• Simon Peyton Jones's avatar
    Zap usage info in CSE (Trac #10218) · d261d4cb
    Simon Peyton Jones authored
    Trac #10218 reports a subtle bug that turned out to be:
    
    - CSE invalidated the usage information computed
      by earlier demand analysis, by increasing sharing
    
    - that made a single-entry thunk into a multi-entry thunk
    
    - and with -feager-blackholing, that led to <<loop>>
    
    The patch fixes it by making the CSE pass zap usage information for
    let-bound identifiers.   It can be restored by -flate-dmd-anal.
    
    (But making -flate-dmd-anal the default needs some careful work;
    see Trac #7782.)
    d261d4cb
Demand.hs 70.7 KB