[llvm] [SelectionDAG] Add MaskedValueIsZero check to allow folding of zero extended variables we know are safe to extend (PR #85573)

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``````````bash
git-clang-format --diff ef395a492aa931f428e99e1c0a93d4ad2fb0fcfa 86e897003bcc9b4dad6f9284b61110f65fd8142d -- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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View the diff from clang-format here.
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``````````diff
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 8ab60b77c0..4957550a21 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -13850,9 +13850,9 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
             // If the shift is too large, then see if we can deduce that the
             // shift is safe anyway.
             // Create a mask that has ones for the bits being shifted out.
-            APInt ShiftOutMask = APInt::getHighBitsSet(
-                ShVal.getValueSizeInBits(),
-                ShAmtC->getAPIntValue().getZExtValue());
+            APInt ShiftOutMask =
+                APInt::getHighBitsSet(ShVal.getValueSizeInBits(),
+                                      ShAmtC->getAPIntValue().getZExtValue());
 
             // Check if the bits being shifted out are known to be zero.
             if (!DAG.MaskedValueIsZero(ShVal, ShiftOutMask))

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https://github.com/llvm/llvm-project/pull/85573