Avoid emitting redundant or unusable directories in DIFile metadata entries.

As discussed on llvm-dev recently, Clang currently emits redundant
directories in DIFile entries, such as

  .file	     1 "/Volumes/Data/llvm" "/Volumes/Data/llvm/tools/clang/test/CodeGen/debug-info-abspath.c"

This patch looks at any common prefix between the compilation
directory and the (absolute) file path and strips the redundant
part. More importantly it leaves the compilation directory empty if
the two paths have no common prefix.

After this patch the above entry is (assuming a compilation dir of "/Volumes/Data/llvm/_build"):

  .file 1 "/Volumes/Data/llvm" "tools/clang/test/CodeGen/debug-info-abspath.c"

When building the FileCheck binary with debug info, this patch makes
the build artifacts ~1kb smaller.

Differential Revision: https://reviews.llvm.org/D55085

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@348154 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index 3492fbacd33a1fe133ef19138ad0925d54324d6f..c556996be09b79be72f6b60f33284f1416833237 100644 (file)
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/lib/CodeGen/CGDebugInfo.cpp
@@ -181,8 +181,7 @@ void CGDebugInfo::setLocation(SourceLocation Loc) {
   SourceManager &SM = CGM.getContext().getSourceManager();
   auto *Scope = cast<llvm::DIScope>(LexicalBlockStack.back());
   PresumedLoc PCLoc = SM.getPresumedLoc(CurLoc);
-
-  if (PCLoc.isInvalid() || Scope->getFilename() == PCLoc.getFilename())
+  if (PCLoc.isInvalid() || Scope->getFile() == getOrCreateFile(CurLoc))
     return;
 
   if (auto *LBF = dyn_cast<llvm::DILexicalBlockFile>(Scope)) {
@@ -410,13 +409,13 @@ llvm::DIFile *CGDebugInfo::getOrCreateFile(SourceLocation Loc) {
   SourceManager &SM = CGM.getContext().getSourceManager();
   PresumedLoc PLoc = SM.getPresumedLoc(Loc);
 
-  if (PLoc.isInvalid() || StringRef(PLoc.getFilename()).empty())
+  StringRef FileName = PLoc.getFilename();
+  if (PLoc.isInvalid() || FileName.empty())
     // If the location is not valid then use main input file.
     return getOrCreateMainFile();
 
   // Cache the results.
-  const char *fname = PLoc.getFilename();
-  auto It = DIFileCache.find(fname);
+  auto It = DIFileCache.find(FileName.data());
 
   if (It != DIFileCache.end()) {
     // Verify that the information still exists.
@@ -431,11 +430,41 @@ llvm::DIFile *CGDebugInfo::getOrCreateFile(SourceLocation Loc) {
   if (CSKind)
     CSInfo.emplace(*CSKind, Checksum);
 
-  llvm::DIFile *F = DBuilder.createFile(
-      remapDIPath(PLoc.getFilename()), remapDIPath(getCurrentDirname()), CSInfo,
-      getSource(SM, SM.getFileID(Loc)));
+  StringRef Dir;
+  StringRef File;
+  std::string RemappedFile = remapDIPath(FileName);
+  std::string CurDir = remapDIPath(getCurrentDirname());
+  SmallString<128> DirBuf;
+  SmallString<128> FileBuf;
+  if (llvm::sys::path::is_absolute(RemappedFile)) {
+    // Strip the common prefix (if it is more than just "/") from current
+    // directory and FileName for a more space-efficient encoding.
+    auto FileIt = llvm::sys::path::begin(RemappedFile);
+    auto FileE = llvm::sys::path::end(RemappedFile);
+    auto CurDirIt = llvm::sys::path::begin(CurDir);
+    auto CurDirE = llvm::sys::path::end(CurDir);
+    for (; CurDirIt != CurDirE && *CurDirIt == *FileIt; ++CurDirIt, ++FileIt)
+      llvm::sys::path::append(DirBuf, *CurDirIt);
+    if (std::distance(llvm::sys::path::begin(CurDir), CurDirIt) == 1) {
+      // The common prefix only the root; stripping it would cause
+      // LLVM diagnostic locations to be more confusing.
+      Dir = {};
+      File = RemappedFile;
+    } else {
+      for (; FileIt != FileE; ++FileIt)
+        llvm::sys::path::append(FileBuf, *FileIt);
+      Dir = DirBuf;
+      File = FileBuf;
+    }
+  } else {
+    Dir = CurDir;
+    File = RemappedFile;
+  }
+  llvm::DIFile *F =
+      DBuilder.createFile(File, Dir, CSInfo,
+                          getSource(SM, SM.getFileID(Loc)));
 
-  DIFileCache[fname].reset(F);
+  DIFileCache[FileName.data()].reset(F);
   return F;
 }
 

diff --git a/lib/CodeGen/CodeGenAction.cpp b/lib/CodeGen/CodeGenAction.cpp
index 1a2b0616dc77337af7897fefd420ff8bc2964b7f..fd4506f2d197e0890d9ff548eccb81c196bd92af 100644 (file)
--- a/lib/CodeGen/CodeGenAction.cpp
+++ b/lib/CodeGen/CodeGenAction.cpp
@@ -549,12 +549,16 @@ const FullSourceLoc BackendConsumer::getBestLocationFromDebugLoc(
   SourceLocation DILoc;
 
