Bug: tint:1427
Change-Id: Ide2b89ac5f61237d0d39c1210dadaf9587c5db97
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/80360
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Stephen White <senorblanco@chromium.org>
Commit-Queue: Stephen White <senorblanco@chromium.org>
Don't lose reference-ness of expression. This is necessary for
assignments via the hoisted variable, for example.
Bug: tint:1300
Change-Id: I8e633f20e50541bb70becc5069019f795ec11e01
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/80540
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
This replaces the @override keyword that was previously used for
pipeline-overridable constants.
Support for pipeline-overridable constants in Dawn is hidden behind
the "disallow-unsafe-APIs" toggle, so we can make this change directly
instead of deprecating and continuing to support the old syntax.
Fixed: tint:1403
Change-Id: I9b2957a1e33b12772bfe449c0f3a31d929f8aa8b
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/80480
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: James Price <jrprice@google.com>
Change-Id: Ifef0b3bb449de2bffc5bc3b84886d4f678971620
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/80521
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Stephen White <senorblanco@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>
(I know it's deprecated, I'm just being a completist.)
Bug: tint:1222
Change-Id: Ie7716d2f5dd2d2bd2245ba2b0fe7ed8705574de0
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/80141
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
These still had vestiges of HLSL.
Bug: tint:1222
Change-Id: I5f93f75e7384db641f0c5421dca24a3e8f2b716e
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/80140
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
For the tint_all_transforms_fuzzer. Exercises the fact we now allow
declarations in any order.
Bug: tint:1266
Change-Id: I9ddfac90aaafe213cd860944f210718216cb3d13
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79770
Reviewed-by: Ryan Harrison <rharrison@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Allow module-scope declarations to be made in any order.
Bug: tint:1266
Change-Id: Ib2607b6c33fad7c83e2c36f85b0a965eac922ec5
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79769
Reviewed-by: David Neto <dneto@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Change-Id: Ib61ff92d373b63c39bbf664a2c67d5f0b8e9bd2e
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/80080
Auto-Submit: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>
Reviewed-by: David Neto <dneto@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
That is, bring back both VarForDynamicIndex and
PromoteInitializersToConstVar. This is not a complete revert, though:
* VarForDynamicIndex no longer depends on ForLoopToLoop
* Both can cope with hoisting from "else if"
* More unit tests were added in the interim
Delete PromoteSideEffectsToDecl for now. This may be brought back to
handle ensuring order of evaluation.
Bug: tint:1300
Change-Id: I8bbae46377ec4603cc02c1eb3f0661a8461a19fa
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79940
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
This is an ongoing LUCI config format migration.
R=jrprice@google.com
Change-Id: I12c2913b61f97ea1a4108ac9e5cc0b46f0be3765
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79960
Auto-Submit: Vadim Shtayura <vadimsh@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Ryan Harrison (use @chromium.org) <rharrison@google.com>
Commit-Queue: Ryan Harrison (use @chromium.org) <rharrison@google.com>
This significantly simplifies the calling code from Dawn.
It does require moving the SingleEntryPoint transform above the
renamer, since we need to call SEP with the original name. That is
probably also an optimization, since we do the subsequent transforms
with a culled AST.
Bug: tint:1268
Change-Id: I1f48ec0238ea76310742c60b119311747dd3dbac
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/80020
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
MultiplanarExternalTexture cannot deal with out-of-order declarations.
Re-work things so that it can.
Bug: tint:1266
Change-Id: Ie2c8237be4f6ddb91120cbeb25f3c186b572ba59
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79768
Reviewed-by: David Neto <dneto@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
As the resolver currently enforces in-order declarations, this does not
change the declaration order from iterating over the
ast::Module::GlobalDeclarations.
The MSL backend has been changed to use the
sem::Module::DependencyOrderedDeclarations list instead of looping over
different declaration types separately.
Bug: tint:1266
Change-Id: I698d612032285311017bfceab3c42adae1928a0e
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79767
Reviewed-by: James Price <jrprice@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Holds `DependencyOrderedDeclarations()`, which will hold the
sorted dependency-graph ordered list of global declarations.
