From 2266e223c56be365cadfdf9f394009c095a37c8b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lukas=20B=C3=B6ger?= <mail@lboeger.de>
Date: Sun, 19 Sep 2021 17:15:21 +0100
Subject: macOS: Speed up rpath install name dir lookup with a cache

Fixes: #20602
---
 Source/cmGeneratorTarget.cxx | 15 +++++++++++++++
 Source/cmGeneratorTarget.h   |  5 +++++
 2 files changed, 20 insertions(+)

diff --git a/Source/cmGeneratorTarget.cxx b/Source/cmGeneratorTarget.cxx
index 4bad7ab..30c022f 100644
--- a/Source/cmGeneratorTarget.cxx
+++ b/Source/cmGeneratorTarget.cxx
@@ -2170,6 +2170,21 @@ bool cmGeneratorTarget::IsImportedSharedLibWithoutSOName(
 bool cmGeneratorTarget::HasMacOSXRpathInstallNameDir(
   const std::string& config) const
 {
+  TargetPtrToBoolMap& cache = this->MacOSXRpathInstallNameDirCache[config];
+  const auto lookup = cache.find(this->Target);
+
+  if (lookup != cache.cend()) {
+    return lookup->second;
+  }
+
+  const bool result = this->DetermineHasMacOSXRpathInstallNameDir(config);
+  cache[this->Target] = result;
+  return result;
+}
+
+bool cmGeneratorTarget::DetermineHasMacOSXRpathInstallNameDir(
+  const std::string& config) const
+{
   bool install_name_is_rpath = false;
   bool macosx_rpath = false;
 
diff --git a/Source/cmGeneratorTarget.h b/Source/cmGeneratorTarget.h
index 0076085..85b4ea0 100644
--- a/Source/cmGeneratorTarget.h
+++ b/Source/cmGeneratorTarget.h
@@ -866,6 +866,11 @@ private:
   mutable std::map<cmSourceFile const*, std::string> Objects;
   std::set<cmSourceFile const*> ExplicitObjectName;
 
+  using TargetPtrToBoolMap = std::unordered_map<cmTarget*, bool>;
+  mutable std::unordered_map<std::string, TargetPtrToBoolMap>
+    MacOSXRpathInstallNameDirCache;
+  bool DetermineHasMacOSXRpathInstallNameDir(const std::string& config) const;
+
   // "config/language" is the key
   mutable std::map<std::string, std::vector<std::string>> SystemIncludesCache;
 
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