make release builds the default #17496
Conversation
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cc #8859 |
thestinger
added
the
I-slow
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This has implications on, for example, the nightly distributions. An ICE in the compiler is still quite a frequent occurrence, and it's very handy to request more information via I'd probably be comfortable at this point compiling the standard library with |
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We've made this change (or similar) in the past and then unmade it for the reasons @alexcrichton states. |
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Besides startup time on windows are there other performance improvements? |
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We should do this, however, we should make it easy for developers to get the old behaviour. This is a similar situation to parallel builds where the optimal settings for release vs development are very different. I propose #17665. |
This cuts the compilation time for a trivial Rust program by 15-20% on Windows due to a massive improvement in `rustc` start-up time. The debug logging has a very high cost because it makes extensive use of mutable global variables and those result in expensive relocations. It also makes jemalloc debug assertions / logging tied to the same flag as ones in the standard library or compiler. Enabling debug assertions by default discourages their use, because normal builds will be paying a cost for each one. The few debug assertions not removed before landing a pull request are a significant performance problem for types like `RefCell`. The defaults should cater to users or packagers building Rust rather than compiler developers. A compiler developer can be expected to override a default flag, but the same cannot be said of someone who lacks the same in-depth knowledge of the project. Even someone working on the standard libraries is not going to want to pay the high cost for debug logging. Many people who contribute to the compiler don't use the feature either, because a debugger tends to work a lot better than inconsistent / bit-rotted logging code.
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@thestinger, would you be ok working with @nick29581 to implement what we ended up concluding was the route we wanted to go in? It's a little more involved than just flipping the defaults, but @nick29581 knows the details. |
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That is #17665, btw |
minor: Bump `actions/download-artifact` and `upload-artifact` These will stop working in a couple of days. I think we could still use them in a more efficient way, but more tweaking is needed for that.
This cuts the compilation time for a trivial Rust program by 15-20% on
Windows due to a massive improvement in
rustcstart-up time. The debuglogging has a very high cost because it makes extensive use of mutable
global variables and those result in expensive relocations.
Creating debug builds by default discourages the usage of debug
assertions. The few debug assertions not removed before landing a pull
request are a significant performance problem for types like
RefCell.The defaults should cater to users or packagers building Rust rather
than compiler developers. A compiler developer can be expected to
override a default flag, but the same cannot be said of someone who
lacks the same in-depth knowledge of the project.
Even someone working on the standard libraries is not going to want to
pay the high cost for debug logging. Many people who contribute to the
compiler don't use the feature either, because a debugger tends to work
a lot better than inconsistent / bit-rotted logging code.