[AArch64][GlobalISel] Legalize store <2 x i16>

Differential revision: https://reviews.llvm.org/D105912

llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp

@@ -346,7 +346,8 @@ AArch64LegalizerInfo::AArch64LegalizerInfo(const AArch64Subtarget &ST)
       .clampMaxNumElements(0, s32, 4)
       .clampMaxNumElements(0, s64, 2)
       .lowerIfMemSizeNotPow2()
-      .customIf(IsPtrVecPred);
+      .customIf(IsPtrVecPred)
+      .scalarizeIf(typeIs(0, v2s16), 0);
 
   // Constants
   getActionDefinitionsBuilder(G_CONSTANT)

llvm/test/CodeGen/AArch64/GlobalISel/legalize-load-store.mir

@@ -542,3 +542,26 @@ body:             |
     G_STORE %val(<6 x s64>), %ptr(p0) :: (store (<6 x s64>), align 16)
     RET_ReallyLR
 ...
+---
+name:            store_2xi16
+tracksRegLiveness: true
+body:             |
+  bb.1:
+    liveins: $s0, $x0
+
+    ; CHECK-LABEL: name: store_2xi16
+    ; CHECK: liveins: $s0, $x0
+    ; CHECK: [[COPY:%[0-9]+]]:_(p0) = COPY $x0
+    ; CHECK: [[COPY1:%[0-9]+]]:_(<2 x s16>) = COPY $s0
+    ; CHECK: [[UV:%[0-9]+]]:_(s16), [[UV1:%[0-9]+]]:_(s16) = G_UNMERGE_VALUES [[COPY1]](<2 x s16>)
+    ; CHECK: G_STORE [[UV]](s16), [[COPY]](p0) :: (store (s16), align 4)
+    ; CHECK: [[C:%[0-9]+]]:_(s64) = G_CONSTANT i64 2
+    ; CHECK: [[PTR_ADD:%[0-9]+]]:_(p0) = G_PTR_ADD [[COPY]], [[C]](s64)
+    ; CHECK: G_STORE [[UV1]](s16), [[PTR_ADD]](p0) :: (store (s16) into unknown-address + 2)
+    ; CHECK: RET_ReallyLR
+    %0:_(p0) = COPY $x0
+    %1:_(<2 x s16>) = COPY $s0
+    G_STORE %1(<2 x s16>), %0(p0) :: (store (<2 x s16>))
+    RET_ReallyLR
+
+...