[llvm] [memprof] Add call stack IDs to IndexedAllocationInfo (PR #85888)

[Kazu Hirata via llvm-commits]

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@@ -445,14 +448,20 @@ Error RawMemProfReader::mapRawProfileToRecords() {
       Callstack.append(Frames.begin(), Frames.end());
     }
 
+    auto InsertResult =
+        CallStackToCallStackId.insert({Callstack, CallStacks.size()});
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kazutakahirata wrote:

I just switched to the content hash for call stacks in the latest iteration.  Since computing a hash value requires no data structure to speak of (unlike the sequential `CallStackId`), I've updated the tests to call `hashCallStack` instead of the placeholder `0`.

For now, I am using the same hash function as in `computeStackId` in `MemProfiler.cpp`, but I can switch to `std::hash` also.

https://github.com/llvm/llvm-project/pull/85888