Using main.native:

main.native acts like the clang compiler.  Given several .ll, .c, and .o files,
it will compile the .ll files to .s files (using the Compiler Design backend)
and then combine the results with the .c and .o files to produce an executable
named a.out.  You can also compile the .ll files using clang instead of the
Compiler Design backend, which can be useful for testing purposes.


* To run the automated test harness do:
  ./main.native --test              

* To compile ll files using the Compiler Design backend:
  ./main.native path/to/foo.ll 

  - creates output/foo.s   backend assembly code
  - creates output/foo.o   assembled object file
  - creates a.out          linked executable

 NOTE: by default the .s and .o files are created in 
 a directory called output, and the filenames are 
 chosen so that multiple runs of the compiler will
 not overwrite previous outputs.  foo.ll will be 
 compiled first to foo.s then foo_1.s, foo_2.s, etc.


* To compile ll files using the clang backend:
  ./main.native --clang path/to/foo.ll

* Useful flags:
  --print-oat
    pretty prints the Oat abstract syntax to the terminal

  --print-ll 
    echoes the ll program to the terminal

  --print-x86
    echoes the resulting .s file to the terminal

  --interpret-ll
    runs the ll file through the reference interpreter
    and outputs the results to the console

  --execute-x86
    runs the resulting a.out file natively
    (applies to either the Compiler Design backend or clang-compiled code)

  --clang compiles to assembly using clang, not the Compiler Design backend

  -v
    generates verbose output, showing which commands are used
    for linking, etc.

  -op <dirname>
    change the output path [DEFAULT=output]

  -o 
    change the generated executable's name [DEFAULT=a.out]

  -S
    stop after generating .s files 

  -c 
    stop after generating .o files 

  -h or --help
    display the list of options

* Example uses:

Run the test case /programs/factrect.ll using the Compiler Design backend:


./main.native --execute-x86 programs/factrect.ll 
--------------------------------------------------------------- Executing: a.out
* a.out returned 120