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Potential compile time regression in item-types checking #36947

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Mark-Simulacrum opened this issue Oct 4, 2016 · 3 comments
Closed

Potential compile time regression in item-types checking #36947

Mark-Simulacrum opened this issue Oct 4, 2016 · 3 comments
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A-codegen Area: Code generation regression-from-stable-to-nightly Performance or correctness regression from stable to nightly. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue.

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@Mark-Simulacrum
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Diff: 1cdc0fb...144af3e

Perf.rlo graph, though it basically just shows that item-types checking regressed from 0.67 to 1.006.

cc @brson (the commits in the range are from #36807).

IRC discussion has led @brson to believe that this is a result of memchr changes.
@brson brson added T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. regression-from-stable-to-nightly Performance or correctness regression from stable to nightly. A-codegen Area: Code generation A-libs T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. and removed T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Oct 4, 2016
@brson brson self-assigned this Oct 4, 2016
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brson commented Oct 4, 2016

The only thing in that patch that looks remotely performance sensitive to me is the inlining around memchr. If I accidentally switched the memchr implementation to the slow version, that would also explain it.

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brson commented Oct 4, 2016

The regression disappeared.

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I guess this can then be closed, probably just noise.

@brson brson closed this as completed Oct 4, 2016
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A-codegen Area: Code generation regression-from-stable-to-nightly Performance or correctness regression from stable to nightly. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue.
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