From 19e6acbd51b45cf549387790fe8c51691cf30fc1 Mon Sep 17 00:00:00 2001
From: Ben Langmuir <blangmuir@apple.com>
Date: Fri, 1 Aug 2014 22:12:21 +0000
Subject: [PATCH] Add -fbuild-session-file as an alternative to
 -fbuild-session-timestamp

Build systems tend to traffic in files and modification times, so having
them touch a file at the beginning of the build can be easier than
having them update the compile command they use every time they build.

llvm-svn: 214577
---
 clang/include/clang/Basic/DiagnosticDriverKinds.td |  2 +-
 clang/include/clang/Driver/Options.td              |  3 +++
 clang/lib/Driver/Tools.cpp                         | 16 +++++++++++++++-
 clang/test/Driver/modules.m                        | 20 +++++++++++++++++---
 4 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
index e2afd6c..7202548 100644
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -175,7 +175,7 @@ def err_analyzer_config_multiple_values : Error<
 
 def err_drv_modules_validate_once_requires_timestamp : Error<
   "option '-fmodules-validate-once-per-build-session' requires "
-  "'-fbuild-session-timestamp=<seconds since Epoch>'">;
+  "'-fbuild-session-timestamp=<seconds since Epoch>' or '-fbuild-session-file=<file>'">;
 
 def warn_drv_invoking_fallback : Warning<"falling back to %0">,
   InGroup<Fallback>;
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index f799720..a32d932 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -617,6 +617,9 @@ def fmodules_search_all : Flag <["-"], "fmodules-search-all">, Group<f_Group>,
 def fbuild_session_timestamp : Joined<["-"], "fbuild-session-timestamp=">,
   Group<i_Group>, Flags<[CC1Option]>, MetaVarName<"<time since Epoch in seconds>">,
   HelpText<"Time when the current build session started">;
+def fbuild_session_file : Joined<["-"], "fbuild-session-file=">,
+  Group<i_Group>, MetaVarName<"<file>">,
+  HelpText<"Use the last modification time of <file> as the build session timestamp">;
 def fmodules_validate_once_per_build_session : Flag<["-"], "fmodules-validate-once-per-build-session">,
   Group<i_Group>, Flags<[CC1Option]>,
   HelpText<"Don't verify input files for the modules if the module has been "
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index b607f2f..bcc8056 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -3855,8 +3855,22 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
 
   Args.AddLastArg(CmdArgs, options::OPT_fbuild_session_timestamp);
 
+  if (Arg *A = Args.getLastArg(options::OPT_fbuild_session_file)) {
+    if (Args.hasArg(options::OPT_fbuild_session_timestamp))
+      D.Diag(diag::err_drv_argument_not_allowed_with)
+          << A->getAsString(Args) << "-fbuild-session-timestamp";
+
+    llvm::sys::fs::file_status Status;
+    if (llvm::sys::fs::status(A->getValue(), Status))
+      D.Diag(diag::err_drv_no_such_file) << A->getValue();
+    auto Timestamp = Status.getLastModificationTime().toEpochTime();
+    CmdArgs.push_back(Args.MakeArgString("-fbuild-session-timestamp=" +
+                                         std::to_string(Timestamp)));
+  }
+
   if (Args.getLastArg(options::OPT_fmodules_validate_once_per_build_session)) {
-    if (!Args.getLastArg(options::OPT_fbuild_session_timestamp))
+    if (!Args.getLastArg(options::OPT_fbuild_session_timestamp,
+                         options::OPT_fbuild_session_file))
       D.Diag(diag::err_drv_modules_validate_once_requires_timestamp);
 
     Args.AddLastArg(CmdArgs,
diff --git a/clang/test/Driver/modules.m b/clang/test/Driver/modules.m
index d8e20e4..141269c 100644
--- a/clang/test/Driver/modules.m
+++ b/clang/test/Driver/modules.m
@@ -4,15 +4,29 @@
 // RUN: %clang -fmodules -fno-modules -fmodules -### %s 2>&1 | FileCheck -check-prefix=CHECK-HAS-MODULES %s
 // CHECK-HAS-MODULES: -fmodules
 
-// RUN: %clang -fbuild-session-timestamp=123 -### %s 2>&1 | FileCheck -check-prefix=TIMESTAMP_ONLY %s
-// TIMESTAMP_ONLY: -fbuild-session-timestamp=123
+// RUN: %clang -fbuild-session-file=doesntexist -### %s 2>&1 | FileCheck -check-prefix=NOFILE %s
+// NOFILE: no such file or directory: 'doesntexist'
+
+// REQUIRES: shell
+// RUN: touch -m -a -t 201408011501 %t.build-session-file
+// RUN: %clang -fbuild-session-file=%t.build-session-file -### %s 2>&1 | FileCheck -check-prefix=TIMESTAMP_ONLY %s
+
+// RUN: %clang -fbuild-session-timestamp=1406930460 -### %s 2>&1 | FileCheck -check-prefix=TIMESTAMP_ONLY %s
+// TIMESTAMP_ONLY: -fbuild-session-timestamp=1406930460
+
+// RUN: %clang -fbuild-session-file=%t.build-session-file -fbuild-session-timestamp=123 -### %s 2>&1 | FileCheck -check-prefix=CONFLICT %s
+// CONFLICT: error: invalid argument '-fbuild-session-file={{.*}}.build-session-file' not allowed with '-fbuild-session-timestamp'
 
 // RUN: %clang -fbuild-session-timestamp=123 -fmodules-validate-once-per-build-session -### %s 2>&1 | FileCheck -check-prefix=MODULES_VALIDATE_ONCE %s
 // MODULES_VALIDATE_ONCE: -fbuild-session-timestamp=123
 // MODULES_VALIDATE_ONCE: -fmodules-validate-once-per-build-session
 
+// RUN: %clang -fbuild-session-file=%t.build-session-file -fmodules-validate-once-per-build-session -### %s 2>&1 | FileCheck -check-prefix=MODULES_VALIDATE_ONCE_FILE %s
+// MODULES_VALIDATE_ONCE_FILE: -fbuild-session-timestamp=1406930460
+// MODULES_VALIDATE_ONCE_FILE: -fmodules-validate-once-per-build-session
+
 // RUN: %clang -fmodules-validate-once-per-build-session -### %s 2>&1 | FileCheck -check-prefix=MODULES_VALIDATE_ONCE_ERR %s
-// MODULES_VALIDATE_ONCE_ERR: option '-fmodules-validate-once-per-build-session' requires '-fbuild-session-timestamp=<seconds since Epoch>'
+// MODULES_VALIDATE_ONCE_ERR: option '-fmodules-validate-once-per-build-session' requires '-fbuild-session-timestamp=<seconds since Epoch>' or '-fbuild-session-file=<file>'
 
 // RUN: %clang -### %s 2>&1 | FileCheck -check-prefix=MODULES_VALIDATE_SYSTEM_HEADERS_DEFAULT %s
 // MODULES_VALIDATE_SYSTEM_HEADERS_DEFAULT-NOT: -fmodules-validate-system-headers
-- 
2.7.4