tint/writer: Do not attempt to use invalid programs

Attempting to emit shader code from an invalid program is unsafe.

The WGSL writer is used for dumping information which is valuable for debugging bad programs, so this has not been changed.

Bug: chromium:1327461
Change-Id: I4497fcb19d126ef6c872e2bcda8e9b79044aeb68
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/91163
Reviewed-by: David Neto <dneto@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>

src/tint/writer/glsl/generator.cc

@@ -30,6 +30,10 @@ Result::Result(const Result&) = default;
 
 Result Generate(const Program* program, const Options& options, const std::string& entry_point) {
     Result result;
+    if (!program->IsValid()) {
+        result.error = "input program is not valid";
+        return result;
+    }
 
     // Sanitize the program.
     auto sanitized_result = Sanitize(program, options, entry_point);

src/tint/writer/glsl/generator_impl_test.cc

@@ -19,6 +19,15 @@ namespace {
 
 using GlslGeneratorImplTest = TestHelper;
 
+TEST_F(GlslGeneratorImplTest, InvalidProgram) {
+    Diagnostics().add_error(diag::System::Writer, "make the program invalid");
+    ASSERT_FALSE(IsValid());
+    auto program = std::make_unique<Program>(std::move(*this));
+    ASSERT_FALSE(program->IsValid());
+    auto result = Generate(program.get(), Options{}, "");
+    EXPECT_EQ(result.error, "input program is not valid");
+}
+
 TEST_F(GlslGeneratorImplTest, Generate) {
     Func("my_func", ast::VariableList{}, ty.void_(), ast::StatementList{}, ast::AttributeList{});
 

src/tint/writer/hlsl/generator.cc

@@ -29,6 +29,10 @@ Result::Result(const Result&) = default;
 
 Result Generate(const Program* program, const Options& options) {
     Result result;
+    if (!program->IsValid()) {
+        result.error = "input program is not valid";
+        return result;
+    }
 
     // Sanitize the program.
     auto sanitized_result = Sanitize(program, options);

src/tint/writer/hlsl/generator_impl_test.cc

@@ -19,6 +19,15 @@ namespace {
 
 using HlslGeneratorImplTest = TestHelper;
 
+TEST_F(HlslGeneratorImplTest, InvalidProgram) {
+    Diagnostics().add_error(diag::System::Writer, "make the program invalid");
+    ASSERT_FALSE(IsValid());
+    auto program = std::make_unique<Program>(std::move(*this));
+    ASSERT_FALSE(program->IsValid());
+    auto result = Generate(program.get(), Options{});
+    EXPECT_EQ(result.error, "input program is not valid");
+}
+
 TEST_F(HlslGeneratorImplTest, Generate) {
     Func("my_func", ast::VariableList{}, ty.void_(), ast::StatementList{}, ast::AttributeList{});
 

src/tint/writer/msl/generator.cc

@@ -31,6 +31,10 @@ Result::Result(const Result&) = default;
 
 Result Generate(const Program* program, const Options& options) {
     Result result;
+    if (!program->IsValid()) {
+        result.error = "input program is not valid";
+        return result;
+    }
 
     // Sanitize the program.
     auto sanitized_result = Sanitize(program, options);

src/tint/writer/msl/generator_impl_test.cc

@@ -22,6 +22,15 @@ namespace {
 
 using MslGeneratorImplTest = TestHelper;
 
+TEST_F(MslGeneratorImplTest, InvalidProgram) {
+    Diagnostics().add_error(diag::System::Writer, "make the program invalid");
+    ASSERT_FALSE(IsValid());
+    auto program = std::make_unique<Program>(std::move(*this));
+    ASSERT_FALSE(program->IsValid());
+    auto result = Generate(program.get(), Options{});
+    EXPECT_EQ(result.error, "input program is not valid");
+}
+
 TEST_F(MslGeneratorImplTest, Generate) {
     Func("my_func", ast::VariableList{}, ty.void_(), ast::StatementList{},
          ast::AttributeList{

src/tint/writer/spirv/builder_test.cc

@@ -20,6 +20,15 @@ namespace {
 
 using BuilderTest = TestHelper;
 
+TEST_F(BuilderTest, InvalidProgram) {
+    Diagnostics().add_error(diag::System::Writer, "make the program invalid");
+    ASSERT_FALSE(IsValid());
+    auto program = std::make_unique<Program>(std::move(*this));
+    ASSERT_FALSE(program->IsValid());
+    auto result = Generate(program.get(), Options{});
+    EXPECT_EQ(result.error, "input program is not valid");
+}
+
 TEST_F(BuilderTest, TracksIdBounds) {
     spirv::Builder& b = Build();
 

src/tint/writer/spirv/generator.cc

@@ -26,6 +26,10 @@ Result::Result(const Result&) = default;
 
 Result Generate(const Program* program, const Options& options) {
     Result result;
+    if (!program->IsValid()) {
+        result.error = "input program is not valid";
+        return result;
+    }
 
     // Sanitize the program.
     auto sanitized_result = Sanitize(program, options);