[llvm] r201380 - DebugInfo: Don't include the name of the CU file in the line table file list when it's unneeded

[David Blaikie]

Author: dblaikie
Date: Thu Feb 13 19:57:59 2014
New Revision: 201380

URL: http://llvm.org/viewvc/llvm-project?rev=201380&view=rev
Log:
DebugInfo: Don't include the name of the CU file in the line table file list when it's unneeded

Recommitting r201351 and r201355 (reverted in r201351 and r201355)

We weren't emitting the an empty (header only) line table when the line
table was empty - this made the DWARF invalid (the compile unit would
point to the zero-size debug_lines section where there should've been an
empty line table but there was nothing at all). Fix that, and as a
consequence this works around/addresses PR18809.

Added:
    llvm/trunk/test/DebugInfo/empty.ll
Modified:
    llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
    llvm/trunk/lib/MC/MCObjectStreamer.cpp
    llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll

Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=201380&r1=201379&r2=201380&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Thu Feb 13 19:57:59 2014
@@ -756,9 +756,6 @@ DwarfCompileUnit *DwarfDebug::constructD
   InfoHolder.addUnit(NewCU);
 
   FileIDCUMap[NewCU->getUniqueID()] = 0;
-  // Call this to emit a .file directive if it wasn't emitted for the source
-  // file this CU comes from yet.
-  getOrCreateSourceID(FN, CompilationDir, NewCU->getUniqueID());
 
   NewCU->addString(Die, dwarf::DW_AT_producer, DIUnit.getProducer());
   NewCU->addUInt(Die, dwarf::DW_AT_language, dwarf::DW_FORM_data2,

Modified: llvm/trunk/lib/MC/MCObjectStreamer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCObjectStreamer.cpp?rev=201380&r1=201379&r2=201380&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCObjectStreamer.cpp (original)
+++ llvm/trunk/lib/MC/MCObjectStreamer.cpp Thu Feb 13 19:57:59 2014
@@ -379,7 +379,8 @@ void MCObjectStreamer::EmitZeros(uint64_
 void MCObjectStreamer::FinishImpl() {
   // Dump out the dwarf file & directory tables and line tables.
   const MCSymbol *LineSectionSymbol = NULL;
-  if (getContext().hasDwarfFiles())
+  if (!getContext().getMCLineTableSymbols().empty() ||
+      getContext().hasDwarfFiles())
     LineSectionSymbol = MCDwarfFileTable::Emit(this);
 
   // If we are generating dwarf for assembly source files dump out the sections.

Modified: llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll?rev=201380&r1=201379&r2=201380&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll Thu Feb 13 19:57:59 2014
@@ -125,6 +125,14 @@
 ; CHECK: DW_TAG_member
 ; CHECK-NEXT: DW_AT_name{{.*}}"a"
 
+; CHECK-LABEL: .debug_line contents:
+; CHECK: Line table prologue
+; CHECK-NOT: file_names[
+; CHECK: file_names{{.*}} bar.h
+; CHECK: file_names{{.*}} bar.cpp
+; CHECK-NOT: file_names[
+; CHECK-LABEL: .debug_str contents:
+
 ; Use the unit size as a rough hash/identifier for the unit we're dealing with
 ; it happens to be unambiguous at the moment, but it's hardly ideal.
 ; CHECK-LABEL: .debug_pubtypes contents:

Added: llvm/trunk/test/DebugInfo/empty.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/empty.ll?rev=201380&view=auto
==============================================================================
--- llvm/trunk/test/DebugInfo/empty.ll (added)
+++ llvm/trunk/test/DebugInfo/empty.ll Thu Feb 13 19:57:59 2014
@@ -0,0 +1,20 @@
+; RUN: llc %s -o %t -filetype=obj
+; RUN: llvm-dwarfdump -debug-dump=line %t | FileCheck %s
+
+; PR18809
+; XFAIL: cygwin,mingw32
+
+; Expect no line table entry since there are no functions and file references in this compile unit
+; CHECK: .debug_line contents:
+; CHECK: Line table prologue:
+; CHECK: total_length: 0x00000019
+; CHECK-NOT: file_names[
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!5}
+
+!0 = metadata !{i32 720913, metadata !4, i32 12, metadata !"clang version 3.1 (trunk 143523)", i1 true, metadata !"", i32 0, metadata !2, metadata !2, metadata !2, metadata !2, null, metadata !""} ; [ DW_TAG_compile_unit ]
+!2 = metadata !{}
+!3 = metadata !{i32 786473, metadata !4} ; [ DW_TAG_file_type ]
+!4 = metadata !{metadata !"empty.c", metadata !"/home/nlewycky"}
+!5 = metadata !{i32 1, metadata !"Debug Info Version", i32 1}