[PATCH] D61891: DWARF v5: emit DW_AT_addr_base if DW_AT_low_pc references .debug_addr

[Fangrui Song via Phabricator via llvm-commits]

MaskRay created this revision.
MaskRay added reviewers: aprantl, dblaikie, echristo, labath.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.
MaskRay retitled this revision from "DWARF v5: emit DW_AT_addr_base for LineTablesOnly" to "DWARF v5: emit DW_AT_addr_base if DW_AT_low_pc references .debug_addr".
MaskRay edited the summary of this revision.
Herald added a subscriber: ormris.

The condition !AddrPool.empty() is tested before attachRangesOrLowHighPC(), which may add an entry to AddrPool. We thus may incorrectly omit DW_AT_addr_base for LineTablesOnly.

Fix this by moving !AddrPool.empty() below.

This was discovered while investigating a lld SIGSEGV issue (D61889 <https://reviews.llvm.org/D61889>).


Repository:
  rL LLVM

https://reviews.llvm.org/D61891

Files:
  lib/CodeGen/AsmPrinter/DwarfDebug.cpp
  test/DebugInfo/Generic/line-table-addrx.ll
  test/DebugInfo/X86/convert-debugloc.ll
  test/DebugInfo/X86/fission-ranges.ll


Index: test/DebugInfo/X86/fission-ranges.ll
===================================================================
--- test/DebugInfo/X86/fission-ranges.ll
+++ test/DebugInfo/X86/fission-ranges.ll
@@ -12,6 +12,8 @@
 ; CHECK-NEXT: DW_AT_GNU_dwo_name
 ; CHECK-NEXT: DW_AT_GNU_dwo_id
 ; CHECK-NEXT: DW_AT_GNU_ranges_base
+; CHECK-NEXT: DW_AT_low_pc
+; CHECK-NEXT: DW_AT_high_pc
 ; CHECK-NEXT: DW_AT_GNU_addr_base [DW_FORM_sec_offset]                   (0x00000000)
 
 ; CHECK: .debug_info.dwo contents:
Index: test/DebugInfo/X86/convert-debugloc.ll
===================================================================
--- test/DebugInfo/X86/convert-debugloc.ll
+++ test/DebugInfo/X86/convert-debugloc.ll
@@ -11,9 +11,9 @@
 ; DW5-CHECK-NEXT:               DW_AT_str_offsets_base	(0x00000008)
 ; DW5-CHECK-NEXT:               DW_AT_stmt_list	(0x00000000)
 ; DW5-CHECK-NEXT:               DW_AT_comp_dir {{.*}}
-; DW5-CHECK-NEXT:               DW_AT_addr_base	(0x00000008)
 ; DW5-CHECK-NEXT:               DW_AT_low_pc	(0x0000000000000000)
 ; DW5-CHECK-NEXT:               DW_AT_high_pc	(0x0000000000000007)
+; DW5-CHECK-NEXT:               DW_AT_addr_base	(0x00000008)
 ; DW5-CHECK-NEXT:               DW_AT_loclists_base	(0x0000000c)
 ; DW5-CHECK-EMPTY:
 ; DW5-CHECK-NEXT: 0x00000027:   DW_TAG_base_type
Index: test/DebugInfo/Generic/line-table-addrx.ll
===================================================================
--- /dev/null
+++ test/DebugInfo/Generic/line-table-addrx.ll
@@ -0,0 +1,21 @@
+; RUN: %llc_dwarf -filetype=obj %s -o - | llvm-dwarfdump -v -debug-info - | FileCheck %s
+
+;; We used to omit DW_AT_addr_base for LineTablesOnly in DWARF v5.
+; CHECK: DW_AT_low_pc [DW_FORM_addrx]
+; CHECK: DW_AT_addr_base
+
+define i64 @foo() !dbg !7 {
+entry:
+  ret i64 0
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, emissionKind: LineTablesOnly, enums: !2)
+!1 = !DIFile(filename: "a.cc", directory: "/tmp")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 5}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!7 = distinct !DISubprogram(name: "a", scope: !1, file: !1, line: 22, type: !8, scopeLine: 22, unit: !0, retainedNodes: !2)
+!8 = !DISubroutineType(types: !2)
Index: lib/CodeGen/AsmPrinter/DwarfDebug.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -901,13 +901,6 @@
     // ranges for all subprogram DIEs for mach-o.
     DwarfCompileUnit &U = SkCU ? *SkCU : TheCU;
 
-    // We don't keep track of which addresses are used in which CU so this
-    // is a bit pessimistic under LTO.
-    if (!AddrPool.isEmpty() &&
-        (getDwarfVersion() >= 5 ||
-         (SkCU && !empty(TheCU.getUnitDie().children()))))
-      U.addAddrTableBase();
-
     if (unsigned NumRanges = TheCU.getRanges().size()) {
       if (NumRanges > 1 && useRangesSection())
         // A DW_AT_low_pc attribute may also be specified in combination with
@@ -920,6 +913,13 @@
       U.attachRangesOrLowHighPC(U.getUnitDie(), TheCU.takeRanges());
     }
 
+    // We don't keep track of which addresses are used in which CU so this
+    // is a bit pessimistic under LTO.
+    if (!AddrPool.isEmpty() &&
+        (getDwarfVersion() >= 5 ||
+         (SkCU && !empty(TheCU.getUnitDie().children()))))
+      U.addAddrTableBase();
+
     if (getDwarfVersion() >= 5) {
       if (U.hasRangeLists())
         U.addRnglistsBase();


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