[ELF] --gdb-index: use lower_bound to compute relative CU index in the object file
Summary:
This reinstates what I originally intended to do in D54361.
It removes the assumption that .debug_gnu_pubnames has increasing CuOffset.
Now we do better than gold here: when .debug_gnu_pubnames contains
multiple sets, gold would think every set has the same CU index as the
first set (incorrect).
Reviewed By: ruiu
Reviewers: ruiu, dblaikie, espindola
Subscribers: emaste, arichardson, arphaman, llvm-commits
Differential Revision: https://reviews.llvm.org/D54483
git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@347820 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/ELF/SyntheticSections.cpp b/ELF/SyntheticSections.cpp
index c2eeaf5..a0dab23 100644
--- a/ELF/SyntheticSections.cpp
+++ b/ELF/SyntheticSections.cpp
@@ -2434,16 +2434,17 @@
std::vector<GdbIndexSection::NameAttrEntry> Ret;
for (const DWARFSection *Pub : {&PubNames, &PubTypes}) {
DWARFDebugPubTable Table(Obj, *Pub, Config->IsLE, true);
- uint32_t I = 0;
for (const DWARFDebugPubTable::Set &Set : Table.getData()) {
// The value written into the constant pool is Kind << 24 | CuIndex. As we
// don't know how many compilation units precede this object to compute
// CuIndex, we compute (Kind << 24 | CuIndexInThisObject) instead, and add
// the number of preceding compilation units later.
- //
- // We assume both CUs[*].CuOff and Set.Offset are increasing.
- while (I < CUs.size() && CUs[I].CuOffset < Set.Offset)
- ++I;
+ uint32_t I =
+ lower_bound(CUs, Set.Offset,
+ [](GdbIndexSection::CuEntry CU, uint32_t Offset) {
+ return CU.CuOffset < Offset;
+ }) -
+ CUs.begin();
for (const DWARFDebugPubTable::Entry &Ent : Set.Entries)
Ret.push_back({{Ent.Name, computeGdbHash(Ent.Name)},
(Ent.Descriptor.toBits() << 24) | I});
diff --git a/test/ELF/gdb-index-multiple-cu.s b/test/ELF/gdb-index-multiple-cu.s
index fc1d83e..9a8c2ea 100644
--- a/test/ELF/gdb-index-multiple-cu.s
+++ b/test/ELF/gdb-index-multiple-cu.s
@@ -3,20 +3,27 @@
# RUN: ld.lld --gdb-index %t.o -o %t
# RUN: llvm-dwarfdump -gdb-index %t | FileCheck %s
-# Attributes << 24 | CuIndex = 48 << 24 | 1 = 0x30000001
-# CHECK: Constant pool
-# CHECK-NEXT: 0(0x0): 0x30000001
+# CuIndexAndAttrs of _start:
+# Attributes << 24 | CuIndex = 48 << 24 | 0 = 0x30000000
+# CuIndexAndAttrs of foo:
+# Attributes << 24 | CuIndex = 48 << 24 | 1 = 0x30000001
+# CHECK: Symbol table
+# CHECK-DAG: String name: _start, CU vector index: 0
+# CHECK-DAG: String name: foo, CU vector index: 1
+# CHECK: Constant pool
+# CHECK-NEXT: 0(0x0): 0x30000000
+# CHECK-NEXT: 1(0x8): 0x30000001
-.globl _start
+.globl _start, foo
_start:
- ret
+foo:
.section .debug_abbrev,"",@progbits
.byte 1 # Abbreviation Code
.byte 17 # DW_TAG_compile_unit
.byte 1 # DW_CHILDREN_yes
.ascii "\264B" # DW_AT_GNU_pubnames
- .byte 12 # DW_FORM_flag
+ .byte 25 # DW_FORM_flag_present
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 2 # Abbreviation Code
@@ -34,8 +41,11 @@
.short 4 # DWARF version number
.long 0 # Offset Into Abbrev. Section
.byte 4 # Address Size
+.Ldie0:
.byte 1 # Abbrev [1] DW_TAG_compile_unit
- .byte 0 # DW_AT_GNU_pubnames
+ .byte 2 # Abbrev [2] DW_TAG_subprogram
+ .asciz "_start" # DW_AT_name
+ .byte 0
.byte 0
.Lcu_end0:
.Lcu_begin1:
@@ -43,23 +53,36 @@
.short 4 # DWARF version number
.long 0 # Offset Into Abbrev. Section
.byte 4 # Address Size
-.Ldie:
+.Ldie1:
.byte 1 # Abbrev [1] DW_TAG_compile_unit
- .byte 1 # DW_AT_GNU_pubnames
.byte 2 # Abbrev [2] DW_TAG_subprogram
- .asciz "_start" # DW_AT_name
+ .asciz "foo" # DW_AT_name
.byte 0
.Lcu_end1:
-# .debug_gnu_pubnames has just one set, associated with .Lcu_begin1 (CuIndex: 1)
+# Swap sets to test the case where pubnames are in a
+# different order than the CUs they refer to.
.section .debug_gnu_pubnames,"",@progbits
- .long .LpubNames_end1-.LpubNames_begin1
+ # CuIndex: 1
+ .long .LpubNames_end1 - .LpubNames_begin1
.LpubNames_begin1:
.short 2 # Version
.long .Lcu_begin1 # CU Offset
.long .Lcu_end1 - .Lcu_begin1
- .long .Ldie - .Lcu_begin1
+ .long .Ldie1 - .Lcu_begin1
+ .byte 48 # Attributes: FUNCTION, EXTERNAL
+ .asciz "foo" # External Name
+ .long 0
+.LpubNames_end1:
+
+ # CuIndex: 0
+ .long .LpubNames_end0 - .LpubNames_begin0
+.LpubNames_begin0:
+ .short 2 # Version
+ .long .Lcu_begin0 # CU Offset
+ .long .Lcu_end0 - .Lcu_begin0
+ .long .Ldie0 - .Lcu_begin0
.byte 48 # Attributes: FUNCTION, EXTERNAL
.asciz "_start" # External Name
.long 0
-.LpubNames_end1:
+.LpubNames_end0:
