[llvm] Prevent duplicate files in debug line header in dwarf 5: another attempt

Another attempt to land the changes in debug line header to prevent duplicate
files in Dwarf 5. I rolled back my previous commit because of a mistake in
generating the object file in a test. Meanwhile, I addressed some offline
comments and changed the implementation; the largest difference is that
MCDwarfLineTableHeader does not keep DwarfVersion but gets it as a parameter. I
also merged the patch to fix two lld tests that will strt to fail into this
patch.

Original Commit:

https://reviews.llvm.org/D59515

Original Message:
Motivation: In previous dwarf versions, file name indexes started from 1, and
the primary source file was not explicit. Dwarf 5 standard (6.2.4) prescribes
the primary source file to be explicitly given an entry with an index number 0.

The current implementation honors the specification by just duplicating the
main source file, once with index number 0, and later maybe with another
index number. While this is compliant with the letter of the standard, the
duplication causes problems for consumers of this information such as lldb.
(Some files are duplicated, where only some of them have a line table although
all refer to the same file)

With this change, dwarf 5 debug line section files always start from 0, and
the zeroth entry is not duplicated whenever possible. This requires different
handling of dwarf 4 and dwarf 5 during generation (e.g. when a function returns
an index zero for a file name, it signals an error in dwarf 4, but not in dwarf
5) However, I think the minor complication is worth it, because it enables all
consumers (lldb, gdb, dwarfdump, objdump, and so on) to treat all files in the
file name list homogenously.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@358732 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/DebugInfo/DWARF/DWARFDebugLine.h b/include/llvm/DebugInfo/DWARF/DWARFDebugLine.h
index 0fc34a8e7e48ccaa7df7593cd76cc93bb144802c..1503a923ea40324bafc08e7bfa701ff4697fee53 100644 (file)
--- a/include/llvm/DebugInfo/DWARF/DWARFDebugLine.h
+++ b/include/llvm/DebugInfo/DWARF/DWARFDebugLine.h
@@ -243,6 +243,9 @@ public:
     bool hasFileAtIndex(uint64_t FileIndex) const;
 
     /// Extracts filename by its index in filename table in prologue.
+    /// In Dwarf 4, the files are 1-indexed and the current compilation file
+    /// name is not represented in the list. In Dwarf 5, the files are
+    /// 0-indexed and the primary source file has the index 0.
     /// Returns true on success.
     bool getFileNameByIndex(uint64_t FileIndex, const char *CompDir,
                             DILineInfoSpecifier::FileLineInfoKind Kind,
@@ -275,6 +278,8 @@ public:
     SequenceVector Sequences;
 
   private:
+    const llvm::DWARFDebugLine::FileNameEntry &
+    getFileNameEntry(uint64_t Index) const;
     uint32_t findRowInSeq(const DWARFDebugLine::Sequence &Seq,
                           object::SectionedAddress Address) const;
     Optional<StringRef>

diff --git a/include/llvm/MC/MCDwarf.h b/include/llvm/MC/MCDwarf.h
index 63040cb194ecf344d3cabdab7d320cc223dab3c1..2a24347075a7d1bcf07737a75f3f533321630d96 100644 (file)
--- a/include/llvm/MC/MCDwarf.h
+++ b/include/llvm/MC/MCDwarf.h
@@ -41,11 +41,14 @@ class raw_ostream;
 class SMLoc;
 class SourceMgr;
 
-/// Instances of this class represent the name of the dwarf
-/// .file directive and its associated dwarf file number in the MC file,
-/// and MCDwarfFile's are created and uniqued by the MCContext class where
-/// the file number for each is its index into the vector of DwarfFiles (note
-/// index 0 is not used and not a valid dwarf file number).
+/// Instances of this class represent the name of the dwarf .file directive and
+/// its associated dwarf file number in the MC file. MCDwarfFile's are created
+/// and uniqued by the MCContext class. In Dwarf 4 file numbers start from 1;
+/// i.e. the entry with file number 1 is the first element in the vector of
+/// DwarfFiles and there is no MCDwarfFile with file number 0. In Dwarf 5 file
+/// numbers start from 0, with the MCDwarfFile with file number 0 being the
+/// primary source file, and file numbers correspond to their index in the
+/// vector.
 struct MCDwarfFile {
   // The base name of the file without its directory path.
   std::string Name;
@@ -225,6 +228,7 @@ public:
   Expected<unsigned> tryGetFile(StringRef &Directory, StringRef &FileName,
                                 Optional<MD5::MD5Result> Checksum,
                                 Optional<StringRef> Source,
+                                uint16_t DwarfVersion,
                                 unsigned FileNumber = 0);
   std::pair<MCSymbol *, MCSymbol *>
   Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
@@ -245,6 +249,18 @@ public:
     return MCDwarfFiles.empty() || (HasAllMD5 == HasAnyMD5);
   }
 
