Add support for multisampled textures.

This Cl adds the AST, WGSL-Reader and SPIRV-Writer support for the
`texture_multisampled_2d` type.

Bug: tint:237
Change-Id: Ib3eb831227b49f32162801f1e1b4e474774c78b3
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/28480
Commit-Queue: dan sinclair <dsinclair@chromium.org>
Reviewed-by: David Neto <dneto@google.com>
diff --git a/src/reader/wgsl/lexer.cc b/src/reader/wgsl/lexer.cc
index 66a2dc2..37bfeb5 100644
--- a/src/reader/wgsl/lexer.cc
+++ b/src/reader/wgsl/lexer.cc
@@ -657,6 +657,10 @@
     return {Token::Type::kTextureDepthCubeArray, source,
             "texture_depth_cube_array"};
   }
+  if (str == "texture_multisampled_2d") {
+    return {Token::Type::kTextureMultisampled2d, source,
+            "texture_multisampled_2d"};
+  }
   if (str == "texture_ro_1d")
     return {Token::Type::kTextureStorageReadonly1d, source, "texture_ro_1d"};
   if (str == "texture_ro_1d_array")
@@ -681,12 +685,6 @@
     return {Token::Type::kTextureSampled2dArray, source,
             "texture_sampled_2d_array"};
   }
-  if (str == "texture_sampled_2d_ms")
-    return {Token::Type::kTextureSampled2dMs, source, "texture_sampled_2d_ms"};
-  if (str == "texture_sampled_2d_ms_array") {
-    return {Token::Type::kTextureSampled2dMsArray, source,
-            "texture_sampled_2d_ms_array"};
-  }
   if (str == "texture_sampled_3d")
     return {Token::Type::kTextureSampled3d, source, "texture_sampled_3d"};
   if (str == "texture_sampled_cube")
diff --git a/src/reader/wgsl/lexer_test.cc b/src/reader/wgsl/lexer_test.cc
index 4806cb6..d21f3b6 100644
--- a/src/reader/wgsl/lexer_test.cc
+++ b/src/reader/wgsl/lexer_test.cc
@@ -401,7 +401,7 @@
   Lexer l(params.input);
 
   auto t = l.next();
-  EXPECT_TRUE(t.Is(params.type));
+  EXPECT_TRUE(t.Is(params.type)) << params.input;
   EXPECT_EQ(1u, t.line());
   EXPECT_EQ(1u, t.column());
 
@@ -505,6 +505,8 @@
         TokenData{"texture_depth_cube", Token::Type::kTextureDepthCube},
         TokenData{"texture_depth_cube_array",
                   Token::Type::kTextureDepthCubeArray},
+        TokenData{"texture_multisampled_2d",
+                  Token::Type::kTextureMultisampled2d},
         TokenData{"texture_ro_1d", Token::Type::kTextureStorageReadonly1d},
         TokenData{"texture_ro_1d_array",
                   Token::Type::kTextureStorageReadonly1dArray},
@@ -518,9 +520,6 @@
         TokenData{"texture_sampled_2d", Token::Type::kTextureSampled2d},
         TokenData{"texture_sampled_2d_array",
                   Token::Type::kTextureSampled2dArray},
-        TokenData{"texture_sampled_2d_ms", Token::Type::kTextureSampled2dMs},
-        TokenData{"texture_sampled_2d_ms_array",
-                  Token::Type::kTextureSampled2dMsArray},
         TokenData{"texture_sampled_3d", Token::Type::kTextureSampled3d},
         TokenData{"texture_sampled_cube", Token::Type::kTextureSampledCube},
         TokenData{"texture_sampled_cube_array",
diff --git a/src/reader/wgsl/parser_impl.cc b/src/reader/wgsl/parser_impl.cc
index 82af4cc..a85f7c7 100644
--- a/src/reader/wgsl/parser_impl.cc
+++ b/src/reader/wgsl/parser_impl.cc
@@ -50,6 +50,7 @@
 #include "src/ast/type/f32_type.h"
 #include "src/ast/type/i32_type.h"
 #include "src/ast/type/matrix_type.h"
+#include "src/ast/type/multisampled_texture_type.h"
 #include "src/ast/type/pointer_type.h"
 #include "src/ast/type/sampled_texture_type.h"
 #include "src/ast/type/sampler_type.h"
@@ -582,7 +583,7 @@
 //  : sampler_type
 //  | depth_texture_type
 //  | sampled_texture_type LESS_THAN type_decl GREATER_THAN
-//  | TODO: multisampled_texture_type LESS_THAN type_decl GREATER_THAN
+//  | multisampled_texture_type LESS_THAN type_decl GREATER_THAN
 //  | storage_texture_type LESS_THAN image_storage_type GREATER_THAN
 ast::type::Type* ParserImpl::texture_sampler_types() {
   auto* type = sampler_type();
@@ -595,8 +596,8 @@
     return type;
   }
 
