[PATCH] D145210: [Pipeline] Adjust PostOrderFunctionAttrs placement in simplification pipeline

[Arthur Eubanks via Phabricator via llvm-commits]

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We can infer more attribute information once functions are fully
simplified, so move the PostOrderFunctionAttrs pass after the function
simplification pipeline. However, just doing this can impact
simplification of recursive functions since function simplification
takes advantage of function attributes of callees (some LLVM tests are
actually impacted by this), so keep a copy of PostOrderFunctionAttrs
before the function simplification pipeline that only runs on recursive
functions.

This requires some restructuring of the CGSCC NoRerun feature. We need
to cache the ShouldNotRunFunctionPassesAnalysis analysis after the
simplification is done, which now is after the second
PostOrderFunctionAttrs run, rather than after the function
simplification pipeline.

Compile time impact:
https://llvm-compile-time-tracker.com/compare.php?from=33cf40122279342b50f92a3a53f5c185390b6018&to=1bb2a07875634e508a6bdf2ca1b130f55510f060&stat=instructions:u

Compile time increase from unconditionally running the first PostOrderFunctionAttrs:
https://llvm-compile-time-tracker.com/compare.php?from=1bb2a07875634e508a6bdf2ca1b130f55510f060&to=f4f87e89cc7a35c64e3a103a8036192a84ae002b&stat=instructions:u


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D145210

Files:
  llvm/include/llvm/Transforms/IPO/FunctionAttrs.h
  llvm/lib/Analysis/CGSCCPassManager.cpp
  llvm/lib/Passes/PassBuilderPipelines.cpp
  llvm/lib/Transforms/IPO/FunctionAttrs.cpp
  llvm/test/Transforms/InstCombine/unused-nonnull.ll

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