- 04 Mar, 2019 1 commit
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Ross McIlroy authored
BUG=v8:8801 Change-Id: I9d9d9824c6c9ad0176bbfd3723da1b578b17c256 Reviewed-on: https://chromium-review.googlesource.com/c/1495555 Commit-Queue: Ross McIlroy <rmcilroy@chromium.org> Reviewed-by: Mythri Alle <mythria@chromium.org> Cr-Commit-Position: refs/heads/master@{#60001}
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- 29 Oct, 2018 1 commit
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Benedikt Meurer authored
This introduces Word64 support for the CheckBounds operator, which now lowers to either CheckedUint32Bounds or CheckedUint64Bounds after the representation selection. The right hand side of CheckBounds can now be any positive safe integer on 64-bit architectures, whereas it remains Unsigned31 for 32-bit architectures. We only use the extended Word64 support when the right hand side is outside the Unsigned31 range, so for everything except DataViews this means that the performance should remain the same. The typing rule for the CheckBounds operator was updated to reflect this new behavior. The CheckBounds with a right hand side outside the Unsigned31 range will pass a new Signed64 feedback kind, which is handled with newly introduced CheckedFloat64ToInt64 and CheckedTaggedToInt64 operators in representation selection. The JSCallReducer lowering for DataView getType()/setType() methods was updated to not smi-check the [[ByteLength]] and [[ByteOffset]] anymore, but instead just use the raw uintptr_t values and operate on any value (for 64-bit architectures these fields can hold any positive safe integer, for 32-bit architectures it's limited to Unsigned31 range as before). This means that V8 can now handle huge DataViews fully, without falling off a performance cliff. This refactoring even gave us some performance improvements, on a simple micro-benchmark just exercising different DataView accesses we go from testDataViewGetUint8: 796 ms. testDataViewGetUint16: 997 ms. testDataViewGetInt32: 994 ms. testDataViewGetFloat64: 997 ms. to testDataViewGetUint8: 895 ms. testDataViewGetUint16: 889 ms. testDataViewGetInt32: 888 ms. testDataViewGetFloat64: 890 ms. meaning we lost around 10% on the single byte case, but gained 10% across the board for all the other element sizes. Design-Document: http://bit.ly/turbofan-word64 Bug: chromium:225811, v8:4153, v8:7881, v8:8171, v8:8383 Change-Id: Ic9d1bf152e47802c04dcfd679372e5c85e4abc83 Reviewed-on: https://chromium-review.googlesource.com/c/1303732Reviewed-by: Sigurd Schneider <sigurds@chromium.org> Commit-Queue: Benedikt Meurer <bmeurer@chromium.org> Cr-Commit-Position: refs/heads/master@{#57095}
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- 17 Sep, 2018 1 commit
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Benedikt Meurer authored
This change introduces the necessary conversion operators to convert from Word64 to other representations (Tagged, Word32, Float64, etc.), and plugs in the Word64 representation for NumberAdd/NumberSubtract, such that TurboFan will go to Int64Add/Sub on 64-bit architectures when the inputs and the output of the operation is in safe integer range. This includes the necessary changes to the Deoptimizer to be able to rematerialize Int64 values as Smi/HeapNumber when going back to Ignition later. This change might affect performance, although measurements indicate that there should be no noticable performance impact. The goal is to have TurboFan support Word64 representation to a degree that changing the TypedArray length to an uint64_t (for 64-bit archs) becomes viable and doesn't have any negative performance implications. Independent of that we might get performance improvements in other areas such as for crypto code later. Bug: v8:4153, v8:7881, v8:8171, v8:8178 Design-Document: bit.ly/turbofan-word64 Change-Id: I29d56e2a31c1bae61d04a89d29ea73f21fd49c59 Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel Reviewed-on: https://chromium-review.googlesource.com/1225709 Commit-Queue: Benedikt Meurer <bmeurer@chromium.org> Reviewed-by: Jaroslav Sevcik <jarin@chromium.org> Cr-Commit-Position: refs/heads/master@{#55937}
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