[llvm] [LLVM][DWARF] Add compilation directory and dwo name to TU in dwo section (PR #74909)
Alexander Yermolovich via llvm-commits
llvm-commits at lists.llvm.org
Mon Dec 11 17:12:29 PST 2023
https://github.com/ayermolo updated https://github.com/llvm/llvm-project/pull/74909
>From 0bc7e2c8609050fe2b24857aff5826b9d5f392b1 Mon Sep 17 00:00:00 2001
From: Alexander Yermolovich <ayermolo at meta.com>
Date: Fri, 8 Dec 2023 17:29:02 -0800
Subject: [PATCH 1/3] [LLVM][DWARF] Add compilation directory and dwo name to
TU in dwo section
This adds support to help LLDB when binary is built with split dwarf, has
.debug_names accelerator table and DWP file.
Final linked binary might have Type Units (TUs) with the same type signature in multiple
compilation units. Although the signature is the same, TUs are not guranted to
be bit identical. This is not a problem when they are in .o/.dwo files as LLDB
can find them by looking at the right one based on DW_AT_comp_dir/DW_AT_name in
skeleton CU. Once DWP is created, TUs are de-duplicated, and we need to know
from which CU remaining one came from.
This approach allows LLDB to figure it out, with minimal changes to the rest of
the tooling. As would have been the case if .debug-tu-index section in DWP was
modified.
---
llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp | 6 +++++
llvm/test/CodeGen/X86/dwarf-headers.ll | 6 ++---
llvm/test/DebugInfo/X86/debug-names-types.ll | 28 ++++++++++++++++++--
3 files changed, 35 insertions(+), 5 deletions(-)
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index ab29020bf1d7bb..1db295cd76536a 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -3478,6 +3478,12 @@ void DwarfDebug::addDwarfTypeUnitType(DwarfCompileUnit &CU,
Ins.first->second = Signature;
if (useSplitDwarf()) {
+ if (getDwarfVersion() >= 5) {
+ if (!CompilationDir.empty())
+ NewTU.addString(UnitDie, dwarf::DW_AT_comp_dir, CompilationDir);
+ NewTU.addString(UnitDie, dwarf::DW_AT_dwo_name,
+ Asm->TM.Options.MCOptions.SplitDwarfFile);
+ }
MCSection *Section =
getDwarfVersion() <= 4
? Asm->getObjFileLowering().getDwarfTypesDWOSection()
diff --git a/llvm/test/CodeGen/X86/dwarf-headers.ll b/llvm/test/CodeGen/X86/dwarf-headers.ll
index 4c029de5dbfa17..3a3d9998659b2b 100644
--- a/llvm/test/CodeGen/X86/dwarf-headers.ll
+++ b/llvm/test/CodeGen/X86/dwarf-headers.ll
@@ -75,14 +75,14 @@
; O-5: .debug_info contents:
; O-5: 0x00000000: Compile Unit: {{.*}} version = 0x0005, unit_type = DW_UT_skeleton, abbr_offset
; O-5-SAME: DWO_id = 0xccd7e58ef8bf4aa6
-; O-5: 0x00000014: DW_TAG_skeleton_unit
+; O-5: 0x00000014: DW_TAG_skeleton_unit
;
; DWO-5: .debug_info.dwo contents:
; DWO-5: 0x00000000: Type Unit: {{.*}} version = 0x0005, unit_type = DW_UT_split_type, abbr_offset
; DWO-5: 0x00000018: DW_TAG_type_unit
-; DWO-5: 0x00000033: Compile Unit: {{.*}} version = 0x0005, unit_type = DW_UT_split_compile, abbr_offset
+; DWO-5: 0x00000035: Compile Unit: {{.*}} version = 0x0005, unit_type = DW_UT_split_compile, abbr_offset
; DWO-5-SAME: DWO_id = 0xccd7e58ef8bf4aa6
-; DWO-5: 0x00000047: DW_TAG_compile_unit
+; DWO-5: 0x00000049: DW_TAG_compile_unit
; ModuleID = 't.cpp'
diff --git a/llvm/test/DebugInfo/X86/debug-names-types.ll b/llvm/test/DebugInfo/X86/debug-names-types.ll
index d32691305d1c10..5617c2cafc6f09 100644
--- a/llvm/test/DebugInfo/X86/debug-names-types.ll
+++ b/llvm/test/DebugInfo/X86/debug-names-types.ll
@@ -1,5 +1,6 @@
; UNSUPPORTED: system-windows
; This checks that .debug_names can be generated with monolithic, and split-dwarf, when -fdebug-type-sections is enabled.
