[llvm] [llvm-gsymutil] Ensure stable ordering of merged functions (PR #120796)

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llvmbot wrote:


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Author: None (alx32)

<details>
<summary>Changes</summary>

Previously, the test `llvm/test/tools/llvm-gsymutil/ARM_AArch64/macho-gsym-merged-callsites-dsym.yaml` [was disabled](https://github.com/llvm/llvm-project/pull/119957/files) due to failing on Linux. 

The issue is that the merged functions appear in a different order in the final produced `gSYM`.
To ensure deterministic ordering of merged functions, we change the sorting of functions to use the `stable_sort` algorithm. Before merged functions, this was not an issue as the address is used as a comparator in the sorting algorithm so there was no chance of two functions testing as identical according to the comparator.

---
Full diff: https://github.com/llvm/llvm-project/pull/120796.diff


2 Files Affected:

- (modified) llvm/lib/DebugInfo/GSYM/GsymCreator.cpp (+2-2) 
- (modified) llvm/test/tools/llvm-gsymutil/ARM_AArch64/macho-gsym-merged-callsites-dsym.yaml (-4) 


``````````diff
diff --git a/llvm/lib/DebugInfo/GSYM/GsymCreator.cpp b/llvm/lib/DebugInfo/GSYM/GsymCreator.cpp
index eb26c637a2ca36..14078f5aaf9a46 100644
--- a/llvm/lib/DebugInfo/GSYM/GsymCreator.cpp
+++ b/llvm/lib/DebugInfo/GSYM/GsymCreator.cpp
@@ -200,8 +200,8 @@ void GsymCreator::prepareMergedFunctions(OutputAggregator &Out) {
   if (Funcs.size() < 2)
     return;
 
-  // Sort the function infos by address range first
-  llvm::sort(Funcs);
+  // Sort the function infos by address range first, preserving input order
+  llvm::stable_sort(Funcs);
   std::vector<FunctionInfo> TopLevelFuncs;
 
   // Add the first function info to the top level functions
diff --git a/llvm/test/tools/llvm-gsymutil/ARM_AArch64/macho-gsym-merged-callsites-dsym.yaml b/llvm/test/tools/llvm-gsymutil/ARM_AArch64/macho-gsym-merged-callsites-dsym.yaml
index 001145c01398c5..4cecc79c72b4b3 100644
--- a/llvm/test/tools/llvm-gsymutil/ARM_AArch64/macho-gsym-merged-callsites-dsym.yaml
+++ b/llvm/test/tools/llvm-gsymutil/ARM_AArch64/macho-gsym-merged-callsites-dsym.yaml
@@ -1,7 +1,3 @@
-# FIXME: Currently disabled as it fails on some Linux hosts
-# UNSUPPORTED: true
-
-
 ## Test that reconstructs a dSYM file from YAML and generates a gsym from it. The gsym has callsite info and merged functions.
 
 # RUN: split-file %s %t

``````````

</details>


https://github.com/llvm/llvm-project/pull/120796