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[ELF] - Do not produce duplicate values in .gdb_index's constant pool area. 

I found this when builded llc binary using gcc 5.4.1 + LLD.
gcc produces duplicate entries in .debug_gnu_pubtypes section, ex:

UnifyFunctionExitNodes.cpp.o has:
0x0000ac07 EXTERNAL TYPE "std::success_type<void*>"
0x0000ac07 EXTERNAL TYPE "std::success_type<void*>"

clang produces single entry here:
0x0000d291 EXTERNAL TYPE "std::__success_type<void *>"

If we link output from gcc with LLD, that would produce excessive duplicate
entries in .gdb_index constant pool area. That does not seem affect gdb work,
but makes .gdb_index larger than it can be.

I also checked that gold filters out such duplicates too. Patch fixes it.

Differential revision: https://reviews.llvm.org/D32647

llvm-svn: 303975
This commit is contained in:
George Rimar 2017-05-26 12:09:26 +00:00
parent 9230610f0b
commit c1a0364cd6
3 changed files with 66 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
lld/ELF/SyntheticSections.cpp
View File

@ -1781,8 +1781,7 @@ void GdbIndexSection::readDwarf(InputSection *Sec) {
CuVectors.push_back({});
}
CuVectors[Sym->CuVectorIndex].push_back((Pair.second << 24) |
(uint32_t)CuId);
CuVectors[Sym->CuVectorIndex].insert(CuId | (Pair.second << 24));
}
}
@ -1806,7 +1805,7 @@ void GdbIndexSection::finalizeContents() {
ConstantPoolOffset =
SymTabOffset + SymbolTable.getCapacity() * SymTabEntrySize;
for (std::vector<uint32_t> &CuVec : CuVectors) {
for (std::set<uint32_t> &CuVec : CuVectors) {
CuVectorsOffset.push_back(CuVectorsSize);
CuVectorsSize += OffsetTypeSize * (CuVec.size() + 1);
}
@ -1859,7 +1858,7 @@ void GdbIndexSection::writeTo(uint8_t *Buf) {
}
// Write the CU vectors into the constant pool.
for (std::vector<uint32_t> &CuVec : CuVectors) {
for (std::set<uint32_t> &CuVec : CuVectors) {
write32le(Buf, CuVec.size());
Buf += 4;
for (uint32_t Val : CuVec) {

4
lld/ELF/SyntheticSections.h
View File

@ -27,6 +27,8 @@
#include "llvm/ADT/MapVector.h"
#include "llvm/MC/StringTableBuilder.h"
#include <set>
namespace lld {
namespace elf {
@ -515,7 +517,7 @@ public:
GdbHashTab SymbolTable;
// The CU vector portion of the constant pool.
std::vector<std::vector<uint32_t>> CuVectors;
std::vector<std::set<uint32_t>> CuVectors;
std::vector<AddressEntry> AddressArea;

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

@ -0,0 +1,60 @@
# 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 -debug-dump=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: