[GlobalISel] Avoid repeated hash lookups (NFC) (llvm#127372)

Author: kazutakahirata

llvm/lib/CodeGen/GlobalISel/LegacyLegalizerInfo.cpp

@@ -305,10 +305,10 @@ LegacyLegalizerInfo::findScalarLegalAction(const InstrAspect &Aspect) const {
   if (Aspect.Opcode < FirstOp || Aspect.Opcode > LastOp)
     return {NotFound, LLT()};
   const unsigned OpcodeIdx = getOpcodeIdxForOpcode(Aspect.Opcode);
-  if (Aspect.Type.isPointer() &&
-      AddrSpace2PointerActions[OpcodeIdx].find(Aspect.Type.getAddressSpace()) ==
-          AddrSpace2PointerActions[OpcodeIdx].end()) {
-    return {NotFound, LLT()};
+  if (Aspect.Type.isPointer()) {
+    auto &PA = AddrSpace2PointerActions[OpcodeIdx];
+    if (PA.find(Aspect.Type.getAddressSpace()) == PA.end())
+      return {NotFound, LLT()};
   }
   const SmallVector<SizeAndActionsVec, 1> &Actions =
       Aspect.Type.isPointer()