• Simon Marlow's avatar
    Partial fix for #2917 · 1b62aece
    Simon Marlow authored
     - add newAlignedPinnedByteArray# for allocating pinned BAs with
       arbitrary alignment
    
     - the old newPinnedByteArray# now aligns to 16 bytes
    
    Foreign.alloca will use newAlignedPinnedByteArray#, and so might end
    up wasting less space than before (we used to align to 8 by default).
    Foreign.allocaBytes and Foreign.mallocForeignPtrBytes will get 16-byte
    aligned memory, which is enough to avoid problems with SSE
    instructions on x86, for example.
    
    There was a bug in the old newPinnedByteArray#: it aligned to 8 bytes,
    but would have failed if the header was not a multiple of 8
    (fortunately it always was, even with profiling).  Also we
    occasionally wasted some space unnecessarily due to alignment in
    allocatePinned().
    
    I haven't done anything about Foreign.malloc/mallocBytes, which will
    give you the same alignment guarantees as malloc() (8 bytes on
    Linux/x86 here).
    1b62aece
PrimOps.cmm 67.2 KB