Add If statement type determination.

This CL adds the type determination code for if statements.

Bug: tint:5
Change-Id: Idfe4d62be56ffb7e8a8de197e8710ff119dd4368
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/18834
Reviewed-by: David Neto <dneto@google.com>

src/type_determiner.cc

@@ -19,6 +19,7 @@
 #include "src/ast/case_statement.h"
 #include "src/ast/continue_statement.h"
 #include "src/ast/else_statement.h"
+#include "src/ast/if_statement.h"
 #include "src/ast/scalar_constructor_expression.h"
 #include "src/ast/type_constructor_expression.h"
 
@@ -99,6 +100,20 @@ bool TypeDeterminer::DetermineResultType(ast::Statement* stmt) {
   if (stmt->IsFallthrough()) {
     return true;
   }
+  if (stmt->IsIf()) {
+    auto i = stmt->AsIf();
+    if (!DetermineResultType(i->condition()) ||
+        !DetermineResultType(i->body())) {
+      return false;
+    }
+
+    for (const auto& else_stmt : i->else_statements()) {
+      if (!DetermineResultType(else_stmt.get())) {
+        return false;
+      }
+    }
+    return true;
+  }
   if (stmt->IsKill()) {
     return true;
   }

src/type_determiner_test.cc

@@ -24,6 +24,7 @@
 #include "src/ast/continue_statement.h"
 #include "src/ast/else_statement.h"
 #include "src/ast/float_literal.h"
+#include "src/ast/if_statement.h"
 #include "src/ast/int_literal.h"
 #include "src/ast/scalar_constructor_expression.h"
 #include "src/ast/type/f32_type.h"
@@ -150,6 +151,60 @@ TEST_F(TypeDeterminerTest, Stmt_Else) {
   EXPECT_TRUE(rhs_ptr->result_type()->IsF32());
 }
 
+TEST_F(TypeDeterminerTest, Stmt_If) {
+  ast::type::I32Type i32;
+  ast::type::F32Type f32;
+
+  auto else_lhs = std::make_unique<ast::ScalarConstructorExpression>(
+      std::make_unique<ast::IntLiteral>(&i32, 2));
+  auto else_lhs_ptr = else_lhs.get();
+
+  auto else_rhs = std::make_unique<ast::ScalarConstructorExpression>(
+      std::make_unique<ast::FloatLiteral>(&f32, 2.3f));
+  auto else_rhs_ptr = else_rhs.get();
+
+  ast::StatementList else_body;
+  else_body.push_back(std::make_unique<ast::AssignmentStatement>(
+      std::move(else_lhs), std::move(else_rhs)));
+
+  auto else_stmt = std::make_unique<ast::ElseStatement>(
+      std::make_unique<ast::ScalarConstructorExpression>(
+          std::make_unique<ast::IntLiteral>(&i32, 3)),
+      std::move(else_body));
+
+  ast::ElseStatementList else_stmts;
+  else_stmts.push_back(std::move(else_stmt));
+
+  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::IfStatement stmt(std::make_unique<ast::ScalarConstructorExpression>(
+                            std::make_unique<ast::IntLiteral>(&i32, 3)),
+                        std::move(body));
+  stmt.set_else_statements(std::move(else_stmts));
+
+  EXPECT_TRUE(td()->DetermineResultType(&stmt));
+  ASSERT_NE(stmt.condition()->result_type(), nullptr);
+  ASSERT_NE(else_lhs_ptr->result_type(), nullptr);
+  ASSERT_NE(else_rhs_ptr->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(else_lhs_ptr->result_type()->IsI32());
+  EXPECT_TRUE(else_rhs_ptr->result_type()->IsF32());
+  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(