[llvm] [AArch64] Align nontemporal store/load little-endian checks (PR #177468)

[Florian Hahn via llvm-commits]

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@@ -405,17 +406,34 @@ class AArch64TTIImpl final : public BasicTTIImplBase<AArch64TTIImpl> {
       return NumElements > 1 && isPowerOf2_64(NumElements) && EltSize >= 8 &&
              EltSize <= 128 && isPowerOf2_64(EltSize);
     }
-    return BaseT::isLegalNTStore(DataType, Alignment);
+    return std::nullopt;
   }
 
   bool isLegalNTStore(Type *DataType, Align Alignment) const override {
-    return isLegalNTStoreLoad(DataType, Alignment);
+    // Currently we only support NT stores lowering for little-endian targets.
+    //
+    // Coordinated with STNP constraints in
+    // `llvm/lib/Target/AArch64/AArch64InstrInfo.td` and
+    // `AArch64TargetLowering::LowerNTStore`
+    if (!ST->isLittleEndian())
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fhahn wrote:

can we check little endian in `isLegalNTStoreLoad` as well?

https://github.com/llvm/llvm-project/pull/177468