Add type determination for switch statements.

This CL adds the type determination code for the switch statements.

Bug: tint:5
Change-Id: I96efd96016c03137ef471e3f220e21e7f53d11ba
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/18838
Reviewed-by: David Neto <dneto@google.com>

src/type_determiner.cc

@@ -24,6 +24,7 @@
 #include "src/ast/regardless_statement.h"
 #include "src/ast/return_statement.h"
 #include "src/ast/scalar_constructor_expression.h"
+#include "src/ast/switch_statement.h"
 #include "src/ast/type_constructor_expression.h"
 
 namespace tint {
@@ -125,6 +126,9 @@ bool TypeDeterminer::DetermineResultType(ast::Statement* stmt) {
     return DetermineResultType(l->body()) &&
            DetermineResultType(l->continuing());
   }
+  if (stmt->IsNop()) {
+    return true;
+  }
   if (stmt->IsRegardless()) {
     auto r = stmt->AsRegardless();
     return DetermineResultType(r->condition()) &&
@@ -134,7 +138,16 @@ bool TypeDeterminer::DetermineResultType(ast::Statement* stmt) {
     auto r = stmt->AsReturn();
     return DetermineResultType(r->value());
   }
-  if (stmt->IsNop()) {
+  if (stmt->IsSwitch()) {
+    auto s = stmt->AsSwitch();
+    if (!DetermineResultType(s->condition())) {
+      return false;
+    }
+    for (const auto& case_stmt : s->body()) {
+      if (!DetermineResultType(case_stmt.get())) {
+        return false;
+      }
+    }
     return true;
   }
 

src/type_determiner_test.cc

@@ -30,6 +30,7 @@
 #include "src/ast/regardless_statement.h"
 #include "src/ast/return_statement.h"
 #include "src/ast/scalar_constructor_expression.h"
+#include "src/ast/switch_statement.h"
 #include "src/ast/type/f32_type.h"
 #include "src/ast/type/i32_type.h"
 #include "src/ast/type/vector_type.h"
@@ -293,6 +294,40 @@ TEST_F(TypeDeterminerTest, Stmt_Return) {
   EXPECT_TRUE(cond_ptr->result_type()->IsI32());
 }
 
+TEST_F(TypeDeterminerTest, Stmt_Switch) {
+  ast::type::I32Type i32;
+  ast::type::F32Type f32;
+
+  auto lhs = std::make_unique<ast::ScalarConstructorExpression>(
+      std::make_unique<ast::IntLiteral>(&i32, 2));
+  auto lhs_ptr = lhs.get();
+
+  auto rhs = std::make_unique<ast::ScalarConstructorExpression>(
+      std::make_unique<ast::FloatLiteral>(&f32, 2.3f));
+  auto rhs_ptr = rhs.get();
+
+  ast::StatementList body;
+  body.push_back(std::make_unique<ast::AssignmentStatement>(std::move(lhs),
+                                                            std::move(rhs)));
+
+  ast::CaseStatementList cases;
+  cases.push_back(std::make_unique<ast::CaseStatement>(
+      std::make_unique<ast::IntLiteral>(&i32, 3), std::move(body)));
+
+  ast::SwitchStatement stmt(std::make_unique<ast::ScalarConstructorExpression>(
+                                std::make_unique<ast::IntLiteral>(&i32, 2)),
+                            std::move(cases));
+
+  EXPECT_TRUE(td()->DetermineResultType(&stmt)) << td()->error();
+  ASSERT_NE(stmt.condition()->result_type(), nullptr);
+  ASSERT_NE(lhs_ptr->result_type(), nullptr);
+  ASSERT_NE(rhs_ptr->result_type(), nullptr);
+
+  EXPECT_TRUE(stmt.condition()->result_type()->IsI32());
+  EXPECT_TRUE(lhs_ptr->result_type()->IsI32());
+  EXPECT_TRUE(rhs_ptr->result_type()->IsF32());
+}
+
 TEST_F(TypeDeterminerTest, Expr_Constructor_Scalar) {
   ast::type::F32Type f32;
   ast::ScalarConstructorExpression s(