Add hlsl::TestHelperBase::Validate()

Looks for DXC on PATH.
If found, it will invoke DXC with the shader program generated by the writer to verify the shader can compile.

Change-Id: Iad8b4021bac16d01214b500ddb89b5f743927ce9
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/41943
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>

BUILD.gn

@@ -1265,6 +1265,7 @@ source_set("tint_unittests_hlsl_writer_src") {
     "src/writer/hlsl/generator_impl_unary_op_test.cc",
     "src/writer/hlsl/generator_impl_variable_decl_statement_test.cc",
     "src/writer/hlsl/namer_test.cc",
+    "src/writer/hlsl/test_helper.cc",
     "src/writer/hlsl/test_helper.h",
   ]
 

src/CMakeLists.txt

@@ -785,6 +785,7 @@ if(${TINT_BUILD_TESTS})
       writer/hlsl/generator_impl_unary_op_test.cc
       writer/hlsl/generator_impl_variable_decl_statement_test.cc
       writer/hlsl/namer_test.cc
+      writer/hlsl/test_helper.cc
       writer/hlsl/test_helper.h
     )
   endif()

src/writer/hlsl/test_helper.cc

@@ -0,0 +1,96 @@
+// Copyright 2021 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "src/writer/hlsl/test_helper.h"
+
+#include "src/utils/command.h"
+#include "src/utils/tmpfile.h"
+
+namespace tint {
+namespace writer {
+namespace hlsl {
+
+CompileResult Compile(Program* program, GeneratorImpl* generator) {
+  CompileResult result;
+
+  auto dxc = utils::Command::LookPath("dxc");
+  if (!dxc.Found()) {
+    result.status = CompileResult::Status::kDXCNotFound;
+    return result;
+  }
+
+  std::ostringstream hlsl;
+  if (!generator->Generate(hlsl)) {
+    result.output = generator->error();
+    result.status = CompileResult::Status::kFailed;
+    return result;
+  }
+  result.hlsl = hlsl.str();
+
+  utils::TmpFile file;
+  file << result.hlsl;
+
+  bool found_an_entrypoint = false;
+  for (auto* func : program->AST().Functions()) {
+    if (func->IsEntryPoint()) {
+      found_an_entrypoint = true;
+
+      const char* profile = "";
+
+      switch (func->pipeline_stage()) {
+        case ast::PipelineStage::kNone:
+          result.output = "Invalid PipelineStage";
+          result.status = CompileResult::Status::kFailed;
+          return result;
+        case ast::PipelineStage::kVertex:
+          profile = "-T vs_6_0";
+          break;
+        case ast::PipelineStage::kFragment:
+          profile = "-T ps_6_0";
+          break;
+        case ast::PipelineStage::kCompute:
+          profile = "-T cs_6_0";
+          break;
+      }
+
+      auto res = dxc(profile, file.Path());
+      if (!res.out.empty()) {
+        if (!result.output.empty()) {
+          result.output += "\n";
+        }
+        result.output += res.out;
+      }
+      if (!res.err.empty()) {
+        if (!result.output.empty()) {
+          result.output += "\n";
+        }
+        result.output += res.err;
+      }
+      result.status = (res.error_code == 0) ? CompileResult::Status::kSuccess
+                                            : CompileResult::Status::kFailed;
+    }
+  }
+
+  if (!found_an_entrypoint) {
+    result.output = "No entrypoint found";
+    result.status = CompileResult::Status::kFailed;
+    return result;
+  }
+
+  return result;
+}
+
+}  // namespace hlsl
+}  // namespace writer
+}  // namespace tint

src/writer/hlsl/test_helper.h

@@ -31,6 +31,24 @@ namespace tint {
 namespace writer {
 namespace hlsl {
 
+/// The return structure of Compile()
+struct CompileResult {
+  /// Status is an enumerator of status codes from Compile()
+  enum class Status { kSuccess, kFailed, kDXCNotFound };
+  /// The resulting status of the compile
+  Status status;
+  /// Output of DXC.
+  std::string output;
+  /// The HLSL source that was compiled
+  std::string hlsl;
+};
+
+/// Compile attempts to compile the shader with DXC if found on PATH.
+/// @param program the HLSL program
+/// @param generator the HLSL generator
+/// @return the result of the compile
+CompileResult Compile(Program* program, GeneratorImpl* generator);
+
 /// Helper class for testing
 template <typename BODY>
 class TestHelperBase : public BODY, public ProgramBuilder {
@@ -89,6 +107,19 @@ class TestHelperBase : public BODY, public ProgramBuilder {
     return *gen_;
   }
 
+  /// Validate passes the generated HLSL from the generator to the DXC compiler
+  /// on `PATH` for checking the program can be compiled.
+  /// If DXC finds problems the test will fail.
+  /// If DXC is not on `PATH` then Validate() does nothing.
+  void Validate() const {
+    auto res = Compile(program.get(), gen_.get());
+    if (res.status == CompileResult::Status::kFailed) {
+      FAIL() << "HLSL Validation failed.\n\n"
+             << res.hlsl << "\n\n"
+             << res.output;
+    }
+  }
+
   /// @returns the result string
   std::string result() const { return out.str(); }