[wasm] Change the constant kV8MaxWasmMemoryPages to a command line flag.

src/flags.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/flags.h"
 
 #include <cctype>
 #include <cstdlib>
 #include <sstream>
 
@@ skipping 15 matching lines @@
 // Define all of our flags default values.
 #define FLAG_MODE_DEFINE_DEFAULTS
 #include "src/flag-definitions.h"  // NOLINT(build/include)
 
 namespace {
 
 // This structure represents a single entry in the flag system, with a pointer
 // to the actual flag, default value, comment, etc.  This is designed to be POD
 // initialized as to avoid requiring static constructors.
 struct Flag {
-  enum FlagType { TYPE_BOOL, TYPE_MAYBE_BOOL, TYPE_INT, TYPE_FLOAT,
-                  TYPE_STRING, TYPE_ARGS };
+  enum FlagType {
+    TYPE_BOOL,
+    TYPE_MAYBE_BOOL,
+    TYPE_INT,
+    TYPE_UINT,
+    TYPE_FLOAT,
+    TYPE_STRING,
+    TYPE_ARGS
+  };
 
   FlagType type_;           // What type of flag, bool, int, or string.
   const char* name_;        // Name of the flag, ex "my_flag".
   void* valptr_;            // Pointer to the global flag variable.
   const void* defptr_;      // Pointer to the default value.
   const char* cmt_;         // A comment about the flags purpose.
   bool owns_ptr_;           // Does the flag own its string value?
 
   FlagType type() const { return type_; }
 
   const char* name() const { return name_; }
 
   const char* comment() const { return cmt_; }
 
   bool* bool_variable() const {
     DCHECK(type_ == TYPE_BOOL);
     return reinterpret_cast<bool*>(valptr_);
   }
 
   MaybeBoolFlag* maybe_bool_variable() const {
     DCHECK(type_ == TYPE_MAYBE_BOOL);
     return reinterpret_cast<MaybeBoolFlag*>(valptr_);
   }
 
   int* int_variable() const {
     DCHECK(type_ == TYPE_INT);
     return reinterpret_cast<int*>(valptr_);
   }
 
+  int* uint_variable() const {

[titzer, 2017/01/23 10:20:44]

Should this return an unsigned int*?

[ahaas, 2017/01/23 11:47:37]

Yes, I guess so. Thanks.

+    DCHECK(type_ == TYPE_UINT);
+    return reinterpret_cast<int*>(valptr_);
+  }
+
   double* float_variable() const {
     DCHECK(type_ == TYPE_FLOAT);
     return reinterpret_cast<double*>(valptr_);
   }
 
   const char* string_value() const {
     DCHECK(type_ == TYPE_STRING);
     return *reinterpret_cast<const char**>(valptr_);
   }
 
@@ skipping 13 matching lines @@
   bool bool_default() const {
     DCHECK(type_ == TYPE_BOOL);
     return *reinterpret_cast<const bool*>(defptr_);
   }
 
   int int_default() const {
     DCHECK(type_ == TYPE_INT);
     return *reinterpret_cast<const int*>(defptr_);
   }
 
+  int uint_default() const {

[titzer, 2017/01/23 10:20:44]

unsigned int?

[ahaas, 2017/01/23 11:47:37]

Done.

+    DCHECK(type_ == TYPE_UINT);
+    return *reinterpret_cast<const unsigned int*>(defptr_);
+  }
+
   double float_default() const {
     DCHECK(type_ == TYPE_FLOAT);
     return *reinterpret_cast<const double*>(defptr_);
   }
 
   const char* string_default() const {
     DCHECK(type_ == TYPE_STRING);
     return *reinterpret_cast<const char* const *>(defptr_);
   }
 
   JSArguments args_default() const {
     DCHECK(type_ == TYPE_ARGS);
     return *reinterpret_cast<const JSArguments*>(defptr_);
   }
 
   // Compare this flag's current value against the default.
   bool IsDefault() const {
     switch (type_) {
       case TYPE_BOOL:
         return *bool_variable() == bool_default();
       case TYPE_MAYBE_BOOL:
         return maybe_bool_variable()->has_value == false;
       case TYPE_INT:
         return *int_variable() == int_default();
+      case TYPE_UINT:
+        return *uint_variable() == uint_default();
       case TYPE_FLOAT:
         return *float_variable() == float_default();
       case TYPE_STRING: {
         const char* str1 = string_value();
         const char* str2 = string_default();
         if (str2 == NULL) return str1 == NULL;
         if (str1 == NULL) return str2 == NULL;
         return strcmp(str1, str2) == 0;
       }
       case TYPE_ARGS:
         return args_variable()->argc == 0;
     }
     UNREACHABLE();
     return true;
   }
 
