[wasm] Fix placement of the events section

Before, it was specified between the globals and the exports section.
This changed with
WebAssembly/exception-handling#98. The event
section is now placed between the memory and the globals section.

[email protected]
[email protected]

Bug: v8:10176
Change-Id: Icafeaae4ff7796273c73d61ed417c028fcbcb02d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2116032
Reviewed-by: Jakob Kummerow <[email protected]>
Commit-Queue: Clemens Backes <[email protected]>
Cr-Commit-Position: refs/heads/master@{#66833}

Author: backes

src/wasm/module-decoder.cc

@@ -432,8 +432,8 @@ class ModuleDecoderImpl : public Decoder {
         break;
       case kExceptionSectionCode:
         if (!CheckUnorderedSection(section_code)) return;
-        if (!CheckSectionOrder(section_code, kGlobalSectionCode,
-                               kExportSectionCode))
+        if (!CheckSectionOrder(section_code, kMemorySectionCode,
+                               kGlobalSectionCode))
           return;
         break;
       case kNameSectionCode:

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

@@ -65,7 +65,7 @@ let kElementSectionCode = 9;     // Elements section
 let kCodeSectionCode = 10;       // Function code
 let kDataSectionCode = 11;       // Data segments
 let kDataCountSectionCode = 12;  // Data segment count (between Element & Code)
-let kExceptionSectionCode = 13;  // Exception section (between Global & Export)
+let kExceptionSectionCode = 13;  // Exception section (between Memory & Global)
 
 // Name section types
 let kModuleNameCode = 0;
@@ -1080,6 +1080,18 @@ class WasmModuleBuilder {
       });
     }
 
+    // Add event section.
+    if (wasm.exceptions.length > 0) {
+      if (debug) print("emitting events @ " + binary.length);
+      binary.emit_section(kExceptionSectionCode, section => {
+        section.emit_u32v(wasm.exceptions.length);
+        for (let type of wasm.exceptions) {
+          section.emit_u32v(kExceptionAttribute);
+          section.emit_u32v(type);
+        }
+      });
+    }
+
     // Add global section.
     if (wasm.globals.length > 0) {
       if (debug) print ("emitting globals @ " + binary.length);
@@ -1133,18 +1145,6 @@ class WasmModuleBuilder {
       });
     }
 
-    // Add exceptions.
-    if (wasm.exceptions.length > 0) {
-      if (debug) print("emitting exceptions @ " + binary.length);
-      binary.emit_section(kExceptionSectionCode, section => {
-        section.emit_u32v(wasm.exceptions.length);
-        for (let type of wasm.exceptions) {
-          section.emit_u32v(kExceptionAttribute);
-          section.emit_u32v(type);
-        }
-      });
-    }
-
     // Add export table.
     var mem_export = (wasm.memory !== undefined && wasm.memory.exp);
     var exports_count = wasm.exports.length + (mem_export ? 1 : 0);

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

@@ -724,47 +724,47 @@ TEST_F(WasmModuleVerifyTest, Exception_invalid_attribute) {
 }
 
 TEST_F(WasmModuleVerifyTest, ExceptionSectionCorrectPlacement) {
-  static const byte data[] = {SECTION(Import, ENTRY_COUNT(0)),
+  static const byte data[] = {SECTION(Memory, ENTRY_COUNT(0)),
                               SECTION(Exception, ENTRY_COUNT(0)),
-                              SECTION(Export, ENTRY_COUNT(0))};
+                              SECTION(Global, ENTRY_COUNT(0))};
   FAIL_IF_NO_EXPERIMENTAL_EH(data);
 
   WASM_FEATURE_SCOPE(eh);
   ModuleResult result = DecodeModule(data, data + sizeof(data));
   EXPECT_OK(result);
 }
 
-TEST_F(WasmModuleVerifyTest, ExceptionSectionAfterExport) {
-  static const byte data[] = {SECTION(Export, ENTRY_COUNT(0)),
+TEST_F(WasmModuleVerifyTest, ExceptionSectionAfterGlobal) {
+  static const byte data[] = {SECTION(Global, ENTRY_COUNT(0)),
                               SECTION(Exception, ENTRY_COUNT(0))};
   FAIL_IF_NO_EXPERIMENTAL_EH(data);
 
   WASM_FEATURE_SCOPE(eh);
   ModuleResult result = DecodeModule(data, data + sizeof(data));
   EXPECT_NOT_OK(result,
-                "The Exception section must appear before the Export section");
+                "The Exception section must appear before the Global section");
 }
 
-TEST_F(WasmModuleVerifyTest, ExceptionSectionBeforeGlobal) {
+TEST_F(WasmModuleVerifyTest, ExceptionSectionBeforeMemory) {
   static const byte data[] = {SECTION(Exception, ENTRY_COUNT(0)),
-                              SECTION(Global, ENTRY_COUNT(0))};
+                              SECTION(Memory, ENTRY_COUNT(0))};
   FAIL_IF_NO_EXPERIMENTAL_EH(data);
 
   WASM_FEATURE_SCOPE(eh);
   ModuleResult result = DecodeModule(data, data + sizeof(data));
-  EXPECT_NOT_OK(result, "unexpected section <Global>");
+  EXPECT_NOT_OK(result, "unexpected section <Memory>");
 }
 
-TEST_F(WasmModuleVerifyTest, ExceptionSectionAfterMemoryBeforeGlobal) {
+TEST_F(WasmModuleVerifyTest, ExceptionSectionAfterTableBeforeMemory) {
   STATIC_ASSERT(kMemorySectionCode + 1 == kGlobalSectionCode);
-  static const byte data[] = {SECTION(Memory, ENTRY_COUNT(0)),
+  static const byte data[] = {SECTION(Table, ENTRY_COUNT(0)),
                               SECTION(Exception, ENTRY_COUNT(0)),
-                              SECTION(Global, ENTRY_COUNT(0))};
+                              SECTION(Memory, ENTRY_COUNT(0))};
   FAIL_IF_NO_EXPERIMENTAL_EH(data);
 
   WASM_FEATURE_SCOPE(eh);
   ModuleResult result = DecodeModule(data, data + sizeof(data));
-  EXPECT_NOT_OK(result, "unexpected section <Global>");
+  EXPECT_NOT_OK(result, "unexpected section <Memory>");
 }
 
 TEST_F(WasmModuleVerifyTest, ExceptionImport) {