From 2d52be56ff595341be3c6cec337af6763804ce66 Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Sun, 21 Mar 2010 22:49:54 +0000
Subject: [PATCH] Keep track of the size/modification time of each file
 source-location entry in a precompiled header, so that we can detect modified
 files even when we miss in the stat cache.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@99149 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/clang/Basic/DiagnosticFrontendKinds.td |  3 +++
 lib/Basic/SourceManager.cpp                    |  3 +--
 lib/Frontend/PCHReader.cpp                     | 17 ++++++++++++-----
 lib/Frontend/PCHWriter.cpp                     |  7 +++++++
 4 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/include/clang/Basic/DiagnosticFrontendKinds.td b/include/clang/Basic/DiagnosticFrontendKinds.td
index 3a28282d55..b1453e3f49 100644
--- a/include/clang/Basic/DiagnosticFrontendKinds.td
+++ b/include/clang/Basic/DiagnosticFrontendKinds.td
@@ -57,6 +57,9 @@ def err_fe_pch_malformed_block : Error<
     "malformed block record in PCH file: '%0'">, DefaultFatal;
 def err_fe_pch_error_at_end_block : Error<
     "error at end of module block in PCH file: '%0'">, DefaultFatal;
+def err_fe_pch_file_modified : Error<
+    "file '%0' has been modified since the precompiled header was built">,
+    DefaultFatal;
 def err_fe_unable_to_open_output : Error<
     "unable to open output file '%0': '%1'">;
 def err_fe_unable_to_open_logfile : Error<
diff --git a/lib/Basic/SourceManager.cpp b/lib/Basic/SourceManager.cpp
index 6def967c4c..c34f3e2543 100644
--- a/lib/Basic/SourceManager.cpp
+++ b/lib/Basic/SourceManager.cpp
@@ -93,8 +93,7 @@ const llvm::MemoryBuffer *ContentCache::getBuffer(Diagnostic &Diag,
         << Entry->getName() << ErrorStr;
       Buffer.setInt(true);
     } else if (FileInfo.st_size != Entry->getSize() ||
-               FileInfo.st_mtime != Entry->getModificationTime() ||
-               FileInfo.st_ino != Entry->getInode()) {
+               FileInfo.st_mtime != Entry->getModificationTime()) {
       // Check that the file's size, modification time, and inode are
       // the same as in the file entry (which may have come from a
       // stat cache).
diff --git a/lib/Frontend/PCHReader.cpp b/lib/Frontend/PCHReader.cpp
index e659ff047d..8fd81df098 100644
--- a/lib/Frontend/PCHReader.cpp
+++ b/lib/Frontend/PCHReader.cpp
@@ -905,11 +905,18 @@ PCHReader::PCHReadResult PCHReader::ReadSLocEntryRecord(unsigned ID) {
       return Failure;
     }
 
-    if (Record.size() < 8) {
+    if (Record.size() < 10) {
       Error("source location entry is incorrect");
       return Failure;
     }
 
+    if ((off_t)Record[4] != File->getSize() ||
+        (time_t)Record[5] != File->getModificationTime()) {
+      Diag(diag::err_fe_pch_file_modified)
+        << Filename;
+      return Failure;
+    }
+
     FileID FID = SourceMgr.createFileID(File,
                                 SourceLocation::getFromRawEncoding(Record[1]),
                                        (SrcMgr::CharacteristicKind)Record[2],
@@ -920,10 +927,10 @@ PCHReader::PCHReadResult PCHReader::ReadSLocEntryRecord(unsigned ID) {
 
     // Reconstruct header-search information for this file.
     HeaderFileInfo HFI;
-    HFI.isImport = Record[4];
-    HFI.DirInfo = Record[5];
-    HFI.NumIncludes = Record[6];
-    HFI.ControllingMacroID = Record[7];
+    HFI.isImport = Record[6];
+    HFI.DirInfo = Record[7];
+    HFI.NumIncludes = Record[8];
+    HFI.ControllingMacroID = Record[9];
     if (Listener)
       Listener->ReadHeaderFileInfo(HFI, File->getUID());
     break;
diff --git a/lib/Frontend/PCHWriter.cpp b/lib/Frontend/PCHWriter.cpp
index 4752cd3ea6..6c2d1424c8 100644
--- a/lib/Frontend/PCHWriter.cpp
+++ b/lib/Frontend/PCHWriter.cpp
@@ -921,6 +921,9 @@ static unsigned CreateSLocFileAbbrev(llvm::BitstreamWriter &Stream) {
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Include location
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2)); // Characteristic
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Line directives
+  // FileEntry fields.
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 12)); // Size
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 32)); // Modification time
   // HeaderFileInfo fields.
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isImport
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2)); // DirInfo
@@ -1063,6 +1066,10 @@ void PCHWriter::WriteSourceManagerBlock(SourceManager &SourceMgr,
         // The source location entry is a file. The blob associated
         // with this entry is the file name.
 
+        // Emit size/modification time for this file.
+        Record.push_back(Content->Entry->getSize());
+        Record.push_back(Content->Entry->getModificationTime());
+
         // Emit header-search information associated with this file.
         HeaderFileInfo HFI;
         HeaderSearch &HS = PP.getHeaderSearchInfo();