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Re: [PATCH] [4.0] Fix performance regressions due to inlining


Richard Guenther wrote:

Sorry, I don't see that (MODIFY_EXPR (VAR_DECL) (TARGET_EXPR)) is
related to the problem (due to the lack of understanding of the TARGET_EXPR tree code).

The semantics of TARGET_EXPR are that you create a temporary (initialized by an arbitrary expression) -- unless someone assigns the TARGET_EXPR to something else, in which case you directly initialize that something, and skip the temporary. So, in the expression I give above, the MODIFY_EXPR is free.


> The problem is that estimate_num_insns is
a per-statement and as such local operation - and the frontends

That may need to change in order to get better estimates.


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Mark Mitchell
CodeSourcery, LLC
mark@codesourcery.com
(916) 791-8304


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