[Lldb-commits] [lld] [lldb] [llvm] [AArch64] Support TLS variables in debug info (PR #146572)
Shivam Gupta via lldb-commits
lldb-commits at lists.llvm.org
Sun Jan 18 07:45:46 PST 2026
https://github.com/xgupta updated https://github.com/llvm/llvm-project/pull/146572
>From abed32e6cdb6da80120b325fc32d7a5986581618 Mon Sep 17 00:00:00 2001
From: Shivam Gupta <shivam98.tkg at gmail.com>
Date: Tue, 1 Jul 2025 19:42:48 +0530
Subject: [PATCH 1/2] [AArch64] Support TLS variables in debug info
This adds an implementation of getDebugThreadLocalSymbol for
AArch64 by using AArch::S_DTPREL.
Fixes #83466
---
lld/ELF/Arch/AArch64.cpp | 6 +++
.../Plugins/ObjectFile/ELF/ObjectFileELF.cpp | 1 +
.../AArch64/AArch64TargetObjectFile.cpp | 7 +++-
.../Target/AArch64/AArch64TargetObjectFile.h | 3 ++
.../AArch64/AsmParser/AArch64AsmParser.cpp | 3 ++
.../MCTargetDesc/AArch64ELFObjectWriter.cpp | 5 +++
.../AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp | 2 +
llvm/test/CodeGen/AArch64/tls-dtprel64.ll | 37 ++++++++++++++++++
.../test/DebugInfo/AArch64/tls-at-location.ll | 12 ++++--
llvm/test/MC/AArch64/tls-dtprel64.s | 38 +++++++++++++++++++
10 files changed, 110 insertions(+), 4 deletions(-)
create mode 100644 llvm/test/CodeGen/AArch64/tls-dtprel64.ll
create mode 100644 llvm/test/MC/AArch64/tls-dtprel64.s
diff --git a/lld/ELF/Arch/AArch64.cpp b/lld/ELF/Arch/AArch64.cpp
index 55434ae2151ca..4eb1b727b6c61 100644
--- a/lld/ELF/Arch/AArch64.cpp
+++ b/lld/ELF/Arch/AArch64.cpp
@@ -169,6 +169,8 @@ RelExpr AArch64::getRelExpr(RelType type, const Symbol &s,
return R_ABS;
case R_AARCH64_AUTH_ABS64:
return RE_AARCH64_AUTH;
+ case R_AARCH64_TLS_DTPREL64:
+ return R_DTPREL;
case R_AARCH64_TLSDESC_ADR_PAGE21:
return RE_AARCH64_TLSDESC_PAGE;
case R_AARCH64_AUTH_TLSDESC_ADR_PAGE21:
@@ -544,6 +546,10 @@ void AArch64::relocate(uint8_t *loc, const Relocation &rel,
checkInt(ctx, loc, val, 32, rel);
write32(ctx, loc, val);
break;
+ case R_AARCH64_TLS_DTPREL64:
+ checkInt(ctx, loc, val, 64, rel);
+ write64(ctx, loc, val);
+ break;
case R_AARCH64_ADD_ABS_LO12_NC:
case R_AARCH64_AUTH_GOT_ADD_LO12_NC:
write32Imm12(loc, val);
diff --git a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
index 7d783d5dd6b9f..4931ad3623471 100644
--- a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
+++ b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
@@ -2932,6 +2932,7 @@ unsigned ObjectFileELF::ApplyRelocations(
case llvm::ELF::EM_AARCH64:
switch (reloc_type(rel)) {
case R_AARCH64_ABS64:
+ case R_AARCH64_TLS_DTPREL64:
ApplyELF64ABS64Relocation(symtab, rel, debug_data, rel_section);
break;
case R_AARCH64_ABS32:
diff --git a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
index 85de2d5010286..f5aa34a653fd8 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
@@ -30,7 +30,7 @@ void AArch64_ELFTargetObjectFile::Initialize(MCContext &Ctx,
// AARCH64 ELF ABI does not define static relocation type for TLS offset
// within a module. Do not generate AT_location for TLS variables.
