[wasm] Support undefined indirect table entries, behind a flag.

src/wasm/wasm-module.h

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_WASM_MODULE_H_
 #define V8_WASM_MODULE_H_
 
 #include "src/api.h"
 #include "src/handles.h"
 #include "src/wasm/wasm-opcodes.h"
@@ skipping 23 matching lines @@
   F(Signatures, 1, "type")             \
   F(ImportTable, 2, "import")          \
   F(FunctionSignatures, 3, "function") \
   F(FunctionTable, 4, "table")         \
   F(Memory, 5, "memory")               \
   F(ExportTable, 6, "export")          \
   F(StartFunction, 7, "start")         \
   F(FunctionBodies, 8, "code")         \
   F(DataSegments, 9, "data")           \
   F(Names, 10, "name")                 \
+  F(FunctionTablePad, 11, "table_pad") \
   F(Globals, 0, "global")              \
   F(End, 0, "end")
 
 // Contants for the above section types: {LEB128 length, characters...}.
 #define WASM_SECTION_MEMORY 6, 'm', 'e', 'm', 'o', 'r', 'y'
 #define WASM_SECTION_SIGNATURES 4, 't', 'y', 'p', 'e'
 #define WASM_SECTION_GLOBALS 6, 'g', 'l', 'o', 'b', 'a', 'l'
 #define WASM_SECTION_DATA_SEGMENTS 4, 'd', 'a', 't', 'a'
 #define WASM_SECTION_FUNCTION_TABLE 5, 't', 'a', 'b', 'l', 'e'
 #define WASM_SECTION_END 3, 'e', 'n', 'd'
 #define WASM_SECTION_START_FUNCTION 5, 's', 't', 'a', 'r', 't'
 #define WASM_SECTION_IMPORT_TABLE 6, 'i', 'm', 'p', 'o', 'r', 't'
 #define WASM_SECTION_EXPORT_TABLE 6, 'e', 'x', 'p', 'o', 'r', 't'
 #define WASM_SECTION_FUNCTION_SIGNATURES \
   8, 'f', 'u', 'n', 'c', 't', 'i', 'o', 'n'
 #define WASM_SECTION_FUNCTION_BODIES 4, 'c', 'o', 'd', 'e'
 #define WASM_SECTION_NAMES 4, 'n', 'a', 'm', 'e'
+#define WASM_SECTION_FUNCTION_TABLE_PAD \
+  9, 't', 'a', 'b', 'l', 'e', '_', 'p', 'a', 'd'
 
 // Constants for the above section headers' size (LEB128 + characters).
 #define WASM_SECTION_MEMORY_SIZE ((size_t)7)
 #define WASM_SECTION_SIGNATURES_SIZE ((size_t)5)
 #define WASM_SECTION_GLOBALS_SIZE ((size_t)7)
 #define WASM_SECTION_DATA_SEGMENTS_SIZE ((size_t)5)
 #define WASM_SECTION_FUNCTION_TABLE_SIZE ((size_t)6)
 #define WASM_SECTION_END_SIZE ((size_t)4)
 #define WASM_SECTION_START_FUNCTION_SIZE ((size_t)6)
 #define WASM_SECTION_IMPORT_TABLE_SIZE ((size_t)7)
 #define WASM_SECTION_EXPORT_TABLE_SIZE ((size_t)7)
 #define WASM_SECTION_FUNCTION_SIGNATURES_SIZE ((size_t)9)
 #define WASM_SECTION_FUNCTION_BODIES_SIZE ((size_t)5)
 #define WASM_SECTION_NAMES_SIZE ((size_t)5)
+#define WASM_SECTION_FUNCTION_TABLE_PAD_SIZE ((size_t)10)
 
 class WasmDebugInfo;
 