-  auto sampled_dim = sampled_texture_type();
-  if (sampled_dim != ast::type::TextureDimension::kNone) {
+  auto dim = sampled_texture_type();
+  if (dim != ast::type::TextureDimension::kNone) {
     auto t = next();
     if (!t.IsLessThan()) {
       set_error(peek(), "missing '<' for sampled texture type");
@@ -618,7 +619,33 @@
     }
 
     return ctx_.type_mgr().Get(
-        std::make_unique<ast::type::SampledTextureType>(sampled_dim, subtype));
+        std::make_unique<ast::type::SampledTextureType>(dim, subtype));
+  }
+
+  dim = multisampled_texture_type();
+  if (dim != ast::type::TextureDimension::kNone) {
+    auto t = next();
+    if (!t.IsLessThan()) {
+      set_error(peek(), "missing '<' for multisampled texture type");
+      return nullptr;
+    }
+
+    auto* subtype = type_decl();
+    if (has_error())
+      return nullptr;
+    if (subtype == nullptr) {
+      set_error(peek(), "invalid subtype for multisampled texture type");
+      return nullptr;
+    }
+
+    t = next();
+    if (!t.IsGreaterThan()) {
+      set_error(peek(), "missing '>' for multisampled texture type");
+      return nullptr;
+    }
+
+    return ctx_.type_mgr().Get(
+        std::make_unique<ast::type::MultisampledTextureType>(dim, subtype));
   }
 
   ast::type::TextureDimension storage_dim;
@@ -675,8 +702,6 @@
 //  | TEXTURE_SAMPLED_1D_ARRAY
 //  | TEXTURE_SAMPLED_2D
 //  | TEXTURE_SAMPLED_2D_ARRAY
-//  | TEXTURE_SAMPLED_2D_MS
-//  | TEXTURE_SAMPLED_2D_MS_ARRAY
 //  | TEXTURE_SAMPLED_3D
 //  | TEXTURE_SAMPLED_CUBE
 //  | TEXTURE_SAMPLED_CUBE_ARRAY
@@ -698,14 +723,6 @@
     next();  // Consume the peek
     return ast::type::TextureDimension::k2dArray;
   }
-  if (t.IsTextureSampled2dMs()) {
-    next();  // Consume the peek
-    return ast::type::TextureDimension::k2dMs;
-  }
-  if (t.IsTextureSampled2dMsArray()) {
-    next();  // Consume the peek
-    return ast::type::TextureDimension::k2dMsArray;
-  }
   if (t.IsTextureSampled3d()) {
     next();  // Consume the peek
     return ast::type::TextureDimension::k3d;
@@ -721,6 +738,17 @@
   return ast::type::TextureDimension::kNone;
 }
 
+// multisampled_texture_type
+//  : TEXTURE_MULTISAMPLED_2D
+ast::type::TextureDimension ParserImpl::multisampled_texture_type() {
+  auto t = peek();
+  if (t.IsTextureMultisampled2d()) {
+    next();  // Consume the peek
+    return ast::type::TextureDimension::k2d;
+  }
+  return ast::type::TextureDimension::kNone;
+}
+
 // storage_texture_type
 //  : TEXTURE_RO_1D
 //  | TEXTURE_RO_1D_ARRAY
diff --git a/src/reader/wgsl/parser_impl.h b/src/reader/wgsl/parser_impl.h
index eb35b3d..6da84df 100644
--- a/src/reader/wgsl/parser_impl.h
+++ b/src/reader/wgsl/parser_impl.h
@@ -188,6 +188,10 @@
   /// Parses a `sampler_type` grammar element
   /// @returns the parsed Type or nullptr if none matched.
   ast::type::Type* sampler_type();
+  /// Parses a `multisampled_texture_type` grammar element
+  /// @returns returns the multisample texture dimension or kNone if none
+  /// matched.
+  ast::type::TextureDimension multisampled_texture_type();
   /// Parses a `sampled_texture_type` grammar element
   /// @returns returns the sample texture dimension or kNone if none matched.
   ast::type::TextureDimension sampled_texture_type();
diff --git a/src/reader/wgsl/parser_impl_sampled_texture_type_test.cc b/src/reader/wgsl/parser_impl_sampled_texture_type_test.cc
index da9a461..6e838a2 100644
--- a/src/reader/wgsl/parser_impl_sampled_texture_type_test.cc
+++ b/src/reader/wgsl/parser_impl_sampled_texture_type_test.cc
@@ -57,20 +57,6 @@
   EXPECT_FALSE(p->has_error());
 }
 
