1 // Copyright 2021 The Tint Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14
15 #include "src/transform/external_texture_transform.h"
16
17 #include "src/program_builder.h"
18 #include "src/sem/call.h"
19 #include "src/sem/variable.h"
20
21 TINT_INSTANTIATE_TYPEINFO(tint::transform::ExternalTextureTransform);
22
23 namespace tint {
24 namespace transform {
25
26 ExternalTextureTransform::ExternalTextureTransform() = default;
27 ExternalTextureTransform::~ExternalTextureTransform() = default;
28
Run(CloneContext & ctx,const DataMap &,DataMap &)29 void ExternalTextureTransform::Run(CloneContext& ctx,
30 const DataMap&,
31 DataMap&) {
32 auto& sem = ctx.src->Sem();
33
34 // Within this transform, usages of texture_external are replaced with a
35 // texture_2d<f32>, which will allow us perform operations on a
36 // texture_external without maintaining texture_external-specific code
37 // generation paths in the backends.
38
39 // When replacing instances of texture_external with texture_2d<f32> we must
40 // also modify calls to the texture_external overloads of textureLoad and
41 // textureSampleLevel, which unlike their texture_2d<f32> overloads do not
42 // require a level parameter. To do this we identify calls to textureLoad and
43 // textureSampleLevel that use texture_external as the first parameter and add
44 // a parameter for the level (which is always 0).
45
46 // Scan the AST nodes for calls to textureLoad or textureSampleLevel.
47 for (auto* node : ctx.src->ASTNodes().Objects()) {
48 if (auto* call_expr = node->As<ast::CallExpression>()) {
49 if (auto* intrinsic =
50 sem.Get(call_expr)->Target()->As<sem::Intrinsic>()) {
51 if (intrinsic->Type() == sem::IntrinsicType::kTextureLoad ||
52 intrinsic->Type() == sem::IntrinsicType::kTextureSampleLevel) {
53 // When a textureLoad or textureSampleLevel has been identified, check
54 // if the first parameter is an external texture.
55 if (auto* var =
56 sem.Get(call_expr->args[0])->As<sem::VariableUser>()) {
57 if (var->Variable()
58 ->Type()
59 ->UnwrapRef()
60 ->Is<sem::ExternalTexture>()) {
61 if (intrinsic->Type() == sem::IntrinsicType::kTextureLoad &&
62 call_expr->args.size() != 2) {
63 TINT_ICE(Transform, ctx.dst->Diagnostics())
64 << "expected textureLoad call with a texture_external to "
65 "have 2 parameters, found "
66 << call_expr->args.size() << " parameters";
67 }
68
69 if (intrinsic->Type() ==
70 sem::IntrinsicType::kTextureSampleLevel &&
71 call_expr->args.size() != 3) {
72 TINT_ICE(Transform, ctx.dst->Diagnostics())
73 << "expected textureSampleLevel call with a "
74 "texture_external to have 3 parameters, found "
75 << call_expr->args.size() << " parameters";
76 }
77
78 // Replace the call with another that has the same parameters in
79 // addition to a level parameter (always zero for external
80 // textures).
81 auto* exp = ctx.Clone(call_expr->target.name);
82 auto* externalTextureParam = ctx.Clone(call_expr->args[0]);
83
84 ast::ExpressionList params;
85 if (intrinsic->Type() == sem::IntrinsicType::kTextureLoad) {
86 auto* coordsParam = ctx.Clone(call_expr->args[1]);
87 auto* levelParam = ctx.dst->Expr(0);
88 params = {externalTextureParam, coordsParam, levelParam};
89 } else if (intrinsic->Type() ==
90 sem::IntrinsicType::kTextureSampleLevel) {
91 auto* samplerParam = ctx.Clone(call_expr->args[1]);
92 auto* coordsParam = ctx.Clone(call_expr->args[2]);
93 auto* levelParam = ctx.dst->Expr(0.0f);
94 params = {externalTextureParam, samplerParam, coordsParam,
95 levelParam};
96 }
97
98 auto* newCall = ctx.dst->create<ast::CallExpression>(exp, params);
99 ctx.Replace(call_expr, newCall);
100 }
101 }
102 }
103 }
104 }
105 }
106
107 // Scan the AST nodes for external texture declarations.
108 for (auto* node : ctx.src->ASTNodes().Objects()) {
109 if (auto* var = node->As<ast::Variable>()) {
110 if (::tint::Is<ast::ExternalTexture>(var->type)) {
111 // Replace a single-plane external texture with a 2D, f32 sampled
112 // texture.
113 auto* newType = ctx.dst->ty.sampled_texture(ast::TextureDimension::k2d,
114 ctx.dst->ty.f32());
115 auto clonedSrc = ctx.Clone(var->source);
116 auto clonedSym = ctx.Clone(var->symbol);
117 auto* clonedConstructor = ctx.Clone(var->constructor);
118 auto clonedDecorations = ctx.Clone(var->decorations);
119 auto* newVar = ctx.dst->create<ast::Variable>(
120 clonedSrc, clonedSym, var->declared_storage_class,
121 var->declared_access, newType, var->is_const, clonedConstructor,
122 clonedDecorations);
123
124 ctx.Replace(var, newVar);
125 }
126 }
127 }
128
129 ctx.Clone();
130 }
131
132 } // namespace transform
133 } // namespace tint
134