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

[Snehasish Kumar 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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snehasish wrote:

Sure, I've added `getFilename` and `getDirectory` to the comparison. Note that SamplePGO doesn't rely on file and directory today when using instruction locations.

> would it be reasonable to always pick LocA

I think the pick policy should be independent of the order of the parameters passed to this function. So `getMergedLocation(A, B) == getMergedLocation(B, A)`.

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