[asm.js] Switch StdlibSet to be a uint64_t bit set.

This switches the {StdlibSet} to be a data structure that does not
require dynamic memory allocation. This makes it easier to carry it
around as part of a {CompilationJob} and serialize it into the heap.

R=clemensh@chromium.org

Change-Id: I77b2353cfdcd9438a26f04d00749159fed9b9b6c
Reviewed-on: https://chromium-review.googlesource.com/584868
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46889}

src/asmjs/asm-parser.cc

@@ -550,7 +550,7 @@ void AsmJsParser::ValidateModuleVarNewStdlib(VarInfo* info) {
 #define V(name, _junk1, _junk2, _junk3)                          \
   case TOK(name):                                                \
     DeclareStdlibFunc(info, VarKind::kSpecial, AsmType::name()); \
-    stdlib_uses_.insert(StandardMember::k##name);                \
+    stdlib_uses_.Add(StandardMember::k##name);                   \
     break;
     STDLIB_ARRAY_TYPE_LIST(V)
 #undef V
@@ -573,14 +573,14 @@ void AsmJsParser::ValidateModuleVarStdlib(VarInfo* info) {
   case TOK(name):                                           \
     DeclareGlobal(info, false, AsmType::Double(), kWasmF64, \
                   WasmInitExpr(const_value));               \
-    stdlib_uses_.insert(StandardMember::kMath##name);       \
+    stdlib_uses_.Add(StandardMember::kMath##name);          \
     break;
       STDLIB_MATH_VALUE_LIST(V)
 #undef V
 #define V(name, Name, op, sig)                                      \
   case TOK(name):                                                   \
     DeclareStdlibFunc(info, VarKind::kMath##Name, stdlib_##sig##_); \
-    stdlib_uses_.insert(StandardMember::kMath##Name);               \
+    stdlib_uses_.Add(StandardMember::kMath##Name);                  \
     break;
       STDLIB_MATH_FUNCTION_LIST(V)
 #undef V
@@ -590,11 +590,11 @@ void AsmJsParser::ValidateModuleVarStdlib(VarInfo* info) {
   } else if (Check(TOK(Infinity))) {
     DeclareGlobal(info, false, AsmType::Double(), kWasmF64,
                   WasmInitExpr(std::numeric_limits<double>::infinity()));
-    stdlib_uses_.insert(StandardMember::kInfinity);
+    stdlib_uses_.Add(StandardMember::kInfinity);
   } else if (Check(TOK(NaN))) {
     DeclareGlobal(info, false, AsmType::Double(), kWasmF64,
                   WasmInitExpr(std::numeric_limits<double>::quiet_NaN()));
-    stdlib_uses_.insert(StandardMember::kNaN);
+    stdlib_uses_.Add(StandardMember::kNaN);
   } else {
     FAIL("Invalid member of stdlib");
   }

src/asmjs/asm-parser.h

@@ -47,7 +47,7 @@ class AsmJsParser {
   };
   // clang-format on
 
-  typedef std::unordered_set<StandardMember, std::hash<int>> StdlibSet;
+  typedef EnumSet<StandardMember, uint64_t> StdlibSet;
 
   explicit AsmJsParser(Zone* zone, uintptr_t stack_limit,
                        std::unique_ptr<Utf16CharacterStream> stream);
@@ -55,7 +55,7 @@ class AsmJsParser {
   const char* failure_message() const { return failure_message_; }
   int failure_location() const { return failure_location_; }
   WasmModuleBuilder* module_builder() { return module_builder_; }
-  StdlibSet* stdlib_uses() { return &stdlib_uses_; }
+  const StdlibSet* stdlib_uses() const { return &stdlib_uses_; }
 
  private:
   // clang-format off