[llvm] [LV] Add `-force-target-supports-masked-memory-ops` option (PR #184325)

[Luke Lau via llvm-commits]

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@@ -1178,16 +1183,18 @@ class LoopVectorizationCostModel {
   /// for the given \p DataType and kind of access to \p Ptr.
   bool isLegalMaskedStore(Type *DataType, Value *Ptr, Align Alignment,
                           unsigned AddressSpace) const {
-    return Legal->isConsecutivePtr(DataType, Ptr) &&
-           TTI.isLegalMaskedStore(DataType, Alignment, AddressSpace);
+    return ForceTargetSupportsMaskedMemoryOps ||
----------------
lukel97 wrote:

Oh yup I missed this. FWIW I have this exact patch in my own git stash, but the diff is:

```diff
@@ -1181,16 +1187,16 @@ public:
   /// for the given \p DataType and kind of access to \p Ptr.
   bool isLegalMaskedStore(Type *DataType, Value *Ptr, Align Alignment,
                           unsigned AddressSpace) const {
-    return Legal->isConsecutivePtr(DataType, Ptr) &&
-           TTI.isLegalMaskedStore(DataType, Alignment, AddressSpace);
+    return (Legal->isConsecutivePtr(DataType, Ptr) &&
+           TTI.isLegalMaskedStore(DataType, Alignment, AddressSpace)) || ForceTargetSupportsMaskedLoadStore;
   }
```

https://github.com/llvm/llvm-project/pull/184325