Remove boilerplate in walking logic (#3344)

Also fix the order of walking children, which was wrong in the macro. What's nice
is that fixing it there would fix anything else using the macro automatically
(however, so far nothing else was affected by it).

2 files changed, 29 insertions, 348 deletions

diff --git a/src/wasm-delegations-fields.h b/src/wasm-delegations-fields.h
index df2309474..ddcd2792b 100644
--- a/src/wasm-delegations-fields.h
+++ b/src/wasm-delegations-fields.h
@@ -93,7 +93,7 @@
 #ifndef DELEGATE_FIELD_CHILD_VECTOR
 #ifdef DELEGATE_GET_FIELD
 #define DELEGATE_FIELD_CHILD_VECTOR(id, name)                                  \
-  for (Index i = 0; i < (DELEGATE_GET_FIELD(id, name)).size(); i++) {          \
+  for (int i = int((DELEGATE_GET_FIELD(id, name)).size()) - 1; i >= 0; i--) {  \
     DELEGATE_FIELD_CHILD(id, name[i]);                                         \
   }
 #else
diff --git a/src/wasm-traversal.h b/src/wasm-traversal.h
index 625bef7ab..e3de27f62 100644
--- a/src/wasm-traversal.h
+++ b/src/wasm-traversal.h
@@ -317,353 +317,34 @@ struct PostWalker : public Walker<SubType, VisitorType> {
 
   static void scan(SubType* self, Expression** currp) {
     Expression* curr = *currp;
-    switch (curr->_id) {
-      case Expression::Id::InvalidId:
-        abort();
-      case Expression::Id::BlockId: {
-        self->pushTask(SubType::doVisitBlock, currp);
-        auto& list = curr->cast<Block>()->list;
-        for (int i = int(list.size()) - 1; i >= 0; i--) {
-          self->pushTask(SubType::scan, &list[i]);
-        }
-        break;
-      }
-      case Expression::Id::IfId: {
-        self->pushTask(SubType::doVisitIf, currp);
-        self->maybePushTask(SubType::scan, &curr->cast<If>()->ifFalse);
-        self->pushTask(SubType::scan, &curr->cast<If>()->ifTrue);
-        self->pushTask(SubType::scan, &curr->cast<If>()->condition);
-        break;
-      }
-      case Expression::Id::LoopId: {
-        self->pushTask(SubType::doVisitLoop, currp);
-        self->pushTask(SubType::scan, &curr->cast<Loop>()->body);
-        break;
-      }
-      case Expression::Id::BreakId: {
-        self->pushTask(SubType::doVisitBreak, currp);
-        self->maybePushTask(SubType::scan, &curr->cast<Break>()->condition);
-        self->maybePushTask(SubType::scan, &curr->cast<Break>()->value);
-        break;
-      }
-      case Expression::Id::SwitchId: {
-        self->pushTask(SubType::doVisitSwitch, currp);
-        self->pushTask(SubType::scan, &curr->cast<Switch>()->condition);
-        self->maybePushTask(SubType::scan, &curr->cast<Switch>()->value);
-        break;
-      }
-      case Expression::Id::CallId: {
-        self->pushTask(SubType::doVisitCall, currp);
-        auto& list = curr->cast<Call>()->operands;
-        for (int i = int(list.size()) - 1; i >= 0; i--) {
-          self->pushTask(SubType::scan, &list[i]);
-        }
-        break;
-      }
-      case Expression::Id::CallIndirectId: {
-        self->pushTask(SubType::doVisitCallIndirect, currp);
-        auto& list = curr->cast<CallIndirect>()->operands;
-        self->pushTask(SubType::scan, &curr->cast<CallIndirect>()->target);
-        for (int i = int(list.size()) - 1; i >= 0; i--) {
-          self->pushTask(SubType::scan, &list[i]);
-        }
-        break;
-      }
-      case Expression::Id::LocalGetId: {
-        // TODO: optimize leaves with a direct call?
