[LLVM][DWARF] Make dwarf::getDebugNamesBucketCount return a pair. (llvm#83047)

llvm::dwarf::getDebugNamesBucketCount directly returns the bucket count,
via return statement, but it also returns the hash count via a
parameter. This changes the function to return them both as a std::pair,
in the return statement. It also changes the name of the function to
make it clear it returns both values.

Author: cmtice

llvm/include/llvm/BinaryFormat/Dwarf.h

@@ -615,21 +615,21 @@ enum AcceleratorTable {
 
 // 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) {
+// 'Hashes' input parameter.
+inline std::pair<uint32_t, uint32_t>
+getDebugNamesBucketAndHashCount(MutableArrayRef<uint32_t> Hashes) {
   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;
+  sort(Hashes);
+  uint32_t 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);
+    BucketCount = std::max<uint32_t>(UniqueHashCount, 1);
 
-  return BucketCount;
+  return {BucketCount, UniqueHashCount};
 }
 
 // Constants for the GNU pubnames/pubtypes extensions supporting gdb index.

llvm/lib/CodeGen/AsmPrinter/AccelTable.cpp

@@ -38,7 +38,9 @@ void AccelTableBase::computeBucketCount() {
   for (const auto &E : Entries)
     Uniques.push_back(E.second.HashValue);
 
-  BucketCount = llvm::dwarf::getDebugNamesBucketCount(Uniques, UniqueHashCount);
+  auto Counts = llvm::dwarf::getDebugNamesBucketAndHashCount(Uniques);
+  BucketCount = Counts.first;
+  UniqueHashCount = Counts.second;
 }
 
 void AccelTableBase::finalize(AsmPrinter *Asm, StringRef Prefix) {