[all-commits] [llvm/llvm-project] 04945c: [WIP][Attributor] AAReachability Attribute

[Pankaj Gode via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 04945c92ce00e5388be3ab493135b934a25903b4
      https://github.com/llvm/llvm-project/commit/04945c92ce00e5388be3ab493135b934a25903b4
  Author: Pankaj Gode <pgode at codeaurora.org>
  Date:   2019-11-22 (Fri, 22 Nov 2019)

  Changed paths:
    M llvm/include/llvm/Transforms/IPO/Attributor.h
    M llvm/lib/Transforms/IPO/Attributor.cpp

  Log Message:
  -----------
      [WIP][Attributor] AAReachability Attribute

     Summary: Working towards Johannes's suggestion for fixme, in Attributor's Noalias attribute deduction.
(ii) Check whether the value is captured in the scope using AANoCapture.
FIXME: This is conservative though, it is better to look at CFG and
// check only uses possibly executed before this call site.

A Reachability abstract attribute answers the question "does execution at point A potentially reach point B". If this question is answered with false for all other uses of the value that might be captured, we know it is not *yet* captured and can continue with the noalias deduction. Currently, information AAReachability provides is completely pessimistic.

    Reviewers: jdoerfert

    Reviewed By: jdoerfert

    Subscribers: uenoku, sstefan1, hiraditya, llvm-commits

    Differential Revision: https://reviews.llvm.org/D70233