Compilation ancestry of javac?

[Remi Forax]

On 03/18/2013 10:09 PM, Eric Lefevre-Ardant wrote:
> Hi everyone,
>
> I am preparing a presentation for the Devoxx conference in Paris, and 
> I was hoping to present a slide of how javac is compiled.
> Alex Buckley suggested that this might be the right place to get more 
> information. Feel free to point me to some other place, though.

Hi Eric,
Here is what I know with the name of the people that works
on the different projects so you can contact them if you want more detail.

When I start to use Java, in October 1996, during 1.0/1.1 timeframe,
javac was already written in Java (I think it was bootstraped from a C 
version
by Gosling and al in the early days).
As a trivia, I was using Java on HP-UX but they were no Java VM 
available from HP,
so I was using the Java VM embeded in Netscape with the class library
that I had copy/pasted from the Solaris JDK.

During 1.2 timeframe, IBM releases a fast java compiler written in C++
known as IBM Jikes compiler.

In 1999, as part of the Kaffe Virtual Machine, a new Java compiler
written in Java kjc was developed
(You can ask Dalibor Topic for more info).

During 1.3 timeframe IBM starts the Eclipse project and release ECJ
as a standalone compiler.
SUN, a little later also develops a Java compiler written in C known as 
fastjavac
that was used with the first versions of NetBeans.

During 1.3/1.4 time frame, GJC (generic java compiler) was written to 
add generics to Java
(at least Bracha, Odersky, Stoutamire, and Wadler were involved).
During 1.4 time frame, the old javac was replaced by GCJ, so at that time
the new javac was a compiler using generics internally but compiling 1.4 
Java code without generics.

At FOSDEM 2004, Andrew Haley (RedHat) and Mark Wielaard announce
that GCJ (gcc frontend) and the GNU Classpath were merged.

With the release of Java 1.5, the new javac was faster than fastjavac 
and jikesc
so both were never upgraded to recognize Java 5 features.

Since 2006/2007, Java is Open Source and only two compilers are still used,
OpenJDK javac and Eclipse ECJ. GCJ now uses ECJ as front end.

>
> Specifically, my goal is to establish if javac is always compiled 
> using the previous version of javac. That seems to be the case when 
> looking at the documentation of recent JDKs (my main source is 
> https://blogs.oracle.com/jjg/entry/building_javac_for_jdk7).
>
>   * can someone confirmed that this has always been the case ?
>   * how far does this go back? javac v1.0 ? v0.9.2 ?
>   * finally, how was the bootstrap (not coded in Java) version of
>     javac coded? in C? oak? shell script?
>
> My guess is that, if I wanted to go back that far, then in theory I'd 
> need a Solaris machine from 1995 or so, with the appropriate version 
> of cc.
>
>   * can anyone confirm this?
>   * anyone knows what version of SunOS/cc/some other compiler would be
>     required?
>   * anyone knows whether that bootstrap code would be available? (via
>     legal means)
>
> My goal is to illustrate a point on compiler by showing how far back 
> you could go on javac, if you wanted to build a "pure" version (that 
> is, not based on another javac).
>
> Many thanks for any help you might provide,
>
> Eric

see you at DevoxxFR,
Rémi