[cleanup] Replace some "default:" with explicit cases

When the intention is to handle every case, *and* when we can be
reasonably sure that no invalid enum values will occur (e.g. from
reading untrusted data), then we shouldn't have a "default:" case
in a switch statement so that the compiler will warn us when a
case is missing.

Bug: v8:10506
Change-Id: Iefdebd54802611e7ec3479afa3c4e6506f97a095
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2204284
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67854}

src/wasm/baseline/arm64/liftoff-assembler-arm64.h

@@ -348,8 +348,6 @@ void LiftoffAssembler::Load(LiftoffRegister dst, Register src_addr,
     case LoadType::kS128Load:
       Ldr(dst.fp().Q(), src_op);
       break;
-    default:
-      UNREACHABLE();
   }
 }
 
@@ -386,8 +384,6 @@ void LiftoffAssembler::Store(Register dst_addr, Register offset_reg,
     case StoreType::kS128Store:
       Str(src.fp().Q(), dst_op);
       break;
-    default:
-      UNREACHABLE();
   }
 }
 

src/wasm/baseline/ia32/liftoff-assembler-ia32.h

@@ -336,8 +336,6 @@ void LiftoffAssembler::Load(LiftoffRegister dst, Register src_addr,
     case LoadType::kS128Load:
       movdqu(dst.fp(), src_op);
       break;
-    default:
-      UNREACHABLE();
   }
 }
 
@@ -405,8 +403,6 @@ void LiftoffAssembler::Store(Register dst_addr, Register offset_reg,
     case StoreType::kS128Store:
       Movdqu(dst_op, src.fp());
       break;
-    default:
-      UNREACHABLE();
   }
 }
 

src/wasm/baseline/x64/liftoff-assembler-x64.h

@@ -306,8 +306,6 @@ void LiftoffAssembler::Load(LiftoffRegister dst, Register src_addr,
     case LoadType::kS128Load:
       Movdqu(dst.fp(), src_op);
       break;
-    default:
-      UNREACHABLE();
   }
 }
 
@@ -345,8 +343,6 @@ void LiftoffAssembler::Store(Register dst_addr, Register offset_reg,
     case StoreType::kS128Store:
       Movdqu(dst_op, src.fp());
       break;
-    default:
-      UNREACHABLE();
   }
 }
 

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

@@ -320,10 +320,10 @@ ValueType read_value_type(Decoder* decoder, const byte* pc,
       // Although void is included in ValueType, it is technically not a value
       // type and is only used to indicate a void block return type. The caller
       // of this function is responsible to check for its presence separately.
-      return kWasmBottom;
-    default:
-      return kWasmBottom;
+      break;
   }
+  // Malformed modules specifying invalid types can get here.
+  return kWasmBottom;
 }
 }  // namespace value_type_reader
 
@@ -1623,13 +1623,20 @@ class WasmDecoder : public Decoder {
           }
           case kExprRttGet:
           case kExprRttSub: {
-            // TODO(7748): Impelement.
-            decoder->error(pc, "rtt opcodes not impelemented yet");
+            // TODO(7748): Implement.
+            decoder->error(pc, "rtt opcodes not implemented yet");
             return 2;
           }
 
-          default:
+          case kExprI31New:
+          case kExprI31GetS:
+          case kExprI31GetU:
+          case kExprRefTest:
+          case kExprRefCast:
             return 2;
+
+          default:
+            UNREACHABLE();
         }
       }
       default:
@@ -2705,7 +2712,8 @@ class WasmFullDecoder : public WasmDecoder<validate> {
             case kControlTry:
               TRACE_PART("T");
               break;
-            default:
+            case kControlIfElse:
+            case kControlTryCatch:
               break;
           }
           if (c.start_merge.arity) TRACE_PART("%u-", c.start_merge.arity);

src/wasm/graph-builder-interface.cc

@@ -788,7 +788,9 @@ class WasmGraphBuildingInterface {
       case ValueType::kOptRef:
       case ValueType::kEqRef:
         return builder_->RefNull();
-      default:
+      case ValueType::kStmt:
+      case ValueType::kBottom:
+      case ValueType::kRef:
         UNREACHABLE();
     }
   }

src/wasm/module-compiler.cc

@@ -1782,8 +1782,6 @@ class AsyncCompileJob::CompilationStateCallback {
         // {kFinishedTopTierCompilation}, hence don't remember this in
         // {last_event_}.
         return;
-      default:
-        UNREACHABLE();
     }
 #ifdef DEBUG
     last_event_ = event;

src/wasm/module-decoder.cc

@@ -126,9 +126,8 @@ ValueType TypeOf(const WasmModule* module, const WasmInitExpr& expr) {
       return kWasmNullRef;
     case WasmInitExpr::kRefFuncConst:
       return kWasmFuncRef;
-    default:
-      UNREACHABLE();
   }
+  UNREACHABLE();
 }
 
 // Reads a length-prefixed string, checking that it is within bounds. Returns

src/wasm/wasm-debug.cc

@@ -198,7 +198,6 @@ class InterpreterHandle {
           return false;
         // RUNNING should never occur here.
         case WasmInterpreter::State::RUNNING:
-        default:
           UNREACHABLE();
       }
     }

src/wasm/wasm-module-builder.cc

@@ -595,7 +595,12 @@ void WasmModuleBuilder::WriteTo(ZoneBuffer* buffer) const {
             case ValueType::kEqRef:
               buffer->write_u8(kExprRefNull);
               break;
-            default:
+            case ValueType::kStmt:
+            case ValueType::kS128:
+            case ValueType::kBottom:
+            case ValueType::kRef:
+            case ValueType::kAnyRef:
+            case ValueType::kNullRef:
               UNREACHABLE();
           }
         }

src/wasm/wasm-module.cc

@@ -458,9 +458,8 @@ Handle<JSArray> GetImports(Isolate* isolate,
       case kExternalException:
         import_kind = exception_string;
         break;
-      default:
-        UNREACHABLE();
     }
+    DCHECK(!import_kind->is_null());
 
     Handle<String> import_module =
         WasmModuleObject::ExtractUtf8StringFromModuleBytes(