Set discriminator for call stmts within a same basic block.
tree4cbb14a873a06d06d676cd9818fef58b1c56510a
drwxr-xr-x - gcc-4_6-mobile-vtable-security
drwxr-xr-x - gcc-4_6-mobile
drwxr-xr-x - gcc-4_6
drwxr-xr-x - gcc-4_6_2-mobile
drwxr-xr-x - gcc-4_6_3-mobile
drwxr-xr-x - gcc-4_7-integration
drwxr-xr-x - gcc-4_7-mobile-vtable-verification
drwxr-xr-x - gcc-4_7-mobile
drwxr-xr-x - gcc-4_7
drwxr-xr-x - gcc-4_8
drwxr-xr-x - integration
drwxr-xr-x - main