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Remove a workaround for an old GCC bug. 

This workaround is for GCC 5.4.1. Without this workaround, lld will
produce larger .gdb_index sections for object files compiled with the
buggy version of the compiler.

Since it is not for correctness, and it affects only debug builds (since
you are generating .gdb_index sections), perhaps the hack shouldn't have been
added in the first place. At least, I think it is time to remove this hack.

Differential Revision: https://reviews.llvm.org/D49149

llvm-svn: 336788
This commit is contained in:
Rui Ueyama 2018-07-11 10:52:00 +00:00
parent f6ff75c4c2
commit f51c853cf1
2 changed files with 1 additions and 65 deletions
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6
lld/ELF/SyntheticSections.cpp
View File

@ -2375,11 +2375,7 @@ createSymbols(ArrayRef<std::vector<GdbIndexSection::NameTypeEntry>> NameTypes) {
for (const NameTypeEntry &Ent : Entries) {
size_t &Idx = Map[Ent.Name];
if (Idx) {
// gcc 5.4.1 produces a buggy .debug_gnu_pubnames that contains
// duplicate entries, so we want to dedup them.
std::vector<uint32_t> &Vec = Ret[Idx - 1].CuVector;
if (Vec.empty() || Vec.back() != Ent.Type)
Vec.push_back(Ent.Type);
Ret[Idx - 1].CuVector.push_back(Ent.Type);
continue;
}

60
lld/test/ELF/gdb-index-dup-types.s
View File

@ -1,60 +0,0 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
# RUN: ld.lld --gdb-index %t.o -o %t
# RUN: llvm-dwarfdump -gdb-index %t | FileCheck %s
## Testcase is based on output produced by gcc version 5.4.1 20160904
## it has duplicate entries in .debug_gnu_pubtypes which seems to be
## compiler bug. In that case it is useless to have them in .gdb_index
## and we filter such entries out to reduce size of .gdb_index.
## CHECK: Constant pool offset = {{.*}}, has 1 CU vectors:
## CHECK-NOT: 0(0x0): 0x90000000 0x90000000
.section .debug_abbrev,"",@progbits
.byte 1 # Abbreviation Code
.byte 17 # DW_TAG_compile_unit
.byte 0 # DW_CHILDREN_no
.byte 16 # DW_AT_stmt_list
.byte 23 # DW_FORM_sec_offset
.ascii "\260B" # DW_AT_GNU_dwo_name
.byte 14 # DW_FORM_strp
.byte 27 # DW_AT_comp_dir
.byte 14 # DW_FORM_strp
.ascii "\264B" # DW_AT_GNU_pubnames
.byte 25 # DW_FORM_flag_present
.ascii "\261B" # DW_AT_GNU_dwo_id
.byte 7 # DW_FORM_data8
.ascii "\263B" # DW_AT_GNU_addr_base
.byte 23 # DW_FORM_sec_offset
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 0 # EOM(3)
.section .debug_info,"",@progbits
.Lcu_begin0:
.long 32 # 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:0x19 DW_TAG_compile_unit
.long 0 # DW_AT_stmt_list
.long 0 # DW_AT_GNU_dwo_name
.long 0 # DW_AT_comp_dir
.quad 0 # DW_AT_GNU_dwo_id
.long 0 # DW_AT_GNU_addr_base
.section .debug_gnu_pubtypes,"",@progbits
.long .LpubTypes_end0-.LpubTypes_begin0 # Length of Public Types Info
.LpubTypes_begin0:
.short 2 # DWARF Version
.long .Lcu_begin0 # Offset of Compilation Unit Info
.long 36 # Compilation Unit Length
.long 36 # DIE offset
.byte 144 # Kind: TYPE, STATIC
.asciz "int" # External Name
.long 36 # DIE offset
.byte 144 # Kind: TYPE, STATIC
.asciz "int" # External Name
.long 0 # End Mark
.LpubTypes_end0: