PR47391: Canonicalize DIFiles

Like @aprantl suggested, modify to  use the canonicalized DIFile, if we
don't know the  loc info and filename for the compiler generated
functions for example static initialization functions.

Reviewed By: dblaikie, aprantl

Differential Revision: https://reviews.llvm.org/D87147

3 files changed, 29 insertions, 15 deletions

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 7b20d43b0f17..8bc28b28c048 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -404,17 +404,23 @@ Optional<StringRef> CGDebugInfo::getSource(const SourceManager &SM,
 }
 
 llvm::DIFile *CGDebugInfo::getOrCreateFile(SourceLocation Loc) {
-  if (!Loc.isValid())
-    // If Location is not valid then use main input file.
-    return TheCU->getFile();
-
   SourceManager &SM = CGM.getContext().getSourceManager();
-  PresumedLoc PLoc = SM.getPresumedLoc(Loc);
+  StringRef FileName;
+  FileID FID;
 
-  StringRef FileName = PLoc.getFilename();
-  if (PLoc.isInvalid() || FileName.empty())
-    // If the location is not valid then use main input file.
-    return TheCU->getFile();
+  if (Loc.isInvalid()) {
+    FileName = TheCU->getFile()->getFilename();
+  } else {
+    PresumedLoc PLoc = SM.getPresumedLoc(Loc);
+    FileName = PLoc.getFilename();
+    
+    if (FileName.empty()) {
+      FileName = TheCU->getFile()->getFilename();
+    } else {
+      FileName = PLoc.getFilename();
+    }
+    FID = PLoc.getFileID();
+  }
 
   // Cache the results.
   auto It = DIFileCache.find(FileName.data());
@@ -426,11 +432,7 @@ llvm::DIFile *CGDebugInfo::getOrCreateFile(SourceLocation Loc) {
 
   SmallString<32> Checksum;
 
-  // Compute the checksum if possible. If the location is affected by a #line
-  // directive that refers to a file, PLoc will have an invalid FileID, and we
-  // will correctly get no checksum.
-  Optional<llvm::DIFile::ChecksumKind> CSKind =
-      computeChecksum(PLoc.getFileID(), Checksum);
+  Optional<llvm::DIFile::ChecksumKind> CSKind = computeChecksum(FID, Checksum);
   Optional<llvm::DIFile::ChecksumInfo<StringRef>> CSInfo;
   if (CSKind)
     CSInfo.emplace(*CSKind, Checksum);
diff --git a/clang/test/CodeGen/debug-info-oslog.c b/clang/test/CodeGen/debug-info-oslog.c
index c32c79eb8a6f..11a1cd64dedf 100644
--- a/clang/test/CodeGen/debug-info-oslog.c
+++ b/clang/test/CodeGen/debug-info-oslog.c
@@ -11,5 +11,5 @@ void test_builtin_os_log(void *buf, int i, const char *data) {
 // number between file and type.
 
 // CHECK: distinct !DISubprogram(name: "__os_log_helper_1_0_1_4_0",
-// CHECK-SAME:                   file: !{{[0-9+]}}, type
+// CHECK-SAME:                   file: !{{.*}}, type
 // CHECK-SAME:                   flags: DIFlagArtificial
diff --git a/clang/test/CodeGenCXX/difile_entry.cpp b/clang/test/CodeGenCXX/difile_entry.cpp
new file mode 100644
index 000000000000..9ef80fe8184c
--- /dev/null
+++ b/clang/test/CodeGenCXX/difile_entry.cpp
@@ -0,0 +1,12 @@
+// RUN: rm -rf %t/test_dir
+// RUN: mkdir -p %t/test_dir
+// RUN: cd %t/test_dir
+// RUN: cp %s .
+// RUN: %clang_cc1 -main-file-name difile_entry.cpp  -debug-info-kind=limited ../test_dir/difile_entry.cpp -std=c++11 -emit-llvm -o - | FileCheck  ../test_dir/difile_entry.cpp
+int x();
+static int i = x();
+
+// CHECK: [[FILE: *]] = !DIFile(filename: "{{.*}}difile_entry.cpp",
+// CHECK: {{.*}} = distinct !DISubprogram(name: "__cxx_global_var_init", scope: {{.*}}, file: [[FILE]]
+// CHECK: {{.*}} = distinct !DISubprogram(linkageName: "_GLOBAL__sub_I_difile_entry.cpp", scope: {{.*}}, file: [[FILE]]
+