   // Set a flag back to it's default value.
   void Reset() {
     switch (type_) {
       case TYPE_BOOL:
         *bool_variable() = bool_default();
         break;
       case TYPE_MAYBE_BOOL:
         *maybe_bool_variable() = MaybeBoolFlag::Create(false, false);
         break;
       case TYPE_INT:
         *int_variable() = int_default();
         break;
+      case TYPE_UINT:
+        *uint_variable() = uint_default();
+        break;
       case TYPE_FLOAT:
         *float_variable() = float_default();
         break;
       case TYPE_STRING:
         set_string_value(string_default(), false);
         break;
       case TYPE_ARGS:
         *args_variable() = args_default();
         break;
     }
   }
 };
 
 Flag flags[] = {
 #define FLAG_MODE_META
 #include "src/flag-definitions.h"  // NOLINT(build/include)
 };
 
 const size_t num_flags = sizeof(flags) / sizeof(*flags);
 
 }  // namespace
 
 
 static const char* Type2String(Flag::FlagType type) {
   switch (type) {
     case Flag::TYPE_BOOL: return "bool";
     case Flag::TYPE_MAYBE_BOOL: return "maybe_bool";
     case Flag::TYPE_INT: return "int";
+    case Flag::TYPE_UINT:
+      return "uint";
     case Flag::TYPE_FLOAT: return "float";
     case Flag::TYPE_STRING: return "string";
     case Flag::TYPE_ARGS: return "arguments";
   }
   UNREACHABLE();
   return NULL;
 }
 
 
 std::ostream& operator<<(std::ostream& os, const Flag& flag) {  // NOLINT
   switch (flag.type()) {
     case Flag::TYPE_BOOL:
       os << (*flag.bool_variable() ? "true" : "false");
       break;
     case Flag::TYPE_MAYBE_BOOL:
       os << (flag.maybe_bool_variable()->has_value
                  ? (flag.maybe_bool_variable()->value ? "true" : "false")
                  : "unset");
       break;
     case Flag::TYPE_INT:
       os << *flag.int_variable();
       break;
+    case Flag::TYPE_UINT:
+      os << *flag.uint_variable();
+      break;
     case Flag::TYPE_FLOAT:
       os << *flag.float_variable();
       break;
     case Flag::TYPE_STRING: {
       const char* str = flag.string_value();
       os << (str ? str : "NULL");
       break;
     }
     case Flag::TYPE_ARGS: {
       JSArguments args = *flag.args_variable();
@@ skipping 180 matching lines @@
       switch (flag->type()) {
         case Flag::TYPE_BOOL:
           *flag->bool_variable() = !is_bool;
           break;
         case Flag::TYPE_MAYBE_BOOL:
           *flag->maybe_bool_variable() = MaybeBoolFlag::Create(true, !is_bool);
           break;
         case Flag::TYPE_INT:
           *flag->int_variable() = static_cast<int>(strtol(value, &endp, 10));
           break;
+        case Flag::TYPE_UINT: {
+          // We do not use strtoul because it accepts negative numbers.
+          int64_t val = static_cast<int64_t>(strtoll(value, &endp, 10));
+          if (val < 0 || val > std::numeric_limits<unsigned int>::max()) {
+            PrintF(stderr,
+                   "Error: illegal value for flag %s of type %s\n"

[titzer, 2017/01/23 10:20:44]

Can you add a more helpful error message? E.g. that it must be between the
bounds min and max?

[ahaas, 2017/01/23 11:47:37]

Done.

+                   "Try --help for options\n",
+                   arg, Type2String(flag->type()));
+            return_code = j;
+            break;
+          }
+          *flag->uint_variable() = static_cast<unsigned int>(val);
+          break;
+        }
         case Flag::TYPE_FLOAT:
           *flag->float_variable() = strtod(value, &endp);
           break;
         case Flag::TYPE_STRING:
           flag->set_string_value(value ? StrDup(value) : NULL, true);
           break;
         case Flag::TYPE_ARGS: {
           int start_pos = (value == NULL) ? i : i - 1;
           int js_argc = *argc - start_pos;
           const char** js_argv = NewArray<const char*>(js_argc);
@@ skipping 164 matching lines @@
 #define FLAG_MODE_DEFINE_IMPLICATIONS
 #include "src/flag-definitions.h"  // NOLINT(build/include)
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
   ComputeFlagListHash();
 }
 
 
 uint32_t FlagList::Hash() { return flag_hash; }
 }  // namespace internal
 }  // namespace v8