Revert "Start migration of try/throw/catch to match proposal."

This reverts commit 470a1001.

Reason for revert: GC stress bot failures.
https://uberchromegw.corp.google.com/i/client.v8/builders/V8%20Mac%20GC%20Stress/builds/14522


Original change's description:
> Start migration of try/throw/catch to match proposal.
> 
> This CL does the first baby steps on moving the current (experimental)
> exception handling to match that of the WebAssembly proposal.
> 
> It does the following:
> 
> 1) Use exception tags instead of integers.
> 
> 2) Only handle empty exception signatures (i.e. no values associated
>    with the exception tag.
> 
> 3) Only handle one catch clause.
> 
> 4) Be sure to rethrow the exception if the exception tag does not match.
> 
> Note: There are many things that need to be fixed, and are too
> numerous to list here. However, the code should have TODO's on each
> missing parts of the implementation.
> 
> Also note that the code currently doesn't handle nested catch blocks,
> nor does it change the throw value being an integer. Rather, the
> integer value is still being thrown, and currently is the exception
> tag. Therefore, we don't build an exception object. This is the reason
> why this CL doesn't handle exceptions that pass values.
> 
> Also, the current implementation still can't handle multiple modules
> because tag resolution (between) modules has not be implemented yet.
> 
> Bug: v8:6577
> Change-Id: Id6d08b641b3c42d1eec7d4db582f2dab35406114
> Reviewed-on: https://chromium-review.googlesource.com/591910
> Reviewed-by: Brad Nelson <bradnelson@chromium.org>
> Commit-Queue: Karl Schimpf <kschimpf@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#47087}

TBR=bradnelson@chromium.org,eholk@chromium.org,kschimpf@chromium.org

Change-Id: I01dc8c40cc1057333a988c1d275ce5f457b0cb64
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6577
Reviewed-on: https://chromium-review.googlesource.com/598847Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47090}

src/compiler/wasm-compiler.cc

@@ -1830,18 +1830,12 @@ Node* WasmGraphBuilder::Throw(Node* input) {
                             arraysize(parameters));
 }
 
-Node* WasmGraphBuilder::Rethrow() {
-  SetNeedsStackCheck();
-  Node* result = BuildCallToRuntime(Runtime::kWasmRethrow, nullptr, 0);
-  return result;
-}
-
 Node* WasmGraphBuilder::Catch(Node* input, wasm::WasmCodePosition position) {
   SetNeedsStackCheck();
   CommonOperatorBuilder* common = jsgraph()->common();
 
   Node* parameters[] = {input};  // caught value
-  Node* value = BuildCallToRuntime(Runtime::kWasmSetCaughtExceptionValue,
+  Node* value = BuildCallToRuntime(Runtime::kWasmGetCaughtExceptionValue,
                                    parameters, arraysize(parameters));
 
   Node* is_smi;

src/compiler/wasm-compiler.h

@@ -168,7 +168,6 @@ class WasmGraphBuilder {
              wasm::WasmCodePosition position = wasm::kNoCodePosition);
   Node* GrowMemory(Node* input);
   Node* Throw(Node* input);
-  Node* Rethrow();
   Node* Catch(Node* input, wasm::WasmCodePosition position);
   unsigned InputCount(Node* node);
   bool IsPhiWithMerge(Node* phi, Node* merge);

src/isolate-inl.h

@@ -47,17 +47,6 @@ bool Isolate::has_pending_exception() {
   return !thread_local_top_.pending_exception_->IsTheHole(this);
 }
 
-Object* Isolate::get_wasm_caught_exception() const {
-  return thread_local_top_.wasm_caught_exception_;
-}
-
-void Isolate::set_wasm_caught_exception(Object* exception_obj) {
-  thread_local_top_.wasm_caught_exception_ = exception_obj;
-}
-
-void Isolate::clear_wasm_caught_exception() {
-  thread_local_top_.wasm_caught_exception_ = nullptr;
-}
 
 void Isolate::clear_pending_message() {
   thread_local_top_.pending_message_obj_ = heap_.the_hole_value();

src/isolate.cc

@@ -103,7 +103,6 @@ void ThreadLocalTop::InitializeInternal() {
   // These members are re-initialized later after deserialization
   // is complete.
   pending_exception_ = NULL;
-  wasm_caught_exception_ = NULL;
   rethrowing_message_ = false;
   pending_message_obj_ = NULL;
   scheduled_exception_ = NULL;
@@ -216,7 +215,6 @@ void Isolate::IterateThread(ThreadVisitor* v, char* t) {
 void Isolate::Iterate(RootVisitor* v, ThreadLocalTop* thread) {
   // Visit the roots from the top for a given thread.
   v->VisitRootPointer(Root::kTop, &thread->pending_exception_);
-  v->VisitRootPointer(Root::kTop, &thread->wasm_caught_exception_);
   v->VisitRootPointer(Root::kTop, &thread->pending_message_obj_);
   v->VisitRootPointer(Root::kTop, bit_cast<Object**>(&(thread->context_)));
   v->VisitRootPointer(Root::kTop, &thread->scheduled_exception_);

src/isolate.h

@@ -326,9 +326,6 @@ class ThreadLocalTop BASE_EMBEDDED {
   Context* context_;
   ThreadId thread_id_;
   Object* pending_exception_;
-  // TODO(kschimpf): Change this to a stack of caught exceptions (rather than
-  // just innermost catching try block).
-  Object* wasm_caught_exception_;
 