- SupportDebugThreadLocalLocation = false;
+ SupportDebugThreadLocalLocation = true;
// Make sure the implicitly created empty .text section has the
// SHF_AARCH64_PURECODE flag set if the "+execute-only" target feature is
@@ -186,3 +186,8 @@ MCSection *AArch64_ELFTargetObjectFile::SelectSectionForGlobal(
return TargetLoweringObjectFileELF::SelectSectionForGlobal(GO, Kind, TM);
}
+
+const MCExpr *AArch64_ELFTargetObjectFile::getDebugThreadLocalSymbol(
+ const MCSymbol *Sym) const {
+ return MCSymbolRefExpr::create(Sym, AArch64::S_DTPREL, getContext());
+}
diff --git a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h
index 6b3381452c70b..78c0c22da8d1b 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h
+++ b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h
@@ -40,6 +40,9 @@ class AArch64_ELFTargetObjectFile : public TargetLoweringObjectFileELF {
MCSection *SelectSectionForGlobal(const GlobalObject *GO, SectionKind Kind,
const TargetMachine &TM) const override;
+
+ /// Describe a TLS variable address within debug info.
+ const MCExpr *getDebugThreadLocalSymbol(const MCSymbol *Sym) const override;
};
/// AArch64_MachoTargetObjectFile - This TLOF implementation is used for Darwin.
diff --git a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp b/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
index 5ef3e2e50ec86..37582343fff55 100644
--- a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
+++ b/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
@@ -4669,6 +4669,7 @@ bool AArch64AsmParser::parseSymbolicImmVal(const MCExpr *&ImmVal) {
.Case("prel_g1_nc", AArch64::S_PREL_G1_NC)
.Case("prel_g0", AArch64::S_PREL_G0)
.Case("prel_g0_nc", AArch64::S_PREL_G0_NC)
+ .Case("dtprel", AArch64::S_DTPREL)
.Case("dtprel_g2", AArch64::S_DTPREL_G2)
.Case("dtprel_g1", AArch64::S_DTPREL_G1)
.Case("dtprel_g1_nc", AArch64::S_DTPREL_G1_NC)
@@ -8490,6 +8491,8 @@ bool AArch64AsmParser::parseDataExpr(const MCExpr *&Res) {
Spec = AArch64::S_GOTPCREL;
else if (Identifier == "plt")
Spec = AArch64::S_PLT;
+ else if (Identifier == "dtprel")
+ Spec = AArch64::S_DTPREL;
else if (Identifier == "funcinit")
Spec = AArch64::S_FUNCINIT;
}
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
index 892b8da37eb69..4a390784a3303 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
@@ -232,8 +232,11 @@ unsigned AArch64ELFObjectWriter::getRelocType(const MCFixup &Fixup,
}
if (RefKind == AArch64::S_AUTH || RefKind == AArch64::S_AUTHADDR)
return ELF::R_AARCH64_AUTH_ABS64;
+ if (RefKind == AArch64::S_DTPREL) {
+ return ELF::R_AARCH64_TLS_DTPREL64;
if (RefKind == AArch64::S_FUNCINIT)
return ELF::R_AARCH64_FUNCINIT64;
+ }
return ELF::R_AARCH64_ABS64;
}
case AArch64::fixup_aarch64_add_imm12:
@@ -448,6 +451,8 @@ unsigned AArch64ELFObjectWriter::getRelocType(const MCFixup &Fixup,
return R_CLS(MOVW_PREL_G0);
if (RefKind == AArch64::S_PREL_G0_NC)
return R_CLS(MOVW_PREL_G0_NC);
+ if (RefKind == AArch64::S_DTPREL)
+ return ELF::R_AARCH64_TLS_DTPREL64;
if (RefKind == AArch64::S_DTPREL_G2)
return ELF::R_AARCH64_TLSLD_MOVW_DTPREL_G2;
if (RefKind == AArch64::S_DTPREL_G1)
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp
index bc090c6157eef..c143bb06e24cf 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp
