From 64091d5626581d9be26a206adcd6d3d76ac6eed4 Mon Sep 17 00:00:00 2001 From: George Rimar Date: Mon, 4 Jun 2018 10:28:45 +0000 Subject: [PATCH] [ELF] - Also use DW_AT_linkage_name when gathering information about variables for error messages. Currently, when LLD do a lookup for variables location, it uses DW_AT_name attribute. That is not always enough. Imagine code: namespace A { int bar = 0; } namespace Z { int bar = 1; } int hoho; In this case there are 3 variables and their debug attributes are following: A::bar has: DW_AT_name [DW_FORM_string] ("bar") DW_AT_linkage_name [DW_FORM_strp] ( .debug_str[0x00000006] = "_ZN1A3barE") Z::bar has: DW_AT_name [DW_FORM_string] ("bar") DW_AT_linkage_name [DW_FORM_strp] ( .debug_str[0x0000003f] = "_ZN1Z3barE") hoho has: DW_AT_name [DW_FORM_strp] ( .debug_str[0x0000004a] = "hoho") and has NO DW_AT_linkage_name attribute. Because it would be the same as DW_AT_name and DWARF producers avoids emiting excessive data. Hence LLD should also use DW_AT_linkage_name when it is available. (currently, LLD fails to report location correctly because thinks that A::bar and Z::bar are the same things) Differential revision: https://reviews.llvm.org/D47373 llvm-svn: 333880 --- lld/ELF/InputFiles.cpp | 11 +- lld/test/ELF/conflict-variable-linkage-name.s | 193 ++++++++++++++++++ 2 files changed, 201 insertions(+), 3 deletions(-) create mode 100644 lld/test/ELF/conflict-variable-linkage-name.s diff --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp index 8e4fbe33fa68..853e20f772bf 100644 --- a/lld/ELF/InputFiles.cpp +++ b/lld/ELF/InputFiles.cpp @@ -167,10 +167,15 @@ template void ObjFile::initializeDwarf() { // Get the line number on which the variable is declared. unsigned Line = dwarf::toUnsigned(Die.find(dwarf::DW_AT_decl_line), 0); - // Get the name of the variable and add the collected information to - // VariableLoc. Usually Name is non-empty, but it can be empty if the + // Here we want to take the variable name to add it into VariableLoc. + // Variable can have regular and linkage name associated. At first, we try + // to get linkage name as it can be different, for example when we have + // two variables in different namespaces of the same object. Use common + // name otherwise, but handle the case when it also absent in case if the // input object file lacks some debug info. - StringRef Name = dwarf::toString(Die.find(dwarf::DW_AT_name), ""); + StringRef Name = + dwarf::toString(Die.find(dwarf::DW_AT_linkage_name), + dwarf::toString(Die.find(dwarf::DW_AT_name), "")); if (!Name.empty()) VariableLoc.insert({Name, {LT, File, Line}}); } diff --git a/lld/test/ELF/conflict-variable-linkage-name.s b/lld/test/ELF/conflict-variable-linkage-name.s new file mode 100644 index 000000000000..18ae17a81556 --- /dev/null +++ b/lld/test/ELF/conflict-variable-linkage-name.s @@ -0,0 +1,193 @@ +# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o +# RUN: llvm-dwarfdump %t.o | FileCheck -check-prefix=INPUT %s +# RUN: not ld.lld %t.o %t.o -o %t 2>&1 | FileCheck %s + +# INPUT: DW_TAG_variable +# INPUT-NEXT: DW_AT_name ("bar") +# INPUT-NEXT: DW_AT_type (0x0000003d "int") +# INPUT-NEXT: DW_AT_external (true) +# INPUT-NEXT: DW_AT_decl_file ("/path\1.cpp") +# INPUT-NEXT: DW_AT_decl_line (2) +# INPUT-NEXT: DW_AT_location (DW_OP_addr 0x0) +# INPUT-NEXT: DW_AT_linkage_name ("_ZN1A3barE") +# INPUT: DW_TAG_variable +# INPUT-NEXT: DW_AT_name ("bar") +# INPUT-NEXT: DW_AT_type (0x0000003d "int") +# INPUT-NEXT: DW_AT_external (true) +# INPUT-NEXT: DW_AT_decl_file ("/path\1.cpp") +# INPUT-NEXT: DW_AT_decl_line (6) +# INPUT-NEXT: DW_AT_location (DW_OP_addr 0x0) +# INPUT-NEXT: DW_AT_linkage_name ("_ZN1Z3barE") + +## Check we can report the locations of 2 different "bar" variables. +# CHECK: duplicate symbol: A::bar +# CHECK-NEXT: >>> defined at 1.cpp:2 +# CHECK-NEXT: >>> {{.*}}:(A::bar) +# CHECK-NEXT: >>> defined at 1.cpp:2 +# CHECK-NEXT: >>> {{.*}}:(.bss+0x0) +# CHECK: duplicate symbol: Z::bar +# CHECK-NEXT: >>> defined at 1.cpp:6 +# CHECK-NEXT: >>> {{.