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

[Philip Reames via cfe-commits]

================
@@ -119,6 +119,51 @@ void getFeaturesForCPU(StringRef CPU,
     else
       EnabledFeatures.push_back(F.substr(1));
 }
+
+namespace RISCVExtensionBitmaskTable {
+#define GET_RISCVExtensionBitmaskTable_IMPL
+#include "llvm/TargetParser/RISCVTargetParserDef.inc"
+
+} // namespace RISCVExtensionBitmaskTable
+
+namespace {
+struct LessExtName {
+  bool operator()(const RISCVExtensionBitmaskTable::RISCVExtensionBitmask &LHS,
+                  StringRef RHS) {
+    return StringRef(LHS.Name) < RHS;
+  }
+  bool
+  operator()(StringRef LHS,
+             const RISCVExtensionBitmaskTable::RISCVExtensionBitmask &RHS) {
+    return LHS < StringRef(RHS.Name);
+  }
+};
+} // namespace
+
+static Expected<RISCVExtensionBitmaskTable::RISCVExtensionBitmask>
+getExtensionBitmask(StringRef ExtName) {
+  ArrayRef<RISCVExtensionBitmaskTable::RISCVExtensionBitmask> ExtBitmasks =
+      RISCVExtensionBitmaskTable::ExtensionBitmask;
+  auto *I = llvm::lower_bound(ExtBitmasks, ExtName, LessExtName());
+
+  if (I != ExtBitmasks.end())
+    return *I;
+
+  return createStringError("Unsupport extension");
+}
+
+llvm::SmallVector<uint64_t> getRequireFeatureBitMask(ArrayRef<StringRef> Exts) {
+  llvm::SmallVector<uint64_t> BitMasks(RISCV::RISCVFeatureBitSize);
+
+  for (auto Ext : Exts) {
+    Expected<RISCVExtensionBitmaskTable::RISCVExtensionBitmask> ExtBitmask =
+        getExtensionBitmask(Ext);
+    assert(ExtBitmask && "This extension doesn't has bitmask.");
----------------
preames wrote:

The user interface aspect of this should be handled in clang.  It's entirely possible a user tries to name a extension the compiler doesn't know about.  Say, a custom vendor extension.  We should probably reject or warn on such cases, but we definitely shouldn't crash somewhere deep inside of LLVM.

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