-        self->pushTask(SubType::doVisitLocalGet, currp);
-        break;
-      }
-      case Expression::Id::LocalSetId: {
-        self->pushTask(SubType::doVisitLocalSet, currp);
-        self->pushTask(SubType::scan, &curr->cast<LocalSet>()->value);
-        break;
-      }
-      case Expression::Id::GlobalGetId: {
-        self->pushTask(SubType::doVisitGlobalGet, currp);
-        break;
-      }
-      case Expression::Id::GlobalSetId: {
-        self->pushTask(SubType::doVisitGlobalSet, currp);
-        self->pushTask(SubType::scan, &curr->cast<GlobalSet>()->value);
-        break;
-      }
-      case Expression::Id::LoadId: {
-        self->pushTask(SubType::doVisitLoad, currp);
-        self->pushTask(SubType::scan, &curr->cast<Load>()->ptr);
-        break;
-      }
-      case Expression::Id::StoreId: {
-        self->pushTask(SubType::doVisitStore, currp);
-        self->pushTask(SubType::scan, &curr->cast<Store>()->value);
-        self->pushTask(SubType::scan, &curr->cast<Store>()->ptr);
-        break;
-      }
-      case Expression::Id::AtomicRMWId: {
-        self->pushTask(SubType::doVisitAtomicRMW, currp);
-        self->pushTask(SubType::scan, &curr->cast<AtomicRMW>()->value);
-        self->pushTask(SubType::scan, &curr->cast<AtomicRMW>()->ptr);
-        break;
-      }
-      case Expression::Id::AtomicCmpxchgId: {
-        self->pushTask(SubType::doVisitAtomicCmpxchg, currp);
-        self->pushTask(SubType::scan,
-                       &curr->cast<AtomicCmpxchg>()->replacement);
-        self->pushTask(SubType::scan, &curr->cast<AtomicCmpxchg>()->expected);
-        self->pushTask(SubType::scan, &curr->cast<AtomicCmpxchg>()->ptr);
-        break;
-      }
-      case Expression::Id::AtomicWaitId: {
-        self->pushTask(SubType::doVisitAtomicWait, currp);
-        self->pushTask(SubType::scan, &curr->cast<AtomicWait>()->timeout);
-        self->pushTask(SubType::scan, &curr->cast<AtomicWait>()->expected);
-        self->pushTask(SubType::scan, &curr->cast<AtomicWait>()->ptr);
-        break;
-      }
-      case Expression::Id::AtomicNotifyId: {
-        self->pushTask(SubType::doVisitAtomicNotify, currp);
-        self->pushTask(SubType::scan, &curr->cast<AtomicNotify>()->notifyCount);
-        self->pushTask(SubType::scan, &curr->cast<AtomicNotify>()->ptr);
-        break;
-      }
-      case Expression::Id::AtomicFenceId: {
-        self->pushTask(SubType::doVisitAtomicFence, currp);
-        break;
-      }
-      case Expression::Id::SIMDExtractId: {
-        self->pushTask(SubType::doVisitSIMDExtract, currp);
-        self->pushTask(SubType::scan, &curr->cast<SIMDExtract>()->vec);
-        break;
-      }
-      case Expression::Id::SIMDReplaceId: {
-        self->pushTask(SubType::doVisitSIMDReplace, currp);
-        self->pushTask(SubType::scan, &curr->cast<SIMDReplace>()->value);
-        self->pushTask(SubType::scan, &curr->cast<SIMDReplace>()->vec);
-        break;
-      }
-      case Expression::Id::SIMDShuffleId: {
-        self->pushTask(SubType::doVisitSIMDShuffle, currp);
-        self->pushTask(SubType::scan, &curr->cast<SIMDShuffle>()->right);
-        self->pushTask(SubType::scan, &curr->cast<SIMDShuffle>()->left);
-        break;
-      }
-      case Expression::Id::SIMDTernaryId: {
