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One of our projects causes a compiler crash when targeting jvm:

Fatal error: exception IO.Overflow("write_ui16")
Raised at file "IO.ml", line 669, characters 36-59
Called from file "src/generators/jvm/jvmGlobals.ml", line 160, characters 22-50
Called from file "array.ml", line 77, characters 31-48
Called from file "src/generators/jvm/jvmAttribute.ml", line 221, characters 2-83
Called from file "list.ml", line 55, characters 20-23
Called from file "src/generators/jvm/jvmMethod.ml", line 1110, characters 19-100
Called from file "src/generators/jvm/jvmMethod.ml", line 1125, characters 14-35
Called from file "src/generators/jvm/jvmClass.ml", line 189, characters 25-50
Called from file "list.ml", line 73, characters 12-15
Called from file "src/generators/jvm/jvmClass.ml", line 185, characters 2-243
Called from file "src/generators/genjvm.ml", line 2515, characters 11-53
Called from file "src/generators/genjvm.ml", line 2064, characters 2-6
Called from file "list.ml", line 73, characters 12-15
Called from file "std.ml", line 26, characters 6-9
Re-raised at file "std.ml", line 28, characters 29-30
Called from file "src/generators/genjvm.ml", line 2919, characters 1-82
Called from file "src/compiler/haxe.ml", line 342, characters 2-14
Called from file "src/compiler/haxe.ml", line 1073, characters 25-72
Called from file "src/compiler/haxe.ml", line 633, characters 3-11
Called from file "src/compiler/haxe.ml", line 1238, characters 1-35

I can't share the whole project but I could spend some time trying to isolate a repro case if it would help. It doesn't seem to be using macros/abstracts or anything too crazy, although there is a bunch of level data defined in an array literal about 1000 lines long.

Thanks!

That fails while writing out the LineNumberTable. The specification says that it's alright to have multiple of those, so I guess I can just split them if they get too big.

However, you're likely going to hit some 16bit JVM limit in other places and I don't know if all of them can be worked around.

Actually this isn't going to help because the actual values are still 16bit, so any line or code offset beyond that would still error.

In fact, from reading a bit more it looks like there's a hard 16bit limit for code in general.

macro function make() {
	var num = 21845;
	var acc = [for (_ in 0...num) macro call()];
	return macro $b{acc};
}

@:pure(false)
function call() {}

function main() {
	make();
}

Error: LinkageError occurred while loading main class _Main.Main_Fields_
        java.lang.ClassFormatError: Invalid method Code length 65536 in class file _Main/Main_Fields_
Error: Command failed with error 1

It's a bit strange because the code itself has u4 code_length, but everything related to program counters is u2.

I don't consider this a bug, it's a limitation. The only course of action here would be to somehow split up functions that are too big, but that would come with a lot of complexity. For starters, even detecting this ahead of time is a big issue because we only know that we overflow at a low-level, by which point the overall transformation us already well underway. And even if we detected this, dealing with it while retaining the desired state and control flow would be quite complicated.

So while I'll look into improving the error message, this is something that has to be addressed in user code.

I'm curious if other compile-to-jvm languages try to resolve this somehow.

Ok, no worries :) Thanks for looking into it.

I'm having a similar issue but unrelated (at least indirectly) to function bodies/exprs

I created a Test typedef in stdgo/time/Time.hx:

typedef Test = Int;

then referenced the type:

function main():Void {
    var _x:stdgo.time.Time.Test;
}

Which results in the error: IO.Overflow("write_ui16")

Haxe version: 4.3.0-rc.1 hxjava: 4.2.0