[all-commits] [llvm/llvm-project] 74c8c2: Revert "Recommit "[SCEV] Use nw flag and symbolic ...

[Nikita Popov via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 74c8c2d903e2c849a2132ae798018f8bbe00ea21
      https://github.com/llvm/llvm-project/commit/74c8c2d903e2c849a2132ae798018f8bbe00ea21
  Author: Nikita Popov <nikita.ppv at gmail.com>
  Date:   2020-10-16 (Fri, 16 Oct 2020)

  Changed paths:
    M llvm/include/llvm/Analysis/ScalarEvolution.h
    M llvm/lib/Analysis/ScalarEvolution.cpp
    M llvm/test/Analysis/ScalarEvolution/no-wrap-symbolic-becount.ll
    M llvm/test/Transforms/IndVarSimplify/X86/eliminate-trunc.ll
    M llvm/test/Transforms/IndVarSimplify/promote-iv-to-eliminate-casts.ll

  Log Message:
  -----------
  Revert "Recommit "[SCEV] Use nw flag and symbolic iteration count to sharpen ranges of AddRecs""

This reverts commit 32b72c3165bf65cca2e8e6197b59eb4c4b60392a.

While better than before, this change still introduces a large
compile-time regression (>3% on mafft):
https://llvm-compile-time-tracker.com/compare.php?from=fbd62fe60fb2281ca33da35dc25ca3c87ec0bb51&to=32b72c3165bf65cca2e8e6197b59eb4c4b60392a&stat=instructions

Additionally, the logic here doesn't look quite right to me,
I will comment in more detail on the differential revision.