Add module helper for finding global type

circle.yml

@@ -173,6 +173,7 @@ jobs:
           ./wat2wasm4cpp.py test/unittests/execute_numeric_test.cpp
           ./wat2wasm4cpp.py test/unittests/execute_test.cpp
           ./wat2wasm4cpp.py test/unittests/instantiate_test.cpp
+          ./wat2wasm4cpp.py test/unittests/module_test.cpp
           ./wat2wasm4cpp.py test/unittests/parser_test.cpp
           ./wat2wasm4cpp.py test/unittests/validation_stack_test.cpp
           ./wat2wasm4cpp.py test/unittests/validation_test.cpp

lib/fizzy/module.hpp

@@ -68,19 +68,19 @@ struct Module
         return imported_global_types.size() + globalsec.size();
     }
 
+    GlobalType get_global_type(GlobalIdx idx) const noexcept
+    {
+        assert(idx < get_global_count());
+        return idx < imported_global_types.size() ?
+                   imported_global_types[idx] :
+                   globalsec[idx - imported_global_types.size()].type;
+    }
+
     bool has_table() const noexcept { return !tablesec.empty() || !imported_table_types.empty(); }
 
     bool has_memory() const noexcept
     {
         return !memorysec.empty() || !imported_memory_types.empty();
     }
-
-    bool is_global_mutable(GlobalIdx idx) const noexcept
-    {
-        assert(idx < get_global_count());
-        return idx < imported_global_types.size() ?
-                   imported_global_types[idx].is_mutable :
-                   globalsec[idx - imported_global_types.size()].type.is_mutable;
-    }
 };
 }  // namespace fizzy

lib/fizzy/parser.cpp

@@ -23,7 +23,7 @@ void validate_constant_expression(const ConstantExpression& const_expr, const Mo
     if (global_idx >= module.get_global_count())
         throw validation_error{"invalid global index in constant expression"};
 
-    if (module.is_global_mutable(global_idx))
+    if (module.get_global_type(global_idx).is_mutable)
         throw validation_error{"constant expression can use global.get only for const globals"};
 }
 }  // namespace

lib/fizzy/parser_expr.cpp

@@ -644,7 +644,7 @@ parser_result<Code> parse_expr(const uint8_t* pos, const uint8_t* end, uint32_t
             if (global_idx >= module.get_global_count())
                 throw validation_error{"accessing global with invalid index"};
 
-            if (instr == Instr::global_set && !module.is_global_mutable(global_idx))
+            if (instr == Instr::global_set && !module.get_global_type(global_idx).is_mutable)
                 throw validation_error{"trying to mutate immutable global"};
 
             push(code.immediates, global_idx);

test/unittests/CMakeLists.txt

@@ -17,6 +17,7 @@ target_sources(
     execute_test.cpp
     instantiate_test.cpp
     leb128_test.cpp
+    module_test.cpp
     parser_expr_test.cpp
     parser_test.cpp
     span_test.cpp

test/unittests/module_test.cpp

@@ -0,0 +1,35 @@
+// Fizzy: A fast WebAssembly interpreter
+// Copyright 2019-2020 The Fizzy Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+#include "module.hpp"
+#include "parser.hpp"
+#include <gtest/gtest.h>
+#include <test/utils/hex.hpp>
+
+using namespace fizzy;
+using namespace fizzy::test;
+
+TEST(module, globals)
+{
+    /* wat2wasm
+      (global (import "m" "g1") (mut i32))
+      (global (import "m" "g2") i64)
+      (global f32 (f32.const 0))
+      (global (mut f64) (f64.const 1))
+    */
+    const auto bin = from_hex(
+        "0061736d01000000021102016d026731037f01016d026732037e000615027d0043000000000b7c014400000000"
+        "0000f03f0b");
+    const auto module = parse(bin);
+
+    ASSERT_EQ(module.get_global_count(), 4);
+    EXPECT_EQ(module.get_global_type(0).value_type, ValType::i32);
+    EXPECT_TRUE(module.get_global_type(0).is_mutable);
+    EXPECT_EQ(module.get_global_type(1).value_type, ValType::i64);
+    EXPECT_FALSE(module.get_global_type(1).is_mutable);
+    EXPECT_EQ(module.get_global_type(2).value_type, ValType::f32);
+    EXPECT_FALSE(module.get_global_type(2).is_mutable);
+    EXPECT_EQ(module.get_global_type(3).value_type, ValType::f64);
+    EXPECT_TRUE(module.get_global_type(3).is_mutable);
+}