[stable] Fix std.experimental.allocator.common.effectiveAlignment()#6622
[stable] Fix std.experimental.allocator.common.effectiveAlignment()#6622wilzbach merged 1 commit intodlang:stablefrom
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It was unable to handle alignments > 2^31 bytes, e.g., returning 2 for the 64-bit pointer 0x2FA_00000000. Return a size_t instead of a uint. Note that it's only called in one place, an assertion in a ctor of the BitmappedBlockImpl mixin, which handles size_t fine. This fixes sporadic std.experimental.allocator.building_blocks.bitmapped_block unittest failures for LDC CI on Win64 (something like 1 out of 100 runs failing).
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Thanks for your pull request and interest in making D better, @kinke! We are looking forward to reviewing it, and you should be hearing from a maintainer soon.
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| import std.algorithm.comparison : min; | ||
| immutable initialAlignment = min(parentAlignment, | ||
| 1U << trailingZeros(leadingUlongs * 8)); | ||
| 1U << min(31U, trailingZeros(leadingUlongs * 8))); |
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This was the only other occurrence of dangerous 1U << in the allocator package.
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The CircleCi error can be safely ignored. #6623 is the cherry-pick from master. |
| package size_t effectiveAlignment(void* ptr) | ||
| { | ||
| return 1U << trailingZeros(cast(size_t) ptr); | ||
| return (cast(size_t) 1) << trailingZeros(cast(size_t) ptr); |
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Isn't it possible for trailingZeros to return 64?
assert(trailingZeros(0) == 64);
So maybe trailingZeros needs to be fixed to accept size_t too?
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Right, good point, so for 32-bit size_t(0), trailingZeros() would indeed return 64 as well. Here, it doesn't matter, as effectiveAlignment(null) returns size_t(1) << 64U => 1 for both 32/64-bit size_t.
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Style nit: prefer size_t(1) over cast syntax.
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It was unable to handle alignments > 2^31 bytes, e.g., returning 2 for the 64-bit pointer 0x2FA_00000000. Return a
size_tinstead of auint. Note that it's only called in one place, an assertion in a ctor of theBitmappedBlockImplmixin, which handlessize_tfine.This fixes sporadic
std.experimental.allocator.building_blocks.bitmapped_blockunittest failures for LDC CI on Win64 (something like 1 out of 100 runs failing).