   // Communication channel between Isolate::FindHandler and the CEntryStub.
   Context* pending_handler_context_;
@@ -605,11 +602,6 @@ class Isolate {
   inline void set_pending_exception(Object* exception_obj);
   inline void clear_pending_exception();
 
-  // Interface to wasm caught exception.
-  inline Object* get_wasm_caught_exception() const;
-  inline void set_wasm_caught_exception(Object* exception_obj);
-  inline void clear_wasm_caught_exception();
-
   THREAD_LOCAL_TOP_ADDRESS(Object*, pending_exception)
 
   inline bool has_pending_exception();

src/runtime/runtime-wasm.cc

@@ -142,8 +142,6 @@ RUNTIME_FUNCTION(Runtime_WasmThrowTypeError) {
 }
 
 RUNTIME_FUNCTION(Runtime_WasmThrow) {
-  // TODO(kschimpf): Change this to build a runtime exception with
-  // wasm properties, instead of just an integer.
   HandleScope scope(isolate);
   DCHECK_EQ(2, args.length());
   CONVERT_SMI_ARG_CHECKED(lower, 0);
@@ -158,15 +156,7 @@ RUNTIME_FUNCTION(Runtime_WasmThrow) {
   return isolate->Throw(*isolate->factory()->NewNumberFromInt(thrown_value));
 }
 
-RUNTIME_FUNCTION(Runtime_WasmRethrow) {
-  HandleScope scope(isolate);
-  DCHECK_EQ(0, args.length());
-  Object* exception = isolate->get_wasm_caught_exception();
-  isolate->clear_wasm_caught_exception();
-  return isolate->Throw(exception);
-}
-
-RUNTIME_FUNCTION(Runtime_WasmSetCaughtExceptionValue) {
+RUNTIME_FUNCTION(Runtime_WasmGetCaughtExceptionValue) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());
   Object* exception = args[0];
@@ -174,7 +164,6 @@ RUNTIME_FUNCTION(Runtime_WasmSetCaughtExceptionValue) {
   // Number or a Smi (which we have just converted to a Number.) This logic
   // lives in Isolate::is_catchable_by_wasm(Object*).
   CHECK(exception->IsNumber());
-  isolate->set_wasm_caught_exception(exception);
   return exception;
 }
 

src/runtime/runtime.h

@@ -634,8 +634,7 @@ namespace internal {
   F(ThrowWasmStackOverflow, 0, 1)      \
   F(WasmThrowTypeError, 0, 1)          \
   F(WasmThrow, 2, 1)                   \
-  F(WasmRethrow, 0, 1)                 \
-  F(WasmSetCaughtExceptionValue, 1, 1) \
+  F(WasmGetCaughtExceptionValue, 1, 1) \
   F(WasmRunInterpreter, 3, 1)          \
   F(WasmStackGuard, 0, 1)              \
   F(SetThreadInWasm, 0, 1)             \

src/wasm/function-body-decoder-impl.h

@@ -13,7 +13,6 @@ namespace internal {
 namespace wasm {
 
 struct WasmGlobal;
-struct WasmException;
 
 // Use this macro to check a condition if checked == true, and DCHECK the
 // condition otherwise.
@@ -35,17 +34,6 @@ struct LocalIndexOperand {
   }
 };
 
-template <bool checked>
-struct ExceptionIndexOperand {
-  uint32_t index;
-  const WasmException* exception = nullptr;
-  unsigned length;
-
-  inline ExceptionIndexOperand(Decoder* decoder, const byte* pc) {
-    index = decoder->read_u32v<checked>(pc + 1, &length, "exception index");
-  }
-};
-
 template <bool checked>
 struct ImmI32Operand {
   int32_t value;

src/wasm/function-body-decoder.cc

@@ -44,8 +44,9 @@ namespace wasm {
     break;                                                               \
   }
 
-#define OPCODE_ERROR(opcode, message) \
-  (errorf(pc_, "%s: %s", WasmOpcodes::OpcodeName(opcode), (message)))
+#define PROTOTYPE_NOT_FUNCTIONAL(opcode)            \
+  errorf(pc_, "Prototype still not functional: %s", \
+         WasmOpcodes::OpcodeName(opcode));
 
 // An SsaEnv environment carries the current local variable renaming
 // as well as the current effect and control dependency in the TF graph.
@@ -81,10 +82,8 @@ struct Value {
 struct TryInfo : public ZoneObject {
   SsaEnv* catch_env;
   TFNode* exception;
-  size_t catch_count;  // Number of catch blocks associated with the try.
 
