[llvm] [CGData] Stable Function Map (PR #112662)

[Ellis Hoag via llvm-commits]

================
@@ -0,0 +1,170 @@
+//===-- StableFunctionMap.cpp ---------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This implements the functionality for the StableFunctionMap class, which
+// manages the mapping of stable function hashes to their metadata. It includes
+// methods for inserting, merging, and finalizing function entries, as well as
+// utilities for handling function names and IDs.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CGData/StableFunctionMap.h"
+
+#define DEBUG_TYPE "stable-function-map"
+
+using namespace llvm;
+
+unsigned StableFunctionMap::getIdOrCreateForName(StringRef Name) {
+  auto It = NameToId.find(Name);
+  if (It == NameToId.end()) {
+    unsigned Id = IdToName.size();
+    assert(Id == NameToId.size() && "ID collision");
+    IdToName.emplace_back(Name.str());
+    NameToId[IdToName.back()] = Id;
+    return Id;
+  } else {
+    return It->second;
+  }
----------------
ellishg wrote:

```suggestion
  auto It = NameToId.find(Name);
  if (It != NameToId.end())
    return It->second;
  unsigned Id = IdToName.size();
  assert(Id == NameToId.size() && "ID collision");
  IdToName.emplace_back(Name.str());
  NameToId[IdToName.back()] = Id;
  return Id;
```

https://github.com/llvm/llvm-project/pull/112662