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Up to 7% regression in recent rollup #57115

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alexcrichton opened this issue Dec 25, 2018 · 1 comment
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Up to 7% regression in recent rollup #57115

alexcrichton opened this issue Dec 25, 2018 · 1 comment
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I-compilemem Issue: Problems and improvements with respect to memory usage during compilation. I-compiletime Issue: Problems and improvements with respect to compile times. regression-from-stable-to-nightly Performance or correctness regression from stable to nightly. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.

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@alexcrichton
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Noticed here it looks like something in that rollup has caused a blanket regression in compile time instruction counts while also simultaneously improving memory. The current hypothesis is that #56986 is incorrect and disabled jemalloc entirely.

Another hypothesis is that #56944 had a really weird effect on the build.

In any case, we should investigate!
@alexcrichton alexcrichton added the regression-from-stable-to-nightly Performance or correctness regression from stable to nightly. label Dec 25, 2018
@alexcrichton alexcrichton mentioned this issue Dec 25, 2018
Merged
@Centril Centril added I-slow Issue: Problems and improvements with respect to performance of generated code. I-compilemem Issue: Problems and improvements with respect to memory usage during compilation. I-compiletime Issue: Problems and improvements with respect to compile times. and removed I-slow Issue: Problems and improvements with respect to performance of generated code. labels Dec 25, 2018
@alexcrichton alexcrichton mentioned this issue Jan 2, 2019
Merged
alexcrichton added a commit to alexcrichton/rust that referenced this issue Jan 2, 2019
@alexcrichton
rustc: Fix regression where jemalloc isn't used
5265c31 
In rust-lang#56986 the linkage of jemalloc to the compiler was switched from the
driver library to the rustc binary to ensure that only rustc itself uses
jemalloc. In doing so, however, it turns out jemalloc wasn't actually
linked in at all! None of the symbols were referenced so the static
library wasn't used. This means that jemalloc wasn't pulled in at all.

This commit performs a bit of a dance to reference jemalloc symbols,
attempting to pull it in despite LLVM's optimizations.

Closes rust-lang#57115
@alexcrichton
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I believe this should be fixed in #57287

bors added a commit that referenced this issue Jan 2, 2019
@bors
Auto merge of #57287 - alexcrichton:fix-jemalloc, r=<try>
3550c27 
rustc: Fix regression where jemalloc isn't used

In #56986 the linkage of jemalloc to the compiler was switched from the
driver library to the rustc binary to ensure that only rustc itself uses
jemalloc. In doing so, however, it turns out jemalloc wasn't actually
linked in at all! None of the symbols were referenced so the static
library wasn't used. This means that jemalloc wasn't pulled in at all.

This commit performs a bit of a dance to reference jemalloc symbols,
attempting to pull it in despite LLVM's optimizations.

Closes #57115
@nagisa nagisa added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Jan 3, 2019
alexcrichton added a commit to alexcrichton/rust that referenced this issue Jan 3, 2019
@alexcrichton
rustc: Fix regression where jemalloc isn't used
ccbf28e 
In rust-lang#56986 the linkage of jemalloc to the compiler was switched from the
driver library to the rustc binary to ensure that only rustc itself uses
jemalloc. In doing so, however, it turns out jemalloc wasn't actually
linked in at all! None of the symbols were referenced so the static
library wasn't used. This means that jemalloc wasn't pulled in at all.

This commit performs a bit of a dance to reference jemalloc symbols,
attempting to pull it in despite LLVM's optimizations.

Closes rust-lang#57115
bors added a commit that referenced this issue Jan 6, 2019
@bors
Auto merge of #57287 - alexcrichton:fix-jemalloc, r=nikomatsakis
af2c159 
rustc: Fix regression where jemalloc isn't used

In #56986 the linkage of jemalloc to the compiler was switched from the
driver library to the rustc binary to ensure that only rustc itself uses
jemalloc. In doing so, however, it turns out jemalloc wasn't actually
linked in at all! None of the symbols were referenced so the static
library wasn't used. This means that jemalloc wasn't pulled in at all.

This commit performs a bit of a dance to reference jemalloc symbols,
attempting to pull it in despite LLVM's optimizations.

Closes #57115
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I-compilemem Issue: Problems and improvements with respect to memory usage during compilation. I-compiletime Issue: Problems and improvements with respect to compile times. regression-from-stable-to-nightly Performance or correctness regression from stable to nightly. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue.
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