@@ -40,6 +40,7 @@ const MCAsmInfo::AtSpecifier ELFAtSpecifiers[] = {
{AArch64::S_GOT, "GOT"},
{AArch64::S_GOTPCREL, "GOTPCREL"},
{AArch64::S_PLT, "PLT"},
+ {AArch64::S_DTPREL, "DTPREL"},
{AArch64::S_FUNCINIT, "FUNCINIT"},
};
@@ -76,6 +77,7 @@ StringRef AArch64::getSpecifierName(AArch64::Specifier S) {
case AArch64::S_PREL_G1_NC: return ":prel_g1_nc:";
case AArch64::S_PREL_G0: return ":prel_g0:";
case AArch64::S_PREL_G0_NC: return ":prel_g0_nc:";
+ case AArch64::S_DTPREL: return ":dtprel:";
case AArch64::S_DTPREL_G2: return ":dtprel_g2:";
case AArch64::S_DTPREL_G1: return ":dtprel_g1:";
case AArch64::S_DTPREL_G1_NC: return ":dtprel_g1_nc:";
diff --git a/llvm/test/CodeGen/AArch64/tls-dtprel64.ll b/llvm/test/CodeGen/AArch64/tls-dtprel64.ll
new file mode 100644
index 0000000000000..c481980354905
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/tls-dtprel64.ll
@@ -0,0 +1,37 @@
+; RUN: llc -O0 -mtriple=aarch64-linux-gnu -filetype=obj < %s \
+; RUN: | llvm-objdump -r - | FileCheck %s
+
+; CHECK: R_AARCH64_TLS_DTPREL64
+
+ at var = thread_local global i32 0, align 4, !dbg !0
+
+; Function Attrs: noinline nounwind optnone
+define i32 @foo() #0 !dbg !11 {
+entry:
+ %0 = load i32, ptr @var, align 4, !dbg !14
+ ret i32 %0, !dbg !15
+}
+
+attributes #0 = { noinline nounwind optnone }
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!7, !8, !9}
+!llvm.ident = !{!10}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "var", scope: !2, file: !3, line: 1, type: !6, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 7.0.0", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5)
+!3 = !DIFile(filename: "tls-at-location.c", directory: "/home/lliu0/llvm/tls-at-location/DebugInfo/AArch64")
+!4 = !{}
+!5 = !{!0}
+!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!7 = !{i32 2, !"Dwarf Version", i32 4}
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{i32 1, !"wchar_size", i32 4}
+!10 = !{!"clang version 7.0.0"}
+!11 = distinct !DISubprogram(name: "foo", scope: !3, file: !3, line: 3, type: !12, isLocal: false, isDefinition: true, scopeLine: 3, isOptimized: false, unit: !2)
+!12 = !DISubroutineType(types: !13)
+!13 = !{!6}
+!14 = !DILocation(line: 4, column: 10, scope: !11)
+!15 = !DILocation(line: 4, column: 3, scope: !11)
+
diff --git a/llvm/test/DebugInfo/AArch64/tls-at-location.ll b/llvm/test/DebugInfo/AArch64/tls-at-location.ll
index 20a0afb789771..d619962ccbf69 100644
--- a/llvm/test/DebugInfo/AArch64/tls-at-location.ll
+++ b/llvm/test/DebugInfo/AArch64/tls-at-location.ll
@@ -1,8 +1,14 @@
-; RUN: llc -filetype=obj -mtriple=aarch64--linux-gnu -o - %s | llvm-dwarfdump -v - | FileCheck %s
-;
+; RUN: llc -O0 -mtriple=aarch64-non-linux-gnu -filetype=obj < %s \
+; RUN: | llvm-dwarfdump - | FileCheck %s
+
; CHECK: .debug_info contents:
; CHECK: DW_TAG_variable
-; CHECK-NOT: DW_AT_location
+; CHECK: DW_AT_name ("var")
+; CHECK-NEXT: DW_AT_type (0x00000040 "int")
+; CHECK-NEXT: DW_AT_external (true)
+; CHECK-NEXT: DW_AT_decl_file ("{{.*}}tls-at-location.c")
+; CHECK-NEXT: DW_AT_decl_line (1)
+; CHECK-NEXT: DW_AT_location (DW_OP_const8u 0x0, DW_OP_GNU_push_tls_address)
@var = thread_local global i32 0, align 4, !dbg !0
diff --git a/llvm/test/MC/AArch64/tls-dtprel64.s b/llvm/test/MC/AArch64/tls-dtprel64.s
new file mode 100644
