6705523: Fix for 6695506 will violate spec when used in JDK6

Summary: Make max classfile version number dependent on JDK version
Reviewed-by: acorn, never

src/cpu/sparc/vm/sharedRuntime_sparc.cpp

@@ -2721,7 +2721,8 @@ nmethod *SharedRuntime::generate_dtrace_nmethod(
 #endif /* ASSERT */
 
   VMRegPair zero;
-  zero.set2(G0->as_VMReg());
+  const Register g0 = G0; // without this we get a compiler warning (why??)
+  zero.set2(g0->as_VMReg());
 
   int c_arg, j_arg;
 

src/share/vm/classfile/classFileParser.cpp

@@ -44,6 +44,7 @@
 
 // Used for backward compatibility reasons:
 // - to check for javac bug fixes that happened after 1.5
+// - also used as the max version when running in jdk6
 #define JAVA_6_VERSION                    50
 
 
@@ -3516,9 +3517,11 @@ bool ClassFileParser::has_illegal_visibility(jint flags) {
 }
 
 bool ClassFileParser::is_supported_version(u2 major, u2 minor) {
+  u2 max_version = JDK_Version::is_gte_jdk17x_version() ?
+    JAVA_MAX_SUPPORTED_VERSION : JAVA_6_VERSION;
   return (major >= JAVA_MIN_SUPPORTED_VERSION) &&
-         (major <= JAVA_MAX_SUPPORTED_VERSION) &&
-         ((major != JAVA_MAX_SUPPORTED_VERSION) ||
+         (major <= max_version) &&
+         ((major != max_version) ||
           (minor <= JAVA_MAX_SUPPORTED_MINOR_VERSION));
 }
 

src/share/vm/runtime/java.hpp

@@ -68,8 +68,24 @@ class JDK_Version : AllStatic {
   static bool is_jdk13x_version()           { assert(is_jdk_version_initialized(), "must have been initialized"); return _jdk_version == 3; }
   static bool is_jdk14x_version()           { assert(is_jdk_version_initialized(), "must have been initialized"); return _jdk_version == 4; }
   static bool is_jdk15x_version()           { assert(is_jdk_version_initialized(), "must have been initialized"); return _jdk_version == 5; }
-  static bool is_jdk16x_version()           { assert(is_jdk_version_initialized(), "must have been initialized"); return _jdk_version == 6; }
-  static bool is_jdk17x_version()           { assert(is_jdk_version_initialized(), "must have been initialized"); return _jdk_version == 7; }
+
+  static bool is_jdk16x_version() {
+    if (is_jdk_version_initialized()) {
+      return _jdk_version == 6;
+    } else {
+      assert(is_pre_jdk16_version(), "must have been initialized");
+      return false;
+    }
+  }
+
+  static bool is_jdk17x_version() {
+    if (is_jdk_version_initialized()) {
+      return _jdk_version == 7;
+    } else {
+      assert(is_pre_jdk16_version(), "must have been initialized");
+      return false;
+    }
+  }
 
   static bool supports_thread_park_blocker() { return _version_info.thread_park_blocker; }
 
@@ -85,14 +101,22 @@ class JDK_Version : AllStatic {
   }
   static bool is_gte_jdk16x_version() {
     // Keep the semantics of this that the version number is >= 1.6
-    assert(is_jdk_version_initialized(), "Not initialized");
+    if (is_jdk_version_initialized()) {
       return _jdk_version >= 6;
+    } else {
+      assert(is_pre_jdk16_version(), "Not initialized");
+      return false;
+    }
   }
 
   static bool is_gte_jdk17x_version() {
     // Keep the semantics of this that the version number is >= 1.7
-    assert(is_jdk_version_initialized(), "Not initialized");
+    if (is_jdk_version_initialized()) {
       return _jdk_version >= 7;
+    } else {
+      assert(is_pre_jdk16_version(), "Not initialized");
+      return false;
+    }
   }
 
   static bool is_jdk_version_initialized() {