The documention of each simplications is quite dense and use some implicit conventions for its notation. Document this notation. Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx> --- Documentation/api.rst | 5 +++++ simplify.c | 24 ++++++++++++++++++++++++ 2 files changed, 29 insertions(+) diff --git a/Documentation/api.rst b/Documentation/api.rst index 1270551cb..cb8a09820 100644 --- a/Documentation/api.rst +++ b/Documentation/api.rst @@ -20,3 +20,8 @@ Typing ~~~~~~ .. c:autodoc:: evaluate.h + +Optimization +~~~~~~~~~~~~ + +.. c:autodoc:: simplify.c diff --git a/simplify.c b/simplify.c index e177baf3e..2db6f40a9 100644 --- a/simplify.c +++ b/simplify.c @@ -7,6 +7,30 @@ /// // Instruction simplification // -------------------------- +// +// Notation +// ^^^^^^^^ +// The following conventions are used to describe the simplications: +// * Uppercase letters are reserved for constants: +// * `M` for a constant mask, +// * `S` for a constant shift, +// * `N` for a constant number of bits (usually other than a shift), +// * `C` or 'K' for others constants. +// * Lowercase letters `a`, `b`, `x`, `y`, ... are used for non-constants +// or when it doesn't matter if the pseudo is a constant or not. +// * Primes are used if needed to distinguish symbols (`M`, `M'`, ...). +// * Expressions or sub-expressions involving only constants are +// understood to be evaluated. +// * `$mask(N)` is used for `((1 << N) -1)` +// * `$trunc(x, N)` is used for `(x & $mask(N))` +// * Expressions like `(-1 << S)`, `(-1 >> S)` and others formulae are +// understood to be truncated to the size of the current instruction +// (needed, since in general this size is not the same as the one used +// by sparse for the evaluation of arithmetic operations). +// * `TRUNC(x, N)` is used for a truncation *to* a size of `N` bits +// * `ZEXT(x, N)` is used for a zero-extension *from* a size of `N` bits +// * `OP(x, C)` is used to represent some generic operation using a constant, +// including `TRUNC(x, N)` and `ZEXT(x, N)`. #include <assert.h> -- 2.18.0
