[llvm] [InstCombine] Fold logic of zero-checks to multiplication for MinSize (PR #171805)

[Matt Arsenault via llvm-commits]

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@@ -6648,6 +6649,59 @@ static unsigned getMinMaxOpcodeForFP(SDValue Operand1, SDValue Operand2,
   return ISD::DELETED_NODE;
 }
 
+// Fold the following patterns for small integers in -Oz mode.
+// (X == 0) || (Y == 0) --> (X * Y) == 0
+// (X != 0) && (Y != 0) --> (X * Y) != 0
+SDValue DAGCombiner::foldLogicSetCCToMul(SDNode *N, const SDLoc &DL) {
+  if (OptLevel == CodeGenOptLevel::None ||
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arsenm wrote:

I don't remember the current status of checking the opt level at -O0; I'd expect this to be redundant 

https://github.com/llvm/llvm-project/pull/171805