• Clemens Backes's avatar
    [wasm] Fix flake about missed breakpoints · dfd86b05
    Clemens Backes authored
    If multiple isolates were involved, we did not always hit the breakpoint
    reliably in all isolates.
    
    This CL fixes this flake this via two changes:
    
    1. Remove breakpoint info when tiering up.
       If we keep the breakpoint information, a second isolate that later
       sets the same breakpoint will see that the breakpoint already exists,
       and will not set it again, even though the code containing the
       breakpoint has been replaced at that point.
       This fixes a flake in the debug/wasm/breakpoints test.
    
    2. Don't overwrite code with breakpoints by default "tiered down" code.
       This is achieved by introducing another state in the {ForDebugging}
       enum which marks that code contains breakpoints. Otherwise it could
       happen that two isolates start tiering down (both recompiling missing
       functions in Liftoff), one isolate finishes and immediately sets a
       breakpoint, then the other isolates finishes and overwrites the code
       with breakpoints by the usual {kForDebugging} code.
       Setting breakpoints is synchronized already, so overwriting
       breakpoint code with other breakpoint code is always safe.
    
    R=thibaudm@chromium.org
    
    Bug: v8:10611, v8:10359
    Change-Id: I171d86b110a54f9eb5e4c3fa35108638904212e8
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2316080
    Commit-Queue: Clemens Backes <clemensb@chromium.org>
    Reviewed-by: 's avatarThibaud Michaud <thibaudm@chromium.org>
    Cr-Commit-Position: refs/heads/master@{#69088}
    dfd86b05
wasm-debug.cc 49.9 KB