mark Alloc as an omittable operation if result isn't used
mark Alloc as an omittable operation if result isn't used

Ignore-this: 4a2d1ba0f08b4ac3468f716b3031f669

darcs-hash:b47b212358ebcf7f613ccdbe9c0315e9bc298923

dpwright/jhc,dpwright/jhc,dpwright/jhc,dpwright/jhc