[cfe-dev] Should "imports" list in DICompileUnit have duplication of DIImportedEntity?

[Aboud, Amjad via cfe-dev]

Hi,
It looks like Clang FE does not treat imported entities list ("imports") as a set that has no duplication.
In the below simple example, imported entities list contains a duplication for same DIImportedEntity, which will end up having duplication of this imported entity in the dwarf debug info section (see below).

Should "imports" list in DICompileUnit have duplication of DIImportedEntity?
Do you think we should fix Clang to assure the "imports" list is a unique set?

Notice that there is no added value to have the same entity duplicated!

Thanks,
Amjad


The example (using the attached files):

Command-line: clang -cc1 -S -emit-llvm -o - -debug-info-kind=limited TestIM.cpp
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.9.0 (trunk 261634) (llvm/trunk 261633)", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2, imports: !3)
!1 = !DIFile(filename: " <stdin>", directory: "\\")
!2 = !{}
!3 = !{!4, !4}  <----------------------------  Bug: same entity appears twice in the imported entities list!
!4 = !DIImportedEntity(tag: DW_TAG_imported_declaration, scope: !5, entity: !7, line: 8)
!5 = !DINamespace(name: "Y", scope: null, file: !6, line: 7)


Command-line: clang -cc1 -S -emit-obj -o - -debug-info-kind=limited TestIM.cpp | llvm-dwarfdump.exe -debug-dump=info -
0x0000000b: DW_TAG_compile_unit [1] *
              DW_AT_producer [DW_FORM_strp]     ( .debug_str[0x00000000] = "clang version 3.9.0 (trunk 259349) (llvm/trunk 259357)")
              DW_AT_language [DW_FORM_data2]    (DW_LANG_C_plus_plus)
              DW_AT_name [DW_FORM_strp] ( .debug_str[0x00000037] = " <stdin>")
              DW_AT_stmt_list [DW_FORM_sec_offset]      (0x00000000)
              DW_AT_comp_dir [DW_FORM_strp]     ( .debug_str[0x0000004e] = " \\ ")

0x0000001e:   DW_TAG_namespace [2] *
                DW_AT_name [DW_FORM_strp]       ( .debug_str[0x00000074] = "Y")
                DW_AT_decl_file [DW_FORM_data1] ("TestIM.h")
                DW_AT_decl_line [DW_FORM_data1] (7)

0x00000025:     DW_TAG_imported_declaration [3]
                  DW_AT_decl_file [DW_FORM_data1]       ("TestIM.h")
                  DW_AT_decl_line [DW_FORM_data1]       (8)
                  DW_AT_import [DW_FORM_ref4]   (cu + 0x003b => {0x0000003b})

0x0000002c:     DW_TAG_imported_declaration [3]           <----------------------------  duplication of 0x00000025
                  DW_AT_decl_file [DW_FORM_data1]       ("TestIM.h")
                  DW_AT_decl_line [DW_FORM_data1]       (8)
                  DW_AT_import [DW_FORM_ref4]   (cu + 0x003b => {0x0000003b})

0x00000033:     NULL

---------------------------------------------------------------------
Intel Israel (74) Limited

This e-mail and any attachments may contain confidential material for
the sole use of the intended recipient(s). Any review or distribution
by others is strictly prohibited. If you are not the intended
recipient, please contact the sender and delete all copies.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20160302/206b1483/attachment.html>
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: TestIM.H
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20160302/206b1483/attachment.ksh>
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: TestIM.CPP
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20160302/206b1483/attachment-0001.ksh>