Bug: tint:1266
Change-Id: I9840fae8689abd214973ea4785f71c3ae2587bbc
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79766
Reviewed-by: James Price <jrprice@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
If you attempted to:
* Use a function as a type
* Use a variable as a type
* Use a variable as a call target
You would get an ICE. Replace these with proper error diagnostics.
Change-Id: Ibbe4cd1b59b1aadd451aa0445ad137859aa071eb
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79765
Reviewed-by: James Price <jrprice@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
This toggle controls if the fuzzer will throw a fatal error in the
case that the shader becomes invalid.
Currently the fuzzers do no guarantee that the options that are
provided are correct/valid, so there are many uninteresting cases that
become invalid due to the limited nature of the fuzzers, not due to
bugs in the code. The default off state of this toggle will suppress
this noise.
Once https://bugs.chromium.org/p/tint/issues/detail?id=1356 is
implemented this toggle can be default on.
BUG=tint:1357,chromium:1294533
Change-Id: I7170e5a30691105c97e20d8337aadf81ac2bc3bc
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79840
Reviewed-by: Ben Clayton <bclayton@google.com>
Auto-Submit: Ryan Harrison <rharrison@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Will be used to implement order of execution.
Bug: tint:1300
Change-Id: I027295e482da7a3f9d7ca930b5303e8f89d7fe09
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79824
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
Introduce a glsl::Version, to allow the client to specify ES or
Desktop, as well as the desired GLSL major and minor version.
Bug: tint:1422
Change-Id: I4116bc2da40ae6a553dc2522d042dda1464a0c05
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79700
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
This is a check that has been added to newer versions of clang and is
tripping for me locally. The actual issue is in code being generated
by protobuf.
Updating protobufs has cross-dependency issues with spriv-tools, so is
non-trivial. There is already a special case suppression for internal
protobuf issues, so I am just adding to the carve out.
BUG=tint:1419
Change-Id: I3ecd111a778fb4c65a113382ded8d6160deab462
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79841
Auto-Submit: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Declare the list of transforms once, and use this for the usage message and when a transform does not match.
Simplifies adding new transforms to the command line tool.
Change-Id: I57ec433d8a570dae465d1837f5a4c1d89b8cff05
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79280
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Also make tests more idiomatic by removing diamonds in the Node
hierarchy.
Bug: tint:1300
Change-Id: I681f4251bd8d9bdef169dcdf5de345792c927436
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79680
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
Other shader types don't need this.
Also fix code style of member var.
Bug: tint:1360
Change-Id: Ic3600ec7c6da9b85b57655fabbf1f2e44b0ea7d3
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79640
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
We'll need this to build the GLSL backend in Dawn, since we don't want
glslang there.
Bug: tint:1217
Change-Id: Ied44ca89286c1d53a2e58a7083f0bfb859976770
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79500
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
Currently contains a subset of ast nodes to make it easier to debug.
Bug: tint:1331
Change-Id: I27afe3c57aa752bdf823120e31585100c8adbe36
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79460
Auto-Submit: Antonio Maiorano <amaiorano@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
This is not 100% correct (the exceptions for mat2 and friends are not
implemented yet), but gets more tests passing in Dawn.
Bug: tint:1415
Change-Id: Ia11c63a5236f35e724431a65ddb6ef3c598775d0
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79380
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: David Neto <dneto@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
Use the TypeInfo already obtained from the object instead of calling As<T>() again, which would trigger another virtual call.
Bug: tint:1383
Change-Id: I0394ea049589b0f7f72c80509ac8e9536196f368
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79302
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Use a bloom-filter-style early rejection to eliminate whole blocks of
case statements from the switch type checks. Much like IsAnyOf(), the
list of types considered are recursively tested as a whole and
then binary-chopped if there's a potential match, until we test the
individual switch case types.
Bug: tint:1383
Change-Id: I5b30f19ea070e8352bf6b9363f133da906013182
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78544
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: David Neto <dneto@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Ben Clayton <bclayton@chromium.org>
The MSL headers have annotations that requires that the lod for 1D
textures is a constexpr with value 0. This affects .get_width() and
.read().
