use std::array and add the comment for default map

Author: seven-mile

clang/include/clang/CIR/Dialect/IR/CIRAttrs.td

@@ -707,7 +707,7 @@ def AddressSpaceAttr : CIR_Attr<"AddressSpace", "addrspace"> {
   let extraClassDeclaration = [{
     static constexpr char kTargetKeyword[] = "}]#targetASCase.symbol#[{";
     static constexpr int32_t kFirstTargetASValue = }]#targetASCase.value#[{;
-    using MapTy = unsigned[kFirstTargetASValue];
+    using MapTy = std::array<unsigned, kFirstTargetASValue>;
 
     bool isLang() const;
     bool isTarget() const;

clang/lib/CIR/Dialect/Transforms/TargetLowering/TargetInfo.cpp

@@ -9,7 +9,8 @@ TargetLoweringInfo::TargetLoweringInfo(std::unique_ptr<ABIInfo> Info)
 TargetLoweringInfo::~TargetLoweringInfo() = default;
 
 AddressSpaceAttr::MapTy const &TargetLoweringInfo::getCIRAddrSpaceMap() const {
-  static AddressSpaceAttr::MapTy defaultAddrSpaceMap = {0};
+  // Flatten all non-target address spaces to addrspace(0)
+  static AddressSpaceAttr::MapTy defaultAddrSpaceMap = {};
   return defaultAddrSpaceMap;
 }