+  void setRootFile(StringRef Directory, StringRef FileName,
+                   Optional<MD5::MD5Result> Checksum,
+                   Optional<StringRef> Source) {
+    CompilationDir = Directory;
+    RootFile.Name = FileName;
+    RootFile.DirIndex = 0;
+    RootFile.Checksum = Checksum;
+    RootFile.Source = Source;
+    trackMD5Usage(Checksum.hasValue());
+    HasSource = Source.hasValue();
+  }
+
 private:
   void emitV2FileDirTables(MCStreamer *MCOS) const;
   void emitV5FileDirTables(MCStreamer *MCOS, Optional<MCDwarfLineStr> &LineStr) const;
@@ -252,24 +268,23 @@ private:
 
 class MCDwarfDwoLineTable {
   MCDwarfLineTableHeader Header;
+  bool HasSplitLineTable = false;
 
 public:
   void maybeSetRootFile(StringRef Directory, StringRef FileName,
-                        Optional<MD5::MD5Result> Checksum, Optional<StringRef> Source) {
+                        Optional<MD5::MD5Result> Checksum,
+                        Optional<StringRef> Source) {
     if (!Header.RootFile.Name.empty())
       return;
-    Header.CompilationDir = Directory;
-    Header.RootFile.Name = FileName;
-    Header.RootFile.DirIndex = 0;
-    Header.RootFile.Checksum = Checksum;
-    Header.RootFile.Source = Source;
-    Header.trackMD5Usage(Checksum.hasValue());
-    Header.HasSource = Source.hasValue();
+    Header.setRootFile(Directory, FileName, Checksum, Source);
   }
 
   unsigned getFile(StringRef Directory, StringRef FileName,
-                   Optional<MD5::MD5Result> Checksum, Optional<StringRef> Source) {
-    return cantFail(Header.tryGetFile(Directory, FileName, Checksum, Source));
+                   Optional<MD5::MD5Result> Checksum, uint16_t DwarfVersion,
+                   Optional<StringRef> Source) {
+    HasSplitLineTable = true;
+    return cantFail(Header.tryGetFile(Directory, FileName, Checksum, Source,
+                                      DwarfVersion));
   }
 
   void Emit(MCStreamer &MCOS, MCDwarfLineTableParams Params,
@@ -291,12 +306,13 @@ public:
   Expected<unsigned> tryGetFile(StringRef &Directory, StringRef &FileName,
                                 Optional<MD5::MD5Result> Checksum,
                                 Optional<StringRef> Source,
+                                uint16_t DwarfVersion,
                                 unsigned FileNumber = 0);
   unsigned getFile(StringRef &Directory, StringRef &FileName,
                    Optional<MD5::MD5Result> Checksum, Optional<StringRef> Source,
-                   unsigned FileNumber = 0) {
+                   uint16_t DwarfVersion, unsigned FileNumber = 0) {
     return cantFail(tryGetFile(Directory, FileName, Checksum, Source,
-                               FileNumber));
+                               DwarfVersion, FileNumber));
   }
 
   void setRootFile(StringRef Directory, StringRef FileName,

diff --git a/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index eec10282f57d0eb11f3ed971e88d16114d416c3f..b14eadd2559942b7c9845827c83c1f57586aec24 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -315,7 +315,9 @@ unsigned DwarfTypeUnit::getOrCreateSourceID(const DIFile *File) {
     addSectionOffset(getUnitDie(), dwarf::DW_AT_stmt_list, 0);
   }
   return SplitLineTable->getFile(File->getDirectory(), File->getFilename(),
-                                 getMD5AsBytes(File), File->getSource());
+                                 getMD5AsBytes(File),
+                                 Asm->OutContext.getDwarfVersion(),
+                                 File->getSource());
 }
 
