1. 06 Nov, 2019 1 commit
    • Simon Zünd's avatar
      Introduce REPL mode · fbcc2e87
      Simon Zünd authored
      Design doc: bit.ly/v8-repl-mode
      
      This CL adds a new REPL mode that can be used via
      DebugEvaluate::GlobalREPL. REPL mode only implements re-declaration
      of 'let' bindings at the moment. Example:
      
      REPL Input 1: let x = 21;
      REPL Input 2: let x = 42;
      
      This would normally throw a SyntaxError, but works in REPL mode.
      
      The implementation is done by:
        - Setting a 'repl mode' bit on {Script}, {ScopeInfo}, {ParseInfo}
          and script {Scope}.
        - Each global let declaration still gets a slot reserved in the
          respective {ScriptContext}.
        - When a new REPL mode {ScriptContext} is created, name clashes
          for let bindings are not reported as errors.
        - Declarations, loads and stores for global let in REPL mode are
          now "load/store global" instead of accessing their respective
          context slot directly. This causes a lookup in the ScriptContextTable
          where the found slot for each name is guaranteed to be the same
          (the first one).
      
      Bug: chromium:1004193, chromium:1018158
      Change-Id: Ia6ab526b9f696400dbb8bfb611a4d43606119a47
      Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1876061
      Commit-Queue: Simon Zünd <szuend@chromium.org>
      Reviewed-by: 's avatarRoss McIlroy <rmcilroy@chromium.org>
      Reviewed-by: 's avatarToon Verwaest <verwaest@chromium.org>
      Cr-Commit-Position: refs/heads/master@{#64793}
      fbcc2e87