Compiler

The C compiler I wrote last year: https://github.com/dlang/dmd/blob/master/compiler/src/dmd/cp... is vastly different from the one I wrote in the 1980s: https://github.com/DigitalMars/Compiler/blob/master/dm/src/d... My original evil plan was to recycle the old one, but I just couldn't.

The main cause of that is I was slow to make the compiler open source. It is open source now. https://github.com/DigitalMars/Compiler

> I'm a big believer in technical continuity. So am I. D is designed to be an easy transition from C and C-With-Classes. For example, here is some code in C that was translated to D (it's part of the Digital Mars C++ compiler): C: https://github.com/DigitalMars/Compiler/blob/dmc-cxx/dm/src/... D: https://github.com/DigitalMars/Compiler/blob/master/dm/src/d... They look pretty much the same. The code generated is the same. In those repositories you can also see how I translated the C versions to D with plenty of examples. The biggest impediment is the C preprocessor. You wouldn't really want to carry that forward. After removing dependency on the C preprocessor, most of the work is global search/replacing things like `->` to `.`.

The dmd backend itself used -betterC to make the conversion from the original C-with-Classes code. DMC++ itself underwent the conversion to D using -betterC. https://github.com/DigitalMars/Compiler/tree/master/dm/src/d... It still looks a lot like C.

I don't remember how long it took me to do the spell checker challenge: https://github.com/dlang/dmd/blob/master/src/dmd/root/spelle... but I'm sure it was much longer than it took Peter. This checker is used by the D compiler to look for a misspelled identifier when a symbol lookup fails. The identifiers in scope form the dictionary. It works surprisingly well. I added it to the Digital Mars C++ compiler as well. https://github.com/DigitalMars/Compiler/blob/master/dm/src/d...

I started on the D front end in 1999. It was attached to the NorthwestC/Datalight/Zortech/Symantec/DigitalMars backend (for DMD), to gcc (for GDC) and to LLVM (for LDC). The backend was originally written for my C compiler, then my C++ compiler. The source code can be found here: https://github.com/DigitalMars/Compiler The editor I use is https://github.com/DigitalMars/med which is translated to D from the older C version https://github.com/DigitalMars/me I don't care for IDEs because they only work on one machine (I develop on several). ME works identically on all of them, and is easy to port. I keep thinking of transitioning to vim, but never get around to it. The text editor is not the gating factor to my productivity, anyway. Most of my coding sessions consist of simply staring at the code. What helps most is lots of windows open on a

Digital Mars C and C++ compilers still support 16 bit 8086 code generation and are free: https://www.digitalmars.com/download/freecompiler.html Source code to the compiler/libraries is also free: https://github.com/DigitalMars/dmc https://github.com/DigitalMars/Compiler

Here's the source code: https://github.com/facebookarchive/warp and the one for the C compiler I wrote long ago: https://github.com/DigitalMars/Compiler/blob/master/dm/src/d... which is integrated with the C lexer for speed reasons.

I did complain to the author, but the damage was done. Can't undo a magazine article. I didn't save a copy of the magazine I was so annoyed. BTW, it goes on. A couple years ago a kind soul gently suggested I implement DFA since clang had invented DFA. (No, I didn't invent DFA either, but I do believe that Datalight Optimum C was the first DFA compiler for DOS.) http://www.program-transformation.org/Transform/CCompilerHis... The Data Flow Analysis code: https://github.com/DigitalMars/Compiler/blob/master/dm/src/d...

For comparison, here's the C++ lexer for Digital Mars C++: https://github.com/DigitalMars/Compiler/blob/master/dm/src/d... The parser isn't in its own file, it's intermingled with the semantic processing, a mistake I didn't want to repeat with D :-)

"Use the Source, Luke!" https://github.com/DigitalMars/Compiler/blob/master/dm/src/d...

I forgot to add SROA to the list. DMD does a limited form of SROA I wrote as a proof of concept, it should be generalized. https://github.com/DigitalMars/Compiler/blob/master/dm/src/d... I've also written a loop unroller, but it can be improved: https://github.com/DigitalMars/Compiler/blob/master/dm/src/d... My evaluation was based on comparing the code gen output of the various compilers, not looking at how they were achieved. As for SSA, DMD's optimizer is based on an intermediate representation that is a binary tree. A binary tree is a form of SSA - each operator node is a value assigned once and never modified. > Respectfully No worries. I'm used to people telling me I can't do things :-)

Not really. The two main reasons LLVM and gcc do a better optimization job is they have a better function inliner and loop unroller. Neither are particularly computation intensive. DMD does all the usual data flow analysis optimizations - strength reduction, copy propagation, loop unrolling, dead store elimination, live range analysis, etc. https://github.com/DigitalMars/Compiler/blob/master/dm/src/d... The optimizer / code generator is the same one that Digital Mars C++ uses, which was developed in the 1980's (!). Up until 2000 or so, the code generated was about the same as gcc, though DMC++ ran several times faster. Since 2000, all my attention has been on the D front end, and so the optimizer wasn't getting the devoted attention it had earlier. Just recently I finished converting the DMD optimizer from C to D, and am doing the code ge

I'm pretty clueless here, but from a quick search on GitHub it looks like there's support for NT exception handling, and DWARF exception handling. (I realise this doesn't really answer your question, but it's a start.) https://github.com/DigitalMars/Compiler/blob/7a33233c/dm/src... https://github.com/DigitalMars/Compiler/blob/7a33233c/dm/src...