 struct WasmSection {
   enum class Code : uint32_t {
 #define F(enumerator, order, string) enumerator,
     FOR_EACH_WASM_SECTION_TYPE(F)
 #undef F
         Max
   };
@@ skipping 74 matching lines @@
   const byte* module_end;     // end address for the module bytes.
   uint32_t min_mem_pages;     // minimum size of the memory in 64k pages.
   uint32_t max_mem_pages;     // maximum size of the memory in 64k pages.
   bool mem_export;            // true if the memory is exported.
   bool mem_external;          // true if the memory is external.
   int start_function_index;   // start function, if any.
   ModuleOrigin origin;        // origin of the module
 
   std::vector<WasmGlobal> globals;             // globals in this module.
   uint32_t globals_size;                       // size of globals table.
+  uint32_t indirect_table_size;                // size of indirect function
+                                               //     table (includes padding).
   std::vector<FunctionSig*> signatures;        // signatures in this module.
   std::vector<WasmFunction> functions;         // functions in this module.
   std::vector<WasmDataSegment> data_segments;  // data segments in this module.
   std::vector<uint16_t> function_table;        // function table.
   std::vector<WasmImport> import_table;        // import table.
   std::vector<WasmExport> export_table;        // export table.
 
   WasmModule();
 
   // Get a string stored in the module bytes representing a name.
@@ skipping 28 matching lines @@
   bool BoundsCheck(uint32_t start, uint32_t end) const {
     size_t size = module_end - module_start;
     return start <= size && end <= size;
   }
 
   // Creates a new instantiation of the module in the given isolate.
   MaybeHandle<JSObject> Instantiate(Isolate* isolate, Handle<JSReceiver> ffi,
                                     Handle<JSArrayBuffer> memory) const;
 
   Handle<FixedArray> CompileFunctions(Isolate* isolate) const;
+
+  uint32_t FunctionTableSize() const {
+    if (indirect_table_size > 0) {
+      return indirect_table_size;
+    }
+    DCHECK_LE(function_table.size(), UINT32_MAX);
+    return static_cast<uint32_t>(function_table.size());
+  }
 };
 
 // An instantiated WASM module, including memory, function table, etc.
 struct WasmModuleInstance {
   const WasmModule* module;  // static representation of the module.
   // -- Heap allocated --------------------------------------------------------
   Handle<JSObject> js_object;            // JavaScript module object.
   Handle<Context> context;               // JavaScript native context.
   Handle<JSArrayBuffer> mem_buffer;      // Handle to array buffer of memory.
   Handle<JSArrayBuffer> globals_buffer;  // Handle to array buffer of globals.
@@ skipping 46 matching lines @@
     return module->functions[index].sig;
   }
   FunctionSig* GetImportSignature(uint32_t index) {
     DCHECK(IsValidImport(index));
     return module->import_table[index].sig;
   }
   FunctionSig* GetSignature(uint32_t index) {
     DCHECK(IsValidSignature(index));
     return module->signatures[index];
   }
-  size_t FunctionTableSize() {
-    return module ? module->function_table.size() : 0;
+  uint32_t FunctionTableSize() const {
+    return module->FunctionTableSize();
   }
 
   bool asm_js() { return origin == kAsmJsOrigin; }
 
   Handle<Code> GetCodeOrPlaceholder(uint32_t index) const;
   Handle<Code> GetImportCode(uint32_t index);
-  Handle<FixedArray> GetFunctionTable();
 
   static compiler::CallDescriptor* GetWasmCallDescriptor(Zone* zone,
                                                          FunctionSig* sig);
   static compiler::CallDescriptor* GetI32WasmCallDescriptor(
       Zone* zone, compiler::CallDescriptor* descriptor);
   compiler::CallDescriptor* GetCallDescriptor(Zone* zone, uint32_t index);
 };
 
 // A helper for printing out the names of functions.
 struct WasmFunctionName {
@@ skipping 45 matching lines @@
 // secure. If it turns out that we need more complete checks, we could add a
 // special marker as internal field, which will definitely never occur anywhere
 // else.
 bool IsWasmObject(Object* object);
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_WASM_MODULE_H_