a19c3ffb8f
With very few exceptions, this verifies all skipped write-barriers in CSA and Torque, showing that the MemoryOptimizer together with some type information on the stored value are enough to avoid unsafe skipped write-barriers. Changes to CSA: SKIP_WRITE_BARRIER and Store*NoWriteBarrier are verified by the MemoryOptimizer by default. Type information about the stored values (TNode<Smi>) is exploited to safely skip write barriers for stored Smi values. In some cases, the code is re-structured to make it easier to consume for the MemoryOptimizer (manual branch and load elimination). Changes to the MemoryOptimizer: Improve the MemoryOptimizer to remove write barriers: - When the store happens to a CSA-generated InnerAllocate, by ignoring Bitcasts and additions. - When the stored value is the HeapConstant of an immortal immovable root. - When the stored value is a SmiConstant (recognized by BitcastToTaggedSigned). - Fast C-calls are treated as non-allocating. - Runtime calls can be white-listed as non-allocating. Remaining missing cases: - C++-style iterator loops with inner pointers. - Inner allocates that are reloaded from a field where they were just stored (for example an elements backing store). Load elimination would fix that. - Safe stored value types that cannot be expressed in CSA (e.g., Smi|Hole). We could handle that in Torque. - Double-aligned allocations, which are not lowered in the MemoryOptimizer but in CSA. Drive-by change: Avoid Smi suffix for StoreFixedArrayElement since this can be handled by overload resolution (in Torque and C++). Reland Change: Support pointer compression operands. R=jarin@chromium.org TBR=mvstanton@chromium.org Bug: v8:7793 Change-Id: I84e1831eb6bf9be14f36db3f8b485ee4fab6b22e Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1612904 Auto-Submit: Tobias Tebbi <tebbi@chromium.org> Reviewed-by: Michael Stanton <mvstanton@chromium.org> Commit-Queue: Tobias Tebbi <tebbi@chromium.org> Cr-Commit-Position: refs/heads/master@{#61522} |
||
|---|---|---|
| .. | ||
| binutils | ||
| colorama | ||
| googletest | ||
| inspector_protocol | ||
| v8/builtins | ||
| wasm-api | ||