[LLVM][DWARF] Refactor code for generating DWARF V5 .debug_names (#82394)

[LLVM][DWARF]  Refactor code for generating DWARF v5 .debug_names

Refactor the code that uniques the entries and computes the bucket count
for the DWARF V5 .debug_names accelerator table.

Author: cmtice

llvm/include/llvm/BinaryFormat/Dwarf.h

@@ -613,6 +613,25 @@ enum AcceleratorTable {
   DW_hash_function_djb = 0u
 };
 
+// Uniquify the string hashes and calculate the bucket count for the
+// DWARF v5 Accelerator Table. NOTE: This function effectively consumes the
+// 'hashes' input parameter.
+inline uint32_t getDebugNamesBucketCount(MutableArrayRef<uint32_t> hashes,
+                                         uint32_t &uniqueHashCount) {
+  uint32_t BucketCount = 0;
+
+  sort(hashes);
+  uniqueHashCount = llvm::unique(hashes) - hashes.begin();
+  if (uniqueHashCount > 1024)
+    BucketCount = uniqueHashCount / 4;
+  else if (uniqueHashCount > 16)
+    BucketCount = uniqueHashCount / 2;
+  else
+    BucketCount = std::max<uint32_t>(uniqueHashCount, 1);
+
+  return BucketCount;
+}
+
 // Constants for the GNU pubnames/pubtypes extensions supporting gdb index.
 enum GDBIndexEntryKind {
   GIEK_NONE,

llvm/lib/CodeGen/AsmPrinter/AccelTable.cpp

@@ -33,22 +33,12 @@ using namespace llvm;
 
 void AccelTableBase::computeBucketCount() {
   // First get the number of unique hashes.
-  std::vector<uint32_t> Uniques;
+  SmallVector<uint32_t, 0> Uniques;
   Uniques.reserve(Entries.size());
   for (const auto &E : Entries)
     Uniques.push_back(E.second.HashValue);
-  array_pod_sort(Uniques.begin(), Uniques.end());
-  std::vector<uint32_t>::iterator P =
-      std::unique(Uniques.begin(), Uniques.end());
 
-  UniqueHashCount = std::distance(Uniques.begin(), P);
-
-  if (UniqueHashCount > 1024)
-    BucketCount = UniqueHashCount / 4;
-  else if (UniqueHashCount > 16)
-    BucketCount = UniqueHashCount / 2;
-  else
-    BucketCount = std::max<uint32_t>(UniqueHashCount, 1);
+  BucketCount = llvm::dwarf::getDebugNamesBucketCount(Uniques, UniqueHashCount);
 }
 
 void AccelTableBase::finalize(AsmPrinter *Asm, StringRef Prefix) {