Bug: dawn:814
Change-Id: Ic21d32067061afe67a16fbbeee222ab695b53066
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79301
Reviewed-by: Ben Clayton <bclayton@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Auto-Submit: Corentin Wallez <cwallez@chromium.org>
In GLSL, gl_SampleID and gl_SampleMask[In] require the
GL_OES_sample_variables extension, so output:
"#extension GL_OES_sample_variables : require"
in the header if those builtins is used.
Note that extensions must be inserted before the default precision
declaration, but helpers must be inserted after it, so we set a flag
and emit extensions, then the precision declaration, then helpers.
Further fixes:
- use gl_SampleMaskIn for input builtins, gl_SampleMask for output,
necessitating the addition of a storage class to GLSLBuiltinToString()
- fix the handling of gl_SampleMaskIn: it's array<i32> in GLSL, not
array<u32> as in SPIR-V
- centralize conversions for GLSL builtins used as input variables in
FromGLSLBuiltin()
- implement bitcasts on assignment to GLSL builtin output variables,
centralized in ToGLSLBuiltin()
- update the extension handling in the GLSL writer to check for both
sample_index and sample_mask.
- call UnwrapRef() in GLSL's EmitBitcast(). In the test case, we were
not recognizing the argument as a uint, yielding float() instead of
uintBitsToFloat().
Bug: tint:1408, tint:1412, tint:1414
Change-Id: Ie01541eb6e7cdf4e21347341f988bff916346797
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78920
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
Transform any SPIR-V that has an array with a custom stride:
@stride(S) array<T, N>
into:
struct strided_arr {
@size(S) er : T;
};
array<strided_arr, N>
Also remove any @stride decorations that match the default array stride.
Bug: tint:1394
Bug: tint:1381
Change-Id: I8be8f3a76c5335fdb2bc5183388366091dbc7642
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78781
Reviewed-by: David Neto <dneto@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
A type dispatch helper with replaces chains of:
if (auto* a = obj->As<A>()) {
...
} else if (auto* b = obj->As<B>()) {
...
} else {
...
}
with:
Switch(obj,
[&](A* a) { ... },
[&](B* b) { ... },
[&](Default) { ... });
This new helper provides greater opportunities for optimizations, avoids
scoping issues with if-else blocks, and is slightly cleaner (IMO).
Bug: tint:1383
Change-Id: Ice469a03342ef57cbcf65f69753e4b528ac50137
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78543
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: David Neto <dneto@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
The fields `has_location_decoration` and `location_decoration` are references to `has_location_attribute` and `location_attribute`, respectively, which act as an alias for a field-rename.
The default copy-constructor was copying across the reference (pointer) to the source StageVariable, instead of making a reference to the target's fields. This is causing Bad Things™ to happen in downstream projects.
Credit to dneto@ for identifying the issue, and for making this fix (which I've stolen for this CL).
Change-Id: Id0570e4e389f28980fa5aea29ad63b5100373dc5
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79200
Reviewed-by: David Neto <dneto@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
The CombineSamplers transform was incorrectly flagging StorageTexture
(which in GLSL ends up as image2D) as needing to be combined with a
sampler, or at least renamed. This is incorrect: StorageTexture never
has an associated sampler, so don't try to pair it up and just output
it as image* in GLSL.
In GLSL, textureLoad (aka texelFetch) of depth textures is not allowed.
The fix is to bind the depth texture as the corresponding f32 texture
instead (e.g., texture_depth_2d -> texture_2d<f32>,
texture_depth_cube -> texture_cube<f32>, etc). This requires changing
both the uniform globals and function parameter types. We're now going
to receive a vec4 instead of a float from texelFetch, so add a ".x"
member accessor to retrieve the first component. (Note that we don't
do this inside a CallStatement since this gives the CloneContext
indigestion, and CallStatement is going to ignore the result of the
call anyway.)
