<div dir="ltr">I'm not sure it's really necessary to test the dwarfdump - if we're assuming/modelling these sort of tests as "MC is trivially correct" (ie: we're not testing MC here, using it as a convenient tool for generating binary inputs) then there's no need to test its output here & I'd probably skip that testing here. MC is already tested elsewhere.</div><br><div class="gmail_quote"><div dir="ltr">On Mon, Jun 4, 2018 at 3:32 AM George Rimar via llvm-commits <<a href="mailto:llvm-commits@lists.llvm.org">llvm-commits@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: grimar<br>
Date: Mon Jun 4 03:28:45 2018<br>
New Revision: 333880<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=333880&view=rev" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project?rev=333880&view=rev</a><br>
Log:<br>
[ELF] - Also use DW_AT_linkage_name when gathering information about variables for error messages.<br>
<br>
Currently, when LLD do a lookup for variables location, it uses DW_AT_name attribute.<br>
That is not always enough.<br>
<br>
Imagine code:<br>
<br>
namespace A {<br>
int bar = 0;<br>
}<br>
<br>
namespace Z {<br>
int bar = 1;<br>
}<br>
<br>
int hoho;<br>
In this case there are 3 variables and their debug attributes are following:<br>
<br>
A::bar has: DW_AT_name [DW_FORM_string] ("bar") DW_AT_linkage_name [DW_FORM_strp] ( .debug_str[0x00000006] = "_ZN1A3barE")<br>
Z::bar has: DW_AT_name [DW_FORM_string] ("bar") DW_AT_linkage_name [DW_FORM_strp] ( .debug_str[0x0000003f] = "_ZN1Z3barE")<br>
hoho has: DW_AT_name [DW_FORM_strp] ( .debug_str[0x0000004a] = "hoho") and has NO DW_AT_linkage_name attribute. Because it would be<br>
the same as DW_AT_name and DWARF producers avoids emiting excessive data.<br>
<br>
Hence LLD should also use DW_AT_linkage_name when it is available.<br>
(currently, LLD fails to report location correctly because thinks that A::bar and Z::bar are the same things)<br>
<br>
Differential revision: <a href="https://reviews.llvm.org/D47373" rel="noreferrer" target="_blank">https://reviews.llvm.org/D47373</a><br>
<br>
Added:<br>
lld/trunk/test/ELF/conflict-variable-linkage-name.s<br>
Modified:<br>
lld/trunk/ELF/InputFiles.cpp<br>
<br>
Modified: lld/trunk/ELF/InputFiles.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputFiles.cpp?rev=333880&r1=333879&r2=333880&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/InputFiles.cpp?rev=333880&r1=333879&r2=333880&view=diff</a><br>
==============================================================================<br>
--- lld/trunk/ELF/InputFiles.cpp (original)<br>
+++ lld/trunk/ELF/InputFiles.cpp Mon Jun 4 03:28:45 2018<br>
@@ -167,10 +167,15 @@ template <class ELFT> void ObjFile<ELFT><br>
// Get the line number on which the variable is declared.<br>
unsigned Line = dwarf::toUnsigned(Die.find(dwarf::DW_AT_decl_line), 0);<br>
<br>
- // Get the name of the variable and add the collected information to<br>
- // VariableLoc. Usually Name is non-empty, but it can be empty if the<br>
+ // Here we want to take the variable name to add it into VariableLoc.<br>
+ // Variable can have regular and linkage name associated. At first, we try<br>
+ // to get linkage name as it can be different, for example when we have<br>
+ // two variables in different namespaces of the same object. Use common<br>
+ // name otherwise, but handle the case when it also absent in case if the<br>
// input object file lacks some debug info.<br>
