From 93c5864aa19a9af058910172939db177bd5a3b9f Mon Sep 17 00:00:00 2001
From: Seth R Johnson <johnsonsr@ornl.gov>
Date: Sun, 10 Oct 2021 06:33:33 -0400
Subject: cmBinUtilsMacOSMachOLinker: improve performance by memoizing otool
 calls

Libraries with many repeated transitive dependencies (e.g. Trilinos)
can result in very long runtime dependency call times, especially if
system calls are made more expensive by antivirus software. This
change caches the results of the calls to otool for efficiency.
---
 Source/cmBinUtilsMacOSMachOLinker.cxx | 42 +++++++++++++++++++++++++++--------
 Source/cmBinUtilsMacOSMachOLinker.h   | 10 +++++++++
 2 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/Source/cmBinUtilsMacOSMachOLinker.cxx b/Source/cmBinUtilsMacOSMachOLinker.cxx
index 47f77d8..c064377 100644
--- a/Source/cmBinUtilsMacOSMachOLinker.cxx
+++ b/Source/cmBinUtilsMacOSMachOLinker.cxx
@@ -5,6 +5,8 @@
 
 #include <sstream>
 #include <string>
+#include <type_traits>
+#include <utility>
 #include <vector>
 
 #include <cm/memory>
@@ -52,6 +54,26 @@ bool cmBinUtilsMacOSMachOLinker::Prepare()
   return true;
 }
 
+auto cmBinUtilsMacOSMachOLinker::GetFileInfo(std::string const& file)
+  -> const FileInfo*
+{
+  // Memoize processed rpaths and library dependencies to reduce the number
+  // of calls to otool, especially in the case of heavily recursive libraries
+  auto iter = ScannedFileInfo.find(file);
+  if (iter != ScannedFileInfo.end()) {
+    return &iter->second;
+  }
+
+  FileInfo file_info;
+  if (!this->Tool->GetFileInfo(file, file_info.libs, file_info.rpaths)) {
+    // Call to otool failed
+    return nullptr;
+  }
+
+  auto iter_inserted = ScannedFileInfo.insert({ file, std::move(file_info) });
+  return &iter_inserted.first->second;
+}
+
 bool cmBinUtilsMacOSMachOLinker::ScanDependencies(
   std::string const& file, cmStateEnums::TargetType type)
 {
@@ -65,12 +87,12 @@ bool cmBinUtilsMacOSMachOLinker::ScanDependencies(
   if (!executableFile.empty()) {
     executablePath = cmSystemTools::GetFilenamePath(executableFile);
   }
-  std::vector<std::string> libs;
-  std::vector<std::string> rpaths;
-  if (!this->Tool->GetFileInfo(file, libs, rpaths)) {
+  const FileInfo* file_info = this->GetFileInfo(file);
+  if (file_info == nullptr) {
     return false;
   }
-  return this->ScanDependencies(file, libs, rpaths, executablePath);
+  return this->ScanDependencies(file, file_info->libs, file_info->rpaths,
+                                executablePath);
 }
 
 bool cmBinUtilsMacOSMachOLinker::ScanDependencies(
@@ -98,14 +120,16 @@ bool cmBinUtilsMacOSMachOLinker::GetFileDependencies(
             !IsMissingSystemDylib(path)) {
           auto filename = cmSystemTools::GetFilenameName(path);
           bool unique;
-          std::vector<std::string> libs;
-          std::vector<std::string> depRpaths;
-          if (!this->Tool->GetFileInfo(path, libs, depRpaths)) {
+          const FileInfo* dep_file_info = this->GetFileInfo(path);
+          if (dep_file_info == nullptr) {
             return false;
           }
-          this->Archive->AddResolvedPath(filename, path, unique, depRpaths);
+
+          this->Archive->AddResolvedPath(filename, path, unique,
+                                         dep_file_info->rpaths);
           if (unique &&
-              !this->ScanDependencies(path, libs, depRpaths, executablePath)) {
+              !this->ScanDependencies(path, dep_file_info->libs,
+                                      dep_file_info->rpaths, executablePath)) {
             return false;
           }
         }
diff --git a/Source/cmBinUtilsMacOSMachOLinker.h b/Source/cmBinUtilsMacOSMachOLinker.h
index eae23cc..ac1177b 100644
--- a/Source/cmBinUtilsMacOSMachOLinker.h
+++ b/Source/cmBinUtilsMacOSMachOLinker.h
@@ -5,6 +5,7 @@
 
 #include <memory>
 #include <string>
+#include <unordered_map>
 #include <vector>
 
 #include "cmBinUtilsLinker.h"
@@ -24,7 +25,16 @@ public:
                         cmStateEnums::TargetType type) override;
 
 private:
+  struct FileInfo
+  {
+    std::vector<std::string> libs;
+    std::vector<std::string> rpaths;
+  };
+
   std::unique_ptr<cmBinUtilsMacOSMachOGetRuntimeDependenciesTool> Tool;
+  std::unordered_map<std::string, FileInfo> ScannedFileInfo;
+
+  const FileInfo* GetFileInfo(std::string const& file);
 
   bool ScanDependencies(std::string const& file,
                         std::vector<std::string> const& libs,
-- 
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