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glsl: Update and fix typos in README.

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Andres Gomez 2014-10-16 11:40:39 +03:00 • committed by Kenneth Graunke
parent 2883aff3be
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src/glsl/README
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@ -8,7 +8,7 @@ passed straight through. See glcpp/*
2) lex and yacc-based parser takes the preprocessed string and
generates the AST (abstract syntax tree). Almost no checking is
performed in this stage. See glsl_lexer.lpp and glsl_parser.ypp.
performed in this stage. See glsl_lexer.ll and glsl_parser.yy.
3) The AST is converted to "HIR". This is the intermediate
representation of the compiler. Constructors are generated, function
@ -34,7 +34,7 @@ linked in.
7) The driver performs code generation out of the IR, taking a linked
shader program and producing a compiled program for each stage. See
ir_to_mesa.cpp for Mesa IR code generation.
../mesa/program/ir_to_mesa.cpp for Mesa IR code generation.
FAQ:
@ -126,7 +126,7 @@ optimizations like CSE where one must navigate an expression tree.
Q: Why no SSA representation?
A: Converting an IR tree to SSA form makes dead code elmimination,
A: Converting an IR tree to SSA form makes dead code elimination,
common subexpression elimination, and many other optimizations much
easier. However, in our primarily vector-based language, there's some
major questions as to how it would work. Do we do SSA on the scalar
@ -134,9 +134,9 @@ or vector level? If we do it at the vector level, we're going to end
up with many different versions of the variable when encountering code
like:
(assign (constant bool (1)) (swiz x (var_ref __retval) ) (var_ref a) )
(assign (constant bool (1)) (swiz y (var_ref __retval) ) (var_ref b) )
(assign (constant bool (1)) (swiz z (var_ref __retval) ) (var_ref c) )
(assign (constant bool (1)) (swiz x (var_ref __retval) ) (var_ref a) )
(assign (constant bool (1)) (swiz y (var_ref __retval) ) (var_ref b) )
(assign (constant bool (1)) (swiz z (var_ref __retval) ) (var_ref c) )
If every masked update of a component relies on the previous value of
the variable, then we're probably going to be quite limited in our
@ -183,7 +183,7 @@ ir_validate.cpp (check users have the right types)
You may also need to update the backends if they will see the new expr type:
../mesa/shaders/ir_to_mesa.cpp
../mesa/program/ir_to_mesa.cpp
You can then use the new expression from builtins (if all backends
would rather see it), or scan the IR and convert to use your new
@ -225,4 +225,4 @@ Initially, there really wasn't one. We have since adopted one:
- Files that implement a class that is used throught the code should
take the name of that class (e.g., ir_hierarchical_visitor.cpp).
- Files that contain code not fitting in one of the previous
categories should have a sensible name (e.g., glsl_parser.ypp).
categories should have a sensible name (e.g., glsl_parser.yy).