[llvm] [X86] Remove redundant TEST after shifts when count is non-zero (PR #169069)

[Matt Arsenault via llvm-commits]

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@@ -3698,11 +3699,30 @@ void SelectionDAGBuilder::visitShift(const User &I, unsigned Opcode) {
     if (const PossiblyExactOperator *ExactOp =
             dyn_cast<const PossiblyExactOperator>(&I))
       exact = ExactOp->isExact();
+
+    const Value *ShiftAmt = I.getOperand(1);
+
+    // Look through zext as computeConstantRange does not do this.
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arsenm wrote:

Seems like a problem to solve there? 

https://github.com/llvm/llvm-project/pull/169069