[clang] [llvm] [RISCV][FMV] Support target_clones (PR #85786)

[Piyou Chen via cfe-commits]

================
@@ -63,9 +63,32 @@ class RISCVABIInfo : public DefaultABIInfo {
                                                CharUnits Field2Off) const;
 
   ABIArgInfo coerceVLSVector(QualType Ty) const;
+
+  using ABIInfo::appendAttributeMangling;
+  void appendAttributeMangling(TargetClonesAttr *Attr, unsigned Index,
+                               raw_ostream &Out) const override;
+  void appendAttributeMangling(StringRef AttrStr,
+                               raw_ostream &Out) const override;
 };
 } // end anonymous namespace
 
+void RISCVABIInfo::appendAttributeMangling(TargetClonesAttr *Attr,
+                                           unsigned Index,
+                                           raw_ostream &Out) const {
+  appendAttributeMangling(Attr->getFeatureStr(Index), Out);
+}
+
+void RISCVABIInfo::appendAttributeMangling(StringRef AttrStr,
+                                           raw_ostream &Out) const {
+  if (AttrStr == "default") {
+    Out << ".default";
+    return;
+  }
+
+  Out << '.';
----------------
BeMg wrote:

The format will be the function name appended with the sorted feature string, joined by an underscore.

 ```
<function-name>._<feature>_<feature>...
```

https://github.com/llvm/llvm-project/pull/85786