src/share/vm/utilities/globalDefinitions.cpp

rev 3821 : [mq]: unused

*** 353,357 ****
--- 353,403 ----
      julong result = julong(a) * b / div;
      assert(result <= (size_t)max_uintx, "Integer overflow in lcm");
  
      return size_t(result);
  }
+ 
+ // Clamp an address to be within a specific page
+ // 1. If the address is on the page it is returned as is
+ // 2. If the address is above the page_address the start of the *next* page will be returned
+ // 3. If the address is below the page_address the start of the page will be returned
+ static address clamp_address_in_page(address addr, address page_address, intptr_t page_size) {
+   if (align_size_down(intptr_t(addr), page_size) == align_size_down(intptr_t(page_address), page_size)) {
+     // address is in the specified page, just return it as is
+     return addr;
+   } else if (addr > page_address) {
+     // address is on above specified page, return start of next page
+     return (address)align_size_down(intptr_t(page_address), page_size) + page_size;
+   } else {
+     // address is below specified page, return start of page
+     return (address)align_size_down(intptr_t(page_address), page_size);
+   }
+ }
+ 
+ address clamp_address_in_page(address addr, address page_address) {
+   intptr_t page_size = os::vm_page_size();
+   return clamp_address_in_page(addr, page_address, page_size);
+ }
+ 
+ #ifndef PRODUCT
+ 
+ void GlobalDefinitions::test_globals() {
+   intptr_t page_size = 4096;
+   address a_page = (address)(10*page_size);
+ 
+   // Check that address within page is returned as is
+   assert(clamp_address_in_page(a_page, a_page, 4096) == a_page, "incorrect");
+   assert(clamp_address_in_page(a_page + 128, a_page, 4096) == a_page + 128, "incorrect");
+   assert(clamp_address_in_page(a_page + page_size - 1, a_page, 4096) == a_page + page_size - 1, "incorrect");
+ 
+   // Check that address above page returns start of next page
+   assert(clamp_address_in_page(a_page + page_size, a_page, 4096) == a_page + page_size, "incorrect");
+   assert(clamp_address_in_page(a_page + page_size + 1, a_page, 4096) == a_page + page_size, "incorrect");
+   assert(clamp_address_in_page(a_page + page_size*5 + 1, a_page, 4096) == a_page + page_size, "incorrect");
+ 
+   // Check that address below page returns start of page
+   assert(clamp_address_in_page(a_page - 1, a_page, 4096) == a_page, "incorrect");
+   assert(clamp_address_in_page(a_page - 2*page_size - 1, a_page, 4096) == a_page, "incorrect");
+   assert(clamp_address_in_page(a_page - 5*page_size - 1, a_page, 4096) == a_page, "incorrect");
+ }
+ 
+ #endif // PRODUCT