[js-api] Update wasm-module-builder.js for exnref (WebAssembly#314)

This pulls in some exnref-related changes from
https://github.com/v8/v8/blob/main/test/mjsunit/wasm/wasm-module-builder.js
but does not sync with it completely. That v8 version contains a lot of
features from new proposals that are not really relevant to EH and
exnref, so this pulls only the relevant EH parts in.

This also renames `kWasmStmt` to `kWasmVoid` as in the V8 version,
because it looks more intuitive. Also renames `kTagAttribute` to
`kExceptionAttribute`.

Author: aheejin

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

@@ -90,8 +90,8 @@ let kDeclFunctionImport = 0x02;
 let kDeclFunctionLocals = 0x04;
 let kDeclFunctionExport = 0x08;
 
-// Local types
-let kWasmStmt = 0x40;
+// Value types and related
+let kWasmVoid = 0x40;
 let kWasmI32 = 0x7f;
 let kWasmI64 = 0x7e;
 let kWasmF32 = 0x7d;
@@ -107,6 +107,8 @@ let kWasmFuncRef = -0x10;
 let kWasmAnyFunc = kWasmFuncRef;  // Alias named as in the JS API spec
 let kWasmExternRef = -0x11;
 let kWasmAnyRef = -0x12;
+let kWasmExnRef = -0x17;
+let kWasmNullExnRef = -0x0c;
 
 // Use the positive-byte versions inside function bodies.
 let kLeb128Mask = 0x7f;
@@ -116,6 +118,8 @@ let kExternRefCode = kWasmExternRef & kLeb128Mask;
 let kAnyRefCode = kWasmAnyRef & kLeb128Mask;
 let kNullExternRefCode = kWasmNullExternRef & kLeb128Mask;
 let kNullFuncRefCode = kWasmNullFuncRef & kLeb128Mask;
+let kExnRefCode = kWasmExnRef & kLeb128Mask;
+let kNullExnRefCode = kWasmNullExnRef & kLeb128Mask;
 let kNullRefCode = kWasmNullRef & kLeb128Mask;
 
 let kWasmRefNull = 0x63;
@@ -137,7 +141,7 @@ let kTableZero = 0;
 let kMemoryZero = 0;
 let kSegmentZero = 0;
 
-let kTagAttribute = 0;
+let kExceptionAttribute = 0;
 
 // Useful signatures
 let kSig_i_i = makeSig([kWasmI32], [kWasmI32]);
@@ -217,10 +221,9 @@ let kExprIf = 0x04;
 let kExprElse = 0x05;
 let kExprTry = 0x06;
 let kExprCatch = 0x07;
-let kExprCatchAll = 0x19;
 let kExprThrow = 0x08;
 let kExprRethrow = 0x09;
-let kExprBrOnExn = 0x0a;
+let kExprThrowRef = 0x0a;
 let kExprEnd = 0x0b;
 let kExprBr = 0x0c;
 let kExprBrIf = 0x0d;
@@ -230,8 +233,10 @@ let kExprCallFunction = 0x10;
 let kExprCallIndirect = 0x11;
 let kExprReturnCall = 0x12;
 let kExprReturnCallIndirect = 0x13;
+let kExprCatchAll = 0x19;
 let kExprDrop = 0x1a;
 let kExprSelect = 0x1b;
+let kExprTryTable = 0x1f;
 let kExprLocalGet = 0x20;
 let kExprLocalSet = 0x21;
 let kExprLocalTee = 0x22;
@@ -494,6 +499,12 @@ let kExprI32x4Eq = 0x2c;
 let kExprS1x4AllTrue = 0x75;
 let kExprF32x4Min = 0x9e;
 
+// Exception handling with exnref.
+let kCatchNoRef = 0x0;
+let kCatchRef = 0x1;
+let kCatchAllNoRef = 0x2;
+let kCatchAllRef = 0x3;
+
 class Binary {
   constructor() {
     this.length = 0;
@@ -976,7 +987,7 @@ class WasmModuleBuilder {
             section.emit_u32v(imp.initial); // initial
             if (has_max) section.emit_u32v(imp.maximum); // maximum
           } else if (imp.kind == kExternalTag) {
-            section.emit_u32v(kTagAttribute);
+            section.emit_u32v(kExceptionAttribute);
             section.emit_u32v(imp.type);
           } else {
             throw new Error("unknown/unsupported import kind " + imp.kind);
@@ -1079,7 +1090,7 @@ class WasmModuleBuilder {
       binary.emit_section(kTagSectionCode, section => {
         section.emit_u32v(wasm.tags.length);
         for (let type of wasm.tags) {
-          section.emit_u32v(kTagAttribute);
+          section.emit_u32v(kExceptionAttribute);
           section.emit_u32v(type);
         }
       });

test/legacy/exceptions/js-api/basic.tentative.any.js

@@ -76,7 +76,7 @@ promise_test(async () => {
   const tagIndex= builder.addTag(kSig_v_r);
   builder.addFunction("catch_exception", kSig_r_v)
     .addBody([
-      kExprTry, kWasmStmt,
+      kExprTry, kWasmVoid,
         kExprCallFunction, fnIndex,
       kExprCatch, tagIndex,
         kExprReturn,
@@ -100,7 +100,7 @@ promise_test(async () => {
   const fnIndex = builder.addImport("module", "fn", kSig_v_v);
   builder.addFunction("catch_and_rethrow", kSig_r_v)
     .addBody([
-      kExprTry, kWasmStmt,
+      kExprTry, kWasmVoid,
         kExprCallFunction, fnIndex,
       kExprCatchAll,
         kExprRethrow, 0x00,

test/legacy/exceptions/js-api/identity.tentative.any.js

@@ -35,7 +35,7 @@ test(() => {
   builder
     .addFunction("catch_js_tag_rethrow", kSig_v_v)
     .addBody([
-      kExprTry, kWasmStmt,
+      kExprTry, kWasmVoid,
         kExprCallFunction, throwJSTagExnIndex,
       kExprCatch, jsTagIndex,
         kExprDrop,
@@ -49,7 +49,7 @@ test(() => {
   builder
     .addFunction("catch_wasm_tag_rethrow", kSig_v_v)
     .addBody([
-      kExprTry, kWasmStmt,
+      kExprTry, kWasmVoid,
         kExprCallFunction, throwWasmTagExnIndex,
       kExprCatch, wasmTagIndex,
         kExprDrop,
@@ -63,7 +63,7 @@ test(() => {
   builder
     .addFunction("catch_all_js_tag_rethrow", kSig_v_v)
     .addBody([
-      kExprTry, kWasmStmt,
+      kExprTry, kWasmVoid,
         kExprCallFunction, throwJSTagExnIndex,
       kExprCatchAll,
         kExprRethrow, 0x00,
@@ -76,7 +76,7 @@ test(() => {
   builder
     .addFunction("catch_all_wasm_tag_rethrow", kSig_v_v)
     .addBody([
-      kExprTry, kWasmStmt,
+      kExprTry, kWasmVoid,
         kExprCallFunction, throwWasmTagExnIndex,
       kExprCatchAll,
         kExprRethrow, 0x00,
@@ -103,7 +103,7 @@ test(() => {
   builder
     .addFunction("catch_js_tag_throw_payload", kSig_v_v)
     .addBody([
-      kExprTry, kWasmStmt,
+      kExprTry, kWasmVoid,
         kExprCallFunction, throwJSTagExnIndex,
       kExprCatch, jsTagIndex,
         kExprThrow, jsTagIndex,