spirv-reader: support textureLoad

Both OpImageRead and OpImageFetch map to WGSL textureLoad.

Bug: tint:109
Change-Id: I3c99840c2e62c52dcaaf7177773a3c972de90cc1
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/34425
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Commit-Queue: dan sinclair <dsinclair@chromium.org>
Auto-Submit: David Neto <dneto@google.com>

src/reader/spirv/function.cc

@@ -3719,6 +3719,14 @@ bool FunctionEmitter::EmitImageAccess(const spvtools::opt::Instruction& inst) {
       return Fail() << " image gather is not yet supported";
     case SpvOpImageQueryLod:
       return Fail() << " image query Lod is not yet supported";
+    case SpvOpImageFetch:
+      // Read a single texel from a sampled image.
+      builtin_name = "textureLoad";
+      break;
+    case SpvOpImageRead:
+      // Read a single texel from a storage image.
+      builtin_name = "textureLoad";
+      break;
     case SpvOpImageWrite:
       builtin_name = "textureStore";
       if (arg_index < num_args) {

src/reader/spirv/parser_impl_handle_test.cc

@@ -2823,6 +2823,128 @@ INSTANTIATE_TEST_SUITE_P(
       )
     })"}}));
 
+INSTANTIATE_TEST_SUITE_P(
+    ImageRead_OptionalParams,
+    SpvParserTest_ImageAccessTest,
+    ::testing::ValuesIn(std::vector<ImageAccessCase>{
+        // OpImageRead with no extra params
+        {"%float 2D 0 0 0 2 Rgba32f", "%99 = OpImageRead %v4float %im %vu12",
+         R"(DecoratedVariable{
+    Decorations{
+      SetDecoration{2}
+      BindingDecoration{1}
+    }
+    x_20
+    uniform_constant
+    __storage_texture_read_only_2d_rgba32float
+  })",
+         R"(VariableDeclStatement{
+      VariableConst{
+        x_99
+        none
+        __vec_4__f32
+        {
+          Call[not set]{
+            Identifier[not set]{textureLoad}
+            (
+              Identifier[not set]{x_20}
+              Identifier[not set]{vu12}
+            )
+          }
+        }
+      }
+    })"},
+        // OpImageRead with ConstOffset
+        {"%float 2D 0 0 0 2 Rgba32f",
+         "%99 = OpImageRead %v4float %im %vu12 ConstOffset %offsets2d",
+         R"(DecoratedVariable{
+    Decorations{
+      SetDecoration{2}
+      BindingDecoration{1}
+    }
+    x_20
+    uniform_constant
+    __storage_texture_read_only_2d_rgba32float
+  })",
+         R"(VariableDeclStatement{
+      VariableConst{
+        x_99
+        none
+        __vec_4__f32
+        {
+          Call[not set]{
+            Identifier[not set]{textureLoad}
+            (
+              Identifier[not set]{x_20}
+              Identifier[not set]{vu12}
+              Identifier[not set]{offsets2d}
+            )
+          }
+        }
+      }
+    })"}}));
+
+INSTANTIATE_TEST_SUITE_P(
+    ImageFetch_OptionalParams,
+    SpvParserTest_ImageAccessTest,
+    ::testing::ValuesIn(std::vector<ImageAccessCase>{
+        // OpImageFetch with no extra params
+        {"%float 2D 0 0 0 1 Rgba32f", "%99 = OpImageFetch %v4float %im %vu12",
+         R"(DecoratedVariable{
+    Decorations{
+      SetDecoration{2}
+      BindingDecoration{1}
+    }
+    x_20
+    uniform_constant
+    __sampled_texture_2d__f32
+  })",
+         R"(VariableDeclStatement{
+      VariableConst{
+        x_99
+        none
+        __vec_4__f32
+        {
+          Call[not set]{
+            Identifier[not set]{textureLoad}
+            (
+              Identifier[not set]{x_20}
+              Identifier[not set]{vu12}
+            )
+          }
+        }
+      }
+    })"},
+        // OpImageFetch with ConstOffset
+        {"%float 2D 0 0 0 1 Rgba32f",
+         "%99 = OpImageFetch %v4float %im %vu12 ConstOffset %offsets2d",
+         R"(DecoratedVariable{
+    Decorations{
+      SetDecoration{2}
+      BindingDecoration{1}
+    }
+    x_20
+    uniform_constant
+    __sampled_texture_2d__f32
+  })",
+         R"(VariableDeclStatement{
+      VariableConst{
+        x_99
+        none
+        __vec_4__f32
+        {
+          Call[not set]{
+            Identifier[not set]{textureLoad}
+            (
+              Identifier[not set]{x_20}
+              Identifier[not set]{vu12}
+              Identifier[not set]{offsets2d}
+            )
+          }
+        }
+      }
+    })"}}));
+
 INSTANTIATE_TEST_SUITE_P(
     // The SPIR-V result type could be integral but of different signedness
     // than the sampled texel type.  In these cases the result should be