[wasm] Encode function signatures, bodies, and names as separate sections.

R=binji@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1783593002

Cr-Commit-Position: refs/heads/master@{#34641}

src/wasm/decoder.h

@@ -333,6 +333,7 @@ class Decoder {
 
   const byte* start() { return start_; }
   const byte* pc() { return pc_; }
+  uint32_t pc_offset() { return static_cast<uint32_t>(pc_ - start_); }
 
  protected:
   const byte* start_;

src/wasm/wasm-module.h

@@ -29,17 +29,20 @@ const uint32_t kWasmVersion = 0x0a;
 // internally V8 uses an enum to handle them.
 //
 // Entries have the form F(enumerator, string).
-#define FOR_EACH_WASM_SECTION_TYPE(F)     \
-  F(kDeclMemory, "memory")                \
-  F(kDeclSignatures, "signatures")        \
-  F(kDeclFunctions, "functions")          \
-  F(kDeclGlobals, "globals")              \
-  F(kDeclDataSegments, "data_segments")   \
-  F(kDeclFunctionTable, "function_table") \
-  F(kDeclEnd, "end")                      \
-  F(kDeclStartFunction, "start_function") \
-  F(kDeclImportTable, "import_table")     \
-  F(kDeclExportTable, "export_table")
+#define FOR_EACH_WASM_SECTION_TYPE(F)               \
+  F(kDeclMemory, "memory")                          \
+  F(kDeclSignatures, "signatures")                  \
+  F(kDeclFunctions, "functions")                    \
+  F(kDeclGlobals, "globals")                        \
+  F(kDeclDataSegments, "data_segments")             \
+  F(kDeclFunctionTable, "function_table")           \
+  F(kDeclEnd, "end")                                \
+  F(kDeclStartFunction, "start_function")           \
+  F(kDeclImportTable, "import_table")               \
+  F(kDeclExportTable, "export_table")               \
+  F(kDeclFunctionSignatures, "function_signatures") \
+  F(kDeclFunctionBodies, "function_bodies")         \
+  F(kDeclNames, "names")
 
 enum WasmSectionDeclCode : uint32_t {
 #define F(enumerator, string) enumerator,

test/mjsunit/wasm/wasm-constants.js

@@ -61,6 +61,9 @@ var kDeclStartFunction = 0x07;
 var kDeclImportTable = 0x08;
 var kDeclExportTable = 0x09;
 var kDeclEnd = 0x06;
+var kDeclFunctionSignatures = 0x0a;
+var kDeclFunctionBodies = 0x0b;
+var kDeclNames = 0x0c;
 
 // Function declaration flags
 var kDeclFunctionName   = 0x01;

test/mjsunit/wasm/wasm-module-builder.js

@@ -125,6 +125,12 @@ function emit_varint(bytes, val) {
     }
 }
 
+function emit_bytes(bytes, data) {
+  for (var i = 0; i < data.length; i++) {
+    bytes.push(data[i] & 0xff);
+  }
+}
+
 WasmModuleBuilder.prototype.toArray = function(debug) {
     // Add header bytes
     var bytes = [];
@@ -170,26 +176,26 @@ WasmModuleBuilder.prototype.toArray = function(debug) {
     var names = false;
     var exports = 0;
     if (this.functions.length > 0) {
-        if (debug) print("emitting functions @ " + bytes.length);
-        emit_u8(bytes, kDeclFunctions);
+        var has_names = false;
+
+        // emit function signatures
+        if (debug) print("emitting function sigs @ " + bytes.length);
+        emit_u8(bytes, kDeclFunctionSignatures);
         emit_varint(bytes, this.functions.length);
-        var index = 0;
         for (func of this.functions) {
-            var flags = 0;
-            var hasName = func.name != undefined && func.name.length > 0;
-            names = names || hasName;
-            if (hasName) flags |= kDeclFunctionName;
-            exports += func.exports.length;
-
-            emit_u8(bytes, flags);
-            emit_u16(bytes, func.sig_index);
+          has_names = has_names || (func.name != undefined &&
+                                    func.name.length > 0);
+          exports += func.exports.length;
 
-            if (hasName) emit_string(bytes, func.name);
+          emit_varint(bytes, func.sig_index);
+        }
 
+        // emit function bodies
+        if (debug) print("emitting function bodies @ " + bytes.length);
+        emit_u8(bytes, kDeclFunctionBodies);
+        emit_varint(bytes, this.functions.length);
+        for (func of this.functions) {
             // Function body length will be patched later.
-            var length_pos = bytes.length;
-            emit_u16(bytes, 0);
-
             var local_decls = [];
             var l = func.locals;
             if (l != undefined) {
@@ -207,28 +213,37 @@ WasmModuleBuilder.prototype.toArray = function(debug) {
                 local_decls.push({count: l.f64_count, type: kAstF64});
               }
             }
-            emit_varint(bytes, local_decls.length);
+            var header = new Array();
+
+            emit_varint(header, local_decls.length);
             for (decl of local_decls) {
-              emit_varint(bytes, decl.count);
-              emit_u8(bytes, decl.type);
+              emit_varint(header, decl.count);
+              emit_u8(header, decl.type);
             }
 
