[PATCH] D14228: [FunctionAttrs] Identify norecurse functions

[James Molloy via llvm-commits]

jmolloy updated this revision to Diff 39515.
jmolloy added a comment.

Hi,

Thanks all for the feedback. This new version is rebased to HEAD on top of Chandler's changes, and improves the way the algorithm works.

I've added an extra inference rule - if a function F has only one callsite and that callsite is itself in a norecurse function, then F cannot recurse. Obviously this lends itself to top-down propagation rather than the bottom-up propagation we get with SCC passes.

Now, we do the same bottom-up approach but if we see a function that is not obviously recursive but can't be proven non-recursive we save it and after the SCC is over we go and revisit it, top-down. This allows more functions to be marked norecurse.

I think I've acted on all the review comments so far, and I've added more comments into the code to make it clearer what's going on.

Cheers,

James


Repository:
  rL LLVM

http://reviews.llvm.org/D14228

Files:
  lib/Transforms/IPO/FunctionAttrs.cpp
  test/Analysis/TypeBasedAliasAnalysis/functionattrs.ll
  test/Transforms/FunctionAttrs/2008-09-03-ReadNone.ll
  test/Transforms/FunctionAttrs/2010-10-30-volatile.ll
  test/Transforms/FunctionAttrs/atomic.ll
  test/Transforms/FunctionAttrs/norecurse.ll
  test/Transforms/FunctionAttrs/optnone.ll

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