Precompile headers: Add methods to generate PCH sources

Co-Author: Daniel Pfeifer <daniel@pfeifer-mail.de>

10 files changed, 240 insertions, 4 deletions

diff --git a/Source/cmGeneratorTarget.cxx b/Source/cmGeneratorTarget.cxx
index 9e20b66..04738d8 100644
--- a/Source/cmGeneratorTarget.cxx
+++ b/Source/cmGeneratorTarget.cxx
@@ -21,6 +21,7 @@
 #include "cmCustomCommand.h"
 #include "cmCustomCommandGenerator.h"
 #include "cmCustomCommandLines.h"
+#include "cmGeneratedFileStream.h"
 #include "cmGeneratorExpression.h"
 #include "cmGeneratorExpressionContext.h"
 #include "cmGeneratorExpressionDAGChecker.h"
@@ -3355,6 +3356,115 @@ std::vector<BT<std::string>> cmGeneratorTarget::GetPrecompileHeaders(
   return list;
 }
 
+std::string cmGeneratorTarget::GetPchHeader(const std::string& config,
+                                            const std::string& language) const
+{
+  if (language != "C" && language != "CXX") {
+    return std::string();
+  }
+  if (this->GetPropertyAsBool("DISABLE_PRECOMPILE_HEADERS")) {
+    return std::string();
+  }
+  const auto inserted =
+    this->PchHeaders.insert(std::make_pair(language + config, ""));
+  if (inserted.second) {
+    const std::vector<BT<std::string>> headers =
+      this->GetPrecompileHeaders(config, language);
+    if (headers.empty()) {
+      return std::string();
+    }
+    std::string& filename = inserted.first->second;
+
+    if (this->GetGlobalGenerator()->IsMultiConfig()) {
+      filename =
+        cmStrCat(this->LocalGenerator->GetCurrentBinaryDirectory(), "/");
+    } else {
+      // For GCC we need to have the header file .h[xx]
+      // next to the .h[xx].gch file
+      filename = this->ObjectDirectory;
+    }
+
+    filename = cmStrCat(filename, "CMakeFiles/", this->GetName(),
+                        ".dir/cmake_pch", ((language == "C") ? ".h" : ".hxx"));
+
+    const std::string filename_tmp = cmStrCat(filename, ".tmp");
+    {
+      auto pchPrologue = this->Makefile->GetDefinition("CMAKE_PCH_PROLOGUE");
+      auto pchEpilogue = this->Makefile->GetDefinition("CMAKE_PCH_EPILOGUE");
+
+      cmGeneratedFileStream file(
+        filename_tmp, false,
+        this->GetGlobalGenerator()->GetMakefileEncoding());
+      file << "/* generated by CMake */\n\n";
+      if (pchPrologue) {
+        file << pchPrologue << "\n";
+      }
+      if (this->GetGlobalGenerator()->IsXcode()) {
+        file << "#ifndef CMAKE_SKIP_PRECOMPILE_HEADERS\n";
+      }
+      if (language == "CXX") {
+        file << "#ifdef __cplusplus\n";
+      }
+      for (auto const& header_bt : headers) {
+        if (header_bt.Value.empty()) {
+          continue;
+        }
+        if (header_bt.Value[0] == '<' || header_bt.Value[0] == '"') {
+          file << "#include " << header_bt.Value << "\n";
+        } else {
+          file << "#include \"" << header_bt.Value << "\"\n";
+        }
+      }
+      if (language == "CXX") {
+        file << "#endif // __cplusplus\n";
+      }
+      if (this->GetGlobalGenerator()->IsXcode()) {
+        file << "#endif // CMAKE_SKIP_PRECOMPILE_HEADERS\n";
+      }
+      if (pchEpilogue) {
+        file << pchEpilogue << "\n";
+      }
+    }
+    cmSystemTools::CopyFileIfDifferent(filename_tmp, filename);
+    cmSystemTools::RemoveFile(filename_tmp);
+  }
+  return inserted.first->second;
+}
+
+std::string cmGeneratorTarget::GetPchSource(const std::string& config,
+                                            const std::string& language) const
+{
+  if (language != "C" && language != "CXX") {
+    return std::string();
+  }
+  const auto inserted =
+    this->PchSources.insert(std::make_pair(language + config, ""));
+  if (inserted.second) {
+    const std::string pchHeader = this->GetPchHeader(config, language);
+    if (pchHeader.empty()) {
+      return std::string();
+    }
+    std::string& filename = inserted.first->second;
+    filename = cmStrCat(this->LocalGenerator->GetCurrentBinaryDirectory(),
+                        "/CMakeFiles/", this->GetName(), ".dir/cmake_pch");
+
+    // For GCC the source extension will be tranformed into .h[xx].gch
+    if (!this->Makefile->IsOn("CMAKE_LINK_PCH")) {
+      filename += ((language == "C") ? ".h.c" : ".hxx.cxx");
+    } else {
+      filename += ((language == "C") ? ".c" : ".cxx");
+    }
+    const std::string filename_tmp = cmStrCat(filename, ".tmp");
+    {
+      cmGeneratedFileStream file(filename_tmp);
+      file << "/* generated by CMake */\n";
+    }
+    cmSystemTools::CopyFileIfDifferent(filename_tmp, filename);
+    cmSystemTools::RemoveFile(filename_tmp);
+  }
+  return inserted.first->second;
+}
+
 void cmGeneratorTarget::GetLinkOptions(std::vector<std::string>& result,
                                        const std::string& config,
                                        const std::string& language) const
diff --git a/Source/cmGeneratorTarget.h b/Source/cmGeneratorTarget.h
index 9d422ee..4701071 100644
--- a/Source/cmGeneratorTarget.h
+++ b/Source/cmGeneratorTarget.h
@@ -458,6 +458,11 @@ public:
   std::vector<BT<std::string>> GetPrecompileHeaders(
     const std::string& config, const std::string& language) const;
 
