[PATCH] D78418: [Local] Simplify the alignment limits in getOrEnforceKnownAlignment. NFCI

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: efriedma, spatel.
Herald added a subscriber: hiraditya.
Herald added a project: LLVM.

We previously clamped the trailing zero count to 31 bits. And
then clamped the final alignment to MaximumAlignment which is
1 << 29.

This patch simplifies this to just clamp the trailing zero to
29 using MaxAlignmentExponent.

I was looking into changin this function to use Align/MaybeAlign
and noticed this.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D78418

Files:
  llvm/lib/Transforms/Utils/Local.cpp


Index: llvm/lib/Transforms/Utils/Local.cpp
===================================================================
--- llvm/lib/Transforms/Utils/Local.cpp
+++ llvm/lib/Transforms/Utils/Local.cpp
@@ -1215,13 +1215,11 @@
 
   // Avoid trouble with ridiculously large TrailZ values, such as
   // those computed from a null pointer.
-  TrailZ = std::min(TrailZ, unsigned(sizeof(unsigned) * CHAR_BIT - 1));
+  // LLVM doesn't support alignments larger than (1 << MaxAlignmentExponent).
+  TrailZ = std::min(TrailZ, Value::MaxAlignmentExponent);
 
   unsigned Align = 1u << std::min(Known.getBitWidth() - 1, TrailZ);
 
-  // LLVM doesn't support alignments larger than this currently.
-  Align = std::min(Align, +Value::MaximumAlignment);
-
   if (PrefAlign > Align)
     Align = enforceKnownAlignment(V, Align, PrefAlign, DL);
 


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