- StringRef Name = dwarf::toString(Die.find(dwarf::DW_AT_name), "");<br>
+ StringRef Name =<br>
+ dwarf::toString(Die.find(dwarf::DW_AT_linkage_name),<br>
+ dwarf::toString(Die.find(dwarf::DW_AT_name), ""));<br>
if (!Name.empty())<br>
VariableLoc.insert({Name, {LT, File, Line}});<br>
}<br>
<br>
Added: lld/trunk/test/ELF/conflict-variable-linkage-name.s<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/conflict-variable-linkage-name.s?rev=333880&view=auto" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/conflict-variable-linkage-name.s?rev=333880&view=auto</a><br>
==============================================================================<br>
--- lld/trunk/test/ELF/conflict-variable-linkage-name.s (added)<br>
+++ lld/trunk/test/ELF/conflict-variable-linkage-name.s Mon Jun 4 03:28:45 2018<br>
@@ -0,0 +1,193 @@<br>
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o<br>
+# RUN: llvm-dwarfdump %t.o | FileCheck -check-prefix=INPUT %s<br>
+# RUN: not ld.lld %t.o %t.o -o %t 2>&1 | FileCheck %s<br>
+<br>
+# INPUT: DW_TAG_variable<br>
+# INPUT-NEXT: DW_AT_name ("bar")<br>
+# INPUT-NEXT: DW_AT_type (0x0000003d "int")<br>
+# INPUT-NEXT: DW_AT_external (true)<br>
+# INPUT-NEXT: DW_AT_decl_file ("/path\1.cpp")<br>
+# INPUT-NEXT: DW_AT_decl_line (2)<br>
+# INPUT-NEXT: DW_AT_location (DW_OP_addr 0x0)<br>
+# INPUT-NEXT: DW_AT_linkage_name ("_ZN1A3barE")<br>
+# INPUT: DW_TAG_variable<br>
+# INPUT-NEXT: DW_AT_name ("bar")<br>
+# INPUT-NEXT: DW_AT_type (0x0000003d "int")<br>
+# INPUT-NEXT: DW_AT_external (true)<br>
+# INPUT-NEXT: DW_AT_decl_file ("/path\1.cpp")<br>
+# INPUT-NEXT: DW_AT_decl_line (6)<br>
+# INPUT-NEXT: DW_AT_location (DW_OP_addr 0x0)<br>
+# INPUT-NEXT: DW_AT_linkage_name ("_ZN1Z3barE")<br>
+<br>
+## Check we can report the locations of 2 different "bar" variables.<br>
+# CHECK: duplicate symbol: A::bar<br>
+# CHECK-NEXT: >>> defined at 1.cpp:2<br>
+# CHECK-NEXT: >>> {{.*}}:(A::bar)<br>
+# CHECK-NEXT: >>> defined at 1.cpp:2<br>
+# CHECK-NEXT: >>> {{.*}}:(.bss+0x0)<br>
+# CHECK: duplicate symbol: Z::bar<br>
+# CHECK-NEXT: >>> defined at 1.cpp:6<br>
+# CHECK-NEXT: >>> {{.*}}:(Z::bar)<br>
+# CHECK-NEXT: >>> defined at 1.cpp:6<br>
+# CHECK-NEXT: >>> {{.*}}:(.data+0x0)<br>
+<br>
+# Used reduced output from following code and clang version 7.0.0 (trunk 332701)<br>
+# to produce this input file:<br>
+# Source (1.cpp):<br>
+# namespace A {<br>
+# int bar;<br>
+# }<br>
+# <br>
+# namespace Z {<br>
+# int bar;<br>
+# }<br>
+# Invocation: clang-7 -g -S 1.cpp<br>
+<br>
+.text<br>
+.file "1.cpp"<br>
+.file 1 "/path" "1.cpp"<br>
+<br>
+.type _ZN1A3barE,@object<br>
+.bss<br>
+.globl _ZN1A3barE<br>
+_ZN1A3barE:<br>
+ .long 0<br>
+ .size _ZN1A3barE, 4<br>
+<br>
+.type _ZN1Z3barE,@object<br>
+.data<br>
+.globl _ZN1Z3barE<br>
+_ZN1Z3barE:<br>
+ .long 1<br>
+ .size _ZN1Z3barE, 4<br>
+<br>
+.section .debug_str,"MS",@progbits,1<br>
+.Linfo_string0:<br>
+ .asciz "clang version 7.0.0 (trunk 332701)" # string offset=0<br>
+.Linfo_string1:<br>
+ .asciz "1.cpp" # string offset=35<br>
+.Linfo_string2:<br>
+ .asciz "/path" # string offset=41<br>
+.Linfo_string3:<br>
+ .asciz "A" # string offset=87<br>
+.Linfo_string4:<br>
+ .asciz "bar" # string offset=89<br>
+.Linfo_string5:<br>
+ .asciz "int" # string offset=93<br>
+.Linfo_string6:<br>
+ .asciz "_ZN1A3barE" # string offset=97<br>
+.Linfo_string7:<br>
+ .asciz "Z" # string offset=108<br>
+.Linfo_string8:<br>
+ .asciz "_ZN1Z3barE" # string offset=110<br>
+<br>
