Princeton CS Software lcc, A Retargetable C Compiler Using ASDL with lcc 4.1

Using ASDL with lcc 4.1

The lcc 4.1 distribution includes the files necessary to emit ASDL, as described in:

D. R. Hanson, Early Experience with ASDL in lcc, Software—Practice and Experience 29 (5), 417-435, 4/25/99. (120 KB).
Slides of the talk at the National Compiler Infrastructure Tutorial, PLDI'98, 6/19/98. (71KB).

Rebuilding lcc 4.1 to include ASDL support on UNIX platforms involves the following steps.

1. Install and test lcc 4.1; see Installing lcc.
2. Install ASDL version 1.2. Make sure you set the environement variable ASDL_HOME to the root of your ASDL installation directory.
3. Add the line shown on bold type below to src/inits.c:

   void init(int argc, char *argv[]) {
   
   	{extern void input_init(int, char *[]); input_init(argc, argv);}
   
   	{extern void main_init(int, char *[]); main_init(argc, argv);}
   
   	{extern void prof_init(int, char *[]); prof_init(argc, argv);}
   
   	{extern void trace_init(int, char *[]); trace_init(argc, argv);}
   
   	{extern void type_init(int, char *[]); type_init(argc, argv);}
   
   	{extern void x86linux_init(int, char *[]); x86linux_init(argc, argv);}
   
   	{extern void asdl_init(int, char *[]); asdl_init(argc, argv);}
   
   }

4. Add the following lines to your custom.mk, creating one if necessary.

   EXTRALIBS=-L$(ASDL_HOME)/lib/asdlGen -lasdl -lcii
   
   EXTRAOBJS=$(BUILDDIR)/asdl$O $(BUILDDIR)/rcc$O
   
   
   
   all::	$(BUILDDIR)/pass2$E $(BUILDDIR)/2html$E

   These lines augment the rules in the makefile so that it generates $(BUILDDIR)/rcc.h and $(BUILDDIR)/rcc.c from the ASDL grammar for lcc pickles in src/rcc.asdl, compiles these generated files, and compiles src/asdl.c (the ASDL "back end"), src/pass2.c (reads pickles, emits assembly language), and src/2html.c (reads pickles, emits HTML).

5. Rebuild lcc, i.e., execute

   % make CUSTOM=custom.mk all

   This step builds a new rcc (the compiler proper), pass2, and 2html.

6. Copy pass2 to /usr/local/bin, or a plant a symbolic link to it as suggested in Installation on UNIX. You can also copy to link to 2html, which reads ASDL pickles and emits HTML.

Once you've installed the compiler, you can generate ASDL pickles by giving the -Wf-asdl and -S options, e.g.,

% lcc -Wf-asdl -S -o wf1.pickle tst/wf1.c

As shown, use the -o option to specify the file name for the pickle; if you omit this option, the pickle lands in, for example, wf1.s.

pass2 reads a pickle and emits assembly language, as usual, e.g.,

% pass2 wf1.pickle wf1.s

% lcc wf1.s

These commands generate assembly code from wf1.pickle, and assemble and link it into a.out. The assembly code generated  by pass2 is often identical to that generated by lcc directly. When there are differences, they are usually due to differences in compiler-generated label numbers.

Rebuilding lcc 4.1 on Windows NT/95/98 to support ASDL involves the analogous steps. The Windows makefile, makefile.nt, doesn't support includes, so you'll have to edit the file to add the EXTRALIBS and EXTRAOBJS definitions and the additional prerequisites for the all target.