-  explicit TryInfo(SsaEnv* c)
-      : catch_env(c), exception(nullptr), catch_count(0) {}
+  explicit TryInfo(SsaEnv* c) : catch_env(c), exception(nullptr) {}
 };
 
 struct MergeValues {
@@ -284,15 +283,6 @@ class WasmDecoder : public Decoder {
     return false;
   }
 
-  inline bool Validate(const byte* pc, ExceptionIndexOperand<true>& operand) {
-    if (module_ != nullptr && operand.index < module_->exceptions.size()) {
-      operand.exception = &module_->exceptions[operand.index];
-      return true;
-    }
-    errorf(pc + 1, "Invalid exception index: %u", operand.index);
-    return false;
-  }
-
   inline bool Validate(const byte* pc, GlobalIndexOperand<true>& operand) {
     if (module_ != nullptr && operand.index < module_->globals.size()) {
       operand.global = &module_->globals[operand.index];
@@ -472,15 +462,10 @@ class WasmDecoder : public Decoder {
         return 1 + operand.length;
       }
 
-      case kExprThrow:
-      case kExprCatch: {
-        ExceptionIndexOperand<true> operand(decoder, pc);
-        return 1 + operand.length;
-      }
-
       case kExprSetLocal:
       case kExprTeeLocal:
-      case kExprGetLocal: {
+      case kExprGetLocal:
+      case kExprCatch: {
         LocalIndexOperand<true> operand(decoder, pc);
         return 1 + operand.length;
       }
@@ -767,13 +752,6 @@ class WasmFullDecoder : public WasmDecoder {
     return module_->has_memory;
   }
 
-  template <bool check>
-  inline TFNode* GetExceptionTag(ExceptionIndexOperand<check>& operand) {
-    // TODO(kschimpf): Need to get runtime exception tag values. This
-    // code only handles non-imported/exported exceptions.
-    return BUILD(Int32Constant, operand.index);
-  }
-
   // Decodes the body of a function.
   void DecodeFunctionBody() {
     TRACE("wasm-decode %p...%p (module+%u, %d bytes) %s\n",
@@ -830,20 +808,15 @@ class WasmFullDecoder : public WasmDecoder {
           case kExprRethrow: {
             // TODO(kschimpf): Implement.
             CHECK_PROTOTYPE_OPCODE(eh);
-            OPCODE_ERROR(opcode, "not implemented yet");
+            PROTOTYPE_NOT_FUNCTIONAL(opcode);
             break;
           }
           case kExprThrow: {
+            // TODO(kschimpf): Fix to use type signature of exception.
             CHECK_PROTOTYPE_OPCODE(eh);
-            ExceptionIndexOperand<true> operand(this, pc_);
-            len = 1 + operand.length;
-            if (!Validate(pc_, operand)) break;
-            if (operand.exception->sig->parameter_count() > 0) {
-              // TODO(kschimpf): Fix to pull values off stack and build throw.
-              OPCODE_ERROR(opcode, "can't handle exceptions with values yet");
-              break;
-            }
-            BUILD(Throw, GetExceptionTag(operand));
+            PROTOTYPE_NOT_FUNCTIONAL(opcode);
+            Value value = Pop(0, kWasmI32);
+            BUILD(Throw, value.node);
             // TODO(titzer): Throw should end control, but currently we build a
             // (reachable) runtime call instead of connecting it directly to
             // end.
@@ -865,62 +838,49 @@ class WasmFullDecoder : public WasmDecoder {
           case kExprCatch: {
             // TODO(kschimpf): Fix to use type signature of exception.
             CHECK_PROTOTYPE_OPCODE(eh);
-            ExceptionIndexOperand<true> operand(this, pc_);
+            PROTOTYPE_NOT_FUNCTIONAL(opcode);
+            LocalIndexOperand<true> operand(this, pc_);
             len = 1 + operand.length;
 
-            if (!Validate(pc_, operand)) break;
-
             if (control_.empty()) {
               error("catch does not match any try");
               break;
             }
 
             Control* c = &control_.back();
-            DCHECK_NOT_NULL(c->try_info);
-
             if (!c->is_try()) {
               error("catch does not match any try");
               break;
             }
 
-            if (c->try_info->catch_count > 0) {
-              OPCODE_ERROR(opcode, "multiple catch blocks not implemented");
+            if (c->try_info->catch_env == nullptr) {
+              error(pc_, "catch already present for try with catch");
               break;
             }
-            ++c->try_info->catch_count;
 
             FallThruTo(c);
             stack_.resize(c->stack_depth);
 
+            DCHECK_NOT_NULL(c->try_info);
             SsaEnv* catch_env = c->try_info->catch_env;
+            c->try_info->catch_env = nullptr;
             SetEnv("catch:begin", catch_env);
-
             current_catch_ = c->previous_catch;
 
-            // Get the exception and see if wanted exception.
+            if (Validate(pc_, operand)) {
+              if (ssa_env_->locals) {
                 TFNode* exception_as_i32 =
                     BUILD(Catch, c->try_info->exception, position());
-            TFNode* exception_tag = GetExceptionTag(operand);
-            TFNode* compare_i32 = BUILD(Binop, kExprI32Eq, exception_as_i32,
-                                        exception_tag, position());
-            TFNode* if_true = nullptr;
-            TFNode* if_false = nullptr;
-            BUILD(BranchNoHint, compare_i32, &if_true, &if_false);
-            SsaEnv* end_env = ssa_env_;
-            SsaEnv* false_env = Split(end_env);
-            false_env->control = if_false;
-            SsaEnv* true_env = Steal(ssa_env_);
-            true_env->control = if_true;
-            c->try_info->catch_env = false_env;
-            SetEnv("Try:catch", true_env);
-            len = 1 + operand.length;
-            // TODO(kschimpf): Add code to pop caught exception from isolate.
+                ssa_env_->locals[operand.index] = exception_as_i32;
+              }
+            }
+
             break;
           }
           case kExprCatchAll: {
             // TODO(kschimpf): Implement.
             CHECK_PROTOTYPE_OPCODE(eh);
-            OPCODE_ERROR(opcode, "not implemented yet");
+            PROTOTYPE_NOT_FUNCTIONAL(opcode);
             break;
           }
           case kExprLoop: {
@@ -1009,17 +969,10 @@ class WasmFullDecoder : public WasmDecoder {
               name = "try:end";
 
