Implements https://github.com/gpuweb/gpuweb/pull/1447
SPIR-V Reader is still TODO, but continues to function as the offset
decoration is still supported.
Bug: tint:626
Bug: tint:629
Change-Id: Id574eb3a5c6729559382812de37b23f0c68fd406
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/43640
Commit-Queue: Ben Clayton <bclayton@chromium.org>
Reviewed-by: David Neto <dneto@google.com>
These were supposed to be deleted in 95d4077.
Change-Id: Ic2a08283a8f4255f107492fcfa1bb0f320969f73
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/44500
Auto-Submit: James Price <jrprice@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Remove the decoration groupings (Array, Function, Struct,
StructMember, Type, Variable), such that all *Decoration classes now
subclass ast::Decoration directly. This allows for decorations to be
used in multiple places; for example, builtin decorations are now
valid for both variables and struct members.
Checking that decoration lists only contain decorations that are valid
for the node that they are attached to is now done inside the
validator.
Change-Id: Ie8c0e53e5730a7dedea50a1dec8f26f9e7b00e8d
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/44320
Commit-Queue: James Price <jrprice@google.com>
Reviewed-by: Ben Clayton <bclayton@chromium.org>
The readers must not produce invalid ASTs.
If readers cannot produce a valid AST, then they should error instead.
If a reader does produce an invalid AST, this change catches this bad behavior early, significantly helping identify the root of the broken logic.
IsValid() made a bit more sense in the days where the AST was mutable, and was constructed by calling setters on the nodes to build up the tree.
In order to detect bad ASTs, IsValid() would have to perform an entire AST traversal and give a yes / no answer for the entire tree. Not only was this slow, an answer of 'no' didn't tell you *where* the AST was invalid, resulting in a lot of manual debugging.
Now that the AST is fully immutable, all child nodes need to be built before their parents. The AST node constructors now become a perfect place to perform pointer sanity checking.
The argument for attempting to catch and handle invalid ASTs is not a compelling one.
Invalid ASTs are invalid compiler behavior, not something that should ever happen with a correctly functioning compiler.
If this were to happen in production, the user would be utterly clueless to _why_ the program is invalid, or _how_ to fix it.
Attempting to handle invalid ASTs is just masking a much larger problem.
Let's just let the fuzzers do their job to catch any of these cases early.
Fixed: chromium:1185569
Change-Id: I6496426a3a9da9d42627d2c1ca23917bfd04cc5c
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/44048
Commit-Queue: Ben Clayton <bclayton@chromium.org>
Reviewed-by: David Neto <dneto@google.com>
All includes from .cc to .h are preserved, even when transitively included.
It's clear that there are far too many includes in header files, and we should be more aggressive with forward declarations. tint:532 will continue to track this work.
There are, however, plenty of includes that have accumulated over time which are no longer required directly or transitively, so this change starts with a clean slate of *required* includes.
Bug: tint:532
Change-Id: Ie1718dad565f8309fa180ef91bcf3920e76dba18
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/44042
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
We now keep track of scopes as a tree of BlockInfos that track variables
declared in each scope. For loop scopes, we store the index of the first
variable (if any) that follows the first continue statement. Using this
data structure, when parsing expressions, we validate that used
variables in continuing blocks are not bypassed by a continue statement
in the parent loop block.
Also:
* Validate that continue statements are in a loop in TD. This error is
already caught by the spir-v writer, but better to catch it here.
* Add more utility functions to ProgramBuilder to make it easier to
write tests
Fixed: tint:17
Change-Id: I967bf2cfb63062bac8dcca113d074ba0fe2152e2
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/44120
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
to TINT_INSTANTIATE_TYPEINFO()
ClassID isn't a thing any more.
Change-Id: Ie1c0d4a95e58ef7166d3cab5ef733a2dfc702345
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/42921
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: James Price <jrprice@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
This is a reland of cc4c22ebaa72a2365dc196c4a1496e5a36452cdc
Original change's description:
> Remove deprecated textureLoad overloads with no level param
>
> BUG=tint:516
>
> Change-Id: I7004e0dbd44d703c684118136b05b84cf609c6ba
> Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/42703
> Reviewed-by: Ben Clayton <bclayton@google.com>
> Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Bug: tint:516
Change-Id: Ic52893c78046cd54575cea51c244f6df5a4f843c
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/43620
Auto-Submit: Ryan Harrison <rharrison@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
This reverts commit cc4c22ebaa72a2365dc196c4a1496e5a36452cdc.