+  std::string GetPchHeader(const std::string& config,
+                           const std::string& language) const;
+  std::string GetPchSource(const std::string& config,
+                           const std::string& language) const;
+
   bool IsSystemIncludeDirectory(const std::string& dir,
                                 const std::string& config,
                                 const std::string& language) const;
diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index 57dabd1..d6d2f73 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -18,6 +18,7 @@
 #include "cmRulePlaceholderExpander.h"
 #include "cmSourceFile.h"
 #include "cmSourceFileLocation.h"
+#include "cmSourceFileLocationKind.h"
 #include "cmState.h"
 #include "cmStateDirectory.h"
 #include "cmStateTypes.h"
@@ -37,6 +38,7 @@
 
 #include <algorithm>
 #include <assert.h>
+#include <functional>
 #include <initializer_list>
 #include <iterator>
 #include <memory>
@@ -2113,6 +2115,82 @@ void cmLocalGenerator::AppendFlagEscape(std::string& flags,
   this->AppendFlags(flags, this->EscapeForShell(rawFlag));
 }
 
+void cmLocalGenerator::AddPchDependencies(cmGeneratorTarget* target,
+                                          const std::string& config)
+{
+  const std::string lang = target->GetLinkerLanguage(config);
+  const std::string buildType = cmSystemTools::UpperCase(config);
+  const std::string pchSource = target->GetPchSource(config, lang);
+  const std::string pchHeader = target->GetPchHeader(config, lang);
+
+  if (pchSource.empty() || pchHeader.empty()) {
+    return;
+  }
+
+  const std::string createOptVar =
+    cmStrCat("CMAKE_", lang, "_COMPILE_OPTIONS_CREATE_PCH");
+  std::string createOptionList =
+    this->Makefile->GetSafeDefinition(createOptVar);
+
+  const std::string useOptVar =
+    cmStrCat("CMAKE_", lang, "_COMPILE_OPTIONS_USE_PCH");
+  std::string useOptionList = this->Makefile->GetSafeDefinition(useOptVar);
+
+  const std::string pchExtension =
+    this->Makefile->GetSafeDefinition("CMAKE_PCH_EXTENSION");
+
+  if (createOptionList.empty() || useOptionList.empty() ||
+      pchExtension.empty()) {
+    return;
+  }
+
+  auto pch_sf = this->Makefile->GetOrCreateSource(
+    pchSource, false, cmSourceFileLocationKind::Known);
+  std::string pchFile = pchHeader;
+
+  if (!this->GetGlobalGenerator()->IsXcode()) {
+    // Exclude the pch files from linking
+    if (this->Makefile->IsOn("CMAKE_LINK_PCH")) {
+      cmSystemTools::ReplaceString(pchFile, (lang == "C" ? ".h" : ".hxx"),
+                                   pchExtension);
+      pch_sf->SetProperty("OBJECT_OUTPUTS", pchFile.c_str());
+    } else {
+      pchFile += pchExtension;
+      pch_sf->SetProperty("PCH_EXTENSION", pchExtension.c_str());
+    }
+
+    target->AddSource(pchSource, true);
+
