Simple architecture document

This CL adds the start of an architecture document which can be expanded
as needed. The document is mostly an architecture diagram of how the
various pieces fit together.

Change-Id: I49b6509b9178928d100aece3c284199060969b6c
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/28660
Reviewed-by: David Neto <dneto@google.com>
Commit-Queue: dan sinclair <dsinclair@chromium.org>
This commit is contained in:
dan sinclair 2020-09-21 16:00:11 +00:00 committed by Commit Bot service account
parent cb907b5bc2
commit b6841789bd
1 changed files with 94 additions and 0 deletions

94
docs/arch.md Normal file
View File

@ -0,0 +1,94 @@
# Tint Architecture
```
+--------+ +------+
| SPIR-V | | WGSL |
+----|---+ +---|--+
| |
| |
+---------|---------------------------|--------+
| | Reader | |
| | | |
| +-------|------+ +------|------+ |
| | SPIRV-Reader | | WGSL-Reader | |
| +--------------+ +-------------+ |
+-----------------------|----------------------+
|
|
+--|--+ +---------+
| AST |------| IsValid |
+--|--+ +---------+
|
|
+--------|--------+
| Type Determiner |
+--------|--------+
|
|
+-----|-----+
| Validator |
+-----|-----+
|
|
+------|-----+
| Transforms |
+------|-----+
|
|
+-------------------------------------|------------------------------------+
| Writer |
| |
| +--------------+ +-------------+ +-------------+ +------------+ |
| | SPIRV-Writer | | WGSL-Writer | | HLSL-Writer | | MSL-Writer | |
| +-------|------+ +------|------+ +------|------+ +------|-----+ |
+---------|------------------|------------------|------------------|-------+
| | | |
| | | |
| | | |
+----|---+ +---|--+ +---|--+ +--|--+
| SPIR-V | | WGSL | | HLSL | | MSL |
+--------+ +------+ +------+ +-----+
```
## WGSL Reader
The WGSL reader is a recursive descent parser. It closely follows the WGSL
grammar in the naming of the parse methods.
## AST
After generation the AST will run an `IsValid` method which verifies that the
produced AST is structurally correct. This means that things like `if`
statements have a condition and body attached.
## Type Determiner
The type determination stage assigns a result type to each node in the AST. It
will do the minimal amount of validation required in order to always be
accessing valid nodes, but that doesn't mean the overall AST is valid. (e.g. a
4 component vector type constructor with 5 components will pass type
determination but is invalid.)
## Validation
After the validation step the AST should be a known valid WGSL program.
## Transforms
There maybe various transforms we want to run over the AST. This is for things
like Vertex Pulling or Robust Buffer Access. These transforms will modify the
AST and must produce valid AST after their execution.
Currently the transforms are run individually but we should consider adding
a transform manager to maintain and execute the list of transforms.
## Writers
The writers should be thread safe, we maybe generating the HLSL and MLS output
at the same time on different threads. (The writer portion is the only one
that needs to be thread safe.)