+; It also checks that TU in .debug_info.dwo has correct DW_AT_comp_dir and DW_AT_dwo_name.
; Generated with: clang++ main.cpp -g2 -gdwarf-5 -gpubnames -fdebug-types-section
; RUN: llc -mtriple=x86_64 -generate-type-units -dwarf-version=5 -filetype=obj %s -o %t
@@ -171,7 +172,7 @@
; CHECK-SPLIT-NEXT: Abbrev: [[ABBREV1]]
; CHECK-SPLIT-NEXT: Tag: DW_TAG_structure_type
; CHECK-SPLIT-NEXT: DW_IDX_type_unit: 0x00
-; CHECK-SPLIT-NEXT: DW_IDX_die_offset: 0x0000001f
+; CHECK-SPLIT-NEXT: DW_IDX_die_offset: 0x00000021
; CHECK-SPLIT-NEXT: }
; CHECK-SPLIT-NEXT: Entry @ 0xae {
; CHECK-SPLIT-NEXT: Abbrev: [[ABBREV]]
@@ -199,13 +200,36 @@
; CHECK-SPLIT-NEXT: Abbrev: [[ABBREV4]]
; CHECK-SPLIT-NEXT: Tag: DW_TAG_base_type
; CHECK-SPLIT-NEXT: DW_IDX_type_unit: 0x00
-; CHECK-SPLIT-NEXT: DW_IDX_die_offset: 0x00000034
+; CHECK-SPLIT-NEXT: DW_IDX_die_offset: 0x00000036
; CHECK-SPLIT-NEXT: }
; CHECK-SPLIT-NEXT: }
; CHECK-SPLIT-NEXT: ]
; CHECK-SPLIT-NEXT: }
+
+; RUN: llvm-dwarfdump -debug-info -r 0 %t > %tdebugInfo.txt
+; RUN: llvm-dwarfdump -debug-info -r 0 %t.mainTypes.dwo >> %tdebugInfo.txt
+; RUN: cat %tdebugInfo.txt | FileCheck %s --check-prefixes=CHECK-TYPE
+
+; CHECK-TYPE: DW_TAG_skeleton_unit
+; CHECK-TYPE-NEXT: DW_AT_stmt_list
+; CHECK-TYPE-NEXT: DW_AT_str_offsets_base
+; CHECK-TYPE-NEXT: DW_AT_comp_dir ("/typeSmall")
+; CHECK-TYPE-NEXT: DW_AT_dwo_name
+; CHECK-TYPE-SAME: debug-names-types.ll.tmp.mainTypes.dwo
+; CHECK-TYPE-NEXT: DW_AT_low_pc
+; CHECK-TYPE-NEXT: DW_AT_high_pc
+; CHECK-TYPE-NEXT: DW_AT_addr_base
+
+; CHECK-TYPE: .debug_info.dwo contents
+; CHECK-TYPE: DW_TAG_type_unit
+; CHECK-TYPE-NEXT: DW_AT_language
+; CHECK-TYPE-NEXT: DW_AT_comp_dir ("/typeSmall")
+; CHECK-TYPE-NEXT: DW_AT_dwo_name
+; CHECK-TYPE-SAME: debug-names-types.ll.tmp.mainTypes.dwo
+; CHECK-TYPE-NEXT: DW_AT_stmt_list
+
; ModuleID = 'main.cpp'
source_filename = "main.cpp"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
>From cd750d8ca22e5abe67a048c16f124e06e37796f2 Mon Sep 17 00:00:00 2001
From: Alexander Yermolovich <ayermolo at meta.com>
Date: Fri, 8 Dec 2023 18:22:26 -0800
Subject: [PATCH 2/3] Fix webassembly test.
