Update text syntax for shared memory limits (#1197)

Following WebAssembly/threads#58
e.g. (memory $0 23 256 shared) is now (memory $0 (shared 23 256))

4 files changed, 23 insertions, 16 deletions

diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index 04b649ff6..8bb5175ab 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -718,7 +718,7 @@ struct PrintSExpression : public Visitor<PrintSExpression> {
   void printTableHeader(Table* curr) {
     printOpening(o, "table") << ' ';
     o << curr->initial;
-    if (curr->max != Table::kMaxSize) o << ' ' << curr->max;
+    if (curr->hasMax()) o << ' ' << curr->max;
     o << " anyfunc)";
   }
   void visitTable(Table *curr) {
@@ -746,9 +746,10 @@ struct PrintSExpression : public Visitor<PrintSExpression> {
   void printMemoryHeader(Memory* curr) {
     printOpening(o, "memory") << ' ';
     printName(curr->name) << ' ';
+    if (curr->shared) printOpening(o, "shared ");
     o << curr->initial;
-    if (curr->max && curr->max != Memory::kMaxSize) o << ' ' << curr->max;
-    if (curr->shared) o << " shared";
+    if (curr->hasMax()) o << ' ' << curr->max;
+    if (curr->shared) o << ")";
     o << ")";
   }
   void visitMemory(Memory* curr) {
diff --git a/src/wasm.h b/src/wasm.h
index d2bea45a1..fc167342a 100644
--- a/src/wasm.h
+++ b/src/wasm.h
@@ -672,6 +672,7 @@ public:
   Table() : exists(false), imported(false), initial(0), max(kMaxSize) {
     name = Name::fromInt(0);
   }
+  bool hasMax() { return max != kMaxSize; }
 };
 
 class Memory {
@@ -705,6 +706,7 @@ public:
   Memory() : initial(0), max(kMaxSize), exists(false), imported(false), shared(false) {
     name = Name::fromInt(0);
   }
+  bool hasMax() { return max != kMaxSize; }
 };
 
 class Global {
diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index b8419ad54..0e329067e 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -1512,17 +1512,9 @@ void SExpressionWasmBuilder::stringToBinary(const char* input, size_t size, std:
 Index SExpressionWasmBuilder::parseMemoryLimits(Element& s, Index i) {
   wasm.memory.initial = getCheckedAddress(s[i++], "excessive memory init");
   if (i == s.size()) return i;
-  while (i < s.size() && s[i]->isStr()) {
-    auto* curr = s[i]->c_str();
-    i++;
-    if (strstr(curr, "shared")) {
-      wasm.memory.shared = strncmp(curr, "notshared", 9) != 0;
-      break;
-    }
-    uint64_t max = atoll(curr);
-    if (max > Memory::kMaxSize) throw ParseException("total memory must be <= 4GB");
-    wasm.memory.max = max;
-  }
+  uint64_t max = atoll(s[i++]->c_str());
+  if (max > Memory::kMaxSize) throw ParseException("total memory must be <= 4GB");
+  wasm.memory.max = max;
   return i;
 }
 
@@ -1557,6 +1549,10 @@ void SExpressionWasmBuilder::parseMemory(Element& s, bool preParseImport) {
       if (wasm.getImportOrNull(im->name)) throw ParseException("duplicate import", s.line, s.col);
       wasm.addImport(im.release());
       i++;
+    } else if (inner[0]->str() == "shared") {
+      wasm.memory.shared = true;
+      parseMemoryLimits(inner, 1);
+      i++;
     } else {
       if (!(inner.size() > 0 ? inner[0]->str() != IMPORT : true)) throw ParseException("bad import ending");
       // (memory (data ..)) format
@@ -1565,7 +1561,7 @@ void SExpressionWasmBuilder::parseMemory(Element& s, bool preParseImport) {
       return;
     }
   }
-  i = parseMemoryLimits(s, i);
+  if (!wasm.memory.shared) i = parseMemoryLimits(s, i);
 
   // Parse memory initializers.
   while (i < s.size()) {
@@ -1765,7 +1761,14 @@ void SExpressionWasmBuilder::parseImport(Element& s) {
     }
     // ends with the table element type
   } else if (im->kind == ExternalKind::Memory) {
-    j = parseMemoryLimits(inner, j);
+    if (inner[j]->isList()) {
+      auto& limits = *inner[j];
+      if (!(limits[0]->isStr() && limits[0]->str() == "shared")) throw ParseException("bad memory limit declaration");
+      wasm.memory.shared = true;
+      parseMemoryLimits(limits, 1);
+    } else {
+      parseMemoryLimits(inner, j);
+    }
   }
   if (wasm.getImportOrNull(im->name)) throw ParseException("duplicate import", s.line, s.col);
   wasm.addImport(im.release());
diff --git a/src/wasm/wasm-validator.cpp b/src/wasm/wasm-validator.cpp
index 85e2193fa..cfe84ac3e 100644
--- a/src/wasm/wasm-validator.cpp
+++ b/src/wasm/wasm-validator.cpp
@@ -597,6 +597,7 @@ static bool checkOffset(Expression* curr, Address add, Address max) {
 void WasmValidator::visitMemory(Memory *curr) {
   shouldBeFalse(curr->initial > curr->max, "memory", "memory max >= initial");
   shouldBeTrue(curr->max <= Memory::kMaxSize, "memory", "max memory must be <= 4GB");
+  shouldBeTrue(!curr->shared || curr->hasMax(), "memory", "shared memory must have max size");
   Index mustBeGreaterOrEqual = 0;
   for (auto& segment : curr->segments) {
     if (!shouldBeEqual(segment.offset->type, i32, segment.offset, "segment offset should be i32")) continue;