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hadronized / glsl

GLSL parser for Rust
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Add a symbol table #72

Open jrmuizel opened 5 years ago

jrmuizel commented 5 years ago

This is needed to do semantic analysis and translation to spirv.

Do you have any thoughts on how you'd like to represent it?

glslang builds the symbol table during parsing and refers to it in the resulting parse tree. That has the advantage of not needing to represent both an unresolved syntax tree and a syntax tree with resolved symbols.

hadronized commented 5 years ago

Hm, I need to have more information / find more material about that symbole table they’re using. Do you have any link?

jrmuizel commented 5 years ago

Sure.

The symbol table is defined here: https://github.com/KhronosGroup/glslang/blob/f04f1f93a70f4608ffa9903b20bfb95f20a063f5/glslang/MachineIndependent/SymbolTable.h#L567

Here's an example of what happens:

During parsing declareVariable is called: https://github.com/KhronosGroup/glslang/blob/f04f1f93a70f4608ffa9903b20bfb95f20a063f5/glslang/MachineIndependent/glslang.y#L1056

declareVariable calls into declareNonArray https://github.com/KhronosGroup/glslang/blob/f04f1f93a70f4608ffa9903b20bfb95f20a063f5/glslang/MachineIndependent/ParseHelper.cpp#L6395

declareNonArray adds the typed symbol to the symbol table https://github.com/KhronosGroup/glslang/blob/f04f1f93a70f4608ffa9903b20bfb95f20a063f5/glslang/MachineIndependent/ParseHelper.cpp#L6551

Symbols are looked up during scanning https://github.com/KhronosGroup/glslang/blob/974a586688c169c5724faf34ed5ed6c8e7563711/glslang/MachineIndependent/Scan.cpp#L1643 and used like this https://github.com/KhronosGroup/glslang/blob/f04f1f93a70f4608ffa9903b20bfb95f20a063f5/glslang/MachineIndependent/glslang.y#L303

jrmuizel commented 5 years ago

Alternatively, the mesa glsl compiler parses to a low level AST and then lifts to a HIR: https://github.com/mesa3d/mesa/blob/4bf7e7b17092487b6b6c4aff5e920dbe1fd4470e/src/compiler/glsl/README

jrmuizel commented 5 years ago

I'm experimenting with HIR approach here: https://github.com/jrmuizel/glsl-to-spriv

hadronized commented 5 years ago

@jrmuizel great! I haven’t had enough spare time lately to look into that, but feel free to go for it! I’ll have a look at the code you wrote, I’m interested in the approach. :)