[llvm] [DWARF] Refactor findDebugNamesOffsets (PR #88064)

[Fangrui Song via llvm-commits]

https://github.com/MaskRay created https://github.com/llvm/llvm-project/pull/88064

Address some post-review comments in #82153 and move the function inside
llvm::dwarf, used by certain free functions.


>From f40cc8c50b6e2cda0425cd3a0742f64befcc26f4 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Mon, 8 Apr 2024 15:56:24 -0700
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
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Created using spr 1.3.5-bogner
---
 .../llvm/DebugInfo/DWARF/DWARFAcceleratorTable.h   |  8 +++++---
 llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp | 14 ++++++++------
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/llvm/include/llvm/DebugInfo/DWARF/DWARFAcceleratorTable.h b/llvm/include/llvm/DebugInfo/DWARF/DWARFAcceleratorTable.h
index f1d4fc72d5a727..9543b78ea61309 100644
--- a/llvm/include/llvm/DebugInfo/DWARF/DWARFAcceleratorTable.h
+++ b/llvm/include/llvm/DebugInfo/DWARF/DWARFAcceleratorTable.h
@@ -804,9 +804,11 @@ class DWARFDebugNames : public DWARFAcceleratorTable {
 
 /// Calculates the starting offsets for various sections within the
 /// .debug_names section.
-void findDebugNamesOffsets(DWARFDebugNames::DWARFDebugNamesOffsets &Offsets,
-                           uint64_t HdrSize, const dwarf::DwarfFormat Format,
-                           const DWARFDebugNames::Header &Hdr);
+namespace dwarf {
+DWARFDebugNames::DWARFDebugNamesOffsets
+findDebugNamesOffsets(uint64_t EndOfHeaderOffset,
+                      const DWARFDebugNames::Header &Hdr);
+}
 
 /// If `Name` is the name of a templated function that includes template
 /// parameters, returns a substring of `Name` containing no template
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp b/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
index 9c65d85985f1bb..3a84784ff967f0 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
@@ -552,11 +552,12 @@ DWARFDebugNames::NameIndex::extractAbbrev(uint64_t *Offset) {
   return Abbrev(Code, dwarf::Tag(Tag), AbbrevOffset, std::move(*AttrEncOr));
 }
 
-void llvm::findDebugNamesOffsets(
-    DWARFDebugNames::DWARFDebugNamesOffsets &Offsets, uint64_t HdrSize,
-    dwarf::DwarfFormat Format, const DWARFDebugNames::Header &Hdr) {
-  uint32_t DwarfSize = (Format == llvm::dwarf::DwarfFormat::DWARF64) ? 8 : 4;
-  uint64_t Offset = HdrSize;
+DWARFDebugNames::DWARFDebugNamesOffsets
+dwarf::findDebugNamesOffsets(uint64_t EndOfHeaderOffset,
+                             const DWARFDebugNames::Header &Hdr) {
+  DWARFDebugNames::DWARFDebugNamesOffsets Offsets;
+  uint32_t DwarfSize = Hdr.Format == dwarf::DwarfFormat::DWARF64 ? 8 : 4;
+  uint64_t Offset = EndOfHeaderOffset;
   Offsets.CUsBase = Offset;
   Offset += Hdr.CompUnitCount * DwarfSize;
   Offset += Hdr.LocalTypeUnitCount * DwarfSize;
@@ -577,6 +578,7 @@ void llvm::findDebugNamesOffsets(
 
   Offset += Hdr.AbbrevTableSize;
   Offsets.EntriesBase = Offset;
+  return Offsets;
 }
 
 Error DWARFDebugNames::NameIndex::extract() {
@@ -586,7 +588,7 @@ Error DWARFDebugNames::NameIndex::extract() {
     return E;
 
   const unsigned SectionOffsetSize = dwarf::getDwarfOffsetByteSize(Hdr.Format);
-  findDebugNamesOffsets(Offsets, hdrSize, Hdr.Format, Hdr);
+  Offsets = dwarf::findDebugNamesOffsets(hdrSize, Hdr);
 
   uint64_t Offset =
       Offsets.EntryOffsetsBase + (Hdr.NameCount * SectionOffsetSize);