required: 0, opt: 0, rest: false, receivesKeywords: false, restKey: -1)
  1:         line_num(lineNumber: 4, coverage: false, oneshot: false)
  2: %v_2 := call_1f(fix<1>, fix<1>, fixNum: 1, callType: NORMAL, name: +, potentiallyRefined: false)
  3:         return(%v_2)

block #3: LBL_2:-1

I am guessing something specific where the '...' is in your report is not printing and causing a NPE. You can also try adding -Xlog.backtraces or -Xlog.exceptions. Possibly even -Xbacktrace.style=raw will give your more info where the NPE is happening.