Resolver: collect unique texture/samplers pairs.

GLSL does not support separate textures and samplers, so they must be
replaced with combined samplers. This is the first stage of that change,
where we collect the unique texture/sampler pairs. Within a function,
texture and sampler must be either a global variable or a function
parameter. At the entry point level, all references must resolve to global
variables, so by recursing the call graph we can determine all of the
global pairs required.

This information will be used by an upcoming transform to modify the AST
to be GLSL-compliant: modifying function signatures, call sites, removing
separate globals and adding combined globals. It will also eventually
replace the pair-gathering currently performed by
Inspector::GetSamplerTextureUses().

Bug: tint:1366
Change-Id: I89451b195649da26e45641ea2f6955683ae9fc66
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/75960
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>

src/resolver/resolver.cc

@@ -1400,10 +1400,26 @@ sem::Call* Resolver::IntrinsicCall(
 
   current_function_->AddDirectlyCalledIntrinsic(intrinsic);
 
-  if (IsTextureIntrinsic(intrinsic_type) &&
+  if (IsTextureIntrinsic(intrinsic_type)) {
-      !ValidateTextureIntrinsicFunction(call)) {
+    if (!ValidateTextureIntrinsicFunction(call)) {
       return nullptr;
     }
+    // Collect a texture/sampler pair for this intrinsic.
+    const auto& signature = intrinsic->Signature();
+    int texture_index = signature.IndexOf(sem::ParameterUsage::kTexture);
+    if (texture_index == -1) {
+      TINT_ICE(Resolver, diagnostics_)
+          << "texture intrinsic without texture parameter";
+    }
+
+    auto* texture = args[texture_index]->As<sem::VariableUser>()->Variable();
+    int sampler_index = signature.IndexOf(sem::ParameterUsage::kSampler);
+    const sem::Variable* sampler =
+        sampler_index != -1
+            ? args[sampler_index]->As<sem::VariableUser>()->Variable()
+            : nullptr;
+    current_function_->AddTextureSamplerPair(texture, sampler);
+  }
 
   if (!ValidateIntrinsicCall(call)) {
     return nullptr;
@@ -1439,6 +1455,26 @@ sem::Call* Resolver::FunctionCall(
     for (auto* var : target->TransitivelyReferencedGlobals()) {
       current_function_->AddTransitivelyReferencedGlobal(var);
     }
+
+    // Map all texture/sampler pairs from the target function to the
+    // current function. These can only be global or parameter
+    // variables. Resolve any parameter variables to the corresponding
+    // argument passed to the current function. Leave global variables
+    // as-is. Then add the mapped pair to the current function's list of
+    // texture/sampler pairs.
+    for (sem::VariablePair pair : target->TextureSamplerPairs()) {
+      const sem::Variable* texture = pair.first;
+      const sem::Variable* sampler = pair.second;
+      if (auto* param = texture->As<sem::Parameter>()) {
+        texture = args[param->Index()]->As<sem::VariableUser>()->Variable();
+      }
+      if (sampler) {
+        if (auto* param = sampler->As<sem::Parameter>()) {
+          sampler = args[param->Index()]->As<sem::VariableUser>()->Variable();
+        }
+      }
+      current_function_->AddTextureSamplerPair(texture, sampler);
+    }
   }
 
   target->AddCallSite(call);

