diff -r 2332df8332f7 -r d0e979f2644c SConstruct
--- a/SConstruct	Mon Jul 02 18:21:04 2012 +0100
+++ b/SConstruct	Mon Jul 02 18:33:25 2012 +0100
@@ -167,6 +167,8 @@
                help='Disable style checking hooks')
 AddLocalOption('--lto', dest='lto', action='store_true',
                help='Enable Link-Time Optimization')
+AddLocalOption('--native', dest='native', action='store_true',
+               help='Automatically optimise for native CPU features')
 AddLocalOption('--update-ref', dest='update_ref', action='store_true',
                help='Update test reference outputs')
 AddLocalOption('--verbose', dest='verbose', action='store_true',
@@ -504,6 +506,18 @@
        not compareVersions(gcc_version, '4.4.2'):
         print 'Info: Tree vectorizer in GCC 4.4.1 & 4.4.2 is buggy, disabling.'
         main.Append(CCFLAGS=['-fno-tree-vectorize'])
+
+    if compareVersions(gcc_version, '4.2') >= 0:
+        # If using native optimisation, append the appropriate
+        # flag. Note that support was only added in gcc 4.2.
+        if GetOption('native'):
+            # Append the flag to the compiler flags
+            main.Append(CCFLAGS = ['-march=native'])
+        else:
+            print termcap.Yellow + termcap.Bold + \
+                "Assuming you are compiling and executing on homogenous "\
+                "architectures, using --native may speed up execution." + \
+                termcap.Normal
     if compareVersions(gcc_version, '4.6') >= 0:
         main.Append(CXXFLAGS=['-std=c++0x'])
         # Determine the appropriate Link-Time Optimization (LTO) flags
@@ -555,6 +569,18 @@
 
     if compareVersions(clang_version, "3") >= 0:
         main.Append(CXXFLAGS=['-std=c++0x'])
+
+        # If using native optimisation, append the appropriate
+        # flag. Versions pre-dating 3.0 has known issues, so restrict
+        # it to >= 3.
+        if GetOption('native'):
+            # Append the flag to the compiler flags
+            main.Append(CCFLAGS = ['-march=native'])
+        else:
+            print termcap.Yellow + termcap.Bold + \
+                "Assuming you are compiling and executing on homogenous "\
+                "architectures, using --native may speed up execution." + \
+                termcap.Normal
 else:
     print termcap.Yellow + termcap.Bold + 'Error' + termcap.Normal,
     print "Don't know what compiler options to use for your compiler."