We were failing to find the dummy samplers that Dawn creates for the
calls that actually do require a dummy sampler, since the old Inspector
implementation of GetSamplerTextureUses() does not find them. The fix
is to implement a new Inspector call to return the texture/sampler
pairs the Resolver found during resolution. This will include the
dummy sampler as a null variable pointer.
In order to identify the placeholder sampler, we pass in a BindingPair
to represent it. When we discover a null sampler in the variable pair,
we return the passed-in placeholder binding point to the caller (Dawn).
(Dawn will use a group of kMaxBindGroups, to ensure that it never
collides with an existing sampler.)
Bug: tint:1298
Change-Id: I82e142c2b4318608c27a9fa9521c27f15a6214cd
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78820
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
BUG=tint:1413
Change-Id: I6a4735a97f64003cb4999d6a64b64666d0ce08ad
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79140
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Auto-Submit: Ryan Harrison <rharrison@chromium.org>
Kokoro: Ryan Harrison <rharrison@chromium.org>
Mostly typos and one case of a return not being error checked.
Change-Id: Id33e93402b05c165aa129bb22e4b0c7f55b0a71b
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/79141
Kokoro: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Document how to obtain the commit-msg hook and how to push a change for review.
Change-Id: If39e98e2fc20be549a08c88839b4d96a8ab7935b
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78784
Auto-Submit: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: David Neto <dneto@google.com>
Commit-Queue: David Neto <dneto@google.com>
We haven't been correctly checking the esoteric set of rules around breaks in continuing statements.
Bug: chromium:1288919
Change-Id: Ica6a0e71d06d9b204c359fea5f778db2383e6fa1
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78860
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: David Neto <dneto@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
This matches the term used in the WGSL spec.
Change-Id: I4603332b828450c126ef806f1064ed54f372013f
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78787
Reviewed-by: James Price <jrprice@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
This matches (mostly) the term used in the WGSL spec.
Change-Id: Ie148a1ca8498698e91fdbb60e1aeb0d509b80630
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78786
Reviewed-by: James Price <jrprice@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
1) Append "Shadow" to samplers representing depth textures.
2) Sampling a depth texture returns f32, not vec4<f32>
3) Sampling a depth texture requires a Dref parameter, so we must
generate one if none is provided.
4) GLSL requires Dref to be appended to the texture coordinates vector,
*unless* it's a samplerCubeArrayShadow, since this would require vec5.
In that case, it's passed as a separate parameter.
5) GLSL's textureGather() with a depth sampler always requires a refZ
parameter, so provide zero to emulate WGSL's compare-less textureGather().
6) texelFetch() does not support depth textures, so this will have to be
validated out.
7) textureOffset() does not support sampler2DArrayShadow in GLES, so this will
have to be validated out.
Bug: tint:1298
Change-Id: Idaebe89cac6c1ec97c50a361b1d3aa3b84fb6c12
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78760
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>
Split IsAnyOf() into log(n) stages, where each stage performs a hashcode
check.
Previously there was a single hash test across the bitwise-or of all the
types being considered. If this passed, then each type would be tested
with Is<T>() individually. With this change, the list of types will be
recursively split into two, which each block hash-code checked. This is
repeated until we reach fewer than 4 types to check, where the test
decays to using Is<T>() for each type.
Also renamed `combined_hashcode` to `full_hashcode`, and used the term
CombinedHash for new helpers that bitwise-or the hashes from a number
of types.
Bug: tint:1383
Change-Id: Id056b9f7a9792430bd75ce554cb5fe73221ca4c7
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78580
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
Kokoro: Ben Clayton <bclayton@google.com>
When converting a for-loop to a loop, we were not cloning the for-loop's
body, but rather the statements within it. This worked fine, except if
we also hoisted a variable to a let within that body, which requires the
body to be cloned for the 'insert before' to work. This change clones
the for-loop body, which fixes the problem, but introduces a block in
the destination AST, which is ugly, but not incorrect.
Bug: tint:1300
Change-Id: I478244d87f8cf58837102004242ba1c835e21710
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/78821
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>