               // validate that catch was seen.
-              if (c->try_info->catch_count == 0) {
+              if (c->try_info->catch_env != nullptr) {
                 error(pc_, "missing catch in try");
                 break;
               }
-              SsaEnv* fallthru_ssa_env = ssa_env_;
-              DCHECK_NOT_NULL(c->try_info->catch_env);
-              SetEnv("Catch fail", c->try_info->catch_env);
-              BUILD0(Rethrow);
-              // TODO(karlschimpf): Why not use EndControl ()? (currently fails)
-              FallThruTo(c);
-              SetEnv("Catch fallthru", fallthru_ssa_env);
             }
             FallThruTo(c);
             SetEnv(name, c->end_env);

src/wasm/module-decoder.cc

@@ -31,9 +31,9 @@ namespace wasm {
 #endif
 namespace {
 
-constexpr char kNameString[] = "name";
-constexpr char kExceptionString[] = "exception";
-constexpr char kUnknownString[] = "<unknown>";
+const char kNameString[] = "name";
+
+const char kExceptionString[] = "exception";
 
 template <size_t N>
 constexpr size_t num_chars(const char (&)[N]) {
@@ -71,10 +71,9 @@ const char* SectionName(SectionCode code) {
     case kNameSectionCode:
       return kNameString;
     case kExceptionSectionCode:
-      if (FLAG_experimental_wasm_eh) return kExceptionString;
-      return kUnknownString;
+      return kExceptionString;
     default:
-      return kUnknownString;
+      return "<unknown>";
   }
 }
 
@@ -219,6 +218,11 @@ class WasmSectionIterator {
           strncmp(reinterpret_cast<const char*>(section_name_start),
                   kNameString, num_chars(kNameString)) == 0) {
         section_code = kNameSectionCode;
+      } else if (FLAG_experimental_wasm_eh &&
+                 string.length() == num_chars(kExceptionString) &&
+                 strncmp(reinterpret_cast<const char*>(section_name_start),
+                         kExceptionString, num_chars(kExceptionString)) == 0) {
+        section_code = kExceptionSectionCode;
       }
     } else if (!IsValidSectionCode(section_code)) {
       decoder_.errorf(decoder_.pc(), "unknown section code #0x%02x",
@@ -328,25 +332,9 @@ class ModuleDecoder : public Decoder {
       errorf(pc(), "unexpected section: %s", SectionName(section_code));
       return;
     }
-
-    switch (section_code) {
-      case kUnknownSectionCode:
-        break;
-      case kExceptionSectionCode:
-        // Note: kExceptionSectionCode > kCodeSectionCode, but must appear
-        // before the code section. Hence, treat it as a special case.
-        if (++number_of_exception_sections > 1) {
-          errorf(pc(), "Multiple exception sections not allowed");
-          return;
-        } else if (next_section_ >= kCodeSectionCode) {
-          errorf(pc(), "Exception section must appear before the code section");
-          return;
-        }
-        break;
-      default:
+    if (section_code != kUnknownSectionCode) {
       next_section_ = section_code;
       ++next_section_;
-        break;
     }
 
     switch (section_code) {
@@ -389,11 +377,7 @@ class ModuleDecoder : public Decoder {
         DecodeNameSection();
         break;
       case kExceptionSectionCode:
-        if (FLAG_experimental_wasm_eh) {
         DecodeExceptionSection();
-        } else {
-          errorf(pc(), "unexpected section: %s", SectionName(section_code));
-        }
         break;
       default:
         errorf(pc(), "unexpected section: %s", SectionName(section_code));
@@ -893,7 +877,6 @@ class ModuleDecoder : public Decoder {
   Counters* counters_ = nullptr;
   // The type section is the first section in a module.
   uint8_t next_section_ = kFirstSectionInModule;
-  uint32_t number_of_exception_sections = 0;
   // We store next_section_ as uint8_t instead of SectionCode so that we can
   // increment it. This static_assert should make sure that SectionCode does not
   // get bigger than uint8_t accidentially.

src/wasm/module-decoder.h

@@ -34,17 +34,16 @@ enum SectionCode : int8_t {
   kCodeSectionCode = 10,       // Function code
   kDataSectionCode = 11,       // Data segments
   kNameSectionCode = 12,       // Name section (encoded as a string)
-  kExceptionSectionCode = 13,  // Exception section
+  kExceptionSectionCode = 13,  // Exception section (encoded as a string)
 