 void DwarfUnit::addOpAddress(DIELoc &Die, const MCSymbol *Sym) {
@@ -397,7 +399,6 @@ void DwarfUnit::addSourceLine(DIE &Die, unsigned Line, const DIFile *File) {
     return;
 
   unsigned FileID = getOrCreateSourceID(File);
-  assert(FileID && "Invalid file id");
   addUInt(Die, dwarf::DW_AT_decl_file, None, FileID);
   addUInt(Die, dwarf::DW_AT_decl_line, None, Line);
 }

diff --git a/lib/DebugInfo/DWARF/DWARFDebugLine.cpp b/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
index 47df83e6817226545a52408f7118ce5ec4859a9b..84e13adbef6f9c376086325acde5561f209bd101 100644 (file)
--- a/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
+++ b/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
@@ -969,14 +969,29 @@ bool DWARFDebugLine::LineTable::lookupAddressRangeImpl(
 }
 
 bool DWARFDebugLine::LineTable::hasFileAtIndex(uint64_t FileIndex) const {
+  uint16_t DwarfVersion = Prologue.getVersion();
+  assert(DwarfVersion != 0 && "LineTable has no dwarf version information");
+  if (DwarfVersion >= 5)
+    return FileIndex < Prologue.FileNames.size();
   return FileIndex != 0 && FileIndex <= Prologue.FileNames.size();
 }
 
+const llvm::DWARFDebugLine::FileNameEntry &
+DWARFDebugLine::LineTable::getFileNameEntry(uint64_t Index) const {
+  uint16_t DwarfVersion = Prologue.getVersion();
+  assert(DwarfVersion != 0 && "LineTable has no dwarf version information");
+  // Unlike previous versions, in Dwarf 5 the file names is 0-indexed.
+  if (DwarfVersion >= 5)
+    return Prologue.FileNames[Index];
+  else
+    return Prologue.FileNames[Index - 1];
+}
+
 Optional<StringRef> DWARFDebugLine::LineTable::getSourceByIndex(uint64_t FileIndex,
                                                                 FileLineInfoKind Kind) const {
   if (Kind == FileLineInfoKind::None || !hasFileAtIndex(FileIndex))
     return None;
-  const FileNameEntry &Entry = Prologue.FileNames[FileIndex - 1];
+  const FileNameEntry &Entry = getFileNameEntry(FileIndex);
   if (Optional<const char *> source = Entry.Source.getAsCString())
     return StringRef(*source);
   return None;
@@ -996,7 +1011,7 @@ bool DWARFDebugLine::LineTable::getFileNameByIndex(uint64_t FileIndex,
                                                    std::string &Result) const {
   if (Kind == FileLineInfoKind::None || !hasFileAtIndex(FileIndex))
     return false;
-  const FileNameEntry &Entry = Prologue.FileNames[FileIndex - 1];
+  const FileNameEntry &Entry = getFileNameEntry(FileIndex);
   StringRef FileName = Entry.Name.getAsCString().getValue();
   if (Kind != FileLineInfoKind::AbsoluteFilePath ||
       isPathAbsoluteOnWindowsOrPosix(FileName)) {

diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index ef5c4666d925981e27ccf30c755c2028a5a45059..350502d633dec04e904177d15e1167a710783360 100644 (file)
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/lib/MC/MCAsmStreamer.cpp
@@ -1190,7 +1190,8 @@ Expected<unsigned> MCAsmStreamer::tryEmitDwarfFileDirective(
   MCDwarfLineTable &Table = getContext().getMCDwarfLineTable(CUID);
   unsigned NumFiles = Table.getMCDwarfFiles().size();
   Expected<unsigned> FileNoOrErr =
-      Table.tryGetFile(Directory, Filename, Checksum, Source, FileNo);
+      Table.tryGetFile(Directory, Filename, Checksum, Source,
+                       getContext().getDwarfVersion(), FileNo);
   if (!FileNoOrErr)
     return FileNoOrErr.takeError();
   FileNo = FileNoOrErr.get();

diff --git a/lib/MC/MCContext.cpp b/lib/MC/MCContext.cpp
index 4d16715c0aecd1841abe32ac346eb5db1c0d1ccf..6ca7d3df19da28205ae2c622412980ea1ae76803 100644 (file)
--- a/lib/MC/MCContext.cpp
+++ b/lib/MC/MCContext.cpp
@@ -605,7 +605,8 @@ Expected<unsigned> MCContext::getDwarfFile(StringRef Directory,
                                            Optional<StringRef> Source,
                                            unsigned CUID) {
   MCDwarfLineTable &Table = MCDwarfLineTablesCUMap[CUID];
-  return Table.tryGetFile(Directory, FileName, Checksum, Source, FileNumber);
+  return Table.tryGetFile(Directory, FileName, Checksum, Source, DwarfVersion,
+                          FileNumber);
 }
 
