[llvm-dev] Filename's in DIBuileder

Umesh Kalappa via llvm-dev
Tue, 01 Sep 2020 16:19:34 -0000

Hi All ,

We have a scenario in our debugger to handle the file index in the
debug_ine info like

$llvm-dwarfdump -debug-line test.o
file_names[  1]:
           name: "test.cpp"
      dir_index: 0
       mod_time: 0x00000000
         length: 0x00000000
file_names[  2]:
           name: "test.cpp"
      dir_index: 1
       mod_time: 0x00000000
         length: 0x00000000

Address            Line   Column File   ISA Discriminator Flags
------------------ ------ ------ ------ --- ------------- -------------
0x0000000000000000     12      0      1   0             0  is_stmt
0x0000000000000008     13      1      1   0             0  is_stmt
prologue_end
0x0000000000000010     16      0      1   0             0  is_stmt
0x0000000000000018     17      1      1   0             0  is_stmt
prologue_end
0x0000000000000020     20      0      1   0             0  is_stmt
0x0000000000000028     21      9      1   0             0  is_stmt
prologue_end
0x000000000000002f     22      9      1   0             0  is_stmt
0x0000000000000032     22     10      1   0             0
0x0000000000000035     22      7      1   0             0
0x000000000000003c     23      1      1   0             0  is_stmt
0x0000000000000040     25      0      1   0             0  is_stmt
0x0000000000000044     25     13      1   0             0  is_stmt
prologue_end
0x0000000000000080      0      0      2   0             0  is_stmt
0x000000000000008b      0      0      2   0             0  is_stmt
end_sequence


the debug info is emitted by the DIBuilder like

!3 = !DIFile(filename: "/folk/tmp/test/test.cpp", directory:
"/folk/tmp/test")
!45 = distinct !DISubprogram(linkageName: "_GLOBAL__sub_I_test.cpp",
scope:
!3, file: !3, type: !46, flags: DIFlagArtificial, spFlags:
DISPFlagLocalToUnit | DISPFlagDefinition, unit: !2, retainedNodes: !4)

!8 = !DIFile(filename: "test.cpp", directory:
"/folk/tmp/test")
!16 = !DISubprogram(name: "proc", linkageName:
"_ZN4test4procEv", scope:
!9, file: !8, line: 8, type: !12, scopeLine: 8, flags: DIFlagPublic |
DIFlagPrototyped, spFlags: 0)

Latest clang trunk used like

$clang -std=c++14  -g -eimit-llvm -S   /folk/tmp/test/test.cpp

and the respective files like test.cc ,test.ll and test.s are attached in
the mail for the reference.

the scenario is that why the file-name 's are different is both cases
,where "ZN4test4procEv" is the user defined function and
"_GLOBAL__sub_I_test.cpp"
is generated for the static initialisation ,which leads to the  two file
index like 1 and 2 for  two files in the filename table ,that confuse our
debugger .

So we like to hear from experts here  ,before we investigate the DIBuilder
to fix the same.

Thank you
~Umesh
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