Add a target-independent way to query page size.

llvm-svn: 14232

llvm/include/Config/pagesize.h

@@ -0,0 +1,49 @@
+/* 
+ *                     The LLVM Compiler Infrastructure
+ *
+ * This file was developed by the LLVM research group and is distributed under
+ * the University of Illinois Open Source License. See LICENSE.TXT for details.
+ * 
+ ******************************************************************************
+ *
+ * This header file provides a platform-independent way of quering page size.
+ */
+
+#ifndef PAGESIZE_H
+#define PAGESIZE_H
+
+#include "Config/unistd.h"
+#include <sys/param.h>
+
+namespace llvm {
+
+/* Compatibility chart:
+ *
+ * x86/Linux:        _SC_PAGESIZE, _SC_PAGE_SIZE
+ * MacOS X/PowerPC:  v. 10.2: NBPG, 
+ *                   v. 10.3: _SC_PAGESIZE
+ * Solaris/Sparc:    _SC_PAGESIZE, _SC_PAGE_SIZE
+ */
+
+/**
+ * GetPageSize - wrapper to return page size in bytes for various 
+ *  architecture/OS combinations
+ */ 
+unsigned GetPageSize() {
+#ifdef _SC_PAGESIZE
+  return sysconf(_SC_PAGESIZE);
+#elif defined(_SC_PAGE_SIZE)
+  return sysconf(_SC_PAGE_SIZE);
+#elif defined(NBPG)
+#ifndef CLSIZE
+#define CLSIZE 1
+#endif
+  return NBPG * CLSIZE;
+#else
+  return 4096; /* allocate 4KB as a fall-back */
+#endif
+}
+
+}
+
+#endif