 /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
@@ -613,7 +614,7 @@ Expected<unsigned> MCContext::getDwarfFile(StringRef Directory,
 bool MCContext::isValidDwarfFileNumber(unsigned FileNumber, unsigned CUID) {
   const MCDwarfLineTable &LineTable = getMCDwarfLineTable(CUID);
   if (FileNumber == 0)
-    return getDwarfVersion() >= 5 && LineTable.hasRootFile();
+    return getDwarfVersion() >= 5;
   if (FileNumber >= LineTable.getMCDwarfFiles().size())
     return false;
 

diff --git a/lib/MC/MCDwarf.cpp b/lib/MC/MCDwarf.cpp
index 262c520a06a3d6ddac6d1ccb4c4eb4d1c9cbe819..e8edf6ba1d4c45c58bbb28b9bdc0856714520e14 100644 (file)
--- a/lib/MC/MCDwarf.cpp
+++ b/lib/MC/MCDwarf.cpp
@@ -259,7 +259,7 @@ void MCDwarfLineTable::Emit(MCObjectStreamer *MCOS,
 
 void MCDwarfDwoLineTable::Emit(MCStreamer &MCOS, MCDwarfLineTableParams Params,
                                MCSection *Section) const {
-  if (Header.MCDwarfFiles.empty())
+  if (!HasSplitLineTable)
     return;
   Optional<MCDwarfLineStr> NoLineStr(None);
   MCOS.SwitchSection(Section);
@@ -538,8 +538,17 @@ Expected<unsigned> MCDwarfLineTable::tryGetFile(StringRef &Directory,
                                                 StringRef &FileName,
                                                 Optional<MD5::MD5Result> Checksum,
                                                 Optional<StringRef> Source,
+                                                uint16_t DwarfVersion,
                                                 unsigned FileNumber) {
-  return Header.tryGetFile(Directory, FileName, Checksum, Source, FileNumber);
+  return Header.tryGetFile(Directory, FileName, Checksum, Source, DwarfVersion,
+                           FileNumber);
+}
+
+bool isRootFile(const MCDwarfFile &RootFile, StringRef &Directory,
+                StringRef &FileName, Optional<MD5::MD5Result> Checksum) {
+  if (RootFile.Name.empty() || RootFile.Name != FileName.data())
+    return false;
+  return RootFile.Checksum == Checksum;
 }
 
 Expected<unsigned>
@@ -547,6 +556,7 @@ MCDwarfLineTableHeader::tryGetFile(StringRef &Directory,
                                    StringRef &FileName,
                                    Optional<MD5::MD5Result> Checksum,
                                    Optional<StringRef> Source,
+                                   uint16_t DwarfVersion,
                                    unsigned FileNumber) {
   if (Directory == CompilationDir)
     Directory = "";
@@ -561,6 +571,8 @@ MCDwarfLineTableHeader::tryGetFile(StringRef &Directory,
     trackMD5Usage(Checksum.hasValue());
     HasSource = (Source != None);
   }
+  if (isRootFile(RootFile, Directory, FileName, Checksum) && DwarfVersion >= 5)
+    return 0;
   if (FileNumber == 0) {
     // File numbers start with 1 and/or after any file numbers
     // allocated by inline-assembler .file directives.

