Stackable IRT

SConstruct

Index: SConstruct
diff --git a/SConstruct b/SConstruct
index f281ff3bc876277eaaf56ceea835558a0f55f407..efeca1b8a545c4805d38a9308c4903e80c130d95 100755
--- a/SConstruct
+++ b/SConstruct
@@ -3061,6 +3061,7 @@ irt_only_tests = [
     'tests/random/nacl.scons',
     'tests/sbrk/nacl.scons',
     'tests/translator_size_limits/nacl.scons',
+    'tests/stacked_irt/nacl.scons',
     ]
 
 # These are tests that are worthwhile to run in both IRT and non-IRT variants.
@@ -3307,6 +3308,19 @@ else:
 # of x86-32 C.
 nacl_irt_env.Append(CCFLAGS=['-fasynchronous-unwind-tables'])
 
+irt_env = nacl_irt_env.Clone(
+    BUILD_TYPE = 'stacked_irt',
+    BUILD_TYPE_DESCRIPTION = 'Stacked IRT build',
+    NACL_BUILD_FAMILY = 'UNTRUSTED_IRT',
+)
+
+# Provide access to the IRT build environment from the default environment
+# which is needed when compiling custom IRT for testing purposes.
+nacl_env['IRT_ENV'] = irt_env
+
+# Unlike NaCl IRT, stacked IRT should be position independent
+irt_env.SetBits('nacl_pic')
+
 # TODO(mcgrathr): Clean up uses of these methods.
 def AddLibraryDummy(env, nodes):
   return nodes