Jasmin Assembler: 'l2d' Instruction Giving “java.lang.VerifyError: … Attempt to split long or double on the stack”

Question

I'm writing a compiler to compile a subset of Java to Java bytecode using the Jasmin assembler

I'm having trouble with the 'l2d' instruction (and related ones - but I think they will all work once I have figured out why this one isn't working).

Instruction Reference:

http://cs.au.dk/~mis/dOvs/jvmspec/ref-_l2d.html

The code I'm compiling is:

{
    double d = 10L;
}

So essentially I'm trying to mirror the way that javac does implicit type conversions between primitive numerical types.

The output Jasmin assembly code is:

.source test3.jml
.class Test3
.super java/lang/Object
.method public static main([Ljava/lang/String;)V
    .limit stack 10
    .limit locals 100
    ldc2_w 10 ;Load constant numerical value 10
    l2d ;Convert left hand side to match the type of the right
    dstore 0 ;Store top of stack in 0 (d)
.end method

The important lines which are the three before .end method.

Text after ';' is a comment.

The exact error I get when I try and run the compiled code is:

Exception in thread "main" java.lang.VerifyError:(class: Test3, method: main signature: ([java/lang/String;)V) Attempt to split long or double on the stack
Could not find the main class: Test3. Program will exit.

I reckon it must be something to do with the fact that longs and doubles take up 2 slots on the stack and 2 local variables (explained here), it still perplexes me though.

Answer 1

The Java virtual machine uses local variables to pass parameters, so the local variable with index 0 would be of type String[] in your code. I'm not familiar enough with Jasmine to know whether other local variables have to be declared before use, but can you simply try to store the double into index 1?