• mbrandy's avatar
    PPC: [turbofan] Unify referencing of stack slots · 41870350
    mbrandy authored
    Port cbbaf9ea
    
    Note that the above commit breaks embedded constant pools and will need to
    be revised in a future CL.
    
    Original commit message:
        Previously, it was not possible to specify StackSlotOperands for all
        slots in both the caller and callee stacks. Specifically, the region
        of the callee's stack including the saved return address, frame
        pointer, function pointer and context pointer could not be addressed
        by the register allocator/gap resolver.
    
        In preparation for better tail call support, which will use the gap
        resolver to reconcile outgoing parameters, this change makes it
        possible to address all slots on the stack, because slots in the
        previously inaccessible dead zone may become parameter slots for
        outgoing tail calls. All caller stack slots are accessible as they
        were before, with slot -1 corresponding to the last stack
        parameter. Stack slot indices >= 0 access the callee stack, with slot
        0 corresponding to the callee's saved return address, 1 corresponding
        to the saved frame pointer, 2 corresponding to the current function
        context, 3 corresponding to the frame marker/JSFunction, and slots 4
        and above corresponding to spill slots.
    
        The following changes were specifically     needed:
    
        * Frame     has been changed to explicitly manage three areas of the
          callee frame, the fixed header, the spill slot area, and the
          callee-saved register area.
        * Conversions from stack slot indices to fp offsets all now go through
          a common bottleneck: OptimizedFrame::StackSlotOffsetRelativeToFp
        * The generation of deoptimization translation tables has been changed
          to support the new stack slot indexing scheme. Crankshaft, which
          doesn't support the new slot numbering in its register allocator,
          must adapt the indexes when creating translation tables.
        * Callee-saved parameters are now kept below spill slots, not above,
          to support saving only the optimal set of used registers, which is
          only known after register allocation is finished and spill slots
          have been allocated.
    
    R=danno@chromium.org, titzer@chromium.org, jyan@ca.ibm.com, dstence@us.ibm.com, joransiu@ca.ibm.com
    BUG=
    
    Review URL: https://codereview.chromium.org/1321553002
    
    Cr-Commit-Position: refs/heads/master@{#30396}
    41870350
code-generator-ppc.cc 58.4 KB