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@@ -1,3 +1,6 @@
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+Overview
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+========
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+
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There are three binaries in the toolchain:
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- The compiler "civcc", which compiles CiviC source code to assembly source
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@@ -13,3 +16,41 @@ and runs it through the entire pipeline, deleting intermediate files
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afterwards. E.g. for the first assignment you may want to run:
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$ bin/run.sh euclid.cvc
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<output of your main function>
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+
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+
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+Reference compiler usage
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+========================
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+
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+You can use the output of the reference compiler "civcc" as benchmark for your
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+own compiler. Apart from the extensions in the language reference, it
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+implements constant propagation/folding on compiler-generated variables, and
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+also does rudimentary loop unrolling. You are not expected to reproduce this,
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+these phases are just there to show you how even simple optimizations can have
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+a significant effect on code size.
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+
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+Some other remarks about the compiler:
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+
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+- Optimizations can be disabled with the -noopt flag.
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+
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+- By default it reads CiviC code from stdin, and prints assembly to stdout, so
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+ you can use it with unix pipes.
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+
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+- The "-v 2" verbosity option makes it print the AST after each phase, showing
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+ you step-by-step transformations. This can be very useful when you are
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+ confused about what a milestone should do. You can compile simple example
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+ file and see how the reference compiler transforms it in the different phase.
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+ Use -noopt as well if you want to get something closer to what your own
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+ compiler should do (since you don't need to implement optimizations).
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+
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+- the "-upto ..." argument makes the compiler stop after a certain phase and
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+ print the AST (or assembly) at that point. E.g. when you are implementing
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+ context analysis and want to compare your output to that of the refrence
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+ compiler, use "-upto context" or "-upto context -v 2".
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+
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+- The generated assembly code contains comments that shows to which CiviC code
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+ it corresponds. This can be used for relating instructions to AST nodes
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+ during debugging, and we recommend you do the same in your own compiler
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+ (although it is not required). Note that the last optimization phase
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+ (peephpole optimization) strips these comments, so you will need to pass "-v
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+ 2" or -noopt to actually see them. You can also disable them completely by
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+ passing "-v 0".
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Taddeus Kroes