diff --git a/test/MC/ARM/dwarf-asm-multiple-sections.s b/test/MC/ARM/dwarf-asm-multiple-sections.s
index cff8f0007311de8e253f7abffa5f8fc9dcc2f0b7..f995958d9f8b4bbf09000f27ccc82585883f1cd8 100644 (file)
--- a/test/MC/ARM/dwarf-asm-multiple-sections.s
+++ b/test/MC/ARM/dwarf-asm-multiple-sections.s
@@ -2,9 +2,9 @@
 // RUN: llvm-dwarfdump -v %t | FileCheck -check-prefix DWARF -check-prefix DWARF45 %s
 // RUN: llvm-dwarfdump --debug-line %t | FileCheck -check-prefix DWARF-DL -check-prefix DWARF-DL-5 -DDWVER=5 -DDWFILE=0 %s
 // RUN: llvm-objdump -r %t | FileCheck -check-prefix RELOC -check-prefix RELOC5 %s
-// RUN: llvm-mc < %s -triple=armv7-linux-gnueabi -filetype=obj -o %t -g -fdebug-compilation-dir=/tmp
+// RUN: llvm-mc < %s -triple=armv7-linux-gnueabi -filetype=obj -o %t -g -dwarf-version 4 -fdebug-compilation-dir=/tmp
 // RUN: llvm-dwarfdump -v %t | FileCheck -check-prefix DWARF -check-prefix DWARF45 %s
-// RUN: llvm-dwarfdump --debug-line %t | FileCheck -check-prefix DWARF-DL -DDWVER=4 -DDWFILE=1 %s
+// RUN: llvm-dwarfdump --debug-line %t | FileCheck -check-prefix DWARF-DL -check-prefix DWARF-DL-4 -DDWVER=4 -DDWFILE=1 %s
 // RUN: llvm-objdump -r %t | FileCheck -check-prefix RELOC -check-prefix RELOC4 %s
 // RUN: llvm-mc < %s -triple=armv7-linux-gnueabi -filetype=obj -o %t -g -dwarf-version 3 -fdebug-compilation-dir=/tmp
 // RUN: llvm-dwarfdump -v %t | FileCheck -check-prefix DWARF -check-prefix DWARF3 %s
@@ -57,10 +57,14 @@ b:
 // DWARF-DL-5:    include_directories[  0] = "/tmp"
 // DWARF-DL:      file_names[  [[DWFILE]]]:
 // DWARF-DL:      name: "{{(<stdin>|-)}}"
-// DWARF-DL:      0x0000000000000000     17      0      1   0   0  is_stmt
-// DWARF-DL-NEXT: 0x0000000000000004     17      0      1   0   0  is_stmt end_sequence
-// DWARF-DL-NEXT: 0x0000000000000000     21      0      1   0   0  is_stmt
-// DWARF-DL-NEXT: 0x0000000000000004     21      0      1   0   0  is_stmt end_sequence
+// DWARF-DL-5:      0x0000000000000000     17      0      0   0   0  is_stmt
+// DWARF-DL-5-NEXT: 0x0000000000000004     17      0      0   0   0  is_stmt end_sequence
+// DWARF-DL-5-NEXT: 0x0000000000000000     21      0      0   0   0  is_stmt
+// DWARF-DL-5-NEXT: 0x0000000000000004     21      0      0   0   0  is_stmt end_sequence
+// DWARF-DL-4:      0x0000000000000000     17      0      1   0   0  is_stmt
+// DWARF-DL-4-NEXT: 0x0000000000000004     17      0      1   0   0  is_stmt end_sequence
+// DWARF-DL-4-NEXT: 0x0000000000000000     21      0      1   0   0  is_stmt
+// DWARF-DL-4-NEXT: 0x0000000000000004     21      0      1   0   0  is_stmt end_sequence
 
 
 // DWARF: .debug_ranges contents:

diff --git a/test/MC/ELF/debug-mixed-md5.ll b/test/MC/ELF/debug-mixed-md5.ll
index 2ec8141325f8db87e464e989bdd28cbc1b488aa5..d48e42c8d1214c6c00a88eb51ec185fbac333dc1 100644 (file)
--- a/test/MC/ELF/debug-mixed-md5.ll
+++ b/test/MC/ELF/debug-mixed-md5.ll
@@ -1,8 +1,7 @@
 ; RUN: %llc_dwarf -filetype=asm -dwarf-version=5 %s -o - | FileCheck %s -check-prefix=ASM
 ; RUN: %llc_dwarf -filetype=obj -dwarf-version=5 %s -o - | llvm-dwarfdump -debug-line - | FileCheck %s -check-prefix=OBJ
 ; ASM: .file 0 "{{.+}}" md5
-; ASM: .file 1 "{{.+}}" md5
-; ASM: .file 2 "t1.cpp"
+; ASM: .file 1 "t1.cpp"
 ; ASM-NOT: md5
 ; OBJ: file_names[ 0]:
 ; OBJ-NOT: md5