   if (D.isLocationAvailable()) {
-    D.getLocation(&Filename, &Line, &Column);
-    const FileEntry *FE = FileMgr.getFile(Filename);
-    if (FE && Line > 0) {
-      // If -gcolumn-info was not used, Column will be 0. This upsets the
-      // source manager, so pass 1 if Column is not set.
-      DILoc = SourceMgr.translateFileLineCol(FE, Line, Column ? Column : 1);
+    D.getLocation(Filename, Line, Column);
+    if (Line > 0) {
+      const FileEntry *FE = FileMgr.getFile(Filename);
+      if (!FE)
+        FE = FileMgr.getFile(D.getAbsolutePath());
+      if (FE) {
+        // If -gcolumn-info was not used, Column will be 0. This upsets the
+        // source manager, so pass 1 if Column is not set.
+        DILoc = SourceMgr.translateFileLineCol(FE, Line, Column ? Column : 1);
+      }
     }
     BadDebugInfo = DILoc.isInvalid();
   }

diff --git a/test/CodeGen/debug-info-abspath.c b/test/CodeGen/debug-info-abspath.c
new file mode 100644 (file)
index 0000000..3ca1706
--- /dev/null
+++ b/test/CodeGen/debug-info-abspath.c
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -debug-info-kind=limited -triple %itanium_abi_triple \
+// RUN:   %s -emit-llvm -o - | FileCheck %s
+
+// RUN: cp %s %t.c
+// RUN: %clang_cc1 -debug-info-kind=limited -triple %itanium_abi_triple \
+// RUN:   %t.c -emit-llvm -o - | FileCheck %s --check-prefix=INTREE
+void foo() {}
+
+// Since %s is an absolute path, directory should be a nonempty
+// prefix, but the CodeGen part should be part of the filename.
+
+// CHECK: DIFile(filename: "{{.*}}CodeGen{{.*}}debug-info-abspath.c"
+// CHECK-SAME:   directory: "{{.+}}")
+
+// INTREE: DIFile({{.*}}directory: "{{.+}}CodeGen{{.*}}")

diff --git a/test/CodeGen/debug-prefix-map.c b/test/CodeGen/debug-prefix-map.c
index dfb57bbe2e4b2457f5bad39771f105d31aea16bd..560f25fe0bb2bbfe0297be42a22fcb7e21573230 100644 (file)
--- a/test/CodeGen/debug-prefix-map.c
+++ b/test/CodeGen/debug-prefix-map.c
@@ -17,18 +17,22 @@ void test_rewrite_includes() {
 }
 
 // CHECK-NO-MAIN-FILE-NAME: !DIFile(filename: "/var/empty{{/|\\5C}}<stdin>"
-// CHECK-NO-MAIN-FILE-NAME: !DIFile(filename: "/var/empty{{[/\\]}}{{.*}}"
-// CHECK-NO-MAIN-FILE-NAME: !DIFile(filename: "/var/empty{{[/\\]}}Inputs/stdio.h"
+// CHECK-NO-MAIN-FILE-NAME: !DIFile(filename: "/var/empty{{[/\\]}}{{.*}}",
+// CHECK-NO-MAIN-FILE-NAME-SAME:    directory: "")
+// CHECK-NO-MAIN-FILE-NAME: !DIFile(filename: "/var/empty{{[/\\]}}Inputs/stdio.h",
+// CHECK-NO-MAIN-FILE-NAME-SAME:    directory: "")
 // CHECK-NO-MAIN-FILE-NAME-NOT: !DIFile(filename:
 
 // CHECK-EVIL: !DIFile(filename: "/var=empty{{[/\\]}}{{.*}}"
-// CHECK-EVIL: !DIFile(filename: "/var=empty{{[/\\]}}Inputs/stdio.h"
+// CHECK-EVIL: !DIFile(filename: "/var=empty{{[/\\]}}{{.*}}Inputs/stdio.h",
+// CHECK-EVIL-SAME:    directory: "")
 // CHECK-EVIL-NOT: !DIFile(filename:
 
 // CHECK: !DIFile(filename: "/var/empty{{[/\\]}}{{.*}}"
-// CHECK: !DIFile(filename: "/var/empty{{[/\\]}}Inputs/stdio.h"
+// CHECK: !DIFile(filename: "/var/empty{{[/\\]}}{{.*}}Inputs/stdio.h",
+// CHECK-SAME:    directory: "")
 // CHECK-NOT: !DIFile(filename:
 
-// CHECK-COMPILATION-DIR: !DIFile(filename: "/var/empty{{[/\\]}}{{.*}}", directory: "/var/empty")
-// CHECK-COMPILATION-DIR: !DIFile(filename: "/var/empty{{[/\\]}}Inputs/stdio.h", directory: "/var/empty")
+// CHECK-COMPILATION-DIR: !DIFile(filename: "{{.*}}", directory: "/var/empty")
+// CHECK-COMPILATION-DIR: !DIFile(filename: "Inputs/stdio.h", directory: "/var/empty")
 // CHECK-COMPILATION-DIR-NOT: !DIFile(filename:

diff --git a/test/Modules/module-debuginfo-prefix.m b/test/Modules/module-debuginfo-prefix.m
index c4a7d2b614a82673b370999e8a08b6923332d168..712c1063e9ceb003f3e357e19dff4f43f17a5704 100644 (file)
--- a/test/Modules/module-debuginfo-prefix.m
+++ b/test/Modules/module-debuginfo-prefix.m
@@ -20,4 +20,4 @@
 @import DebugObjC;
 #endif
 
-// CHECK: !DIFile({{.*}}"/OVERRIDE/DebugObjC.h"
+// CHECK: !DIFile(filename: "/OVERRIDE/DebugObjC.h", directory: "")