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Optimize away is_nonconst_rvalue bit for copied in parameters #12

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hsutter opened this issue Nov 28, 2020 · 0 comments
Open

Optimize away is_nonconst_rvalue bit for copied in parameters #12

hsutter opened this issue Nov 28, 2020 · 0 comments
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prototype-codegen-quality Code generation quality

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hsutter commented Nov 28, 2020 •
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When an in parameter is copied (type is small and trivially copyable), there's no need to pass an extra bit to remember whether it was a non-const rvalue.

Repro 1, extra instruction at the call site for an in int parameter: https://cppx.godbolt.org/z/fz78YW

Repro 2, two extra instructions in the callee for an in int parameter: https://cppx.godbolt.org/z/c8rYdY
@hsutter hsutter added the prototype-codegen-quality Code generation quality label Nov 28, 2020
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