[llvm] [Instcombine] Fold away shift in or reduction chain. (PR #137875)

[Yingwei Zheng via llvm-commits]

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@@ -7742,6 +7765,11 @@ Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I) {
     }
   }
 
+  // icmp eq/ne or(shl(a), b), 0 -> icmp eq/ne or(a, b)
+  if (I.isEquality() && match(Op1, m_Zero()) && isa<Instruction>(Op0))
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dtcxzyw wrote:

It would be better to move this fold into `InstCombinerImpl::foldICmpWithZero`.


https://github.com/llvm/llvm-project/pull/137875