• Milad Farazmand's avatar
    PPC/s390: [compiler] Refactor stack check handling · f7f370d2
    Milad Farazmand authored
    Port 0aa204fe
    
    Original Commit Message:
    
        This CL unifies how stack checks are handled in the Turbofan pipeline
        across architectures, in preparation for properly handling stack
        overflows caused by deoptimization in follow-up work. It will also
        open up possibilities to simplify related logic.
    
        How this used to work: JSStackCheck was lowered to a UintLessThan
        with the stack pointer (sp) and stack limit as inputs. On x64 and ia32,
        this node pattern was later recognized during instruction selection
        and rewritten to dedicated operators. On other platforms, including
        arm and arm64, special logic exists to avoid useless
        register-to-register moves when accessing the sp.
    
        This CL introduces a new StackPointerGreaterThan operator, which takes
        the stack limit as its sole input. This is what JSStackCheck now lowers
        to. This is threaded through to code generation, where we emit the
        appropriate code (in the future, we will apply an additional offset to
        the sp here).
    
        In follow-up CLs, we can remove or replace remaining uses of
        LoadStackPointer in CSA, Wasm, and the interpreter; and then remove
        the LoadStackPointer operator, related node matchers, related register
        constraints, and the pseudo-smi stack limit roots.
    
    R=jgruber@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
    BUG=
    LOG=N
    
    Change-Id: I175c110d30190bb543001b6fa77cd65cf22e5874
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1748002Reviewed-by: 's avatarJunliang Yan <jyan@ca.ibm.com>
    Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
    Cr-Commit-Position: refs/heads/master@{#63167}
    f7f370d2
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