   // Helper values
   kFirstSectionInModule = kTypeSectionCode,
-  kLastKnownModuleSection = kExceptionSectionCode,
 };
 
 enum NameSectionType : uint8_t { kModule = 0, kFunction = 1, kLocal = 2 };
 
 inline bool IsValidSectionCode(uint8_t byte) {
-  return kTypeSectionCode <= byte && byte <= kLastKnownModuleSection;
+  return kTypeSectionCode <= byte && byte <= kDataSectionCode;
 }
 
 const char* SectionName(SectionCode code);

src/wasm/wasm-text.cc

@@ -143,14 +143,9 @@ void wasm::PrintWasmText(const WasmModule *module,
       }
       case kExprGetLocal:
       case kExprSetLocal:
-      case kExprTeeLocal: {
-        LocalIndexOperand<false> operand(&i, i.pc());
-        os << WasmOpcodes::OpcodeName(opcode) << ' ' << operand.index;
-        break;
-      }
-      case kExprThrow:
+      case kExprTeeLocal:
       case kExprCatch: {
-        ExceptionIndexOperand<false> operand(&i, i.pc());
+        LocalIndexOperand<false> operand(&i, i.pc());
         os << WasmOpcodes::OpcodeName(opcode) << ' ' << operand.index;
         break;
       }
@@ -188,6 +183,7 @@ void wasm::PrintWasmText(const WasmModule *module,
       case kExprGrowMemory:
       case kExprDrop:
       case kExprSelect:
+      case kExprThrow:
         os << WasmOpcodes::OpcodeName(opcode);
         break;
 

test/mjsunit/mjsunit.status

@@ -177,6 +177,9 @@
 
   # BUG(v8:6306).
   'wasm/huge-memory': [SKIP],
+
+  # BUG(v8:6577).
+  'wasm/exceptions': [SKIP],
 }],  # ALWAYS
 
 ['novfp3 == True', {

test/mjsunit/wasm/exceptions.js

@@ -7,73 +7,6 @@
 load("test/mjsunit/wasm/wasm-constants.js");
 load("test/mjsunit/wasm/wasm-module-builder.js");
 
-// The following method doesn't attempt to catch an raised exception.
-var test_throw = (function () {
-  var builder = new WasmModuleBuilder();
-
-  builder.addException(kSig_v_v);
-
-  builder.addFunction("throw_if_param_not_zero", kSig_i_i)
-      .addBody([
-        kExprGetLocal, 0,
-        kExprI32Const, 0,
-        kExprI32Ne,
-        kExprIf, kWasmStmt,
-        kExprThrow, 0,
-        kExprEnd,
-        kExprI32Const, 1
-      ]).exportFunc();
-
-  return builder.instantiate();
-})();
-
-// Check the test_throw exists.
-assertFalse(test_throw === undefined);
-assertFalse(test_throw === null);
-assertFalse(test_throw === 0);
-assertEquals("object", typeof test_throw.exports);
-assertEquals("function", typeof test_throw.exports.throw_if_param_not_zero);
-
-// Test expected behavior of throws
-assertEquals(1, test_throw.exports.throw_if_param_not_zero(0));
-assertWasmThrows([], function() { test_throw.exports.throw_if_param_not_zero(10) });
-assertWasmThrows([], function() { test_throw.exports.throw_if_param_not_zero(-1) });
-
-// Now that we know throwing works, we test catching the exceptions we raise.
-var test_catch = (function () {
-  var builder = new WasmModuleBuilder();
-
-  builder.addException(kSig_v_v);
-  builder.addFunction("simple_throw_catch_to_0_1", kSig_i_i)
-      .addBody([
-        kExprTry, kWasmI32,
-          kExprGetLocal, 0,
-          kExprI32Eqz,
-          kExprIf, kWasmStmt,
-            kExprThrow, 0,
-          kExprEnd,
-          kExprI32Const, 1,
-        kExprCatch, 0,
-          kExprI32Const, 0,
-        kExprEnd
-      ]).exportFunc();
-
-  return builder.instantiate();
-})();
-
-// Check the test_catch exists.
-assertFalse(test_catch === undefined);
-assertFalse(test_catch === null);
-assertFalse(test_catch === 0);
-assertEquals("object", typeof test_catch.exports);
-assertEquals("function", typeof test_catch.exports.simple_throw_catch_to_0_1);
-
-// Test expected behavior of simple catch.
-assertEquals(0, test_catch.exports.simple_throw_catch_to_0_1(0));
-assertEquals(1, test_catch.exports.simple_throw_catch_to_0_1(1));
-
-/* TODO(kschimpf) Convert these tests to work for the proposed exceptions.
-
 // The following methods do not attempt to catch the exception they raise.
 var test_throw = (function () {
   var builder = new WasmModuleBuilder();
@@ -296,16 +229,16 @@ var test_catch = (function () {
             kExprI32Eq,
             kExprIf, kWasmStmt,
               kExprGetLocal, 2,
-              kExprI32Const, / *64=* / 192, 0,
+              kExprI32Const, /*64=*/ 192, 0,
               kExprI32Ior,
               kExprThrow,
               kExprUnreachable,
             kExprEnd,
-            kExprI32Const, / *128=* / 128, 1,
+            kExprI32Const, /*128=*/ 128, 1,
             kExprI32Ior,
           kExprCatch, 1,
             kExprGetLocal, 1,
-            kExprI32Const, / *256=* / 128, 2,
+            kExprI32Const, /*256=*/ 128, 2,
             kExprI32Ior,
           kExprEnd,
       ])
@@ -319,7 +252,7 @@ var test_catch = (function () {
           kExprTry, kWasmI32,
             kExprGetLocal, 0,
             kExprCallFunction, kWasmThrowFunction,
-            kExprI32Const, / *-1=* / 127,
+            kExprI32Const, /*-1=*/ 127,
           kExprCatch, 1,
             kExprGetLocal, 1,
           kExprEnd
@@ -354,7 +287,7 @@ var test_catch = (function () {
           kExprGetLocal, 0,
           kExprI32Const, 0,
           kExprCallFunction, kFromIndirectCalleeHelper,
-          kExprI32Const, / *-1=* / 127,
+          kExprI32Const, /*-1=*/ 127,
         kExprCatch, 1,
           kExprGetLocal, 1,
         kExprEnd
@@ -368,7 +301,7 @@ var test_catch = (function () {
         kExprTry, kWasmI32,
           kExprGetLocal, 0,
           kExprCallFunction, kJSThrowI,
-          kExprI32Const, / *-1=* / 127,
+          kExprI32Const, /*-1=*/ 127,
         kExprCatch, 1,
           kExprGetLocal, 1,
         kExprEnd,
@@ -448,4 +381,3 @@ assertEquals(-10, test_catch.exports.from_js(-10));
 assertThrowsEquals(test_catch.exports.string_from_js, "use wasm;");
 assertThrowsEquals(test_catch.exports.large_from_js, 1e+28);
 assertThrowsEquals(test_catch.exports.undefined_from_js, undefined);
-*/