Reason for revert: Broke Dawn e2e tests w/ SwiftShader
Original change's description:
> Remove deprecated textureLoad overloads with no level param
>
> BUG=tint:516
>
> Change-Id: I7004e0dbd44d703c684118136b05b84cf609c6ba
> Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/42703
> Reviewed-by: Ben Clayton <bclayton@google.com>
> Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Bug: tint:516
Change-Id: I6b7857304872fd0048c23999ac223ce9dcaf7fe1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/43540
Reviewed-by: Ryan Harrison <rharrison@chromium.org>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Auto-Submit: Ryan Harrison <rharrison@chromium.org>
BUG=tint:516
Change-Id: I7004e0dbd44d703c684118136b05b84cf609c6ba
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/42703
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
With this change, the base IntLiteral class now stores a u32, and
derived UintLiteral and SintLiteral are implemented in terms of it. This
will allow us to improve the current pattern of casting down to each
derived type to retrieve the value.
Change-Id: I0c1e56c5e04333a0d3d5f30a3fb28e784f785843
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/42900
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Statements like `var u : u32 = 0;` should fail because '0' is a signed
integer being used to initialize an unsigned variable.
Added test.
Bug: tint:79
Change-Id: I34f6d21b4355167f49f9a8b5d4ed34a808823185
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/42702
Reviewed-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
BUG=tint:516
Change-Id: Ic075dc52618bc6d2492e82538f0f02d45f925ddf
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/42700
Auto-Submit: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
WGSL recently removed this concept, since it didn't exist in WebGPU,
so excising it from the code.
BUG=tint:515
Change-Id: Ibbca6bd643fd96c2fb10bd33f471c9e9e58de535
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/42320
Auto-Submit: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Lessens the friction of using these macros.
Also allows you to add a message to TINT_UNREACHABLE(), which you couldn't do before.
Change-Id: Ida4d63ec96e1d99af71503e8b80d7a5a712e6a47
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/42020
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Remove the Parser classes from the wgsl and spirv namespaces.
These have been replaced with a Parse() method.
Remove the TypeDeterminer::Run() method, this was not called by tint and
the TypeDeterminer is now non-public API.
Change-Id: I5ddb82768da04398ab3958d1647be44f9fe30c21
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/41840
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Appends an error message with the tint compiler source location to the
provided diagnositic list, and then calls the global error handler if
one is set.
Tests and the sample app now register an error handler to print the
diagnostic list to stderr and abort when NDEBUG is not defined.
All uses of assert(false) have been fixed up to use these macros.
Change-Id: I2f63e51ed86ac23883301d280070bd1a357c6cb2
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/41620
Commit-Queue: dan sinclair <dsinclair@chromium.org>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
The CloneContext was previously dealing with pointers to CastableBase, which has no guarantees that the object was actually cloneable.
Add a Cloneable base class that CloneContext can use instead.
Improves readability and produces cleaner compiler errors if you try to clone a non-cloneable object.
Change-Id: I4352fc5dab3da434e4ab160a54c4c82d50e427b4
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/41722
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Semantic info is no longer part of the ast, so it is now odd to mention semantic info on a clone method for the AST.
Improve the documentation around cloning on the Program methods and the CloneContext.
Change-Id: Ib1cf255acfd994521aaa5add2789e5117db6b072
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/41548
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Reviewed-by: David Neto <dneto@google.com>
Storage classes are unused for constants.
Also trim extra arguments to these variable constructor functions that are already defaulted to the same value.
Change-Id: Ia0b44364de000bfb8799de15827ce08fcce5f5be
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/41541
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Reviewed-by: David Neto <dneto@google.com>
Move the storage parameter after type.
Const() has no use for storage classes, so this parameter will be removed in the next change.
This reordering keeps Var() and Const() parameter types identical for the first two non-optional fields
Change-Id: I66669d19fa2175c4f10f615941e69efcab4c23e1
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/41540
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Other builtins use WGSL terms instead of SPIR-V terms too, and the
WGSL writer is relying on the output of `operator<<(Builtin)`, which
just stringifies the name of the enum. This also matches the
equivalent `semantic::Usage::kSampleIndex` enum.
Added test coverage for WGSL builtin generation.
Bug: tint:372
Change-Id: I8077d22c4a5ddf67b1ad07e7365453db74db8e7d
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/41660
Reviewed-by: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Commit-Queue: dan sinclair <dsinclair@chromium.org>
Auto-Submit: James Price <jrprice@google.com>
In C++ argument evaluation order is undefined. MSVC and Clang evaluate these in different orders, leading to hilarity when writing tests that expect a deterministic ordering.