+    for (auto& str : { std::ref(useOptionList), std::ref(createOptionList) }) {
+      cmSystemTools::ReplaceString(str, "<PCH_HEADER>", pchHeader);
+      cmSystemTools::ReplaceString(str, "<PCH_FILE>", pchFile);
+    }
+  }
+
+  pch_sf->SetProperty("COMPILE_OPTIONS", createOptionList.c_str());
+
+  std::vector<cmSourceFile*> sources;
+  target->GetSourceFiles(sources, buildType);
+  for (cmSourceFile* sf : sources) {
+    if (pch_sf == sf || sf->GetLanguage() != lang) {
+      continue;
+    }
+
+    if (sf->GetPropertyAsBool("SKIP_PRECOMPILE_HEADERS")) {
+      if (this->GetGlobalGenerator()->IsXcode()) {
+        sf->SetProperty("COMPILE_DEFINITIONS",
+                        "CMAKE_SKIP_PRECOMPILE_HEADERS");
+      }
+      continue;
+    }
+
+    if (!this->GetGlobalGenerator()->IsXcode()) {
+      sf->SetProperty("OBJECT_DEPENDS", pchFile.c_str());
+      sf->SetProperty("COMPILE_OPTIONS", useOptionList.c_str());
+    }
+  }
+}
+
 void cmLocalGenerator::AppendIPOLinkerFlags(std::string& flags,
                                             cmGeneratorTarget* target,
                                             const std::string& config,
@@ -2705,6 +2783,11 @@ std::string cmLocalGenerator::GetObjectFileNameWithoutTarget(
       }
     }
 
+    const char* pchExtension = source.GetProperty("PCH_EXTENSION");
+    if (pchExtension) {
+      customOutputExtension = pchExtension;
+    }
+
     // Remove the source extension if it is to be replaced.
     if (replaceExt || customOutputExtension) {
       keptSourceExtension = false;
diff --git a/Source/cmLocalGenerator.h b/Source/cmLocalGenerator.h
index 455e491..f63fe0f 100644
--- a/Source/cmLocalGenerator.h
+++ b/Source/cmLocalGenerator.h
@@ -124,6 +124,8 @@ public:
   virtual void AppendFlags(std::string& flags, const char* newFlags) const;
   virtual void AppendFlagEscape(std::string& flags,
                                 const std::string& rawFlag) const;
+  void AddPchDependencies(cmGeneratorTarget* target,
+                          const std::string& config);
   void AppendIPOLinkerFlags(std::string& flags, cmGeneratorTarget* target,
                             const std::string& config,
                             const std::string& lang);
diff --git a/Source/cmMakefileExecutableTargetGenerator.cxx b/Source/cmMakefileExecutableTargetGenerator.cxx
index 7bc05b1..bebd5c4 100644
--- a/Source/cmMakefileExecutableTargetGenerator.cxx
+++ b/Source/cmMakefileExecutableTargetGenerator.cxx
@@ -40,6 +40,8 @@ cmMakefileExecutableTargetGenerator::cmMakefileExecutableTargetGenerator(
   this->OSXBundleGenerator =
     cm::make_unique<cmOSXBundleGenerator>(target, this->ConfigName);
   this->OSXBundleGenerator->SetMacContentFolders(&this->MacContentFolders);
+
+  this->LocalGenerator->AddPchDependencies(target, this->ConfigName);
 }
 
