DebugInfo: Do not rely on the compilation dir (index 0) for files in line tables...

When emitting assembly there's no support for emitting separate line
tables for each compilation unit - so LLVM emits .loc directives
producing a single line table.

Line tables have an implicit directory (index 0) equal to the
compilation directory (DW_AT_comp_dir) of the compilation unit that
references them.

If multiple compilation units (with possibly disparate compilation
directories) reference the same line table, we must avoid relying on
this ambiguous directory.

Achieve this my simply not setting the compilation directory on the line
table when we're in this situation (multiple units while emitting
assembly).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204094 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 8c499f84936818f7c9dab128de4008d24d4171d9..77765e12f81cd31146066eefed279ab0ae1a097c 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -674,7 +674,8 @@ void DwarfDebug::addGnuPubAttributes(DwarfUnit *U, DIE *D) const {
 
 // Create new DwarfCompileUnit for the given metadata node with tag
 // DW_TAG_compile_unit.
-DwarfCompileUnit *DwarfDebug::constructDwarfCompileUnit(DICompileUnit DIUnit) {
+DwarfCompileUnit *DwarfDebug::constructDwarfCompileUnit(DICompileUnit DIUnit,
+                                                        bool Singular) {
   StringRef FN = DIUnit.getFilename();
   CompilationDir = DIUnit.getDirectory();
 
@@ -682,8 +683,9 @@ DwarfCompileUnit *DwarfDebug::constructDwarfCompileUnit(DICompileUnit DIUnit) {
   DwarfCompileUnit *NewCU = new DwarfCompileUnit(
       InfoHolder.getUnits().size(), Die, DIUnit, Asm, this, &InfoHolder);
   InfoHolder.addUnit(NewCU);
-  Asm->OutStreamer.getContext().setMCLineTableCompilationDir(
-      NewCU->getUniqueID(), CompilationDir);
+  if (!Asm->OutStreamer.hasRawTextSupport() || Singular)
+    Asm->OutStreamer.getContext().setMCLineTableCompilationDir(
+        NewCU->getUniqueID(), CompilationDir);
 
   NewCU->addString(Die, dwarf::DW_AT_producer, DIUnit.getProducer());
   NewCU->addUInt(Die, dwarf::DW_AT_language, dwarf::DW_FORM_data2,
@@ -814,9 +816,13 @@ void DwarfDebug::beginModule() {
   // Emit initial sections so we can reference labels later.
   emitSectionLabels();
 
-  for (MDNode *N : CU_Nodes->operands()) {
+  auto Operands = CU_Nodes->operands();
+
+  bool SingleCU = std::next(Operands.begin()) == Operands.end();
+
+  for (MDNode *N : Operands) {
     DICompileUnit CUNode(N);
-    DwarfCompileUnit *CU = constructDwarfCompileUnit(CUNode);
+    DwarfCompileUnit *CU = constructDwarfCompileUnit(CUNode, SingleCU);
     DIArray ImportedEntities = CUNode.getImportedEntities();
     for (unsigned i = 0, e = ImportedEntities.getNumElements(); i != e; ++i)
       ScopesWithImportedEntities.push_back(std::make_pair(

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 7f4ed6e290a18df535ce335d0be1d375373b6db9..71ff75d640a54282d997591c47805e82491966b1 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -630,7 +630,8 @@ class DwarfDebug : public AsmPrinterHandler {
 
   /// \brief Create new DwarfCompileUnit for the given metadata node with tag
   /// DW_TAG_compile_unit.
-  DwarfCompileUnit *constructDwarfCompileUnit(DICompileUnit DIUnit);
+  DwarfCompileUnit *constructDwarfCompileUnit(DICompileUnit DIUnit,
+                                              bool Singular);
 
   /// \brief Construct subprogram DIE.
   void constructSubprogramDIE(DwarfCompileUnit *TheCU, const MDNode *N);

diff --git a/test/DebugInfo/lto-comp-dir.ll b/test/DebugInfo/lto-comp-dir.ll
index 88d6bf56aef91ce8dcb307295f15203d401d74ac..2637171d6a23f3892f1d3e23ce769b2f2009ea63 100644 (file)
--- a/test/DebugInfo/lto-comp-dir.ll
+++ b/test/DebugInfo/lto-comp-dir.ll
@@ -1,4 +1,5 @@
 ; RUN: %llc_dwarf < %s -filetype=obj | llvm-dwarfdump -debug-dump=line - | FileCheck %s
+; RUN: %llc_dwarf < %s -filetype=asm | FileCheck --check-prefix=ASM %s
 
 ; CHECK: .debug_line contents:
 ; CHECK-NEXT: Line table prologue:
@@ -11,6 +12,9 @@
 ; CHECK: file_names[   1]   0 {{.*}} b.cpp
 ; CHECK-NOT: file_names
 
+; ASM: .file   1 "/tmp/dbginfo/a/a.cpp"
+; ASM: .file   2 "/tmp/dbginfo/b/b.cpp"
+
 ; Generated from the following source compiled to bitcode from within their
 ; respective directories (with debug info) and linked together with llvm-link