-        self->pushTask(SubType::doVisitSIMDTernary, currp);
-        self->pushTask(SubType::scan, &curr->cast<SIMDTernary>()->c);
-        self->pushTask(SubType::scan, &curr->cast<SIMDTernary>()->b);
-        self->pushTask(SubType::scan, &curr->cast<SIMDTernary>()->a);
-        break;
-      }
-      case Expression::Id::SIMDShiftId: {
-        self->pushTask(SubType::doVisitSIMDShift, currp);
-        self->pushTask(SubType::scan, &curr->cast<SIMDShift>()->shift);
-        self->pushTask(SubType::scan, &curr->cast<SIMDShift>()->vec);
-        break;
-      }
-      case Expression::Id::SIMDLoadId: {
-        self->pushTask(SubType::doVisitSIMDLoad, currp);
-        self->pushTask(SubType::scan, &curr->cast<SIMDLoad>()->ptr);
-        break;
-      }
-      case Expression::Id::SIMDLoadStoreLaneId: {
-        self->pushTask(SubType::doVisitSIMDLoadStoreLane, currp);
-        self->pushTask(SubType::scan, &curr->cast<SIMDLoadStoreLane>()->vec);
-        self->pushTask(SubType::scan, &curr->cast<SIMDLoadStoreLane>()->ptr);
-        break;
-      }
-      case Expression::Id::MemoryInitId: {
-        self->pushTask(SubType::doVisitMemoryInit, currp);
-        self->pushTask(SubType::scan, &curr->cast<MemoryInit>()->size);
-        self->pushTask(SubType::scan, &curr->cast<MemoryInit>()->offset);
-        self->pushTask(SubType::scan, &curr->cast<MemoryInit>()->dest);
-        break;
-      }
-      case Expression::Id::DataDropId: {
-        self->pushTask(SubType::doVisitDataDrop, currp);
-        break;
-      }
-      case Expression::Id::MemoryCopyId: {
-        self->pushTask(SubType::doVisitMemoryCopy, currp);
-        self->pushTask(SubType::scan, &curr->cast<MemoryCopy>()->size);
-        self->pushTask(SubType::scan, &curr->cast<MemoryCopy>()->source);
-        self->pushTask(SubType::scan, &curr->cast<MemoryCopy>()->dest);
-        break;
-      }
-      case Expression::Id::MemoryFillId: {
-        self->pushTask(SubType::doVisitMemoryFill, currp);
-        self->pushTask(SubType::scan, &curr->cast<MemoryFill>()->size);
-        self->pushTask(SubType::scan, &curr->cast<MemoryFill>()->value);
-        self->pushTask(SubType::scan, &curr->cast<MemoryFill>()->dest);
-        break;
-      }
-      case Expression::Id::ConstId: {
-        self->pushTask(SubType::doVisitConst, currp);
-        break;
-      }
-      case Expression::Id::UnaryId: {
-        self->pushTask(SubType::doVisitUnary, currp);
-        self->pushTask(SubType::scan, &curr->cast<Unary>()->value);
-        break;
-      }
-      case Expression::Id::BinaryId: {
-        self->pushTask(SubType::doVisitBinary, currp);
-        self->pushTask(SubType::scan, &curr->cast<Binary>()->right);
-        self->pushTask(SubType::scan, &curr->cast<Binary>()->left);
-        break;
-      }
-      case Expression::Id::SelectId: {
-        self->pushTask(SubType::doVisitSelect, currp);
-        self->pushTask(SubType::scan, &curr->cast<Select>()->condition);
-        self->pushTask(SubType::scan, &curr->cast<Select>()->ifFalse);
-        self->pushTask(SubType::scan, &curr->cast<Select>()->ifTrue);
-        break;
-      }
-      case Expression::Id::DropId: {
-        self->pushTask(SubType::doVisitDrop, currp);
-        self->pushTask(SubType::scan, &curr->cast<Drop>()->value);
-        break;
