ELF: --gdb-index: Do not add dead sections to the address area.

Fixes PR33032.

Differential Revision: https://reviews.llvm.org/D33175

llvm-svn: 303088

2 files changed, 158 insertions, 1 deletions

diff --git a/lld/ELF/SyntheticSections.cpp b/lld/ELF/SyntheticSections.cpp
index 3eebc4e7862..a42d1587cee 100644
--- a/lld/ELF/SyntheticSections.cpp
+++ b/lld/ELF/SyntheticSections.cpp
@@ -1704,7 +1704,7 @@ readCuList(DWARFContext &Dwarf, InputSection *Sec) {
 static InputSectionBase *findSection(ArrayRef<InputSectionBase *> Arr,
                                      uint64_t Offset) {
   for (InputSectionBase *S : Arr)
-    if (S && S != &InputSection::Discarded)
+    if (S && S != &InputSection::Discarded && S->Live)
       if (Offset >= S->getOffsetInFile() &&
           Offset < S->getOffsetInFile() + S->getSize())
         return S;
diff --git a/lld/test/ELF/gdb-index-gc-sections.s b/lld/test/ELF/gdb-index-gc-sections.s
new file mode 100644
index 00000000000..70a14754656
--- /dev/null
+++ b/lld/test/ELF/gdb-index-gc-sections.s
@@ -0,0 +1,157 @@
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux -o %t %s
+# RUN: ld.lld --gdb-index --gc-sections -o %t2 %t
+# RUN: llvm-dwarfdump -debug-dump=gdb_index %t2 | FileCheck %s
+
+# CHECK: Address area offset = 0x28, has 1 entries:
+# CHECK-NEXT:    Low/High address = [0x201000, 0x201001) (Size: 0x1), CU id = 0
+
+# Generated with: (clang r302976)
+# echo "void _start() {} void dead() {}" | \
+# clang -Os -g -S -ffunction-sections -o gdb-index-gc-sections.s -x c - -Xclang -fdebug-compilation-dir -Xclang .
+
+	.text
+	.file	"-"
+	.section	.text._start,"ax",@progbits
+	.globl	_start
+	.type	_start,@function
+_start:                                 # @_start
+.Lfunc_begin0:
+	.file	1 "<stdin>"
+	.loc	1 1 0                   # <stdin>:1:0
+	.cfi_startproc
+# BB#0:                                 # %entry
+	.loc	1 1 16 prologue_end     # <stdin>:1:16
+	retq
+.Ltmp0:
+.Lfunc_end0:
+	.size	_start, .Lfunc_end0-_start
+	.cfi_endproc
+
+	.section	.text.dead,"ax",@progbits
+	.globl	dead
+	.type	dead,@function
+dead:                                   # @dead
+.Lfunc_begin1:
+	.loc	1 1 0                   # <stdin>:1:0
+	.cfi_startproc
+# BB#0:                                 # %entry
+	.loc	1 1 31 prologue_end     # <stdin>:1:31
+	retq
+.Ltmp1:
+.Lfunc_end1:
+	.size	dead, .Lfunc_end1-dead
+	.cfi_endproc
+
+	.section	.debug_str,"MS",@progbits,1
+.Linfo_string0:
+	.asciz	"clang version 5.0.0 "  # string offset=0
+.Linfo_string1:
+	.asciz	"-"                     # string offset=21
+.Linfo_string2:
+	.asciz	"."                     # string offset=23
+.Linfo_string3:
+	.asciz	"_start"                # string offset=25
+.Linfo_string4:
+	.asciz	"dead"                  # string offset=32
+	.section	.debug_loc,"",@progbits
+	.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
+	.byte	17                      # DW_AT_low_pc
+	.byte	1                       # DW_FORM_addr
+	.byte	85                      # DW_AT_ranges
+	.byte	23                      # DW_FORM_sec_offset
+	.byte	0                       # EOM(1)
+	.byte	0                       # EOM(2)
+	.byte	2                       # Abbreviation Code
+	.byte	46                      # DW_TAG_subprogram
