[llvm] [LTO] Preserve use list order in save-temps (PR #165882)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-lto

Author: Nikita Popov (nikic)

<details>
<summary>Changes</summary>

save-temps is debugging functionality, so it should preserve use-lists to keep the optimization/codegen behavior of the dumped bitcode as close to the in-memory IR as possible.

---
Full diff: https://github.com/llvm/llvm-project/pull/165882.diff


1 Files Affected:

- (modified) llvm/lib/LTO/LTOBackend.cpp (+1-1) 


``````````diff
diff --git a/llvm/lib/LTO/LTOBackend.cpp b/llvm/lib/LTO/LTOBackend.cpp
index 93118becedbac..8efde8efb3cb1 100644
--- a/llvm/lib/LTO/LTOBackend.cpp
+++ b/llvm/lib/LTO/LTOBackend.cpp
@@ -124,7 +124,7 @@ Error Config::addSaveTemps(std::string OutputFileName, bool UseInputModulePath,
       // directly and exit.
       if (EC)
         reportOpenError(Path, EC.message());
-      WriteBitcodeToFile(M, OS, /*ShouldPreserveUseListOrder=*/false);
+      WriteBitcodeToFile(M, OS, /*ShouldPreserveUseListOrder=*/true);
       return true;
     };
   };

``````````

</details>


https://github.com/llvm/llvm-project/pull/165882