diff --git a/test/MC/ELF/dwarf-file0.s b/test/MC/ELF/dwarf-file0.s
index 1a3afb6875fd598bb767f05cc0d243ab038a5f7b..f98fdcc2b40d9fd88c275102621e0c9d24009bab 100644 (file)
--- a/test/MC/ELF/dwarf-file0.s
+++ b/test/MC/ELF/dwarf-file0.s
@@ -19,16 +19,14 @@
 # CHECK:       file_names[ 1]:
 # CHECK-NEXT:  name: "header.h"
 # CHECK-NEXT:  dir_index: 1
-# CHECK:       file_names[ 2]:
-# CHECK-NEXT:  name: "root.cpp"
+# CHECK-4:     file_names[ 2]:
+# CHECK-4-NEXT: name: "root.cpp"
 # CHECK-4-NEXT: dir_index: 2
-# CHECK-5-NEXT: dir_index: 0
 
 # ASM-NOT: .file
 # ASM-5:   .file 0 "/test" "root.cpp"
 # ASM:     .file 1 "/include" "header.h"
 # ASM-4:   .file 2 "/test" "root.cpp"
-# ASM-5:   .file 2 "root.cpp"
 # ASM-NOT: .file
 
 # WARN:      file 0 not supported prior to DWARF-5

diff --git a/test/tools/llvm-objdump/Inputs/embedded-source b/test/tools/llvm-objdump/Inputs/embedded-source
index 072b5a90c5c83aadeb6396d0523f57962d6f586e..8274a6619ed7e867c376451db1d2d5db42aa5f68 100644 (file)
Binary files a/test/tools/llvm-objdump/Inputs/embedded-source and b/test/tools/llvm-objdump/Inputs/embedded-source differ

diff --git a/test/tools/llvm-objdump/X86/function-sections-line-numbers.s b/test/tools/llvm-objdump/X86/function-sections-line-numbers.s
index b932a5d3f32f0dca18827050d243ba798afc2087..46607440cb9bde9490ce69e47a4e2851ec768043 100644 (file)
--- a/test/tools/llvm-objdump/X86/function-sections-line-numbers.s
+++ b/test/tools/llvm-objdump/X86/function-sections-line-numbers.s
@@ -30,8 +30,7 @@
 _Z2f1v:                                 # @_Z2f1v
 .Lfunc_begin0:
        .file   0 "/home/avl" "test.cpp" md5 0xefae234cc05b45384d782316d3a5d338
-       .file   1 "test.cpp" md5 0xefae234cc05b45384d782316d3a5d338
-       .loc    1 1 0                   # test.cpp:1:0
+       .loc    0 1 0                   # test.cpp:1:0
        .cfi_startproc
 # %bb.0:                                # %entry
        pushq   %rbp
@@ -40,7 +39,7 @@ _Z2f1v:                                 # @_Z2f1v
        movq    %rsp, %rbp
        .cfi_def_cfa_register %rbp
 .Ltmp0:
-       .loc    1 1 12 prologue_end     # test.cpp:1:12
+       .loc    0 1 12 prologue_end     # test.cpp:1:12
        popq    %rbp
        .cfi_def_cfa %rsp, 8
        retq
@@ -55,7 +54,7 @@ _Z2f1v:                                 # @_Z2f1v
        .type   _Z2f2v,@function
 _Z2f2v:                                 # @_Z2f2v
 .Lfunc_begin1:
-       .loc    1 2 0                   # test.cpp:2:0
+       .loc    0 2 0                   # test.cpp:2:0
        .cfi_startproc
 # %bb.0:                                # %entry
        pushq   %rbp
@@ -64,7 +63,7 @@ _Z2f2v:                                 # @_Z2f2v
        movq    %rsp, %rbp
        .cfi_def_cfa_register %rbp
 .Ltmp2:
-       .loc    1 2 12 prologue_end     # test.cpp:2:12
+       .loc    0 2 12 prologue_end     # test.cpp:2:12
        popq    %rbp
        .cfi_def_cfa %rsp, 8
        retq