-TEST_F(ParserImplTest, SampledTextureType_2dMs) {
-  auto* p = parser("texture_sampled_2d_ms");
-  auto t = p->sampled_texture_type();
-  EXPECT_EQ(t, ast::type::TextureDimension::k2dMs);
-  EXPECT_FALSE(p->has_error());
-}
-
-TEST_F(ParserImplTest, SampledTextureType_2dMsArray) {
-  auto* p = parser("texture_sampled_2d_ms_array");
-  auto t = p->sampled_texture_type();
-  EXPECT_EQ(t, ast::type::TextureDimension::k2dMsArray);
-  EXPECT_FALSE(p->has_error());
-}
-
 TEST_F(ParserImplTest, SampledTextureType_3d) {
   auto* p = parser("texture_sampled_3d");
   auto t = p->sampled_texture_type();
diff --git a/src/reader/wgsl/parser_impl_texture_sampler_types_test.cc b/src/reader/wgsl/parser_impl_texture_sampler_types_test.cc
index 3174004..649920f 100644
--- a/src/reader/wgsl/parser_impl_texture_sampler_types_test.cc
+++ b/src/reader/wgsl/parser_impl_texture_sampler_types_test.cc
@@ -13,6 +13,7 @@
 // limitations under the License.
 
 #include "gtest/gtest.h"
+#include "src/ast/type/multisampled_texture_type.h"
 #include "src/ast/type/sampled_texture_type.h"
 #include "src/ast/type/sampler_type.h"
 #include "src/reader/wgsl/parser_impl.h"
@@ -33,67 +34,68 @@
 TEST_F(ParserImplTest, TextureSamplerTypes_Sampler) {
   auto* p = parser("sampler");
   auto* t = p->texture_sampler_types();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(t, nullptr);
   ASSERT_TRUE(t->IsSampler());
   ASSERT_FALSE(t->AsSampler()->IsComparison());
-  EXPECT_FALSE(p->has_error());
 }
 
 TEST_F(ParserImplTest, TextureSamplerTypes_SamplerComparison) {
   auto* p = parser("sampler_comparison");
   auto* t = p->texture_sampler_types();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(t, nullptr);
   ASSERT_TRUE(t->IsSampler());
   ASSERT_TRUE(t->AsSampler()->IsComparison());
-  EXPECT_FALSE(p->has_error());
 }
 
 TEST_F(ParserImplTest, TextureSamplerTypes_DepthTexture) {
   auto* p = parser("texture_depth_2d");
   auto* t = p->texture_sampler_types();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(t, nullptr);
   ASSERT_TRUE(t->IsTexture());
   ASSERT_TRUE(t->AsTexture()->IsDepth());
   EXPECT_EQ(t->AsTexture()->dim(), ast::type::TextureDimension::k2d);
-  EXPECT_FALSE(p->has_error());
 }
 
 TEST_F(ParserImplTest, TextureSamplerTypes_SampledTexture_F32) {
   auto* p = parser("texture_sampled_1d<f32>");
   auto* t = p->texture_sampler_types();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(t, nullptr);
   ASSERT_TRUE(t->IsTexture());
   ASSERT_TRUE(t->AsTexture()->IsSampled());
   ASSERT_TRUE(t->AsTexture()->AsSampled()->type()->IsF32());
   EXPECT_EQ(t->AsTexture()->dim(), ast::type::TextureDimension::k1d);
-  EXPECT_FALSE(p->has_error());
 }
 
 TEST_F(ParserImplTest, TextureSamplerTypes_SampledTexture_I32) {
   auto* p = parser("texture_sampled_2d<i32>");
   auto* t = p->texture_sampler_types();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(t, nullptr);
   ASSERT_TRUE(t->IsTexture());
   ASSERT_TRUE(t->AsTexture()->IsSampled());
   ASSERT_TRUE(t->AsTexture()->AsSampled()->type()->IsI32());
   EXPECT_EQ(t->AsTexture()->dim(), ast::type::TextureDimension::k2d);
-  EXPECT_FALSE(p->has_error());
 }
 
 TEST_F(ParserImplTest, TextureSamplerTypes_SampledTexture_U32) {
   auto* p = parser("texture_sampled_3d<u32>");
   auto* t = p->texture_sampler_types();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(t, nullptr);
   ASSERT_TRUE(t->IsTexture());
   ASSERT_TRUE(t->AsTexture()->IsSampled());
   ASSERT_TRUE(t->AsTexture()->AsSampled()->type()->IsU32());
   EXPECT_EQ(t->AsTexture()->dim(), ast::type::TextureDimension::k3d);
-  EXPECT_FALSE(p->has_error());
 }
 
