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 compilerdesign 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 compilerdesign backend, which can
be useful for testing purposes.


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

* To compile ll files using the compilerdesign 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-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

  --simulate-x86
    runs the resulting .s file through the reference 
    x86 simulator and outputs the result to the console

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

  -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 compilerdesign backend:


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