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[ELF] Improve undefined symbol message w/ DW_TAG_variable of the enclosing symbol but w/o line number information #70854

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Merged
merged 1 commit into from
Nov 3, 2023
Merged

[ELF] Improve undefined symbol message w/ DW_TAG_variable of the enclosing symbol but w/o line number information #70854

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5 changes: 4 additions & 1 deletion lld/ELF/Relocations.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -739,7 +739,10 @@ static void reportUndefinedSymbol(const UndefinedDiag &undef,
uint64_t offset = l.offset;

msg += "\n>>> referenced by ";
std::string src = sec.getSrcMsg(sym, offset);
// In the absence of line number information, utilize DW_TAG_variable (if
// present) for the enclosing symbol (e.g. var in `int *a[] = {&undef};`).
Symbol *enclosing = sec.getEnclosingSymbol(offset);
std::string src = sec.getSrcMsg(enclosing ? *enclosing : sym, offset);
if (!src.empty())
msg += src + "\n>>> ";
msg += sec.getObjMsg(offset);
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1 change: 1 addition & 0 deletions lld/test/ELF/Inputs/undef-debug.s
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
## Variables with line number information
.file 1 "dir/undef-debug.s"
.loc 1 3
.quad zed3
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200 changes: 200 additions & 0 deletions lld/test/ELF/Inputs/undef-debug2.s
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Original file line number Diff line number Diff line change
@@ -0,0 +1,200 @@
## Generate from:
##
## extern int zed9;
## namespace ns {
## int *var[] = {
## &zed9
## };
## }
.text
.file "undef-debug2.cc"
.file 0 "dir" "undef-debug2.cc" md5 0xd7caefb836c47f6c56303f19e96f2587
.type _ZN2ns3varE,@object # @_ZN2ns3varE
.data
.globl _ZN2ns3varE
.p2align 3, 0x0
_ZN2ns3varE:
.quad zed9
.size _ZN2ns3varE, 8