 cmMakefileExecutableTargetGenerator::~cmMakefileExecutableTargetGenerator() =
diff --git a/Source/cmMakefileLibraryTargetGenerator.cxx b/Source/cmMakefileLibraryTargetGenerator.cxx
index 252279f..4244402 100644
--- a/Source/cmMakefileLibraryTargetGenerator.cxx
+++ b/Source/cmMakefileLibraryTargetGenerator.cxx
@@ -42,6 +42,8 @@ cmMakefileLibraryTargetGenerator::cmMakefileLibraryTargetGenerator(
   this->OSXBundleGenerator =
     cm::make_unique<cmOSXBundleGenerator>(target, this->ConfigName);
   this->OSXBundleGenerator->SetMacContentFolders(&this->MacContentFolders);
+
+  this->LocalGenerator->AddPchDependencies(target, this->ConfigName);
 }
 
 cmMakefileLibraryTargetGenerator::~cmMakefileLibraryTargetGenerator() =
diff --git a/Source/cmMakefileTargetGenerator.cxx b/Source/cmMakefileTargetGenerator.cxx
index f99fe4e..90d8ea9 100644
--- a/Source/cmMakefileTargetGenerator.cxx
+++ b/Source/cmMakefileTargetGenerator.cxx
@@ -239,10 +239,15 @@ void cmMakefileTargetGenerator::WriteTargetBuildRules()
   this->GeneratorTarget->GetExtraSources(extraSources, config);
   this->OSXBundleGenerator->GenerateMacOSXContentStatements(
     extraSources, this->MacOSXContentGenerator);
+  const char* pchExtension =
+    this->Makefile->GetDefinition("CMAKE_PCH_EXTENSION");
   std::vector<cmSourceFile const*> externalObjects;
   this->GeneratorTarget->GetExternalObjects(externalObjects, config);
   for (cmSourceFile const* sf : externalObjects) {
-    this->ExternalObjects.push_back(sf->GetFullPath());
+    auto const& objectFileName = sf->GetFullPath();
+    if (!cmSystemTools::StringEndsWith(objectFileName, pchExtension)) {
+      this->ExternalObjects.push_back(objectFileName);
+    }
   }
   std::vector<cmSourceFile const*> objectSources;
   this->GeneratorTarget->GetObjectSources(objectSources, config);
@@ -1238,7 +1243,14 @@ void cmMakefileTargetGenerator::WriteObjectsVariable(
   if (!lineContinue) {
     lineContinue = "\\";
   }
+
+  const char* pchExtension =
+    this->Makefile->GetDefinition("CMAKE_PCH_EXTENSION");
+
   for (std::string const& obj : this->Objects) {
+    if (cmSystemTools::StringEndsWith(obj, pchExtension)) {
+      continue;
+    }
     *this->BuildFileStream << " " << lineContinue << "\n";
     *this->BuildFileStream
       << cmLocalUnixMakefileGenerator3::ConvertToQuotedOutputPath(
@@ -1331,10 +1343,16 @@ private:
 void cmMakefileTargetGenerator::WriteObjectsStrings(
   std::vector<std::string>& objStrings, std::string::size_type limit)
 {
+  const char* pchExtension =
+    this->Makefile->GetDefinition("CMAKE_PCH_EXTENSION");
+
   cmMakefileTargetGeneratorObjectStrings helper(
     objStrings, this->LocalGenerator,
     this->LocalGenerator->GetStateSnapshot().GetDirectory(), limit);
   for (std::string const& obj : this->Objects) {
+    if (cmSystemTools::StringEndsWith(obj, pchExtension)) {
+      continue;
+    }
     helper.Feed(obj);
   }
   for (std::string const& obj : this->ExternalObjects) {
diff --git a/Source/cmMakefileUtilityTargetGenerator.cxx b/Source/cmMakefileUtilityTargetGenerator.cxx
index 8ed6be5..556191f 100644
--- a/Source/cmMakefileUtilityTargetGenerator.cxx
+++ b/Source/cmMakefileUtilityTargetGenerator.cxx
@@ -25,6 +25,8 @@ cmMakefileUtilityTargetGenerator::cmMakefileUtilityTargetGenerator(
   this->OSXBundleGenerator =
     cm::make_unique<cmOSXBundleGenerator>(target, this->ConfigName);
   this->OSXBundleGenerator->SetMacContentFolders(&this->MacContentFolders);
+
+  this->LocalGenerator->AddPchDependencies(target, this->ConfigName);
 }
 