Pull out all the argument expressions to create() in the clone functions so a cloned program is deterministic in its ordering between compilers.
Change-Id: I8e2de31398960c480ce7ee1dfaac4f67652d2dbc
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/41544
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Auto-Submit: Ben Clayton <bclayton@google.com>
Change 41302 correctly fixed up Module::Clone(), but this wasn't actually called by the CloneContext, as Module::Clone() returns a new Module, where as the CloneContext needs to clone into an existing Module.
Refactor the code so that this duplicated logic is moved into a single Module::Copy() method.
Fixed: 1177275
Change-Id: Ia8c45ef05e03b2891b5785ee6f425dd01cb989c6
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/41542
Reviewed-by: James Price <jrprice@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Commit-Queue: dan sinclair <dsinclair@chromium.org>
Adds a vector<CastableBase*> to ast::Module which stores the list of
global variables, functions, and types, in the order that they were
declared.
This will be used to fix validation and backend issues around name
uniqueness.
Change-Id: I14491f6ebc0fc7341bd3fb3b3f408faa234a91f7
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/41301
Commit-Queue: James Price <jrprice@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Automatically set the storage class to UniformConstant.
Producing an error if an explicit storage class is given is deferred
until downstream users have caught up.
Bug: tint:332
Change-Id: I70e7390dc95d6f578a0fdeb675ca63a8b5b4fa26
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/40160
Commit-Queue: dan sinclair <dsinclair@chromium.org>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Auto-Submit: James Price <jrprice@google.com>
Pull the mutable 'is_swizzled' semantic field from ast::MemberAccessorExpression and into a new semantic::MemberAccessorExpression node.
Have the TypeDeterminer create these semantic::MemberAccessorExpression nodes.
Bug: tint:390
Change-Id: I8fc6e36dabb417190528536a94d027af54059222
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/40142
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: David Neto <dneto@google.com>
This is more a property of a MemberAccessorExpression than the identifier itself.
Change-Id: Icb17df1fe43a959332d73df026e77ca4e07d23ed
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/40140
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: David Neto <dneto@google.com>
semantic::Call derives from semantic::Expression, and Type() is the return type of the function
Pull the mutable semantic field from ast::Identifier and into a new semantic nodes.
Have the TypeDeterminer create these new semantic nodes.
Note: This change also fixes the node that holds the semantic information for a call.
Previously this was on the identifier, and this is now correctly on the CallExpression.
The identifier of the CallExpression should resolve to the target function, not the return type.
Functions can currently be represented as a type, and the identifier of a CallExpression now has no semantic information.
Bug: tint:390
Change-Id: I03521da5634815d35022f45ba521372cbbdb6bc7
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/40065
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: David Neto <dneto@google.com>
The subtype of a storage texture is statically determinisic from the ImageFormat, and does not need to be late-set by the TypeDeterminer.
Add StorageTexture::SubtypeFor() helper for returning the subtype for a given ImageFormat, and add the subtype as another immutable constructor parameter.
Bug: tint:390
Change-Id: Ibe732293e3142064b60f4e666a7eb39ae8db50e7
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/40064
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: David Neto <dneto@google.com>
Pull the mutable semantic field from ast::Variable and into a new semantic::Variable node.
Have the TypeDeterminer create these semantic::Variable nodes.
Bug: tint:390
Change-Id: Ia13f5e7b065941ed66ea5a86c6ccb288071feff3
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/40063
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: David Neto <dneto@google.com>
Make private all TypeDeterminer::DetermineXXX() methods, forcing all tests to use the root-level TypeDeterminer::Determine() method.
Remove TypeDeterminer::RegisterVariableForTesting().
The main use for calling the TypeDeterminer::DetermineXXX() methods was to perform type determination on a partial AST.
This was messy and often resulting in multiple calls into TypeDeterminer. Most tests already perform a full TypeDeterminer::Determine() call when the program is built, so many of these were redundant.
The exposure of these internal methods for testing also makes refactoring the TypeDeterminer extremely difficult.
Add a number of ProgramBuilder helper methods for attaching the partial AST in these tests to the root of the AST, greatly simplifying the use of the TypeDeterminer:
* ProgramBuilder::Global() and ProgramBuilder::GlobalConst() are helpers that register the variable returned by ProgramBuilder::Var() and ProgramBuilder::Const(), respectively.
* ProgramBuilder::WrapInFunction() is a variadic function that accepts variables, expressions and statements, attaching these to the root of the AST via a dummy function.
Most test classes now no longer use their own TypeDeterminer, and instead properly depend on the automatic type determination performed at Program build time.