test/mjsunit/wasm/wasm-constants.js

@@ -64,7 +64,6 @@ let kElementSectionCode = 9;     // Elements section
 let kCodeSectionCode = 10;      // Function code
 let kDataSectionCode = 11;     // Data segments
 let kNameSectionCode = 12;     // Name section (encoded as string)
-let kExceptionSectionCode = 13;  // Exception section (must appear before code section)
 
 // Name section types
 let kModuleNameCode = 0;
@@ -358,7 +357,8 @@ function assertTraps(trap, code) {
   throw new MjsUnitAssertionError('Did not trap, expected: ' + kTrapMsgs[trap]);
 }
 
-function assertWasmThrows(values, code) {
+function assertWasmThrows(value, code) {
+  assertEquals('number', typeof value);
   try {
     if (typeof code === 'function') {
       code();
@@ -366,11 +366,10 @@ function assertWasmThrows(values, code) {
       eval(code);
     }
   } catch (e) {
-    // TODO(kschimpf): Extract values from the exception.
-    let e_values = [];
-    assertEquals(values, e_values);
+    assertEquals('number', typeof e);
+    assertEquals(value, e);
     // Success.
     return;
   }
-  throw new MjsUnitAssertionError('Did not throw, expected: ' + values);
+  throw new MjsUnitAssertionError('Did not throw, expected: ' + value);
 }

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

@@ -153,7 +153,6 @@ class WasmModuleBuilder {
     this.imports = [];
     this.exports = [];
     this.globals = [];
-    this.exceptions = [];
     this.functions = [];
     this.function_table = [];
     this.function_table_length = 0;
@@ -209,13 +208,6 @@ class WasmModuleBuilder {
     return glob;
   }
 
-  addException(type) {
-    if (type.results.length != 0)
-      throw new Error('Invalid exception signature: ' + type);
-    this.exceptions.push(type);
-    return this.exceptions.length - 1;
-  }
-
   addFunction(name, type) {
     let type_index = (typeof type) == "number" ? type : this.addType(type);
     let func = new WasmFunctionBuilder(this, name, type_index);
@@ -495,20 +487,6 @@ 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(type.params.length);
-          for (let param of type.params) {
-            section.enit_u8(param);
-          }
-        }
-      });
-    }
-
     // Add function bodies.
     if (wasm.functions.length > 0) {
       // emit function bodies

test/unittests/wasm/function-body-decoder-unittest.cc

@@ -186,9 +186,6 @@ class FunctionBodyDecoderTest : public TestWithZone {
 };
 
 namespace {
-
-constexpr size_t kMaxByteSizedLeb128 = 127;
-
 // A helper for tests that require a module environment for functions,
 // globals, or memories.
 class TestModuleEnv : public ModuleEnv {
@@ -199,12 +196,12 @@ class TestModuleEnv : public ModuleEnv {
   }
   byte AddGlobal(ValueType type, bool mutability = true) {
     mod.globals.push_back({type, mutability, WasmInitExpr(), 0, false, false});
-    CHECK(mod.globals.size() <= kMaxByteSizedLeb128);
+    CHECK(mod.globals.size() <= 127);
     return static_cast<byte>(mod.globals.size() - 1);
   }
   byte AddSignature(FunctionSig* sig) {
     mod.signatures.push_back(sig);
-    CHECK(mod.signatures.size() <= kMaxByteSizedLeb128);
+    CHECK(mod.signatures.size() <= 127);
     return static_cast<byte>(mod.signatures.size() - 1);
   }
   byte AddFunction(FunctionSig* sig) {
@@ -215,7 +212,7 @@ class TestModuleEnv : public ModuleEnv {
                              {0, 0},   // code
                              false,    // import
                              false});  // export
-    CHECK(mod.functions.size() <= kMaxByteSizedLeb128);
+    CHECK(mod.functions.size() <= 127);
     return static_cast<byte>(mod.functions.size() - 1);
   }
   byte AddImport(FunctionSig* sig) {
@@ -223,11 +220,6 @@ class TestModuleEnv : public ModuleEnv {
     mod.functions[result].imported = true;
     return result;
   }
-  byte AddException(WasmExceptionSig* sig) {
-    mod.exceptions.emplace_back(sig);
-    CHECK(mod.signatures.size() <= kMaxByteSizedLeb128);
-    return static_cast<byte>(mod.exceptions.size() - 1);
-  }
 
   void InitializeMemory() {
     mod.has_memory = true;
@@ -2241,53 +2233,28 @@ TEST_F(FunctionBodyDecoderTest, Select_TypeCheck) {
 