*}}:(Z::bar) +# CHECK-NEXT: >>> defined at 1.cpp:6 +# CHECK-NEXT: >>> {{.*}}:(.data+0x0) + +# Used reduced output from following code and clang version 7.0.0 (trunk 332701) +# to produce this input file: +# Source (1.cpp): +# namespace A { +# int bar; +# } +# +# namespace Z { +# int bar; +# } +# Invocation: clang-7 -g -S 1.cpp + +.text +.file "1.cpp" +.file 1 "/path" "1.cpp" + +.type _ZN1A3barE,@object +.bss +.globl _ZN1A3barE +_ZN1A3barE: + .long 0 + .size _ZN1A3barE, 4 + +.type _ZN1Z3barE,@object +.data +.globl _ZN1Z3barE +_ZN1Z3barE: + .long 1 + .size _ZN1Z3barE, 4 + +.section .debug_str,"MS",@progbits,1 +.Linfo_string0: + .asciz "clang version 7.0.0 (trunk 332701)" # string offset=0 +.Linfo_string1: + .asciz "1.cpp" # string offset=35 +.Linfo_string2: + .asciz "/path" # string offset=41 +.Linfo_string3: + .asciz "A" # string offset=87 +.Linfo_string4: + .asciz "bar" # string offset=89 +.Linfo_string5: + .asciz "int" # string offset=93 +.Linfo_string6: + .asciz "_ZN1A3barE" # string offset=97 +.Linfo_string7: + .asciz "Z" # string offset=108 +.Linfo_string8: + .asciz "_ZN1Z3barE" # string offset=110 + +.section .debug_abbrev,"",@progbits + .byte 1 # Abbreviation Code + .byte 17 # DW_TAG_compile_unit + .byte 1 # DW_CHILDREN_yes + .byte 37 # DW_AT_producer + .byte 14 # DW_FORM_strp + .byte 19 # DW_AT_language + .byte 5 # DW_FORM_data2 + .byte 3 # DW_AT_name + .byte 14 # DW_FORM_strp + .byte 16 # DW_AT_stmt_list + .byte 23 # DW_FORM_sec_offset + .byte 27 # DW_AT_comp_dir + .byte 14 # DW_FORM_strp + .ascii "\264B" # DW_AT_GNU_pubnames + .byte 25 # DW_FORM_flag_present + .byte 0 # EOM(1) + .byte 0 # EOM(2) + + .byte 2 # Abbreviation Code + .byte 57 # DW_TAG_namespace + .byte 1 # DW_CHILDREN_yes + .byte 3 # DW_AT_name + .byte 14 # DW_FORM_strp + .byte 0 # EOM(1) + .byte 0 # EOM(2) + + .byte 3 # Abbreviation Code + .byte 52 # DW_TAG_variable + .byte 0 # DW_CHILDREN_no + .byte 3 # DW_AT_name + .byte 14 # DW_FORM_strp + .byte 73 # DW_AT_type + .byte 19 # DW_FORM_ref4 + .byte 63 # DW_AT_external + .byte 25 # DW_FORM_flag_present + .byte 58 # DW_AT_decl_file + .byte 11 # DW_FORM_data1 + .byte 59 # DW_AT_decl_line + .byte 11 # DW_FORM_data1 + .byte 2 # DW_AT_location + .byte 24 # DW_FORM_exprloc + .byte 110 # DW_AT_linkage_name + .byte 14 # DW_FORM_strp + .byte 0 # EOM(1) + .byte 0 # EOM(2) + + .byte 4 # Abbreviation Code + .byte 36 # DW_TAG_base_type + .byte 0 # DW_CHILDREN_no + .byte 3 # DW_AT_name + .byte 14 # DW_FORM_strp + .byte 62 # DW_AT_encoding + .byte 11 # DW_FORM_data1 + .byte 11 # DW_AT_byte_size + .byte 11 # DW_FORM_data1 + .byte 0 # EOM(1) + .byte 0 # EOM(2) + .byte 0 # EOM(3) + + .section .debug_info,"",@progbits + .long 96 # Length of Unit + .short 4 # DWARF version number + .long .debug_abbrev # Offset Into Abbrev. Section + .byte 8 # Address Size (in bytes) + + .byte 1 # Abbrev [1] 0xb:0x59 DW_TAG_compile_unit + .long .Linfo_string0 # DW_AT_producer + .short 4 # DW_AT_language + .long .Linfo_string1 # DW_AT_name + .long 0 # DW_AT_stmt_list + .long .Linfo_string2 # DW_AT_comp_dir + # DW_AT_GNU_pubnames + + .byte 2 # Abbrev [2] 0x1e:0x1f DW_TAG_namespace + .long .Linfo_string3 # DW_AT_name + + .byte 3 # Abbrev [3] 0x23:0x19 DW_TAG_variable + .long .Linfo_string4 # DW_AT_name + .long 61 # DW_AT_type + # DW_AT_external + .byte 1 # DW_AT_decl_file + .byte 2 # DW_AT_decl_line + .byte 9 # DW_AT_location + .byte 3 + .quad _ZN1A3barE + .long .Linfo_string6 # DW_AT_linkage_name + .byte 0 # End Of Children Mark + + .byte 4 # Abbrev [4] 0x3d:0x7 DW_TAG_base_type + .long .Linfo_string5 # DW_AT_name + .byte 5 # DW_AT_encoding + .byte 4 # DW_AT_byte_size + + .byte 2 # Abbrev [2] 0x44:0x1f DW_TAG_namespace + .long .Linfo_string7 # DW_AT_name + + .byte 3 # Abbrev [3] 0x49:0x19 DW_TAG_variable + .long .Linfo_string4 # DW_AT_name + .long 61 # DW_AT_type + # DW_AT_external + .byte 1 # DW_AT_decl_file + .byte 6 # DW_AT_decl_line + .byte 9 # DW_AT_location + .byte 3 + .quad _ZN1Z3barE + .long .Linfo_string8 # DW_AT_linkage_name + + .byte 0 # End Of Children Mark + .byte 0 # End Of Children Mark