-            for (var i = 0; i < func.body.length; i++) {
-                emit_u8(bytes, func.body[i]);
-            }
-            var length = bytes.length - length_pos - 2;
-            bytes[length_pos] = length & 0xff;
-            bytes[length_pos + 1] = (length >> 8) & 0xff;
+            emit_varint(bytes, header.length + func.body.length);
+            emit_bytes(bytes, header);
+            emit_bytes(bytes, func.body);
+        }
+    }
 
-            index++;
+    // emit function names
+    if (has_names) {
+        if (debug) print("emitting names @ " + bytes.length);
+        emit_u8(bytes, kDeclNames);
+        emit_varint(bytes, this.functions.length);
+        for (func of this.functions) {
+            var name = func.name == undefined ? "" : func.name;
+           emit_string(bytes, name);
+           emit_u8(bytes, 0);  // local names count == 0
         }
     }
 
     // Add start function section.
     if (this.start_index != undefined) {
         if (debug) print("emitting start function @ " + bytes.length);
-      emit_u8(bytes, kDeclStartFunction);
-      emit_varint(bytes, this.start_index);
+        emit_u8(bytes, kDeclStartFunction);
+        emit_varint(bytes, this.start_index);
     }
 
     if (this.function_table.length > 0) {
@@ -259,18 +274,14 @@ WasmModuleBuilder.prototype.toArray = function(debug) {
         for (seg of this.data_segments) {
             emit_varint(bytes, seg.addr);
             emit_varint(bytes, seg.data.length);
-            for (var i = 0; i < seg.data.length; i++) {
-                emit_u8(bytes, seg.data[i]);
-            }
+            emit_bytes(bytes, seg.data);
         }
     }
 
     // Emit any explicitly added sections
     for (exp of this.explicit) {
         if (debug) print("emitting explicit @ " + bytes.length);
-        for (var i = 0; i < exp.length; i++) {
-            emit_u8(bytes, exp[i]);
-        }
+        emit_bytes(bytes, exp);
     }
 
     // End the module.

test/unittests/wasm/module-decoder-unittest.cc

@@ -13,6 +13,8 @@ namespace internal {
 namespace wasm {
 
 #define EMPTY_FUNCTION(sig_index) 0, SIG_INDEX(sig_index), U16_LE(0)
+#define EMPTY_BODY 0
+#define NOP_BODY 2, 0, kExprNop
 #define VOID_VOID_SIG 0, kLocalVoid
 #define INT_INT_SIG 1, kLocalI32, kLocalI32
 
@@ -1059,12 +1061,20 @@ TEST_F(WasmModuleVerifyTest, ImportTable_off_end) {
   EXPECT_OFF_END_FAILURE(data, 5, sizeof(data));
 }
 
-TEST_F(WasmModuleVerifyTest, ExportTable_empty) {
-  static const byte data[] = {kDeclSignatures,  0, kDeclFunctions, 0,
+TEST_F(WasmModuleVerifyTest, ExportTable_empty1) {
+  static const byte data[] = {kDeclSignatures,  1, VOID_VOID_SIG,
+                              kDeclFunctions,   1, EMPTY_FUNCTION(0),
                               kDeclExportTable, 0};
   EXPECT_VERIFIES(data);
 }
 
+TEST_F(WasmModuleVerifyTest, ExportTable_empty2) {
+  static const byte data[] = {kDeclSignatures,  0, kDeclFunctions, 0,
+                              kDeclExportTable, 0};
+  // TODO(titzer): current behavior treats empty functions section as missing.
+  EXPECT_FAILURE(data);
+}
+
 TEST_F(WasmModuleVerifyTest, ExportTable_NoFunctions1) {
   static const byte data[] = {kDeclSignatures, 0, kDeclExportTable, 0};
   EXPECT_FAILURE(data);
@@ -1162,6 +1172,96 @@ TEST_F(WasmModuleVerifyTest, ExportTableOne_off_end) {
   }
 }
 