 TEST_F(FunctionBodyDecoderTest, Throw) {
   EXPERIMENTAL_FLAG_SCOPE(eh);
-  TestModuleEnv module_env;
-  module = &module_env;
-
-  module_env.AddException(sigs.v_v());
-  module_env.AddException(sigs.v_i());
-  AddLocals(kWasmI32, 1);
-
-  EXPECT_VERIFIES(v_v, kExprThrow, 0);
-
-  // exception index out of range.
-  EXPECT_FAILURE(v_v, kExprThrow, 2);
-
-  // TODO(kschimpf): Fix when we can create exceptions with values.
-  EXPECT_FAILURE(v_v, WASM_I32V(0), kExprThrow, 1);
+  // TODO(kschimpf): Need to fix throw to use declared exception.
+  EXPECT_FAILURE(v_i, WASM_GET_LOCAL(0), kExprThrow);
 
-  // TODO(kschimpf): Add more tests.
+  EXPECT_FAILURE(i_d, WASM_GET_LOCAL(0), kExprThrow, WASM_I32V(0));
+  EXPECT_FAILURE(i_f, WASM_GET_LOCAL(0), kExprThrow, WASM_I32V(0));
+  EXPECT_FAILURE(l_l, WASM_GET_LOCAL(0), kExprThrow, WASM_I64V(0));
 }
 
 TEST_F(FunctionBodyDecoderTest, ThrowUnreachable) {
   // TODO(titzer): unreachable code after throw should validate.
-  EXPERIMENTAL_FLAG_SCOPE(eh);
-  TestModuleEnv module_env;
-  module = &module_env;
-
-  module_env.AddException(sigs.v_v());
-  module_env.AddException(sigs.v_i());
-  AddLocals(kWasmI32, 1);
-  EXPECT_VERIFIES(i_i, kExprThrow, 0, WASM_GET_LOCAL(0));
-
-  // TODO(kschimpf): Add more (block-level) tests of unreachable to see
-  // if they validate.
+  // EXPERIMENTAL_FLAG_SCOPE(eh);
+  // EXPECT_VERIFIES(v_i, WASM_GET_LOCAL(0), kExprThrow, kExprSetLocal, 0);
 }
 
 #define WASM_TRY_OP kExprTry, kLocalVoid
 
-#define WASM_CATCH(index) kExprCatch, static_cast<byte>(index)
+#define WASM_CATCH(local) kExprCatch, static_cast<byte>(local)
 
 TEST_F(FunctionBodyDecoderTest, TryCatch) {
   EXPERIMENTAL_FLAG_SCOPE(eh);
-
-  TestModuleEnv module_env;
-  module = &module_env;
-  module_env.AddException(sigs.v_v());
-  module_env.AddException(sigs.v_v());
-
   // TODO(kschimpf): Need to fix catch to use declared exception.
-  EXPECT_VERIFIES(v_v, WASM_TRY_OP, WASM_CATCH(0), kExprEnd);
+  EXPECT_FAILURE(v_i, WASM_TRY_OP, WASM_CATCH(0), kExprEnd);
 
   // Missing catch.
   EXPECT_FAILURE(v_v, WASM_TRY_OP, kExprEnd);
@@ -2296,8 +2263,7 @@ TEST_F(FunctionBodyDecoderTest, TryCatch) {
   EXPECT_FAILURE(v_i, WASM_TRY_OP, WASM_CATCH(0));
 
   // Double catch.
-  // TODO(kschimpf): Fix this to verify.
-  EXPECT_FAILURE(v_i, WASM_TRY_OP, WASM_CATCH(0), WASM_CATCH(1), kExprEnd);
+  EXPECT_FAILURE(v_i, WASM_TRY_OP, WASM_CATCH(0), WASM_CATCH(0), kExprEnd);
 }
 
 TEST_F(FunctionBodyDecoderTest, MultiValBlock1) {
@@ -2450,7 +2416,7 @@ TEST_F(WasmOpcodeLengthTest, Statements) {
   EXPECT_LENGTH(1, kExprSelect);
   EXPECT_LENGTH(2, kExprBr);
   EXPECT_LENGTH(2, kExprBrIf);
-  EXPECT_LENGTH(2, kExprThrow);
+  EXPECT_LENGTH(1, kExprThrow);
   EXPECT_LENGTH(2, kExprTry);
   EXPECT_LENGTH(2, kExprCatch);
 }

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

@@ -50,16 +50,10 @@ namespace wasm {
 #define EMPTY_FUNCTION_SIGNATURES_SECTION SECTION(Function, 1), 0
 #define EMPTY_FUNCTION_BODIES_SECTION SECTION(Code, 1), 0
 #define SECTION_NAMES(size) SECTION(Unknown, size + 5), 4, 'n', 'a', 'm', 'e'
-#define SECTION_EXCEPTIONS(size) SECTION(Exception, size)
+#define SECTION_EXCEPTIONS(size) \
+  SECTION(Unknown, size + 10), 9, 'e', 'x', 'c', 'e', 'p', 't', 'i', 'o', 'n'
 #define EMPTY_NAMES_SECTION SECTION_NAMES(1), 0
 