+.section .debug_abbrev,"",@progbits<br>
+ .byte 1 # Abbreviation Code<br>
+ .byte 17 # DW_TAG_compile_unit<br>
+ .byte 1 # DW_CHILDREN_yes<br>
+ .byte 37 # DW_AT_producer<br>
+ .byte 14 # DW_FORM_strp<br>
+ .byte 19 # DW_AT_language<br>
+ .byte 5 # DW_FORM_data2<br>
+ .byte 3 # DW_AT_name<br>
+ .byte 14 # DW_FORM_strp<br>
+ .byte 16 # DW_AT_stmt_list<br>
+ .byte 23 # DW_FORM_sec_offset<br>
+ .byte 27 # DW_AT_comp_dir<br>
+ .byte 14 # DW_FORM_strp<br>
+ .ascii "\264B" # DW_AT_GNU_pubnames<br>
+ .byte 25 # DW_FORM_flag_present<br>
+ .byte 0 # EOM(1)<br>
+ .byte 0 # EOM(2)<br>
+ <br>
+ .byte 2 # Abbreviation Code<br>
+ .byte 57 # DW_TAG_namespace<br>
+ .byte 1 # DW_CHILDREN_yes<br>
+ .byte 3 # DW_AT_name<br>
+ .byte 14 # DW_FORM_strp<br>
+ .byte 0 # EOM(1)<br>
+ .byte 0 # EOM(2)<br>
+ <br>
+ .byte 3 # Abbreviation Code<br>
+ .byte 52 # DW_TAG_variable<br>
+ .byte 0 # DW_CHILDREN_no<br>
+ .byte 3 # DW_AT_name<br>
+ .byte 14 # DW_FORM_strp<br>
+ .byte 73 # DW_AT_type<br>
+ .byte 19 # DW_FORM_ref4<br>
+ .byte 63 # DW_AT_external<br>
+ .byte 25 # DW_FORM_flag_present<br>
+ .byte 58 # DW_AT_decl_file<br>
+ .byte 11 # DW_FORM_data1<br>
+ .byte 59 # DW_AT_decl_line<br>
+ .byte 11 # DW_FORM_data1<br>
+ .byte 2 # DW_AT_location<br>
+ .byte 24 # DW_FORM_exprloc<br>
+ .byte 110 # DW_AT_linkage_name<br>
+ .byte 14 # DW_FORM_strp<br>
+ .byte 0 # EOM(1)<br>
+ .byte 0 # EOM(2)<br>
+ <br>
+ .byte 4 # Abbreviation Code<br>
+ .byte 36 # DW_TAG_base_type<br>
+ .byte 0 # DW_CHILDREN_no<br>
+ .byte 3 # DW_AT_name<br>
+ .byte 14 # DW_FORM_strp<br>
+ .byte 62 # DW_AT_encoding<br>
+ .byte 11 # DW_FORM_data1<br>
+ .byte 11 # DW_AT_byte_size<br>
+ .byte 11 # DW_FORM_data1<br>
+ .byte 0 # EOM(1)<br>
+ .byte 0 # EOM(2)<br>
+ .byte 0 # EOM(3)<br>
+<br>
+ .section .debug_info,"",@progbits<br>
+ .long 96 # Length of Unit<br>
+ .short 4 # DWARF version number<br>
+ .long .debug_abbrev # Offset Into Abbrev. Section<br>
+ .byte 8 # Address Size (in bytes)<br>
+ <br>
+ .byte 1 # Abbrev [1] 0xb:0x59 DW_TAG_compile_unit<br>
+ .long .Linfo_string0 # DW_AT_producer<br>
+ .short 4 # DW_AT_language<br>
+ .long .Linfo_string1 # DW_AT_name<br>
+ .long 0 # DW_AT_stmt_list<br>
+ .long .Linfo_string2 # DW_AT_comp_dir<br>
+ # DW_AT_GNU_pubnames<br>
+<br>
+ .byte 2 # Abbrev [2] 0x1e:0x1f DW_TAG_namespace<br>
+ .long .Linfo_string3 # DW_AT_name<br>
+ <br>
+ .byte 3 # Abbrev [3] 0x23:0x19 DW_TAG_variable<br>
+ .long .Linfo_string4 # DW_AT_name<br>
+ .long 61 # DW_AT_type<br>
+ # DW_AT_external<br>
+ .byte 1 # DW_AT_decl_file<br>
+ .byte 2 # DW_AT_decl_line<br>
+ .byte 9 # DW_AT_location<br>
+ .byte 3<br>
+ .quad _ZN1A3barE<br>
+ .long .Linfo_string6 # DW_AT_linkage_name<br>
+ .byte 0 # End Of Children Mark<br>
+ <br>
+ .byte 4 # Abbrev [4] 0x3d:0x7 DW_TAG_base_type<br>
+ .long .Linfo_string5 # DW_AT_name<br>
+ .byte 5 # DW_AT_encoding<br>
+ .byte 4 # DW_AT_byte_size<br>
+ <br>
+ .byte 2 # Abbrev [2] 0x44:0x1f DW_TAG_namespace<br>
+ .long .Linfo_string7 # DW_AT_name<br>
+ <br>
+ .byte 3 # Abbrev [3] 0x49:0x19 DW_TAG_variable<br>
+ .long .Linfo_string4 # DW_AT_name<br>
+ .long 61 # DW_AT_type<br>
+ # DW_AT_external<br>
+ .byte 1 # DW_AT_decl_file<br>
+ .byte 6 # DW_AT_decl_line<br>
+ .byte 9 # DW_AT_location<br>
+ .byte 3<br>
+ .quad _ZN1Z3barE<br>
+ .long .Linfo_string8 # DW_AT_linkage_name<br>
+ <br>
+ .byte 0 # End Of Children Mark<br>
+ .byte 0 # End Of Children Mark<br>
<br>
<br>
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</blockquote></div>