[llvm] [DebugInfo] Preserve line and column number when merging debug info. (PR #129960)

[Reid Kleckner via llvm-commits]

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@@ -125,6 +132,14 @@ DILocation *DILocation::getMergedLocation(DILocation *LocA, DILocation *LocB) {
   if (LocA == LocB)
     return LocA;
 
+  if (PreserveMergedDebugInfo) {
+    auto A = std::make_tuple(LocA->getLine(), LocA->getColumn(),
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rnk wrote:

Should filenames be compared here? DILocation has `getFilename` and `getDirectory`, which return StringRefs, so you can fill them in here in a reasonably straightforward way.

However, given the use case, would it be reasonable to always pick `LocA`?

Regardless, I think adding directories and files would follow the principle of least surprise.

https://github.com/llvm/llvm-project/pull/129960