-#define FAIL_IF_NO_EXPERIMENTAL_EH(data)                                 \
-  do {                                                                   \
-    ModuleResult result = DecodeModule((data), (data) + sizeof((data))); \
-    EXPECT_FALSE(result.ok());                                           \
-    EXPECT_EQ(0u, result.val->exceptions.size());                        \
-  } while (0)
-
 #define X1(...) __VA_ARGS__
 #define X2(...) __VA_ARGS__, __VA_ARGS__
 #define X3(...) __VA_ARGS__, __VA_ARGS__, __VA_ARGS__
@@ -375,22 +369,31 @@ TEST_F(WasmModuleVerifyTest, ZeroExceptions) {
   static const byte data[] = {
       SECTION_EXCEPTIONS(1), 0,
   };
-  FAIL_IF_NO_EXPERIMENTAL_EH(data);
 
+  {
+    // Should decode exception section with no exceptions
     EXPERIMENTAL_FLAG_SCOPE(eh);
     ModuleResult result = DecodeModule(data, data + sizeof(data));
     EXPECT_OK(result);
     EXPECT_EQ(0u, result.val->exceptions.size());
+  }
+  {
+    // Should read exception section as unknown section.
+    ModuleResult result = DecodeModule(data, data + sizeof(data));
+    EXPECT_OK(result);
+    EXPECT_EQ(0u, result.val->exceptions.size());
+  }
 }
 
 TEST_F(WasmModuleVerifyTest, OneI32Exception) {
   static const byte data[] = {
       SECTION_EXCEPTIONS(3), 1,
-      // except[0] (i32)
-      1, kLocalI32,
+      1,  // except[0] (i32)
+      kLocalI32,
   };
-  FAIL_IF_NO_EXPERIMENTAL_EH(data);
 
+  {
+    // Should decode to exactly one exception
     EXPERIMENTAL_FLAG_SCOPE(eh);
     ModuleResult result = DecodeModule(data, data + sizeof(data));
     EXPECT_OK(result);
@@ -399,16 +402,25 @@ TEST_F(WasmModuleVerifyTest, OneI32Exception) {
     const WasmException& e0 = result.val->exceptions.front();
     EXPECT_EQ(1u, e0.sig->parameter_count());
     EXPECT_EQ(MachineRepresentation::kWord32, e0.sig->GetParam(0));
+  }
+  {
+    // Should read exception section as unknown section.
+    ModuleResult result = DecodeModule(data, data + sizeof(data));
+    EXPECT_OK(result);
+    EXPECT_EQ(0u, result.val->exceptions.size());
+  }
 }
 
 TEST_F(WasmModuleVerifyTest, TwoExceptions) {
-  static const byte data[] = {SECTION_EXCEPTIONS(6), 2,
-                              // except[0] (f32, i64)
-                              2, kLocalF32, kLocalI64,
-                              // except[1] (i32)
-                              1, kLocalI32};
-  FAIL_IF_NO_EXPERIMENTAL_EH(data);
-
+  static const byte data[] = {SECTION_EXCEPTIONS(6),
+                              2,
+                              2,  // except[0] (f32, i64)
+                              kLocalF32,
+                              kLocalI64,
+                              1,  // except[1] (i32)
+                              kLocalI32};
+  {
+    // Should decode to exactly two exceptions
     EXPERIMENTAL_FLAG_SCOPE(eh);
     ModuleResult result = DecodeModule(data, data + sizeof(data));
     EXPECT_OK(result);
@@ -417,20 +429,32 @@ TEST_F(WasmModuleVerifyTest, TwoExceptions) {
     EXPECT_EQ(2u, e0.sig->parameter_count());
     EXPECT_EQ(MachineRepresentation::kFloat32, e0.sig->GetParam(0));
     EXPECT_EQ(MachineRepresentation::kWord64, e0.sig->GetParam(1));
-  const WasmException& e1 = result.val->exceptions.back();
-  EXPECT_EQ(MachineRepresentation::kWord32, e1.sig->GetParam(0));
+  }
+  {
+    // Should read exception section as unknown section.
+    ModuleResult result = DecodeModule(data, data + sizeof(data));
+    EXPECT_OK(result);
+    EXPECT_EQ(0u, result.val->exceptions.size());
+  }
 }
 
 TEST_F(WasmModuleVerifyTest, Exception_invalid_type) {
   static const byte data[] = {SECTION_EXCEPTIONS(3), 1,
-                              // except[0] (?)
-                              1, 64};
-  FAIL_IF_NO_EXPERIMENTAL_EH(data);
+                              1,  // except[0] (?)
+                              64};
 
+  {
     // Should fail decoding exception section.
     EXPERIMENTAL_FLAG_SCOPE(eh);
     ModuleResult result = DecodeModule(data, data + sizeof(data));
     EXPECT_FALSE(result.ok());
+  }
+  {
+    // Should read exception section as unknown section.
+    ModuleResult result = DecodeModule(data, data + sizeof(data));
+    EXPECT_OK(result);
+    EXPECT_EQ(0u, result.val->exceptions.size());
+  }
 }
 
 TEST_F(WasmModuleVerifyTest, OneSignature) {