src/resolver/resolver_test.cc

@@ -2021,6 +2021,146 @@ TEST_F(ResolverTest, UnaryOp_Negation) {
   EXPECT_FALSE(r()->Resolve());
   EXPECT_EQ(r()->error(), "12:34 error: cannot negate expression of type 'u32");
 }
+
+TEST_F(ResolverTest, TextureSampler_TextureSample) {
+  Global("t", ty.sampled_texture(ast::TextureDimension::k2d, ty.f32()),
+         GroupAndBinding(1, 1));
+  Global("s", ty.sampler(ast::SamplerKind::kSampler), GroupAndBinding(1, 2));
+
+  auto* call = CallStmt(Call("textureSample", "t", "s", vec2<f32>(1.0f, 2.0f)));
+  const ast::Function* f = Func("test_function", {}, ty.void_(), {call},
+                                {Stage(ast::PipelineStage::kFragment)});
+
+  EXPECT_TRUE(r()->Resolve()) << r()->error();
+
+  const sem::Function* sf = Sem().Get(f);
+  auto pairs = sf->TextureSamplerPairs();
+  ASSERT_EQ(pairs.size(), 1u);
+  EXPECT_TRUE(pairs[0].first != nullptr);
+  EXPECT_TRUE(pairs[0].second != nullptr);
+}
+
+TEST_F(ResolverTest, TextureSampler_TextureSampleInFunction) {
+  Global("t", ty.sampled_texture(ast::TextureDimension::k2d, ty.f32()),
+         GroupAndBinding(1, 1));
+  Global("s", ty.sampler(ast::SamplerKind::kSampler), GroupAndBinding(1, 2));
+
+  auto* inner_call =
+      CallStmt(Call("textureSample", "t", "s", vec2<f32>(1.0f, 2.0f)));
+  const ast::Function* inner_func =
+      Func("inner_func", {}, ty.void_(), {inner_call});
+  auto* outer_call = CallStmt(Call("inner_func"));
+  const ast::Function* outer_func =
+      Func("outer_func", {}, ty.void_(), {outer_call},
+           {Stage(ast::PipelineStage::kFragment)});
+
+  EXPECT_TRUE(r()->Resolve()) << r()->error();
+
+  auto inner_pairs = Sem().Get(inner_func)->TextureSamplerPairs();
+  ASSERT_EQ(inner_pairs.size(), 1u);
+  EXPECT_TRUE(inner_pairs[0].first != nullptr);
+  EXPECT_TRUE(inner_pairs[0].second != nullptr);
+
+  auto outer_pairs = Sem().Get(outer_func)->TextureSamplerPairs();
+  ASSERT_EQ(outer_pairs.size(), 1u);
+  EXPECT_TRUE(outer_pairs[0].first != nullptr);
+  EXPECT_TRUE(outer_pairs[0].second != nullptr);
+}
+
+TEST_F(ResolverTest, TextureSampler_TextureSampleFunctionDiamondSameVariables) {
+  Global("t", ty.sampled_texture(ast::TextureDimension::k2d, ty.f32()),
+         GroupAndBinding(1, 1));
+  Global("s", ty.sampler(ast::SamplerKind::kSampler), GroupAndBinding(1, 2));
+
+  auto* inner_call_1 =
+      CallStmt(Call("textureSample", "t", "s", vec2<f32>(1.0f, 2.0f)));
+  const ast::Function* inner_func_1 =
+      Func("inner_func_1", {}, ty.void_(), {inner_call_1});
+  auto* inner_call_2 =
+      CallStmt(Call("textureSample", "t", "s", vec2<f32>(3.0f, 4.0f)));
+  const ast::Function* inner_func_2 =
+      Func("inner_func_2", {}, ty.void_(), {inner_call_2});
+  auto* outer_call_1 = CallStmt(Call("inner_func_1"));
+  auto* outer_call_2 = CallStmt(Call("inner_func_2"));
+  const ast::Function* outer_func =
+      Func("outer_func", {}, ty.void_(), {outer_call_1, outer_call_2},
+           {Stage(ast::PipelineStage::kFragment)});
+
+  EXPECT_TRUE(r()->Resolve()) << r()->error();
+
+  auto inner_pairs_1 = Sem().Get(inner_func_1)->TextureSamplerPairs();
+  ASSERT_EQ(inner_pairs_1.size(), 1u);
+  EXPECT_TRUE(inner_pairs_1[0].first != nullptr);
+  EXPECT_TRUE(inner_pairs_1[0].second != nullptr);
+
+  auto inner_pairs_2 = Sem().Get(inner_func_2)->TextureSamplerPairs();
+  ASSERT_EQ(inner_pairs_1.size(), 1u);
+  EXPECT_TRUE(inner_pairs_2[0].first != nullptr);
+  EXPECT_TRUE(inner_pairs_2[0].second != nullptr);
+
+  auto outer_pairs = Sem().Get(outer_func)->TextureSamplerPairs();
+  ASSERT_EQ(outer_pairs.size(), 1u);
+  EXPECT_TRUE(outer_pairs[0].first != nullptr);
+  EXPECT_TRUE(outer_pairs[0].second != nullptr);
+}
+
+TEST_F(ResolverTest,
+       TextureSampler_TextureSampleFunctionDiamondDifferentVariables) {
+  Global("t1", ty.sampled_texture(ast::TextureDimension::k2d, ty.f32()),
+         GroupAndBinding(1, 1));
+  Global("t2", ty.sampled_texture(ast::TextureDimension::k2d, ty.f32()),
+         GroupAndBinding(1, 2));
+  Global("s", ty.sampler(ast::SamplerKind::kSampler), GroupAndBinding(1, 3));
+
+  auto* inner_call_1 =
+      CallStmt(Call("textureSample", "t1", "s", vec2<f32>(1.0f, 2.0f)));
+  const ast::Function* inner_func_1 =
+      Func("inner_func_1", {}, ty.void_(), {inner_call_1});
+  auto* inner_call_2 =
+      CallStmt(Call("textureSample", "t2", "s", vec2<f32>(3.0f, 4.0f)));
+  const ast::Function* inner_func_2 =
+      Func("inner_func_2", {}, ty.void_(), {inner_call_2});
+  auto* outer_call_1 = CallStmt(Call("inner_func_1"));
+  auto* outer_call_2 = CallStmt(Call("inner_func_2"));
+  const ast::Function* outer_func =
+      Func("outer_func", {}, ty.void_(), {outer_call_1, outer_call_2},
+           {Stage(ast::PipelineStage::kFragment)});
+
+  EXPECT_TRUE(r()->Resolve()) << r()->error();
+
+  auto inner_pairs_1 = Sem().Get(inner_func_1)->TextureSamplerPairs();
+  ASSERT_EQ(inner_pairs_1.size(), 1u);
+  EXPECT_TRUE(inner_pairs_1[0].first != nullptr);
+  EXPECT_TRUE(inner_pairs_1[0].second != nullptr);
+
+  auto inner_pairs_2 = Sem().Get(inner_func_2)->TextureSamplerPairs();
+  ASSERT_EQ(inner_pairs_2.size(), 1u);
+  EXPECT_TRUE(inner_pairs_2[0].first != nullptr);
+  EXPECT_TRUE(inner_pairs_2[0].second != nullptr);
+
+  auto outer_pairs = Sem().Get(outer_func)->TextureSamplerPairs();
+  ASSERT_EQ(outer_pairs.size(), 2u);
+  EXPECT_TRUE(outer_pairs[0].first == inner_pairs_1[0].first);
+  EXPECT_TRUE(outer_pairs[0].second == inner_pairs_1[0].second);
+  EXPECT_TRUE(outer_pairs[1].first == inner_pairs_2[0].first);
+  EXPECT_TRUE(outer_pairs[1].second == inner_pairs_2[0].second);
+}
+
+TEST_F(ResolverTest, TextureSampler_TextureDimensions) {
+  Global("t", ty.sampled_texture(ast::TextureDimension::k2d, ty.f32()),
+         GroupAndBinding(1, 2));
+
+  auto* call = Call("textureDimensions", "t");
+  const ast::Function* f = WrapInFunction(call);
+
+  EXPECT_TRUE(r()->Resolve()) << r()->error();
+
+  const sem::Function* sf = Sem().Get(f);
+  auto pairs = sf->TextureSamplerPairs();
+  ASSERT_EQ(pairs.size(), 1u);
+  EXPECT_TRUE(pairs[0].first != nullptr);
+  EXPECT_TRUE(pairs[0].second == nullptr);
+}
 }  // namespace
 }  // namespace resolver
 }  // namespace tint

