• Igor Sheludko's avatar
    [csa] Fix semantics of PopAndReturn · 5e5eaf79
    Igor Sheludko authored
    This CL prohibits using PopAndReturn from the builtins that
    have calling convention with arguments on the stack.
    
    This CL also updates the PopAndReturn tests so that even off-by-one
    errors in the number of poped arguments are caught which was not the
    case before.
    
    Motivation:
    
    PopAndReturn is supposed to be using ONLY in CSA/Torque builtins for
    dropping ALL JS arguments that are currently located on the stack.
    Disallowing PopAndReturn in builtins with stack arguments simplifies
    semantics of this instruction because in case of presence of declared
    stack parameters it's impossible to distinguish the following cases:
    1) stack parameter is included in JS arguments (and therefore it will
       be dropped as a part of 'pop' number of arguments),
    2) stack parameter is NOT included in JS arguments (and therefore it
       should be dropped in ADDITION to the 'pop' number of arguments).
    
    This issue wasn't noticed before because builtins with stack parameters
    relied on adapter frames machinery to ensure that the expected
    parameters are present on the stack, but on the same time the adapter
    frame tearing down code was effectively recovering the stack pointer
    potentially broken by the CSA builtin.
    
    Once we get rid of the arguments adapter frames keeping stack pointer
    in a valid state becomes crucial.
    
    Bug: v8:5269, v8:10201
    Change-Id: Id3ea9730bb0d41d17999c73136c4dfada374a822
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2460819
    Commit-Queue: Igor Sheludko <ishell@chromium.org>
    Reviewed-by: 's avatarTobias Tebbi <tebbi@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#70454}
    5e5eaf79
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