-      }
-      case Expression::Id::ReturnId: {
-        self->pushTask(SubType::doVisitReturn, currp);
-        self->maybePushTask(SubType::scan, &curr->cast<Return>()->value);
-        break;
-      }
-      case Expression::Id::MemorySizeId:
-        self->pushTask(SubType::doVisitMemorySize, currp);
-        break;
-      case Expression::Id::MemoryGrowId:
-        self->pushTask(SubType::doVisitMemoryGrow, currp);
-        self->pushTask(SubType::scan, &curr->cast<MemoryGrow>()->delta);
-        break;
-      case Expression::Id::RefNullId: {
-        self->pushTask(SubType::doVisitRefNull, currp);
-        break;
-      }
-      case Expression::Id::RefIsNullId: {
-        self->pushTask(SubType::doVisitRefIsNull, currp);
-        self->pushTask(SubType::scan, &curr->cast<RefIsNull>()->value);
-        break;
-      }
-      case Expression::Id::RefFuncId: {
-        self->pushTask(SubType::doVisitRefFunc, currp);
-        break;
-      }
-      case Expression::Id::RefEqId: {
-        self->pushTask(SubType::doVisitRefEq, currp);
-        self->pushTask(SubType::scan, &curr->cast<RefEq>()->right);
-        self->pushTask(SubType::scan, &curr->cast<RefEq>()->left);
-        break;
-      }
-      case Expression::Id::TryId: {
-        self->pushTask(SubType::doVisitTry, currp);
-        self->pushTask(SubType::scan, &curr->cast<Try>()->catchBody);
-        self->pushTask(SubType::scan, &curr->cast<Try>()->body);
-        break;
-      }
-      case Expression::Id::ThrowId: {
-        self->pushTask(SubType::doVisitThrow, currp);
-        auto& list = curr->cast<Throw>()->operands;
-        for (int i = int(list.size()) - 1; i >= 0; i--) {
-          self->pushTask(SubType::scan, &list[i]);
-        }
-        break;
-      }
-      case Expression::Id::RethrowId: {
-        self->pushTask(SubType::doVisitRethrow, currp);
-        self->pushTask(SubType::scan, &curr->cast<Rethrow>()->exnref);
-        break;
-      }
-      case Expression::Id::BrOnExnId: {
-        self->pushTask(SubType::doVisitBrOnExn, currp);
-        self->pushTask(SubType::scan, &curr->cast<BrOnExn>()->exnref);
-        break;
-      }
-      case Expression::Id::NopId: {
-        self->pushTask(SubType::doVisitNop, currp);
-        break;
-      }
-      case Expression::Id::UnreachableId: {
-        self->pushTask(SubType::doVisitUnreachable, currp);
-        break;
-      }
-      case Expression::Id::PopId: {
-        self->pushTask(SubType::doVisitPop, currp);
-        break;
-      }
-      case Expression::Id::TupleMakeId: {
-        self->pushTask(SubType::doVisitTupleMake, currp);
-        auto& operands = curr->cast<TupleMake>()->operands;
-        for (int i = int(operands.size()) - 1; i >= 0; --i) {
-          self->pushTask(SubType::scan, &operands[i]);
-        }
-        break;
-      }
-      case Expression::Id::TupleExtractId: {
-        self->pushTask(SubType::doVisitTupleExtract, currp);
-        self->pushTask(SubType::scan, &curr->cast<TupleExtract>()->tuple);
-        break;
-      }
-      case Expression::Id::I31NewId: {
-        self->pushTask(SubType::doVisitI31New, currp);
-        self->pushTask(SubType::scan, &curr->cast<I31New>()->value);
-        break;
-      }
-      case Expression::Id::I31GetId: {
-        self->pushTask(SubType::doVisitI31Get, currp);
