X-Git-Url: https://git.stderr.nl/gitweb?p=matthijs%2Fmaster-project%2Freport.git;a=blobdiff_plain;f=Chapters%2FNormalization.tex;h=3d53853a58129f8b8cf90e5a22b8da3f02f75d30;hp=03f379244e0299b787ae294c90e4db2c07eab829;hb=901c9881c60ac1897aa8efb63d082798272e1ae7;hpb=68e92ccd2b456b9ce81b0617417bc8abdaff6fa3 diff --git a/Chapters/Normalization.tex b/Chapters/Normalization.tex index 03f3792..3d53853 100644 --- a/Chapters/Normalization.tex +++ b/Chapters/Normalization.tex @@ -28,11 +28,7 @@ core can describe expressions that do not have a direct hardware interpretation. - \todo{Describe core properties not supported in \VHDL, and describe how the - \VHDL we want to generate should look like.} - \section{Normal form} - \todo{Refresh or refer to distinct hardware per application principle} The transformations described here have a well-defined goal: To bring the program in a well-defined form that is directly translatable to hardware, while fully preserving the semantics of the program. We refer to this form as @@ -629,9 +625,11 @@ In particular, we define no particular order of transformations. Since transformation order should not influence the resulting normal form, - \todo{This is not really true, but would like it to be...} this leaves - the implementation free to choose any application order that results in - an efficient implementation. + this leaves the implementation free to choose any application order that + results in an efficient implementation. Unfortunately this is not + entirely true for the current set of transformations. See + \in{section}[sec:normalization:non-determinism] for a discussion of this + problem. When applying a single transformation, we try to apply it to every (sub)expression in a function, not just the top level function body. This allows us to @@ -798,6 +796,7 @@ normal form. \placeintermezzo{}{ + \defref{substitution notation} \startframedtext[width=8cm,background=box,frame=no] \startalignment[center] {\tfa Substitution notation} @@ -890,7 +889,8 @@ This transformation is not needed to get an expression into intended normal form (since these bindings are part of the intended normal form), but makes the resulting \small{VHDL} a lot shorter. - + + \refdef{substitution notation} \starttrans letrec a0 = E0 @@ -1822,6 +1822,7 @@ solves (part of) the polymorphism, higher order values and unrepresentable literals in an expression. + \refdef{substitution notation} \starttrans letrec a0 = E0 @@ -2013,7 +2014,7 @@ let y = (a * b) in y + y \stoplambda - \subsection{Non-determinism} + \subsection[sec:normalization:non-determinism]{Non-determinism} As an example, again consider the following expression: \startlambda