codegen: sizeof optimizations #24129
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vchuravy
approved these changes
Oct 18, 2017
Like with Arguments attributes, the dereferenceable metadata on a Load also requires knowing the eltype size of the loaded pointer. Also add a few more attributes for known properties and some other small code improvements.
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vtjnash
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Repurposed this PR to provide LLVM more general sizeof and alignof optimization opportunities (extension of #27945). |
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@nanosoldier |
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Your benchmark job has completed - possible performance regressions were detected. A full report can be found here. cc @ararslan |
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jl_datatype_sizeis rounded up to the allocation size, however, many allocations in llvm are instead shrink-wrapped to the actual size of the dataFor loading data, this is perhaps overly conservative (valgrind might disagree, but dereferencing the trailing bytes should be inbounds as far as the page table is concerned), but for writing alloca slots, we may have been stomping on our stack before.EDIT: I've effectively stolen this PR and repurposed it to apply more metadata attributes instead. The bugfixes I thought I was chasing before were due to an incorrect Type (which had an actual wrong size).