CodeAlloc changes to eliminate dependency on 4K system page size (bug 545295 r=edwsmith+)

--HG--
extra : convert_revision : f1734da5dae9a73cf52692fc8dd72c25d0f12a14

js/src/nanojit/CodeAlloc.cpp

@@ -54,14 +54,15 @@ namespace nanojit
 #else
     static const int pagesPerAlloc = 16;
 #endif
-    static const int bytesPerPage = 4096;
-    static const int bytesPerAlloc = pagesPerAlloc * bytesPerPage;
 
     CodeAlloc::CodeAlloc()
         : heapblocks(0)
         , availblocks(0)
         , totalAllocated(0)
-    {}
+        , bytesPerPage(VMPI_getVMPageSize())
+        , bytesPerAlloc(pagesPerAlloc * bytesPerPage)
+    {
+    }
 
     CodeAlloc::~CodeAlloc() {
         reset();

js/src/nanojit/CodeAlloc.h

@@ -121,6 +121,12 @@ namespace nanojit
         CodeList* availblocks;
         size_t totalAllocated;
 
+        /** Cached value of VMPI_getVMPageSize */
+        const size_t bytesPerPage;
+        
+        /** Number of bytes to request from VMPI layer, always a multiple of the page size */
+        const size_t bytesPerAlloc;
+
         /** remove one block from a list */
         static CodeList* removeBlock(CodeList* &list);
 
@@ -137,7 +143,7 @@ namespace nanojit
         void sanity_check();
 
         /** find the beginning of the heapblock terminated by term */
-        static CodeList* firstBlock(CodeList* term);
+        CodeList* firstBlock(CodeList* term);
 
         //
         // CodeAlloc's SPI.  Implementations must be defined by nanojit embedder.