src/sem/function.h

@@ -132,6 +132,23 @@ class Function : public Castable<Function, CallTarget> {
     directly_called_intrinsics_.add(intrinsic);
   }
 
+  /// Adds the given texture/sampler pair to the list of unique pairs
+  /// that this function uses (directly or indirectly). These can only
+  /// be parameters to this function or global variables. Uniqueness is
+  /// ensured by texture_sampler_pairs_ being a UniqueVector.
+  /// @param texture the texture (must be non-null)
+  /// @param sampler the sampler (null indicates a texture-only reference)
+  void AddTextureSamplerPair(const sem::Variable* texture,
+                             const sem::Variable* sampler) {
+    texture_sampler_pairs_.add(VariablePair(texture, sampler));
+  }
+
+  /// @returns the list of texture/sampler pairs that this function uses
+  /// (directly or indirectly).
+  const std::vector<VariablePair>& TextureSamplerPairs() const {
+    return texture_sampler_pairs_;
+  }
+
   /// @returns the list of direct calls to functions / intrinsics made by this
   /// function
   std::vector<const Call*> DirectCallStatements() const {
@@ -259,6 +276,7 @@ class Function : public Castable<Function, CallTarget> {
   utils::UniqueVector<const GlobalVariable*> transitively_referenced_globals_;
   utils::UniqueVector<const Function*> transitively_called_functions_;
   utils::UniqueVector<const Intrinsic*> directly_called_intrinsics_;
+  utils::UniqueVector<VariablePair> texture_sampler_pairs_;
   std::vector<const Call*> direct_calls_;
   std::vector<const Call*> callsites_;
   std::vector<const Function*> ancestor_entry_points_;

src/sem/variable.h

@@ -15,6 +15,7 @@
 #ifndef SRC_SEM_VARIABLE_H_
 #define SRC_SEM_VARIABLE_H_
 
+#include <utility>
 #include <vector>
 
 #include "src/ast/access.h"
@@ -248,7 +249,25 @@ class VariableUser : public Castable<VariableUser, Expression> {
   const sem::Variable* const variable_;
 };
 
+/// A pair of sem::Variables. Can be hashed.
+typedef std::pair<const Variable*, const Variable*> VariablePair;
+
 }  // namespace sem
 }  // namespace tint
 
+namespace std {
+
+/// Custom std::hash specialization for VariablePair
+template <>
+class hash<tint::sem::VariablePair> {
+ public:
+  /// @param i the variable pair to create a hash for
+  /// @return the hash value
+  inline std::size_t operator()(const tint::sem::VariablePair& i) const {
+    return tint::utils::Hash(i.first, i.second);
+  }
+};
+
+}  // namespace std
+
 #endif  // SRC_SEM_VARIABLE_H_

src/transform/transform.cc

@@ -142,6 +142,9 @@ const ast::Type* Transform::CreateASTTypeFor(CloneContext& ctx,
   if (auto* t = ty->As<sem::DepthMultisampledTexture>()) {
     return ctx.dst->create<ast::DepthMultisampledTexture>(t->dim());
   }
+  if (ty->Is<sem::ExternalTexture>()) {
+    return ctx.dst->create<ast::ExternalTexture>();
+  }
   if (auto* t = ty->As<sem::MultisampledTexture>()) {
     return ctx.dst->create<ast::MultisampledTexture>(
         t->dim(), CreateASTTypeFor(ctx, t->type()));