[heap] Internalize kExternalAllocationLimit

src/globals.h

 // Copyright 2012 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.
 
 #ifndef V8_GLOBALS_H_
 #define V8_GLOBALS_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 164 matching lines @@
 const size_t kCodeRangeAreaAlignment = 4 * KB;  // OS page.
 #else
 const bool kRequiresCodeRange = false;
 const size_t kMaximalCodeRangeSize = 0 * MB;
 const size_t kMinimumCodeRangeSize = 0 * MB;
 const size_t kReservedCodeRangePages = 0;
 const size_t kCodeRangeAreaAlignment = 4 * KB;  // OS page.
 #endif
 #endif
 
+// The external allocation limit should be below 256 MB on all architectures
+// to avoid that resource-constrained embedders run low on memory.
+const int kExternalAllocationLimit = 192 * 1024 * 1024;
+
 STATIC_ASSERT(kPointerSize == (1 << kPointerSizeLog2));
 
 const int kBitsPerByte = 8;
 const int kBitsPerByteLog2 = 3;
 const int kBitsPerPointer = kPointerSize * kBitsPerByte;
 const int kBitsPerInt = kIntSize * kBitsPerByte;
 
 // IEEE 754 single precision floating point number bit layout.
 const uint32_t kBinary32SignMask = 0x80000000u;
 const uint32_t kBinary32ExponentMask = 0x7f800000u;
@@ skipping 894 matching lines @@
   return static_cast<uint32_t>(bit_cast<uintptr_t>(address) >>
                                kPointerSizeLog2);
 }
 
 }  // namespace internal
 }  // namespace v8
 
 namespace i = v8::internal;
 
 #endif  // V8_GLOBALS_H_