 TEST_F(ParserImplTest, TextureSamplerTypes_SampledTexture_Invalid) {
   auto* p = parser("texture_sampled_1d<abc>");
   auto* t = p->texture_sampler_types();
+  ASSERT_TRUE(p->has_error());
   EXPECT_EQ(t, nullptr);
   EXPECT_EQ(p->error(), "1:20: unknown type alias 'abc'");
 }
@@ -101,6 +103,7 @@
 TEST_F(ParserImplTest, TextureSamplerTypes_SampledTexture_MissingType) {
   auto* p = parser("texture_sampled_1d<>");
   auto* t = p->texture_sampler_types();
+  ASSERT_TRUE(p->has_error());
   EXPECT_EQ(t, nullptr);
   EXPECT_EQ(p->error(), "1:20: invalid subtype for sampled texture type");
 }
@@ -108,6 +111,7 @@
 TEST_F(ParserImplTest, TextureSamplerTypes_SampledTexture_MissingLessThan) {
   auto* p = parser("texture_sampled_1d");
   auto* t = p->texture_sampler_types();
+  ASSERT_TRUE(p->has_error());
   EXPECT_EQ(t, nullptr);
   EXPECT_EQ(p->error(), "1:19: missing '<' for sampled texture type");
 }
@@ -115,13 +119,58 @@
 TEST_F(ParserImplTest, TextureSamplerTypes_SampledTexture_MissingGreaterThan) {
   auto* p = parser("texture_sampled_1d<u32");
   auto* t = p->texture_sampler_types();
+  ASSERT_TRUE(p->has_error());
   EXPECT_EQ(t, nullptr);
   EXPECT_EQ(p->error(), "1:23: missing '>' for sampled texture type");
 }
 
+TEST_F(ParserImplTest, TextureSamplerTypes_MultisampledTexture_I32) {
+  auto* p = parser("texture_multisampled_2d<i32>");
+  auto* t = p->texture_sampler_types();
+  ASSERT_FALSE(p->has_error()) << p->error();
+  ASSERT_NE(t, nullptr);
+  ASSERT_TRUE(t->IsTexture());
+  ASSERT_TRUE(t->AsTexture()->IsMultisampled());
+  ASSERT_TRUE(t->AsTexture()->AsMultisampled()->type()->IsI32());
+  EXPECT_EQ(t->AsTexture()->dim(), ast::type::TextureDimension::k2d);
+}
+
+TEST_F(ParserImplTest, TextureSamplerTypes_MultisampledTexture_Invalid) {
+  auto* p = parser("texture_multisampled_2d<abc>");
+  auto* t = p->texture_sampler_types();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(t, nullptr);
+  EXPECT_EQ(p->error(), "1:25: unknown type alias 'abc'");
+}
+
+TEST_F(ParserImplTest, TextureSamplerTypes_MultisampledTexture_MissingType) {
+  auto* p = parser("texture_multisampled_2d<>");
+  auto* t = p->texture_sampler_types();
+  ASSERT_TRUE(p->has_error());
+  EXPECT_EQ(t, nullptr);
+  EXPECT_EQ(p->error(), "1:25: invalid subtype for multisampled texture type");
+}
+
+TEST_F(ParserImplTest,
+       TextureSamplerTypes_MultisampledTexture_MissingLessThan) {
+  auto* p = parser("texture_multisampled_2d");
+  auto* t = p->texture_sampler_types();
+  EXPECT_EQ(t, nullptr);
+  EXPECT_EQ(p->error(), "1:24: missing '<' for multisampled texture type");
+}
+
+TEST_F(ParserImplTest,
+       TextureSamplerTypes_MultisampledTexture_MissingGreaterThan) {
+  auto* p = parser("texture_multisampled_2d<u32");
+  auto* t = p->texture_sampler_types();
+  EXPECT_EQ(t, nullptr);
+  EXPECT_EQ(p->error(), "1:28: missing '>' for multisampled texture type");
+}
+
 TEST_F(ParserImplTest, TextureSamplerTypes_StorageTexture_Readonly1dR8Unorm) {
   auto* p = parser("texture_ro_1d<r8unorm>");
   auto* t = p->texture_sampler_types();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(t, nullptr);
   ASSERT_TRUE(t->IsTexture());
   ASSERT_TRUE(t->AsTexture()->IsStorage());
@@ -130,12 +179,12 @@
   EXPECT_EQ(t->AsTexture()->AsStorage()->access(),
             ast::type::StorageAccess::kRead);
   EXPECT_EQ(t->AsTexture()->dim(), ast::type::TextureDimension::k1d);
-  EXPECT_FALSE(p->has_error());
 }
 
