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src/share/vm/utilities/globalDefinitions.hpp

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rev 7386 : 8064457: Introduce compressed oops mode disjoint base and improve compressed heap handling.

@@ -122,13 +122,10 @@
 extern int LogBytesPerHeapOop;                // Oop within a java object
 extern int LogBitsPerHeapOop;
 extern int BytesPerHeapOop;
 extern int BitsPerHeapOop;
 
-// Oop encoding heap max
-extern uint64_t OopEncodingHeapMax;
-
 const int BitsPerJavaInteger = 32;
 const int BitsPerJavaLong    = 64;
 const int BitsPerSize_t      = size_tSize * BitsPerByte;
 
 // Size of a char[] needed to represent a jint as a string in decimal.

@@ -193,11 +190,10 @@
 // bytes.
 inline size_t heap_word_size(size_t byte_size) {
   return (byte_size + (HeapWordSize-1)) >> LogHeapWordSize;
 }
 
-
 const size_t K                  = 1024;
 const size_t M                  = K*K;
 const size_t G                  = M*K;
 const size_t HWperKB            = K / sizeof(HeapWord);
 

@@ -395,11 +391,20 @@
 const int LogKlassAlignmentInBytes = 3;
 const int LogKlassAlignment        = LogKlassAlignmentInBytes - LogHeapWordSize;
 const int KlassAlignmentInBytes    = 1 << LogKlassAlignmentInBytes;
 const int KlassAlignment           = KlassAlignmentInBytes / HeapWordSize;
 
-// Klass encoding metaspace max size
+// Maximal size of heap where unscaled compression can be used. Also upper bound
+// for heap placement: 4GB.
+const  uint64_t UnscaledOopHeapMax = 4*G;
+// Maximal size of heap where compressed oops can be used. Also upper bound for heap
+// placement for zero based compression algorithm: UnscaledOopHeapMax << LogMinObjAlignmentInBytes.
+extern uint64_t OopEncodingHeapMax;
+
+// Maximal size of compressed class space. Above this limit compression is not possible.
+// Also upper bound for placement of zero based class space. (Class space is further limited
+// to be < 3G, see arguments.cpp.)
 const uint64_t KlassEncodingMetaspaceMax = (uint64_t(max_juint) + 1) << LogKlassAlignmentInBytes;
 
 // Machine dependent stuff
 
 #if defined(X86) && defined(COMPILER2) && !defined(JAVASE_EMBEDDED)
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