[clang] [llvm] [LLVM][DWARF] Fix accelerator swtiching with TU re-use (PR #77511)
Alexander Yermolovich via cfe-commits
cfe-commits at lists.llvm.org
Tue Jan 9 11:00:27 PST 2024
https://github.com/ayermolo created https://github.com/llvm/llvm-project/pull/77511
This bug is triggered when a TU is already created, and we process the same
DICompositeType at a top level. We would switch to TU accelerator table, but
would not switch back on early exit. As the result we would add CU entries to the TU
accelerator table. When we try to write out TUs and normalize entries, the
offsets for DIEs that are part of a CU would not have been computed, and it
would assert on getOffset().
>From 5e6ee63fabac0dabc692c00d3c017e2542c98273 Mon Sep 17 00:00:00 2001
From: Alexander Yermolovich <ayermolo at meta.com>
Date: Tue, 9 Jan 2024 10:51:55 -0800
Subject: [PATCH] [LLVM][DWARF] Fix accelerator swtiching with TU re-use
This bug is triggered when a TU is already created, and we process the same
DICompositeType at a top level. We would switch to TU accelerator table, but
would not switch back on early exit. As the result we would add CU entries to the TU
accelerator table. When we try to write out TUs and normalize entries, the
offsets for DIEs that are part of a CU would not have been computed, and it
would assert on getOffset().
---
.../CodeGen/thinlto-debug-names-tu-reuse.ll | 58 +++++++++++++++++++
llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp | 10 +++-
llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h | 2 +
3 files changed, 69 insertions(+), 1 deletion(-)
create mode 100644 clang/test/CodeGen/thinlto-debug-names-tu-reuse.ll
diff --git a/clang/test/CodeGen/thinlto-debug-names-tu-reuse.ll b/clang/test/CodeGen/thinlto-debug-names-tu-reuse.ll
new file mode 100644
index 00000000000000..53aec43a050f8b
--- /dev/null
+++ b/clang/test/CodeGen/thinlto-debug-names-tu-reuse.ll
@@ -0,0 +1,58 @@
+; REQUIRES: asserts
+
+;; Tests that accelerator table switches correctly from TU to CU when a top level TU is re-used.
+;; Assert is not triggered.
+;; File1
+;; struct Foo {
+;; char fChar;
+;; };
+;; Foo fGlobal;
+;; FIle2
+;; struct Foo {
+;; char fChar;
+;; };
+;; Foo fGlobal2;
+;; clang++ <file>.cpp -O0 -g2 -fdebug-types-section -gpubnames -S -emit-llvm -o <file>.ll
+;; llvm-link file1.ll file2.ll -S -o thinlto-debug-names-tu-reuse.ll
+
+; RUN: llc -O0 -dwarf-version=5 -generate-type-units -filetype=obj < %s -o %t.o
+; RUN: llvm-readelf --sections %t.o | FileCheck --check-prefix=OBJ %s
+
+; OBJ: debug_names
+
+; ModuleID = 'llvm-link'
+source_filename = "llvm-link"
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.Foo = type { i8 }
+
+ at fGlobal = dso_local global %struct.Foo zeroinitializer, align 1, !dbg !0
+ at fGlobal2 = dso_local global %struct.Foo zeroinitializer, align 1, !dbg !9
+
+!llvm.dbg.cu = !{!2, !11}
+!llvm.ident = !{!14, !14}
+!llvm.module.flags = !{!15, !16, !17, !18, !19, !20, !21}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "fGlobal", scope: !2, file: !3, line: 5, type: !5, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !3, producer: "clang version 18.0.0git", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, globals: !4, splitDebugInlining: false)
+!3 = !DIFile(filename: "main.cpp", directory: "/smallTUReuse", checksumkind: CSK_MD5, checksum: "4f1831504f0948b03880356fae49cb58")
+!4 = !{!0}
+!5 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Foo", file: !3, line: 2, size: 8, flags: DIFlagTypePassByValue, elements: !6, identifier: "_ZTS3Foo")
