[PATCH] D48229: [NFC][SCEV] Add tests related to bit masking (PR37793)

Roman Lebedev via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Mon Jun 18 09:24:21 PDT 2018


lebedev.ri added inline comments.


================
Comment at: lib/Transforms/InstCombine/InstCombineShifts.cpp:625-629
-    // Be careful about hiding shl instructions behind bit masks. They are used
-    // to represent multiplies by a constant, and it is important that simple
-    // arithmetic expressions are still recognizable by scalar evolution.
-    // The inexact versions are deferred to DAGCombine, so we don't hide shl
-    // behind a bit mask.
----------------
spatel wrote:
> Better to just add a 'FIXME' note until we actually make the code change here to ignore 'exact'?
Yes, indeed. Will add.


Repository:
  rL LLVM

https://reviews.llvm.org/D48229





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