Avoid unnecessary scratch datums for by-copy function arguments #7237
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Currently, by-copy function arguments are always stored into a scratch datum, which serves two purposes. First, it is required to be able to have a temporary cleanup, in case that the call fails before the callee actually takes ownership of the value. Second, if the argument is to be passed by reference, the copy is required, so that the function doesn't get a reference to the original value. But in case that the datum does not need a drop glue call and it is passed by value, there's no need to perform the extra copy. Reduces the time for the LLVM passes when compiling librustc by about 10%.
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I somehow messed up the time measurement. Since this is now contained in #7259 I'll close this one. |
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…ip1995 Add the command to add upstream remote changelog: none Adding this command should better help new contributors.
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Rollup of 3 pull requests Successful merges: - rust-lang#7235 (Fix another manual_unwrap_or deref FP) - rust-lang#7237 (Add the command to add upstream remote) - rust-lang#7239 (CI: update rustup before installing the toolchain on windows) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup changelog: rollup
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Currently, by-copy function arguments are always stored into a scratch
datum, which serves two purposes. First, it is required to be able to
have a temporary cleanup, in case that the call fails before the callee
actually takes ownership of the value. Second, if the argument is to be
passed by reference, the copy is required, so that the function doesn't
get a reference to the original value.
But in case that the datum does not need a drop glue call and it is
passed by value, there's no need to perform the extra copy.
Reduces the time for the LLVM passes when compiling librustc by about
10%.