[llvm] Calculate KnownBits from Metadata correctly for vector loads (PR #128908)

[Matt Arsenault via llvm-commits]

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@@ -4027,15 +4027,19 @@ KnownBits SelectionDAG::computeKnownBits(SDValue Op, const APInt &DemandedElts,
       // Fill in any known bits from range information. There are 3 types being
       // used. The results VT (same vector elt size as BitWidth), the loaded
       // MemoryVT (which may or may not be vector) and the range VTs original
-      // type. The range matadata needs the full range (i.e
+      // type. The range metadata needs the full range (i.e
       // MemoryVT().getSizeInBits()), which is truncated to the correct elt size
       // if it is know. These are then extended to the original VT sizes below.
       if (const MDNode *MD = LD->getRanges()) {
+        ConstantInt *Lower = mdconst::extract<ConstantInt>(MD->getOperand(0));
+
+        // FIXME: If loads are modified (e.g. type legalization)
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arsenm wrote:

You're adding the fixme, but this is what this patch is fixing? 

https://github.com/llvm/llvm-project/pull/128908