[libc-commits] [libc] Libc/attribute (PR #79891)

[Schrodinger ZHU Yifan via libc-commits]

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@@ -87,6 +89,71 @@ void writeAPIFromIndex(APIIndexer &G,
   if (G.Enumerations.size() != 0)
     OS << "};\n\n";
 
+  // declare macros for attributes
+  llvm::DenseMap<llvm::StringRef, llvm::Record *> MacroAttr;
+  for (auto &Name : EntrypointNameList) {
+    if (G.FunctionSpecMap.find(Name) == G.FunctionSpecMap.end()) {
+      continue;
+    }
+    llvm::Record *FunctionSpec = G.FunctionSpecMap[Name];
+    auto Attributes = FunctionSpec->getValueAsListOfDefs("Attributes");
+    for (auto *Attr : Attributes) {
+      MacroAttr[Attr->getValueAsString("Macro")] = Attr;
+    }
+  }
+
+  auto GetStyle = [](llvm::Record *Instance) {
+    auto Style = Instance->getValueAsString("Style");
+    if (Style == "cxx11")
+      return AttributeStyle::Cxx11;
+    if (Style == "gnu")
+      return AttributeStyle::Gnu;
+    return AttributeStyle::Declspec;
+  };
+
+  for (auto &[Macro, Attr] : MacroAttr) {
+    auto Instances = Attr->getValueAsListOfDefs("Instances");
+    llvm::SmallVector<std::pair<AttributeStyle, llvm::Record *>> Styles;
+    std::transform(Instances.begin(), Instances.end(),
+                   std::back_inserter(Styles),
+                   [&](llvm::Record *Instance)
+                       -> std::pair<AttributeStyle, llvm::Record *> {
+                     auto Style = GetStyle(Instance);
+                     return {Style, Instance};
+                   });
+    // Effectively sort on the first field
+    std::sort(Styles.begin(), Styles.end());
+    for (auto &[Style, Instance] : Styles) {
+      if (Style == AttributeStyle::Cxx11) {
+        OS << "#if !defined(" << Macro << ") && defined(__cplusplus)\n";
+        OS << "#define " << Macro << " [[";
+        auto Namespace = Instance->getValueAsString("Namespace");
+        if (Namespace != "")
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SchrodingerZhu wrote:

Should we check `clang` or `gcc`?

https://github.com/llvm/llvm-project/pull/79891