Changeset 259552 in webkit
- Timestamp:
- Apr 5, 2020 11:11:30 AM (4 years ago)
- Location:
- trunk/Source/JavaScriptCore
- Files:
-
- 2 edited
Legend:
- Unmodified
- Added
- Removed
-
trunk/Source/JavaScriptCore/ChangeLog
r259549 r259552 1 2020-04-05 Mark Lam <mark.lam@apple.com> 2 3 Change s_entropyBitsShiftForStructurePointer to 48 bits. 4 https://bugs.webkit.org/show_bug.cgi?id=210022 5 <rdar://problem/61310696> 6 7 Reviewed by Keith Miller. 8 9 This is ok because the top 16 bits of the 64-bit address is not used. We can 10 fill out the top 16-bits of the encodedStructureBits with the lowest 16-bits of 11 the StructureID (which includes the 7-bits of entropy). 12 13 * runtime/StructureIDTable.h: 14 1 15 2020-04-05 Yusuke Suzuki <ysuzuki@apple.com> 2 16 -
trunk/Source/JavaScriptCore/runtime/StructureIDTable.h
r259547 r259552 146 146 // which are encoded from the structure pointer as such: 147 147 // 148 // ---------------------------------------------------------------- 149 // | 7 entropy bits | 57structure pointer bits |150 // ---------------------------------------------------------------- 148 // ----------------------------------------------------------------- 149 // | 9 low index bits | 7 entropy bits | 48 structure pointer bits | 150 // ----------------------------------------------------------------- 151 151 // 152 152 // The entropy bits here are the same 7 bits used in the encoding of the … … 155 155 static constexpr uint32_t s_numberOfNukeBits = 1; 156 156 static constexpr uint32_t s_numberOfEntropyBits = 7; 157 static constexpr uint32_t s_entropyBitsShiftForStructurePointer = (sizeof( intptr_t) * 8) - s_numberOfEntropyBits;157 static constexpr uint32_t s_entropyBitsShiftForStructurePointer = (sizeof(EncodedStructureBits) * 8) - 16; 158 158 159 159 static constexpr uint32_t s_maximumNumberOfStructures = 1 << (32 - s_numberOfEntropyBits - s_numberOfNukeBits);
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