---
llvm/test/DebugInfo/WebAssembly/dwarf-headers.ll | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/llvm/test/DebugInfo/WebAssembly/dwarf-headers.ll b/llvm/test/DebugInfo/WebAssembly/dwarf-headers.ll
index b2be5487b9cd15..efa3d1c4a46e12 100644
--- a/llvm/test/DebugInfo/WebAssembly/dwarf-headers.ll
+++ b/llvm/test/DebugInfo/WebAssembly/dwarf-headers.ll
@@ -77,14 +77,14 @@
; O-5: .debug_info contents:
; O-5: 0x00000000: Compile Unit: {{.*}} version = 0x0005, unit_type = DW_UT_skeleton, abbr_offset
; O-5-SAME: DWO_id = 0xccd7e58ef8bf4aa6
-; O-5: 0x00000014: DW_TAG_skeleton_unit
+; O-5: 0x00000014: DW_TAG_skeleton_unit
;
; DWO-5: .debug_info.dwo contents:
; DWO-5: 0x00000000: Type Unit: {{.*}} version = 0x0005, unit_type = DW_UT_split_type, abbr_offset
; DWO-5: 0x00000018: DW_TAG_type_unit
-; DWO-5: 0x00000033: Compile Unit: {{.*}} version = 0x0005, unit_type = DW_UT_split_compile, abbr_offset
+; DWO-5: 0x00000035: Compile Unit: {{.*}} version = 0x0005, unit_type = DW_UT_split_compile, abbr_offset
; DWO-5-SAME: DWO_id = 0xccd7e58ef8bf4aa6
-; DWO-5: 0x00000047: DW_TAG_compile_unit
+; DWO-5: 0x00000049: DW_TAG_compile_unit
; ModuleID = 't.cpp'
>From c9061432513c4c7dec58b1c0b0e43ac8a91d5cae Mon Sep 17 00:00:00 2001
From: Alexander Yermolovich <ayermolo at meta.com>
Date: Mon, 11 Dec 2023 17:11:38 -0800
Subject: [PATCH 3/3] updated test, added comments to code
---
llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp | 4 ++++
llvm/test/DebugInfo/X86/debug-names-types.ll | 11 +++++------
2 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 1db295cd76536a..41afbea4561433 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -3478,6 +3478,10 @@ void DwarfDebug::addDwarfTypeUnitType(DwarfCompileUnit &CU,
Ins.first->second = Signature;
if (useSplitDwarf()) {
+ // Although multiple type units can have the same signature, they are not
+ // guranteed to be bit identical. When LLDB uses .debug_names it needs to
+ // know from which CU a type unit came from. These two attrbutes help it to
+ // figure that out.
if (getDwarfVersion() >= 5) {
if (!CompilationDir.empty())
NewTU.addString(UnitDie, dwarf::DW_AT_comp_dir, CompilationDir);
diff --git a/llvm/test/DebugInfo/X86/debug-names-types.ll b/llvm/test/DebugInfo/X86/debug-names-types.ll
index 5617c2cafc6f09..501b7efd88eb9a 100644
--- a/llvm/test/DebugInfo/X86/debug-names-types.ll
+++ b/llvm/test/DebugInfo/X86/debug-names-types.ll
@@ -222,13 +222,12 @@
; CHECK-TYPE-NEXT: DW_AT_high_pc
; CHECK-TYPE-NEXT: DW_AT_addr_base
-; CHECK-TYPE: .debug_info.dwo contents
-; CHECK-TYPE: DW_TAG_type_unit
-; CHECK-TYPE-NEXT: DW_AT_language
-; CHECK-TYPE-NEXT: DW_AT_comp_dir ("/typeSmall")
-; CHECK-TYPE-NEXT: DW_AT_dwo_name
+; CHECK-TYPE: DW_TAG_type_unit
+; CHECK-TYPE-NOT: DW_TAG
+; CHECK-TYPE: DW_AT_comp_dir ("/typeSmall")
+; CHECK-TYPE-NOT: DW_TAG
+; CHECK-TYPE: DW_AT_dwo_name
; CHECK-TYPE-SAME: debug-names-types.ll.tmp.mainTypes.dwo
-; CHECK-TYPE-NEXT: DW_AT_stmt_list
; ModuleID = 'main.cpp'
source_filename = "main.cpp"
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