• mtrofin's avatar
    [turbofan] Spill rsi and rdi in their existing locations. · 20f3a077
    mtrofin authored
    We push the context and the js function onto the stack as part of the
    frame construction. The register allocator is presented with virtual
    registers for the above as defined from their corresponding registers. It
    then goes on to spilling them somewhere else on the stack.
    
    This means each function spends two redundant spills and two
    unnecessary stack slots.
    
    This change addresses this issue.
    
    We present these parameters (context and function) to the register
    allocator as an UnallocatedOperand having a "secondary storage". The
    secondary storage is then associated to the live range as its
    spill operand. We capture the definition of the live range so that we can
    then commit the spill (in this case, eliminate) through a variation of the
    mechanics of the CommitAssignment phase.
    
    The register allocator validator also needed update to understand
    UnallocatedOperands with a secondary storage.
    
    The change renames the SpillAtDefinitionList and related APIs to better
    capture their intent - the old names suggested spills happened upon
    calling. In reality, potential spill locations were thus recorded, and later
    committed (or not, in certain cases) after register allocation.
    
    BUG= v8:4548
    LOG=n
    
    Review URL: https://codereview.chromium.org/1426943010
    
    Cr-Commit-Position: refs/heads/master@{#31988}
    20f3a077
instruction.h 42.5 KB