[llvm] [InstCombine] Reduce range of ctpop for non zero argument (PR #100899)

[Andreas Jonson via llvm-commits]

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@@ -694,8 +694,13 @@ static Instruction *foldCtpop(IntrinsicInst &II, InstCombinerImpl &IC) {
   // Add range attribute since known bits can't completely reflect what we know.
   if (BitWidth != 1 && !II.hasRetAttr(Attribute::Range) &&
       !II.getMetadata(LLVMContext::MD_range)) {
-    ConstantRange Range(APInt(BitWidth, Known.countMinPopulation()),
-                        APInt(BitWidth, Known.countMaxPopulation() + 1));
+    unsigned KnownMinPop = Known.countMinPopulation();
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andjo403 wrote:

added the test and when for a combination of our solutions that reduced number of calls to intersectWith also used full set range if old is missing as it is faster in intersectWith

https://github.com/llvm/llvm-project/pull/100899