DebugInfo: Avoid creating DILexicalScopeFiles when the filename in the current scope has not changed.

This looks like the right way for this check to work, but there is
another semi-obvious bug, I would think: why is CurLoc not zero'd out
between functions? The possibility for it to bleed between them seems
problematic. (& indeed I caused tests to fail when I fixed this a
different way, by setting CurLoc to SourceLocation() and the end of
EmitFunctionEnd... )

The changes to debug-info-blocks.m are due to a mismatch between the
source manager's file naming and CGDebugInfo's default handling when no
-main-file-name is specified. This actually reveals somewhat of a bug in
the debug info when using source files from standard in, too. See the
comment in CGDebugInfo::CreateCompileUnit for more details.

llvm-svn: 208742

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -112,17 +112,14 @@ void CGDebugInfo::setLocation(SourceLocation Loc) {
   if (LexicalBlockStack.empty()) return;
 
   SourceManager &SM = CGM.getContext().getSourceManager();
+  llvm::DIScope Scope(LexicalBlockStack.back());
   PresumedLoc PCLoc = SM.getPresumedLoc(CurLoc);
-  PresumedLoc PPLoc = SM.getPresumedLoc(PrevLoc);
 
-  if (PCLoc.isInvalid() || PPLoc.isInvalid() ||
-      !strcmp(PPLoc.getFilename(), PCLoc.getFilename()))
+  if (PCLoc.isInvalid() || Scope.getFilename() == PCLoc.getFilename())
     return;
 
-  llvm::MDNode *LB = LexicalBlockStack.back();
-  llvm::DIScope Scope = llvm::DIScope(LB);
   if (Scope.isLexicalBlockFile()) {
-    llvm::DILexicalBlockFile LBF = llvm::DILexicalBlockFile(LB);
+    llvm::DILexicalBlockFile LBF = llvm::DILexicalBlockFile(Scope);
     llvm::DIDescriptor D
       = DBuilder.createLexicalBlockFile(LBF.getScope(),
                                         getOrCreateFile(CurLoc));
@@ -317,11 +314,18 @@ StringRef CGDebugInfo::getCurrentDirname() {
 /// CreateCompileUnit - Create new compile unit.
 void CGDebugInfo::CreateCompileUnit() {
 
+  // Should we be asking the SourceManager for the main file name, instead of
+  // accepting it as an argument? This just causes the main file name to
+  // mismatch with source locations and create extra lexical scopes or
+  // mismatched debug info (a CU with a DW_AT_file of "-", because that's what
+  // the driver passed, but functions/other things have DW_AT_file of "<stdin>"
+  // because that's what the SourceManager says)
+
   // Get absolute path name.
   SourceManager &SM = CGM.getContext().getSourceManager();
   std::string MainFileName = CGM.getCodeGenOpts().MainFileName;
   if (MainFileName.empty())
-    MainFileName = "<unknown>";
+    MainFileName = "<stdin>";
 
   // The main file name provided via the "-main-file-name" option contains just
   // the file name itself with no path information. This file name may have had

clang/test/CodeGen/debug-info-scope-file.c

@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -g -emit-llvm < %s | FileCheck %s
+
+// Check that, just because we emitted a function from a different file doesn't
+// mean we insert a file-change inside the next function.
+
+// CHECK: ret void, !dbg [[F1_LINE:![0-9]*]]
+// CHECK: ret void, !dbg [[F2_LINE:![0-9]*]]
+// CHECK: [[F1:![0-9]*]] = {{.*}} ; [ DW_TAG_subprogram ] {{.*}} [def] [f1]
+// CHECK: [[F2:![0-9]*]] = {{.*}} ; [ DW_TAG_subprogram ] {{.*}} [def] [f2]
+// CHECK: [[F1_LINE]] = {{.*}}, metadata [[F1]], null}
+// CHECK: [[F2_LINE]] = {{.*}}, metadata [[F2]], null}
+
+void f1() {
+}
+
+# 2 "foo.c"
+
+void f2() {
+}
+

clang/test/CodeGenObjC/debug-info-blocks.m

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -emit-llvm -fblocks -g  -triple x86_64-apple-darwin10 -fobjc-dispatch-method=mixed  %s -o - | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm -fblocks -g  -triple x86_64-apple-darwin10 -fobjc-dispatch-method=mixed -x objective-c < %s -o - | FileCheck %s
 
 // rdar://problem/9279956
 // Test that we generate the proper debug location for a captured self.