.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 37 # DW_FORM_strx1
.byte 19 # DW_AT_language
.byte 5 # DW_FORM_data2
.byte 3 # DW_AT_name
.byte 37 # DW_FORM_strx1
.byte 114 # DW_AT_str_offsets_base
.byte 23 # DW_FORM_sec_offset
.byte 16 # DW_AT_stmt_list
.byte 23 # DW_FORM_sec_offset
.byte 27 # DW_AT_comp_dir
.byte 37 # DW_FORM_strx1
.byte 115 # DW_AT_addr_base
.byte 23 # DW_FORM_sec_offset
.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 37 # DW_FORM_strx1
.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 37 # DW_FORM_strx1
.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 37 # DW_FORM_strx1
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 4 # Abbreviation Code
.byte 1 # DW_TAG_array_type
.byte 1 # DW_CHILDREN_yes
.byte 73 # DW_AT_type
.byte 19 # DW_FORM_ref4
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 5 # Abbreviation Code
.byte 33 # DW_TAG_subrange_type
.byte 0 # DW_CHILDREN_no
.byte 73 # DW_AT_type
.byte 19 # DW_FORM_ref4
.byte 55 # DW_AT_count
.byte 11 # DW_FORM_data1
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 6 # Abbreviation Code
.byte 15 # DW_TAG_pointer_type
.byte 0 # DW_CHILDREN_no
.byte 73 # DW_AT_type
.byte 19 # DW_FORM_ref4
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 7 # Abbreviation Code
.byte 36 # DW_TAG_base_type
.byte 0 # DW_CHILDREN_no
.byte 3 # DW_AT_name
.byte 37 # DW_FORM_strx1
.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 8 # Abbreviation Code
.byte 36 # DW_TAG_base_type
.byte 0 # DW_CHILDREN_no
.byte 3 # DW_AT_name
.byte 37 # DW_FORM_strx1
.byte 11 # DW_AT_byte_size
.byte 11 # DW_FORM_data1
.byte 62 # DW_AT_encoding
.byte 11 # DW_FORM_data1
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 0 # EOM(3)
.section .debug_info,"",@progbits
.Lcu_begin0:
.long .Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
.Ldebug_info_start0:
.short 5 # DWARF version number
.byte 1 # DWARF Unit Type
.byte 8 # Address Size (in bytes)
.long .debug_abbrev # Offset Into Abbrev. Section
.byte 1 # Abbrev [1] 0xc:0x3b DW_TAG_compile_unit
.byte 0 # DW_AT_producer
.short 33 # DW_AT_language
.byte 1 # DW_AT_name
.long .Lstr_offsets_base0 # DW_AT_str_offsets_base
.long .Lline_table_start0 # DW_AT_stmt_list
.byte 2 # DW_AT_comp_dir
.long .Laddr_table_base0 # DW_AT_addr_base
.byte 2 # Abbrev [2] 0x1e:0xf DW_TAG_namespace
.byte 3 # DW_AT_name
.byte 3 # Abbrev [3] 0x20:0xc DW_TAG_variable
.byte 4 # DW_AT_name
.long 45 # DW_AT_type
# DW_AT_external
.byte 0 # DW_AT_decl_file
.byte 3 # DW_AT_decl_line
.byte 2 # DW_AT_location
.byte 161
.byte 0
.byte 7 # DW_AT_linkage_name
.byte 0 # End Of Children Mark
.byte 4 # Abbrev [4] 0x2d:0xc DW_TAG_array_type
.long 57 # DW_AT_type
.byte 5 # Abbrev [5] 0x32:0x6 DW_TAG_subrange_type
.long 66 # DW_AT_type
.byte 1 # DW_AT_count
.byte 0 # End Of Children Mark
.byte 6 # Abbrev [6] 0x39:0x5 DW_TAG_pointer_type
.long 62 # DW_AT_type
.byte 7 # Abbrev [7] 0x3e:0x4 DW_TAG_base_type
.byte 5 # DW_AT_name
.byte 5 # DW_AT_encoding
.byte 4 # DW_AT_byte_size
.byte 8 # Abbrev [8] 0x42:0x4 DW_TAG_base_type
.byte 6 # DW_AT_name
.byte 8 # DW_AT_byte_size
.byte 7 # DW_AT_encoding
.byte 0 # End Of Children Mark
.Ldebug_info_end0:
.section .debug_str_offsets,"",@progbits
.long 36 # Length of String Offsets Set
.short 5
.short 0
.Lstr_offsets_base0:
.section .debug_str,"MS",@progbits,1
.Linfo_string0:
.asciz "clang version 18.0.0" # string offset=0
.Linfo_string1:
.asciz "undef-debug2.cc" # string offset=21
.Linfo_string2:
.asciz "dir" # string offset=37
.Linfo_string3:
.asciz "ns" # string offset=44
.Linfo_string4:
.asciz "var" # string offset=47
.Linfo_string5:
.asciz "int" # string offset=51
.Linfo_string6:
.asciz "__ARRAY_SIZE_TYPE__" # string offset=55
.Linfo_string7:
.asciz "_ZN2ns3varE" # string offset=75
.section .debug_str_offsets,"",@progbits
.long .Linfo_string0
.long .Linfo_string1
.long .Linfo_string2
.long .Linfo_string3
.long .Linfo_string4
.long .Linfo_string5
.long .Linfo_string6
.long .Linfo_string7
.section .debug_addr,"",@progbits
.long .Ldebug_addr_end0-.Ldebug_addr_start0 # Length of contribution
.Ldebug_addr_start0:
.short 5 # DWARF version number
.byte 8 # Address size
.byte 0 # Segment selector size
.Laddr_table_base0:
.quad _ZN2ns3varE
.Ldebug_addr_end0:
.section .debug_line,"",@progbits
.Lline_table_start0:
9 changes: 7 additions & 2 deletions lld/test/ELF/undef.s
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Original file line number Diff line number Diff line change
Expand Up @@ -3,11 +3,12 @@
# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/undef.s -o %t2.o
# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/undef-debug.s -o %t3.o
# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/undef-bad-debug.s -o %t4.o
# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/undef-debug2.s -o %t5.o
# RUN: rm -f %t2.a
# RUN: llvm-ar rc %t2.a %t2.o
# RUN: not ld.lld --threads=1 %t.o %t2.a %t3.o %t4.o -o /dev/null 2>&1 \
# RUN: not ld.lld --threads=1 %t.o %t2.a %t3.o %t4.o %t5.o -o /dev/null 2>&1 \
# RUN: | FileCheck %s --implicit-check-not="error:" --implicit-check-not="warning:"
# RUN: not ld.lld --threads=1 -pie %t.o %t2.a %t3.o %t4.o -o /dev/null 2>&1 \
# RUN: not ld.lld --threads=1 -pie %t.o %t2.a %t3.o %t4.o %t5.o -o /dev/null 2>&1 \
# RUN: | FileCheck %s --implicit-check-not="error:" --implicit-check-not="warning:"

# CHECK: error: undefined symbol: foo
Expand Down Expand Up @@ -82,6 +83,10 @@
# CHECK-NEXT: >>> referenced by undef-bad-debug2.s:11 (dir2{{/|\\}}undef-bad-debug2.s:11)
# CHECK-NEXT: >>> {{.*}}tmp4.o:(.text+0x18)

# CHECK: error: undefined symbol: zed9
# CHECK-NEXT: >>> referenced by undef-debug2.cc:3 (dir{{/|\\}}undef-debug2.cc:3)
# CHECK-NEXT: >>> {{.*}}tmp5.o:(ns::var)

# RUN: not ld.lld %t.o %t2.a -o /dev/null -no-demangle 2>&1 | \
# RUN: FileCheck -check-prefix=NO-DEMANGLE %s
# NO-DEMANGLE: error: undefined symbol: _Z3fooi
Expand Down