+#define SIGNATURES_SECTION(count, ...) \
+  kDeclSignatures, U32V_1(count), __VA_ARGS__
+#define FUNCTION_SIGNATURES_SECTION(count, ...) \
+  kDeclFunctionSignatures, U32V_1(count), __VA_ARGS__
+#define FUNCTION_BODIES_SECTION(count, ...) \
+  kDeclFunctionBodies, U32V_1(count), __VA_ARGS__
+#define NAMES_SECTION(count, ...) kDeclNames, U32V_1(count), __VA_ARGS__
+
+#define FOO_STRING 3, 'f', 'o', 'o'
+#define NO_LOCAL_NAMES 0
+
+#define EMPTY_SIGNATURES_SECTION kDeclSignatures, 0
+#define EMPTY_FUNCTION_SIGNATURES_SECTION kDeclFunctionSignatures, 0
+#define EMPTY_FUNCTION_BODIES_SECTION kDeclFunctionBodies, 0
+#define EMPTY_NAMES_SECTION kDeclNames, 0
+
+TEST_F(WasmModuleVerifyTest, FunctionSignatures_empty) {
+  static const byte data[] = {kDeclSignatures, 0, kDeclFunctionSignatures, 0};
+  EXPECT_VERIFIES(data);
+}
+
+TEST_F(WasmModuleVerifyTest, FunctionSignatures_one) {
+  static const byte data[] = {SIGNATURES_SECTION(1, VOID_VOID_SIG),
+                              FUNCTION_SIGNATURES_SECTION(1, 0)};
+  EXPECT_VERIFIES(data);
+}
+
+TEST_F(WasmModuleVerifyTest, FunctionBodies_empty) {
+  static const byte data[] = {EMPTY_SIGNATURES_SECTION,
+                              EMPTY_FUNCTION_SIGNATURES_SECTION,
+                              EMPTY_FUNCTION_BODIES_SECTION};
+  EXPECT_VERIFIES(data);
+}
+
+TEST_F(WasmModuleVerifyTest, FunctionBodies_one_empty) {
+  static const byte data[] = {SIGNATURES_SECTION(1, VOID_VOID_SIG),
+                              FUNCTION_SIGNATURES_SECTION(1, 0),
+                              FUNCTION_BODIES_SECTION(1, EMPTY_BODY)};
+  EXPECT_VERIFIES(data);
+}
+
+TEST_F(WasmModuleVerifyTest, FunctionBodies_one_nop) {
+  static const byte data[] = {SIGNATURES_SECTION(1, VOID_VOID_SIG),
+                              FUNCTION_SIGNATURES_SECTION(1, 0),
+                              FUNCTION_BODIES_SECTION(1, NOP_BODY)};
+  EXPECT_VERIFIES(data);
+}
+
+TEST_F(WasmModuleVerifyTest, FunctionBodies_count_mismatch1) {
+  static const byte data[] = {SIGNATURES_SECTION(1, VOID_VOID_SIG),
+                              FUNCTION_SIGNATURES_SECTION(2, 0, 0),
+                              FUNCTION_BODIES_SECTION(1, EMPTY_BODY)};
+  EXPECT_FAILURE(data);
+}
+
+TEST_F(WasmModuleVerifyTest, FunctionBodies_count_mismatch2) {
+  static const byte data[] = {SIGNATURES_SECTION(1, VOID_VOID_SIG),
+                              FUNCTION_SIGNATURES_SECTION(1, 0),
+                              FUNCTION_BODIES_SECTION(2, NOP_BODY, NOP_BODY)};
+  EXPECT_FAILURE(data);
+}
+
+TEST_F(WasmModuleVerifyTest, Names_empty) {
+  static const byte data[] = {
+      EMPTY_SIGNATURES_SECTION, EMPTY_FUNCTION_SIGNATURES_SECTION,
+      EMPTY_FUNCTION_BODIES_SECTION, EMPTY_NAMES_SECTION};
+  EXPECT_VERIFIES(data);
+}
+
+TEST_F(WasmModuleVerifyTest, Names_one_empty) {
+  static const byte data[] = {
+      SIGNATURES_SECTION(1, VOID_VOID_SIG),         // --
+      FUNCTION_SIGNATURES_SECTION(1, 0),            // --
+      FUNCTION_BODIES_SECTION(1, EMPTY_BODY),       // --
+      NAMES_SECTION(1, FOO_STRING, NO_LOCAL_NAMES)  // --
+  };
+  EXPECT_VERIFIES(data);
+}
+
+TEST_F(WasmModuleVerifyTest, Names_two_empty) {
+  static const byte data[] = {
+      SIGNATURES_SECTION(1, VOID_VOID_SIG),                // --
+      FUNCTION_SIGNATURES_SECTION(2, 0, 0),                // --
+      FUNCTION_BODIES_SECTION(2, EMPTY_BODY, EMPTY_BODY),  // --
+      NAMES_SECTION(2, FOO_STRING, NO_LOCAL_NAMES,         // --
+                    FOO_STRING, NO_LOCAL_NAMES)            // --
+  };
+  EXPECT_VERIFIES(data);
+}
+
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8