[llvm] [GISel] Combine out-of-range shifts with value to 0 or -1 (PR #123510)

[Jay Foad via llvm-commits]

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@@ -6590,12 +6590,55 @@ bool CombinerHelper::matchRedundantBinOpInEquality(MachineInstr &MI,
   return CmpInst::isEquality(Pred) && Y.isValid();
 }
 
-bool CombinerHelper::matchShiftsTooBig(MachineInstr &MI) const {
+static std::optional<unsigned>
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jayfoad wrote:

This function needs a comment. It seems like it is returning the min useless shift amount, not the max useful one.

https://github.com/llvm/llvm-project/pull/123510