[llvm] [NFC][DWARF][DebugInfo] Consolidate NextCUOffset checks (PR #146958)

[via llvm-commits]

https://github.com/tltao created https://github.com/llvm/llvm-project/pull/146958

Some error checking code involving `getNextUnitOffset()` looks a bit strange and what is tested may not be equal to what is reported if any changes are made to `getNextUnitOffset()`.

Change this so what is tested is consistent with what is reported. Also remove unnecessary calls when the value is already available in the function.

>From 7960c9431a130bbe4202981e45586df68961c2dd Mon Sep 17 00:00:00 2001
From: Tony Tao <tonytao at ca.ibm.com>
Date: Thu, 3 Jul 2025 14:01:13 -0400
Subject: [PATCH] make NextCUOffset checks consistent

---
 llvm/lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp | 2 +-
 llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp           | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp
index 4f0a6d96ace9e..06f0999b6e034 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp
@@ -30,7 +30,7 @@ bool DWARFDebugInfoEntry::extractFast(const DWARFUnit &U, uint64_t *OffsetPtr,
                           "DWARF unit from offset 0x%8.8" PRIx64 " incl. "
                           "to offset 0x%8.8" PRIx64 " excl. "
                           "tries to read DIEs at offset 0x%8.8" PRIx64,
-                          U.getOffset(), U.getNextUnitOffset(), *OffsetPtr));
+                          U.getOffset(), UEndOffset, *OffsetPtr));
     return false;
   }
   assert(DebugInfoData.isValidOffset(UEndOffset - 1));
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp b/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
index ef59c82fc6a01..f19fa5a1169d5 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFUnit.cpp
@@ -294,9 +294,9 @@ Error DWARFUnitHeader::extract(DWARFContext &Context,
   // Header fields all parsed, capture the size of this unit header.
   assert(*offset_ptr - Offset <= 255 && "unexpected header size");
   Size = uint8_t(*offset_ptr - Offset);
-  uint64_t NextCUOffset = Offset + getUnitLengthFieldByteSize() + getLength();
+  uint64_t NextCUOffset = getNextUnitOffset();
 
-  if (!debug_info.isValidOffset(getNextUnitOffset() - 1))
+  if (!debug_info.isValidOffset(NextCUOffset - 1))
     return createStringError(errc::invalid_argument,
                              "DWARF unit from offset 0x%8.8" PRIx64 " incl. "
                              "to offset  0x%8.8" PRIx64 " excl. "