• ishell@chromium.org's avatar
    [ext-code-space] Add InterpreterEntryTrampolineForProfiling builtin · 1067c6ac
    ishell@chromium.org authored
    ... - a code range size agnostic version of InterpreterEntryTrampoline
    builtin. The new builtin is fully compatible with the default version
    and used as a template for creating interpreter entry trampoline
    Code objects when --interpreted-frames-native-stack is enabled.
    
    This CL introduces a new assembler option "position_independent_code"
    which affects the way builtin calls are generated.
    This mode is enabled only for InterpreterEntryTrampolineForProfiling.
    
    Motivation:
    
    * InterpreterEntryTrampoline uses RelocInfo::CODE_TARGET for calling
      other builtins which requires the code range to be small enough to
      allow PC-relative jumps/calls between Code objects. This is the
      reason why --interpreted-frames-native-stack was not supported on
      arm and might not work on arm64 because the code range is bigger
      than the max PC-relative distance for call/jump instructions.
      The new builtin calls other builtins via builtins entry table which
      makes the code fully relocatable and usable for any code range size.
    
    * RelocInfo::CODE_TARGET requires a target code to be materialized
      as a Code object which contradicts the Code-less builtins goal.
    
    * The --interpreted-frames-native-stack is rarely used in the wild but
      we have to pay the price of deserializing InterpreterEntryTrampoline
      builtin as a Code object which consumes address space in the code
      range and thus limits the number of V8 isolates that can be created
      because of code range exhaustion. Now the pointer compression cage
      becomes the limiting factor instead of the code range.
    
    * We can remove complicated logic of Factory::CopyCode() and respective
      support on GC side.
    
    Bug: v8:11880, v8:8713, v8:12592
    Change-Id: Ib72e28c03496c43db42f6fe46622def12e102f31
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3811287Reviewed-by: 's avatarJakob Linke <jgruber@chromium.org>
    Commit-Queue: Igor Sheludko <ishell@chromium.org>
    Reviewed-by: 's avatarDominik Inführ <dinfuehr@chromium.org>
    Cr-Commit-Position: refs/heads/main@{#82263}
    1067c6ac
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