[llvm] [LLVM][DWARF] Refactor code for generating DWARF V4 .debug_names acce… (PR #82394)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-binary-utilities

@llvm/pr-subscribers-debuginfo

Author: None (cmtice)

<details>
<summary>Changes</summary>

…lerator table.

Update computeDebugNamesUniqueHashes function to start with lowercase letter, to use a MutableArrayRef for the hashes parameter instead of SmallVector, and made uniqueHashCount a reference parameter, to allow the accelerator table class member to be properly updated. Also removed redundant namespace qualifier.

---
Full diff: https://github.com/llvm/llvm-project/pull/82394.diff


2 Files Affected:

- (modified) llvm/include/llvm/BinaryFormat/Dwarf.h (+19) 
- (modified) llvm/lib/CodeGen/AsmPrinter/AccelTable.cpp (+3-12) 


``````````diff
diff --git a/llvm/include/llvm/BinaryFormat/Dwarf.h b/llvm/include/llvm/BinaryFormat/Dwarf.h
index 869352b35e3235..c926b34f9d9048 100644
--- a/llvm/include/llvm/BinaryFormat/Dwarf.h
+++ b/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.
+inline uint32_t
+computeDebugNamesUniqueHashes(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,
diff --git a/llvm/lib/CodeGen/AsmPrinter/AccelTable.cpp b/llvm/lib/CodeGen/AsmPrinter/AccelTable.cpp
index 22d995a9cc3c56..f8528b489c3c0b 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AccelTable.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AccelTable.cpp
@@ -33,22 +33,13 @@ 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::computeDebugNamesUniqueHashes(Uniques,
+                                                           UniqueHashCount);
 }
 
 void AccelTableBase::finalize(AsmPrinter *Asm, StringRef Prefix) {

``````````

</details>


https://github.com/llvm/llvm-project/pull/82394