 TEST_F(ParserImplTest, TextureSamplerTypes_StorageTexture_Writeonly2dR16Float) {
   auto* p = parser("texture_wo_2d<r16float>");
   auto* t = p->texture_sampler_types();
+  ASSERT_FALSE(p->has_error()) << p->error();
   ASSERT_NE(t, nullptr);
   ASSERT_TRUE(t->IsTexture());
   ASSERT_TRUE(t->AsTexture()->IsStorage());
@@ -144,7 +193,6 @@
   EXPECT_EQ(t->AsTexture()->AsStorage()->access(),
             ast::type::StorageAccess::kWrite);
   EXPECT_EQ(t->AsTexture()->dim(), ast::type::TextureDimension::k2d);
-  EXPECT_FALSE(p->has_error());
 }
 
 TEST_F(ParserImplTest, TextureSamplerTypes_StorageTexture_InvalidType) {
diff --git a/src/reader/wgsl/token.cc b/src/reader/wgsl/token.cc
index 58d60f4..dd1ad3e 100644
--- a/src/reader/wgsl/token.cc
+++ b/src/reader/wgsl/token.cc
@@ -289,6 +289,8 @@
       return "texture_depth_cube";
     case Token::Type::kTextureDepthCubeArray:
       return "texture_depth_cube_array";
+    case Token::Type::kTextureMultisampled2d:
+      return "texture_multisampled_2d";
     case Token::Type::kTextureStorageReadonly1d:
       return "texture_ro_1d";
     case Token::Type::kTextureStorageReadonly1dArray:
@@ -307,10 +309,6 @@
       return "texture_sampled_2d";
     case Token::Type::kTextureSampled2dArray:
       return "texture_sampled_2d_array";
-    case Token::Type::kTextureSampled2dMs:
-      return "texture_sampled_2d_ms";
-    case Token::Type::kTextureSampled2dMsArray:
-      return "texture_sampled_2d_ms_array";
     case Token::Type::kTextureSampled3d:
       return "texture_sampled_3d";
     case Token::Type::kTextureSampledCube:
diff --git a/src/reader/wgsl/token.h b/src/reader/wgsl/token.h
index 2e9f2da..da18df3 100644
--- a/src/reader/wgsl/token.h
+++ b/src/reader/wgsl/token.h
@@ -300,6 +300,8 @@
     kTextureDepthCube,
     /// A 'texture_depth_cube_array'
     kTextureDepthCubeArray,
+    /// A 'texture_multisampled_2d'
+    kTextureMultisampled2d,
     /// A 'texture_ro_1d'
     kTextureStorageReadonly1d,
     /// A 'texture_ro_2d_array'
@@ -318,10 +320,6 @@
     kTextureSampled2d,
     /// A 'texture_sampled_2d_array'
     kTextureSampled2dArray,
-    /// A 'texture_sampled_2d_ms'
-    kTextureSampled2dMs,
-    /// A 'texture_sampled_2d_ms_array'
-    kTextureSampled2dMsArray,
     /// A 'texture_sampled_3d'
     kTextureSampled3d,
     /// A 'texture_sampled_cube'
@@ -689,6 +687,10 @@
   bool IsTextureDepthCubeArray() const {
     return type_ == Type::kTextureDepthCubeArray;
   }
+  /// @returns true if the token is a 'texture_multisample_2d'
+  bool IsTextureMultisampled2d() const {
+    return type_ == Type::kTextureMultisampled2d;
+  }
   /// @returns true if token is a 'texture_ro_1d'
   bool IsTextureStorageReadonly1d() const {
     return type_ == Type::kTextureStorageReadonly1d;
@@ -721,14 +723,6 @@
   bool IsTextureSampled2dArray() const {
     return type_ == Type::kTextureSampled2dArray;
   }
-  /// @returns true if token is a 'texture_sampled_2d_ms'
-  bool IsTextureSampled2dMs() const {
-    return type_ == Type::kTextureSampled2dMs;
-  }
-  /// @returns true if token is a 'texture_sampled_2d_ms_array'
-  bool IsTextureSampled2dMsArray() const {
-    return type_ == Type::kTextureSampled2dMsArray;
-  }
   /// @returns true if token is a 'texture_sampled_3d'
   bool IsTextureSampled3d() const { return type_ == Type::kTextureSampled3d; }
   /// @returns true if token is a 'texture_sampled_cube'