Bug: tint:390
Change-Id: Ie901890420c5de170cdf2a7aaef9b96fc3bebd60
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/40062
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: David Neto <dneto@google.com>
Pull the mutable semantic fields from ast::Function and into a new semantic::Function node.
Have the TypeDeterminer create these semantic::Function nodes.
Bug: tint:390
Change-Id: I237b1bed8709dd9a3cfa24d85d48fc77b7e532da
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/39902
Reviewed-by: David Neto <dneto@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
With the ast::Module::Functions().
Also remove pointless calls to td.Determine() that will automatically be
done when the program is built.
Change-Id: Ia7506e430b04d91d4f6b02fb6b678d0ea9912bcd
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/39900
Commit-Queue: dan sinclair <dsinclair@chromium.org>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Remove the mutable `result_type` from the ast::Expression.
Replace this with the use of semantic::Expression.
Bug: tint:390
Change-Id: I1f0eaf0dce8fde46fefe50bf2c5fe5b2e4d2d2df
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/39007
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Add helpers on Program and ProgramBuilder that significantly simplify
usage.
Also demangle - this also reduces a bunch of copy-pasta code.
Change-Id: I6215c346e7f6e49c20aced058a6150603253ed93
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/39342
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Will hold the mutable fields that currently reside in the otherwise immutable-AST.
Change the AST string methods to accept a `const semantic::Info&`. This is required as some nodes include type-resolved information in their output strings.
Bug: tint:390
Change-Id: Iba494a9c5645ce2096da0a8cfe63a4309a9d9c3c
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/39003
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
By putting diagnostics into the program, we can hold all the diagnostic messages for parsing and type determination in one place.
This also means that we can simplify the public WGSL and SPIR-V Parser interfaces to a single function.
Change-Id: Ib6ab5fa180addd45c4aaf0c6b192d47182ffb50a
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/38920
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>
This CL updates the type determiner to record if an identifier
expression is a swizzle and then uses that in the MSL and HLSL generator
to output the swizzle name directly.
Change-Id: I77c0e1e80dce9e2f09cbbd37476a146b06555ee2
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/38960
Auto-Submit: dan sinclair <dsinclair@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Program is now immutable*, and remains part of the public Tint
interface.
ProgramBuilder is the mutable builder for Programs, and is not part of
the public Tint interface. ast::Builder has been folded into
ProgramBuilder.
Immutable Programs can be cloned into a mutable ProgramBuilder with
Program::CloneAsBuilder().
Mutable ProgramBuilders can be moved into immutable Programs.
* - mostly immutable. It still has a move constructor and move
assignment operator - required for practical usage - and the
semantic information on AST nodes is still mutable.
Bug: tint:390
Change-Id: Ia856c50b1880c2f95c91467a9eef5024cbc380c6
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/38240
Reviewed-by: dan sinclair <dsinclair@chromium.org>
This builder will be merged into ProgramBuilder, where these will become methods.
To breakup this change, perform the refactoring as a separate change.
Bug: tint:390
Change-Id: I2c9151cd9f198e99d88eaf296dd994293df6c425
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/38720
Reviewed-by: dan sinclair <dsinclair@chromium.org>
This is required in order to support move operators for TypesBuilder.
Bug: tint:390
Change-Id: I9667bda5f5be267df092f5cd94dc40db053ae6e2
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/38555
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Have this take a SymbolTable instead of a Program.
Program will be split into Program (immutable) and ProgramBuilder (mutable). We'll need Demangler to support both.
Bug: tint:390
Change-Id: I6447dd9674919d4867ed8ba126880cdfd9bf7128
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/38550
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Holds the global variables, constructed types and functions.
Deprecate the functions on program that forward on to the module.
These will be fixed up in another change.
Bug: tint:390
Change-Id: I47b6921a7d84be18113dec830c8435d4e0d4182d
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/38544
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Enforce all places where Dawn passes in or returns a ast::Module, now takes a `const Program* ` or returns a `Program`.
As the end goal of all this is to have immutable Programs, all Program inputs take a pointer instead of moving the actual object.
As consumers of a Program are now all const, we have to const_cast to work around all the places we've been incorrectly mutating a ast::Module.
These const_casts are temporary, and will be fixed in the next set of changes.
Depends on https://dawn-review.googlesource.com/c/dawn/+/38522
Bug: tint:390
Change-Id: Ie05b112b16134937d1b601e9b713ea4ec4e1c677
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/38541
Reviewed-by: dan sinclair <dsinclair@chromium.org>