+!6 = !{!7}
+!7 = !DIDerivedType(tag: DW_TAG_member, name: "fChar", scope: !5, file: !3, line: 3, baseType: !8, size: 8)
+!8 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!9 = !DIGlobalVariableExpression(var: !10, expr: !DIExpression())
+!10 = distinct !DIGlobalVariable(name: "fGlobal2", scope: !11, file: !12, line: 5, type: !5, isLocal: false, isDefinition: true)
+!11 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !12, producer: "clang version 18.0.0git", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, globals: !13, splitDebugInlining: false)
+!12 = !DIFile(filename: "helper.cpp", directory: "/smallTUReuse", checksumkind: CSK_MD5, checksum: "014145d46991fd1eb6a2192d382feb75")
+!13 = !{!9}
+!14 = !{!"clang version 18.0.0git"}
+!15 = !{i32 7, !"Dwarf Version", i32 5}
+!16 = !{i32 2, !"Debug Info Version", i32 3}
+!17 = !{i32 1, !"wchar_size", i32 4}
+!18 = !{i32 8, !"PIC Level", i32 2}
+!19 = !{i32 7, !"PIE Level", i32 2}
+!20 = !{i32 7, !"uwtable", i32 2}
+!21 = !{i32 7, !"frame-pointer", i32 2}
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 41afbea4561433..0a922fcd54a061 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -3448,7 +3448,6 @@ uint64_t DwarfDebug::makeTypeSignature(StringRef Identifier) {
void DwarfDebug::addDwarfTypeUnitType(DwarfCompileUnit &CU,
StringRef Identifier, DIE &RefDie,
const DICompositeType *CTy) {
- setCurrentDWARF5AccelTable(DWARF5AccelTableKind::TU);
// Fast path if we're building some type units and one has already used the
// address pool we know we're going to throw away all this work anyway, so
// don't bother building dependent types.
@@ -3461,6 +3460,7 @@ void DwarfDebug::addDwarfTypeUnitType(DwarfCompileUnit &CU,
return;
}
+ setCurrentDWARF5AccelTable(DWARF5AccelTableKind::TU);
bool TopLevelType = TypeUnitsUnderConstruction.empty();
AddrPool.resetUsedFlag();
@@ -3580,6 +3580,14 @@ void DwarfDebug::addAccelNameImpl(
break;
case AccelTableKind::Dwarf: {
DWARF5AccelTable &Current = getCurrentDWARF5AccelTable();
+ assert((CurrentKind == DWARF5AccelTableKind::TU) ||
+ ((CurrentKind == DWARF5AccelTableKind::CU) &&
+ (Unit.getUnitDie().getTag() != dwarf::DW_TAG_type_unit)) &&
+ "Kind is CU but TU is being processed.");
+ assert((CurrentKind == DWARF5AccelTableKind::CU) ||
+ ((CurrentKind == DWARF5AccelTableKind::TU) &&
+ (Unit.getUnitDie().getTag() == dwarf::DW_TAG_type_unit)) &&
+ "Kind is TU but CU is being processed.");
// The type unit can be discarded, so need to add references to final
// acceleration table once we know it's complete and we emit it.
Current.addName(Ref, Die, Unit.getUniqueID());
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 452485b632c45f..09e9ca07624f83 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -509,6 +509,7 @@ class DwarfDebug : public DebugHandlerBase {
DWARF5AccelTable AccelTypeUnitsDebugNames;
/// Used to hide which DWARF5AccelTable we are using now.
DWARF5AccelTable *CurrentDebugNames = &AccelDebugNames;
+ DWARF5AccelTableKind CurrentKind = DWARF5AccelTableKind::CU;
AccelTable<AppleAccelTableOffsetData> AccelNames;
AccelTable<AppleAccelTableOffsetData> AccelObjC;
AccelTable<AppleAccelTableOffsetData> AccelNamespace;
@@ -925,6 +926,7 @@ class DwarfDebug : public DebugHandlerBase {
/// Sets the current DWARF5AccelTable to use.
void setCurrentDWARF5AccelTable(const DWARF5AccelTableKind Kind) {
+ CurrentKind = Kind;
switch (Kind) {
case DWARF5AccelTableKind::CU:
CurrentDebugNames = &AccelDebugNames;
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