1. 07 Apr, 2022 2 commits
    • Leszek Swirski's avatar
      Revert "[osr] Add an install-by-offset mechanism" · bb5cc0d5
      Leszek Swirski authored
      This reverts commit 51b99213.
      
      Reason for revert: Speculative revert for MSAN failure  https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux%20-%20arm64%20-%20sim%20-%20MSAN/43080/overview
      
      Original change's description:
      > [osr] Add an install-by-offset mechanism
      >
      > .. for concurrent OSR. There, the challenge is to hit the correct
      > JumpLoop bytecode once compilation completes, since execution has
      > moved on in the meantime.
      >
      > This CL adds a new mechanism to request installation at a specific
      > bytecode offset. We add a new `osr_install_target` field to the
      > BytecodeArray:
      >
      >   bitfield struct OSRUrgencyAndInstallTarget extends uint16 {
      >     osr_urgency: uint32: 3 bit;
      >     osr_install_target: uint32: 13 bit;
      >   }
      >
      >   // [...]
      >   osr_urgency_and_install_target: OSRUrgencyAndInstallTarget;
      >   bytecode_age: uint16;  // Only 3 bits used.
      >   // [...]
      >
      > Note urgency and install target are packed into one 16 bit field,
      > we can thus merge both checks into one comparison within JumpLoop.
      > Note also that these fields are adjacent to the bytecode age; we
      > still reset both OSR state and age with a single (now 32-bit)
      > store.
      >
      > The install target is the lowest 13 bits of the bytecode offset.
      > When set, every reached JumpLoop will check `is this my offset?`,
      > and if yes, jump into runtime to tier up.
      >
      > Drive-by: Rename BaselineAssembler::LoadByteField to LoadWord8Field.
      >
      > Bug: v8:12161
      > Change-Id: I275d468b19df3a4816392a2fec0713a8d211ef80
      > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3571812
      > Reviewed-by: Leszek Swirski <leszeks@chromium.org>
      > Commit-Queue: Jakob Linke <jgruber@chromium.org>
      > Cr-Commit-Position: refs/heads/main@{#79853}
      
      Bug: v8:12161
      Change-Id: I0c47499544465c80b5b23a492c00ec1c62815caa
      No-Presubmit: true
      No-Tree-Checks: true
      No-Try: true
      Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3576121
      Auto-Submit: Leszek Swirski <leszeks@chromium.org>
      Owners-Override: Leszek Swirski <leszeks@chromium.org>
      Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
      Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
      Cr-Commit-Position: refs/heads/main@{#79855}
      bb5cc0d5
    • Jakob Gruber's avatar
      [osr] Add an install-by-offset mechanism · 51b99213
      Jakob Gruber authored
      .. for concurrent OSR. There, the challenge is to hit the correct
      JumpLoop bytecode once compilation completes, since execution has
      moved on in the meantime.
      
      This CL adds a new mechanism to request installation at a specific
      bytecode offset. We add a new `osr_install_target` field to the
      BytecodeArray:
      
        bitfield struct OSRUrgencyAndInstallTarget extends uint16 {
          osr_urgency: uint32: 3 bit;
          osr_install_target: uint32: 13 bit;
        }
      
        // [...]
        osr_urgency_and_install_target: OSRUrgencyAndInstallTarget;
        bytecode_age: uint16;  // Only 3 bits used.
        // [...]
      
      Note urgency and install target are packed into one 16 bit field,
      we can thus merge both checks into one comparison within JumpLoop.
      Note also that these fields are adjacent to the bytecode age; we
      still reset both OSR state and age with a single (now 32-bit)
      store.
      
      The install target is the lowest 13 bits of the bytecode offset.
      When set, every reached JumpLoop will check `is this my offset?`,
      and if yes, jump into runtime to tier up.
      
      Drive-by: Rename BaselineAssembler::LoadByteField to LoadWord8Field.
      
      Bug: v8:12161
      Change-Id: I275d468b19df3a4816392a2fec0713a8d211ef80
      Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3571812Reviewed-by: 's avatarLeszek Swirski <leszeks@chromium.org>
      Commit-Queue: Jakob Linke <jgruber@chromium.org>
      Cr-Commit-Position: refs/heads/main@{#79853}
      51b99213
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