+	.byte	0                       # DW_CHILDREN_no
+	.byte	17                      # DW_AT_low_pc
+	.byte	1                       # DW_FORM_addr
+	.byte	18                      # DW_AT_high_pc
+	.byte	6                       # DW_FORM_data4
+	.byte	64                      # DW_AT_frame_base
+	.byte	24                      # DW_FORM_exprloc
+	.byte	3                       # DW_AT_name
+	.byte	14                      # DW_FORM_strp
+	.byte	58                      # DW_AT_decl_file
+	.byte	11                      # DW_FORM_data1
+	.byte	59                      # DW_AT_decl_line
+	.byte	11                      # DW_FORM_data1
+	.byte	63                      # DW_AT_external
+	.byte	25                      # DW_FORM_flag_present
+	.byte	0                       # EOM(1)
+	.byte	0                       # EOM(2)
+	.byte	0                       # EOM(3)
+	.section	.debug_info,"",@progbits
+.Lcu_begin0:
+	.long	81                      # 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:0x4a DW_TAG_compile_unit
+	.long	.Linfo_string0          # DW_AT_producer
+	.short	12                      # DW_AT_language
+	.long	.Linfo_string1          # DW_AT_name
+	.long	.Lline_table_start0     # DW_AT_stmt_list
+	.long	.Linfo_string2          # DW_AT_comp_dir
+	.quad	0                       # DW_AT_low_pc
+	.long	.Ldebug_ranges0         # DW_AT_ranges
+	.byte	2                       # Abbrev [2] 0x2a:0x15 DW_TAG_subprogram
+	.quad	.Lfunc_begin0           # DW_AT_low_pc
+	.long	.Lfunc_end0-.Lfunc_begin0 # DW_AT_high_pc
+	.byte	1                       # DW_AT_frame_base
+	.byte	87
+	.long	.Linfo_string3          # DW_AT_name
+	.byte	1                       # DW_AT_decl_file
+	.byte	1                       # DW_AT_decl_line
+                                        # DW_AT_external
+	.byte	2                       # Abbrev [2] 0x3f:0x15 DW_TAG_subprogram
+	.quad	.Lfunc_begin1           # DW_AT_low_pc
+	.long	.Lfunc_end1-.Lfunc_begin1 # DW_AT_high_pc
+	.byte	1                       # DW_AT_frame_base
+	.byte	87
+	.long	.Linfo_string4          # DW_AT_name
+	.byte	1                       # DW_AT_decl_file
+	.byte	1                       # DW_AT_decl_line
+                                        # DW_AT_external
+	.byte	0                       # End Of Children Mark
+	.section	.debug_ranges,"",@progbits
+.Ldebug_ranges0:
+	.quad	.Lfunc_begin0
+	.quad	.Lfunc_end0
+	.quad	.Lfunc_begin1
+	.quad	.Lfunc_end1
+	.quad	0
+	.quad	0
+	.section	.debug_macinfo,"",@progbits
+.Lcu_macro_begin0:
+	.byte	0                       # End Of Macro List Mark
+	.section	.debug_pubnames,"",@progbits
+	.long	.LpubNames_end0-.LpubNames_begin0 # Length of Public Names Info
+.LpubNames_begin0:
+	.short	2                       # DWARF Version
+	.long	.Lcu_begin0             # Offset of Compilation Unit Info
+	.long	85                      # Compilation Unit Length
+	.long	42                      # DIE offset
+	.asciz	"_start"                # External Name
+	.long	63                      # DIE offset
+	.asciz	"dead"                  # External Name
+	.long	0                       # End Mark
+.LpubNames_end0:
+
+	.ident	"clang version 5.0.0 "
+	.section	".note.GNU-stack","",@progbits
+	.section	.debug_line,"",@progbits
+.Lline_table_start0: