Use Names instead of indices to identify segments (#5618)

All top-level Module elements are identified and referred to by Name, but for
historical reasons element and data segments were referred to by index instead.
Fix this inconsistency by using Names to refer to segments from expressions that
use them. Also parse and print segment names like we do for other elements.

The C API is partially converted to use names instead of indices, but there are
still many functions that refer to data segments by index. Finishing the
conversion can be done in the future once it becomes necessary.

1 files changed, 37 insertions, 5 deletions

diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index 1afdefe87..51df46544 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -510,6 +510,19 @@ Name SExpressionWasmBuilder::getTableName(Element& s) {
   }
 }
 
+Name SExpressionWasmBuilder::getElemSegmentName(Element& s) {
+  if (s.dollared()) {
+    return s.str();
+  } else {
+    // index
+    size_t offset = parseIndex(s);
+    if (offset >= elemSegmentNames.size()) {
+      throw ParseException("unknown elem segment", s.line, s.col);
+    }
+    return elemSegmentNames[offset];
+  }
+}
+
 bool SExpressionWasmBuilder::isMemory64(Name memoryName) {
   auto* memory = wasm.getMemoryOrNull(memoryName);
   if (!memory) {
@@ -535,6 +548,19 @@ Name SExpressionWasmBuilder::getMemoryName(Element& s) {
   }
 }
 
+Name SExpressionWasmBuilder::getDataSegmentName(Element& s) {
+  if (s.dollared()) {
+    return s.str();
+  } else {
+    // index
+    size_t offset = parseIndex(s);
+    if (offset >= dataSegmentNames.size()) {
+      throw ParseException("unknown data segment", s.line, s.col);
+    }
+    return dataSegmentNames[offset];
+  }
+}
+
 Name SExpressionWasmBuilder::getGlobalName(Element& s) {
   if (s.dollared()) {
     return s.str();
@@ -2289,7 +2315,7 @@ Expression* SExpressionWasmBuilder::makeMemoryInit(Element& s) {
     memory = getMemoryNameAtIdx(0);
   }
   ret->memory = memory;
-  ret->segment = parseIndex(*s[i++]);
+  ret->segment = getDataSegmentName(*s[i++]);
   ret->dest = parseExpression(s[i++]);
   ret->offset = parseExpression(s[i++]);
   ret->size = parseExpression(s[i]);
@@ -2299,7 +2325,7 @@ Expression* SExpressionWasmBuilder::makeMemoryInit(Element& s) {
 
 Expression* SExpressionWasmBuilder::makeDataDrop(Element& s) {
   auto ret = allocator.alloc<DataDrop>();
-  ret->segment = parseIndex(*s[1]);
+  ret->segment = getDataSegmentName(*s[1]);
   ret->finalize();
   return ret;
 }
@@ -2951,7 +2977,8 @@ Expression* SExpressionWasmBuilder::makeArrayNew(Element& s, bool default_) {
 Expression* SExpressionWasmBuilder::makeArrayNewSeg(Element& s,
                                                     ArrayNewSegOp op) {
   auto heapType = parseHeapType(*s[1]);
-  Index seg = parseIndex(*s[2]);
+  Name seg =
+    op == NewData ? getDataSegmentName(*s[2]) : getElemSegmentName(*s[2]);
   Expression* offset = parseExpression(*s[3]);
   Expression* size = parseExpression(*s[4]);
   return Builder(wasm).makeArrayNewSeg(op, heapType, seg, offset, size);
@@ -3312,8 +3339,9 @@ void SExpressionWasmBuilder::parseMemory(Element& s, bool preParseImport) {
       } else {
         offset->set(Literal(int32_t(0)));
       }
-      auto seg = Builder::makeDataSegment(
-        Name::fromInt(dataCounter++), memory->name, false, offset);
+      auto segName = Name::fromInt(dataCounter++);
+      auto seg = Builder::makeDataSegment(segName, memory->name, false, offset);
+      dataSegmentNames.push_back(segName);
       parseInnerData(inner, j, seg);
       memory->initial = seg->data.size();
       wasm.addDataSegment(std::move(seg));
@@ -3358,6 +3386,7 @@ void SExpressionWasmBuilder::parseMemory(Element& s, bool preParseImport) {
                                               data.data(),
                                               data.size());
       segment->hasExplicitName = false;
+      dataSegmentNames.push_back(segment->name);
       wasm.addDataSegment(std::move(segment));
     } else {
       auto segment = Builder::makeDataSegment(
@@ -3382,6 +3411,7 @@ void SExpressionWasmBuilder::parseData(Element& s) {
     name = s[i++]->str();
     hasExplicitName = true;
   }
+  dataSegmentNames.push_back(name);
 
   if (s[i]->isList()) {
     // Optional (memory <memoryidx>)
@@ -3764,6 +3794,7 @@ void SExpressionWasmBuilder::parseElem(Element& s, Table* table) {
     Expression* offset = allocator.alloc<Const>()->set(Literal(int32_t(0)));
     auto segment = std::make_unique<ElementSegment>(table->name, offset);
     segment->setName(name, hasExplicitName);
+    elemSegmentNames.push_back(name);
     parseElemFinish(s, segment, i, s[i]->isList());
     return;
   }
@@ -3772,6 +3803,7 @@ void SExpressionWasmBuilder::parseElem(Element& s, Table* table) {
     name = s[i++]->str();
     hasExplicitName = true;
   }
+  elemSegmentNames.push_back(name);
   if (s[i]->isStr() && s[i]->str() == DECLARE) {
     // We don't store declared segments in the IR
     return;