[PATCH] D74691: [Attributor] Detect possibly unbounded cycles in functions

[omar ahmed via Phabricator via llvm-commits]

omarahmed updated this revision to Diff 248960.
omarahmed added a comment.

[Attributor] Detect possibly unbounded cycles in functions

This patch changes the approach of containsCycle function of looping on
the CFG by depth_first to another approach as the depth_first function approach detects if-then-else part in
functions as a loop and that result in wrong behaviour, so this approach checks first the analysis of the function if no analysis available for the function then it loops on the SCCs and checkss if the SCC is a cycle or not,this is done with the assumption that any cycle is unbounded.
If analysis is present for the function then we check for irreducible control to check if there is a non loop cycles if there weren't any then we loop on the loop cycles in the function and check the maxTripCount of the loop.
This patch also uses maxTripCount to check if a function have bounded loop cycles.
Loops with maximum trip count are considered bounded, any other cycle not.
It also contains some fixed tests and some added tests contain bounded and
unbounded loops and non-loop cycles.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D74691/new/

https://reviews.llvm.org/D74691

Files:
  llvm/lib/Transforms/IPO/Attributor.cpp
  llvm/test/Transforms/Attributor/read_write_returned_arguments_scc.ll
  llvm/test/Transforms/Attributor/willreturn.ll

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