-        self->pushTask(SubType::scan, &curr->cast<I31Get>()->i31);
-        break;
-      }
-      case Expression::Id::RefTestId:
-        self->pushTask(SubType::doVisitRefTest, currp);
-        WASM_UNREACHABLE("TODO (gc): ref.test");
-        break;
-      case Expression::Id::RefCastId:
-        self->pushTask(SubType::doVisitRefCast, currp);
-        WASM_UNREACHABLE("TODO (gc): ref.cast");
-        break;
-      case Expression::Id::BrOnCastId:
-        self->pushTask(SubType::doVisitBrOnCast, currp);
-        WASM_UNREACHABLE("TODO (gc): br_on_cast");
-        break;
-      case Expression::Id::RttCanonId:
-        self->pushTask(SubType::doVisitRttCanon, currp);
-        WASM_UNREACHABLE("TODO (gc): rtt.canon");
-        break;
-      case Expression::Id::RttSubId:
-        self->pushTask(SubType::doVisitRttSub, currp);
-        WASM_UNREACHABLE("TODO (gc): rtt.sub");
-        break;
-      case Expression::Id::StructNewId:
-        self->pushTask(SubType::doVisitStructNew, currp);
-        WASM_UNREACHABLE("TODO (gc): struct.new");
-        break;
-      case Expression::Id::StructGetId:
-        self->pushTask(SubType::doVisitStructGet, currp);
-        WASM_UNREACHABLE("TODO (gc): struct.get");
-        break;
-      case Expression::Id::StructSetId:
-        self->pushTask(SubType::doVisitStructSet, currp);
-        WASM_UNREACHABLE("TODO (gc): struct.set");
-        break;
-      case Expression::Id::ArrayNewId:
-        self->pushTask(SubType::doVisitArrayNew, currp);
-        WASM_UNREACHABLE("TODO (gc): array.new");
-        break;
-      case Expression::Id::ArrayGetId:
-        self->pushTask(SubType::doVisitArrayGet, currp);
-        WASM_UNREACHABLE("TODO (gc): array.get");
-        break;
-      case Expression::Id::ArraySetId:
-        self->pushTask(SubType::doVisitArraySet, currp);
-        WASM_UNREACHABLE("TODO (gc): array.set");
-        break;
-      case Expression::Id::ArrayLenId:
-        self->pushTask(SubType::doVisitArrayLen, currp);
-        WASM_UNREACHABLE("TODO (gc): array.len");
-        break;
-      case Expression::Id::NumExpressionIds:
-        WASM_UNREACHABLE("unexpected expression type");
-    }
+
+#define DELEGATE_ID curr->_id
+
+#define DELEGATE_START(id)                                                     \
+  self->pushTask(SubType::doVisit##id, currp);                                 \
+  auto* cast = curr->cast<id>();                                               \
+  WASM_UNUSED(cast);
+
+#define DELEGATE_GET_FIELD(id, name) cast->name
+
+#define DELEGATE_FIELD_CHILD(id, name)                                         \
+  self->pushTask(SubType::scan, &cast->name);
+
+#define DELEGATE_FIELD_OPTIONAL_CHILD(id, name)                                \
+  self->maybePushTask(SubType::scan, &cast->name);
+
+#define DELEGATE_FIELD_INT(id, name)
+#define DELEGATE_FIELD_INT_ARRAY(id, name)
+#define DELEGATE_FIELD_LITERAL(id, name)
+#define DELEGATE_FIELD_NAME(id, name)
+#define DELEGATE_FIELD_SCOPE_NAME_DEF(id, name)
+#define DELEGATE_FIELD_SCOPE_NAME_USE(id, name)
+#define DELEGATE_FIELD_SCOPE_NAME_USE_VECTOR(id, name)
+#define DELEGATE_FIELD_SIGNATURE(id, name)
+#define DELEGATE_FIELD_TYPE(id, name)
+#define DELEGATE_FIELD_ADDRESS(id, name)
+
+#include "wasm-delegations-fields.h"
   }
 };