 cmMakefileUtilityTargetGenerator::~cmMakefileUtilityTargetGenerator() =
diff --git a/Source/cmNinjaNormalTargetGenerator.cxx b/Source/cmNinjaNormalTargetGenerator.cxx
index 2841245..462746a 100644
--- a/Source/cmNinjaNormalTargetGenerator.cxx
+++ b/Source/cmNinjaNormalTargetGenerator.cxx
@@ -59,6 +59,8 @@ cmNinjaNormalTargetGenerator::cmNinjaNormalTargetGenerator(
   this->OSXBundleGenerator =
     cm::make_unique<cmOSXBundleGenerator>(target, this->GetConfigName());
   this->OSXBundleGenerator->SetMacContentFolders(&this->MacContentFolders);
+
+  GetLocalGenerator()->AddPchDependencies(target, this->GetConfigName());
 }
 
 cmNinjaNormalTargetGenerator::~cmNinjaNormalTargetGenerator() = default;
diff --git a/Source/cmNinjaTargetGenerator.cxx b/Source/cmNinjaTargetGenerator.cxx
index 3d3d80d..29e8b74 100644
--- a/Source/cmNinjaTargetGenerator.cxx
+++ b/Source/cmNinjaTargetGenerator.cxx
@@ -790,10 +790,16 @@ void cmNinjaTargetGenerator::WriteObjectBuildStatements()
       extraSources, this->MacOSXContentGenerator.get());
   }
   {
+    const char* pchExtension =
+      GetMakefile()->GetDefinition("CMAKE_PCH_EXTENSION");
+
     std::vector<cmSourceFile const*> externalObjects;
     this->GeneratorTarget->GetExternalObjects(externalObjects, config);
     for (cmSourceFile const* sf : externalObjects) {
-      this->Objects.push_back(this->GetSourceFilePath(sf));
+      const auto objectFileName = this->GetSourceFilePath(sf);
+      if (!cmSystemTools::StringEndsWith(objectFileName, pchExtension)) {
+        this->Objects.push_back(objectFileName);
+      }
     }
   }
 
@@ -955,8 +961,12 @@ void cmNinjaTargetGenerator::WriteObjectBuildStatement(
     vars["FLAGS"], vars["DEFINES"], vars["INCLUDES"]);
 
   objBuild.Outputs.push_back(objectFileName);
-  // Add this object to the list of object files.
-  this->Objects.push_back(objectFileName);
+  const char* pchExtension =
+    this->GetMakefile()->GetDefinition("CMAKE_PCH_EXTENSION");
+  if (!cmSystemTools::StringEndsWith(objectFileName, pchExtension)) {
+    // Add this object to the list of object files.
+    this->Objects.push_back(objectFileName);
+  }
 
   objBuild.ExplicitDeps.push_back(sourceFileName);