[llvm] [BOLT] Fix debug line emission for functions in multiple compilation units (PR #151230)

[Grigory Pastukhov via llvm-commits]

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@@ -852,6 +832,86 @@ class DwarfLineTable {
   // Returns DWARF Version for this line table.
   uint16_t getDwarfVersion() const { return DwarfVersion; }
 };
+
+/// ClusteredRows represents a collection of debug line table row references.
+///
+/// MEMORY LAYOUT AND DESIGN:
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grigorypas wrote:

The original code used a very hacky approach by reinterpreting a pointer as a struct. I assumed this was done to minimize memory usage. Therefore, I tried to keep any regression in memory consumption and performance—caused by extra pointer dereferencing—to a minimum.

https://github.com/llvm/llvm-project/pull/151230