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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.
By using "void" instead of "{}" as the LLVM type for nil, we can avoid
the alloca/store/load sequence for the return value, resulting in less
and simpler IR code.
This reduces compile times by about 10%.
bors
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Jun 21, 2013
The changes in these commits improve the IR codegen by removing unnecessary copies for certain function call arguments and stopping to allocate return values for functions returning nil. They reduce compile times by about 10% in total.
flip1995
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Jun 3, 2021
…_trait, r=llogiq Fix invalid syntax in `from_iter_instead_of_collect` suggestion First attempt at contributing, hopefully this is a good start and can be improved. :) fixes rust-lang#7259 changelog: [`from_iter_instead_of_collect`] fix invalid suggestion involving "as Trait"
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The changes in these commits improve the IR codegen by removing unnecessary copies for certain function call arguments and stopping to allocate return values for functions returning nil. They reduce compile times by about 10% in total.