Re: [boost] [review][LEAF] Review of LEAF starts today : May 22 - May 31

On Sat, May 30, 2020 at 7:43 AM Bjorn Reese via Boost wrote:

On 2020-05-22 21:30, Emil Dotchevski via Boost wrote:

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- Does LEAF incur any memory or runtime performance overhead in the non-error case? If so what is the impact of this when compared to the itanium zero-cost exception handling ABI?

Generally, no.

Can you elaborate on this with regards to runtime performance?

In the successful case, the runtime overhead of C++ try-catch blocks is a jump over the catch block.

By "generally no" I meant that the work is mostly limited to try_catch. In more details, on the happy path:: - At try_catch: a local tuple is initialized, where E... is basically the argument types of all the error handlers, with duplicates removed. Each slot<E> zeroes an int, and a TLS pointer for each of E... is set to point the corresponding slot<E>... . When exiting the try_catch, this is undone. - Things like preload cache all their arguments locally, by moving, later to be discarded if no error has occurred.