[llvm] [CodeGen] Emit a more efficient magic number multiplication for exact udivs (PR #87161)

[Craig Topper via llvm-commits]

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@@ -5087,7 +5117,7 @@ MachineInstr *CombinerHelper::buildUDivUsingMul(MachineInstr &MI) {
     // TODO: Use undef values for divisor of 1.
     if (!Divisor.isOne()) {
       UnsignedDivisionByConstantInfo magics =
-          UnsignedDivisionByConstantInfo::get(Divisor);
+          UnsignedDivisionByConstantInfo::get(Divisor, KnownLeadingZeros);
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topperc wrote:

This is a non-exact udiv change right?

https://github.com/llvm/llvm-project/pull/87161