index 0000000000000..7cb47f9543f68
--- /dev/null
+++ b/llvm/test/MC/AArch64/tls-dtprel64.s
@@ -0,0 +1,38 @@
+# RUN: llvm-mc -filetype=obj -triple=aarch64-none-linux-gnu %s | llvm-readobj -r - | FileCheck %s
+
+# CHECK: Relocations [
+# CHECK: Section {{.*}} .rela.debug_info {
+# CHECK: 0x{{[0-9A-F]+}} R_AARCH64_TLS_DTPREL64 var {{.*}}
+# CHECK: }
+
+.section .tdata,"awT", at progbits
+.globl var
+var:
+ .word 0
+
+.section .debug_abbrev,"", at progbits
+.byte 1 // Abbreviation Code
+.byte 17 // DW_TAG_compile_unit
+.byte 1 // DW_CHILDREN_yes
+.byte 0 // EOM(1)
+.byte 0 // EOM(2)
+
+.byte 2 // Abbreviation Code
+.byte 52 // DW_TAG_variable
+.byte 0 // DW_CHILDREN_no
+.byte 2; // DW_AT_location
+.byte 24 // DW_FORM_exprloc
+.byte 0 // EOM(1)
+.byte 0 // EOM(2)
+
+.section .debug_info,"", at progbits
+.Lcu_begin0:
+ .word .Lcu_end - .Lcu_body // Length of Unit
+.Lcu_body:
+ .hword 4 // DWARF version number
+ .word .debug_abbrev // Offset Into Abbrev. Section
+ .byte 8 // Address Size (in bytes)
+ .byte 1 // Abbrev [1] DW_TAG_compile_unit
+ .byte 2 // Abbrev [2] DW_TAG_variable
+ .xword var at DTPREL
+.Lcu_end:
>From 34bd97da928a949b9e8b89471184acb8718b9660 Mon Sep 17 00:00:00 2001
From: Shivam Gupta <shivam98.tkg at gmail.com>
Date: Sun, 18 Jan 2026 21:14:48 +0530
Subject: [PATCH 2/2] Address reviewer's comments
---
llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp | 2 --
.../Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp | 3 +--
llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp | 1 +
llvm/test/CodeGen/AArch64/tls-dtprel64.ll | 4 ++--
llvm/test/DebugInfo/AArch64/tls-at-location.ll | 2 +-
5 files changed, 5 insertions(+), 7 deletions(-)
diff --git a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
index f5aa34a653fd8..2d3fa1244c607 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
@@ -28,8 +28,6 @@ void AArch64_ELFTargetObjectFile::Initialize(MCContext &Ctx,
PLTRelativeSpecifier = AArch64::S_PLT;
SupportIndirectSymViaGOTPCRel = true;
- // AARCH64 ELF ABI does not define static relocation type for TLS offset
- // within a module. Do not generate AT_location for TLS variables.
SupportDebugThreadLocalLocation = true;
// Make sure the implicitly created empty .text section has the
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
index 4a390784a3303..36c87be9acb4c 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64ELFObjectWriter.cpp
@@ -232,11 +232,10 @@ unsigned AArch64ELFObjectWriter::getRelocType(const MCFixup &Fixup,
}
if (RefKind == AArch64::S_AUTH || RefKind == AArch64::S_AUTHADDR)
return ELF::R_AARCH64_AUTH_ABS64;
- if (RefKind == AArch64::S_DTPREL) {
+ if (RefKind == AArch64::S_DTPREL)
return ELF::R_AARCH64_TLS_DTPREL64;
if (RefKind == AArch64::S_FUNCINIT)
return ELF::R_AARCH64_FUNCINIT64;
- }
return ELF::R_AARCH64_ABS64;
}
case AArch64::fixup_aarch64_add_imm12:
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp
index c143bb06e24cf..3e9edd0b1fabf 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCAsmInfo.cpp
@@ -147,6 +147,7 @@ AArch64MCAsmInfoDarwin::AArch64MCAsmInfoDarwin(bool IsILP32) {
SupportsDebugInformation = true;
UseDataRegionDirectives = true;
UseAtForSpecifier = false;
+ HasDataExpressions = true;
ExceptionsType = ExceptionHandling::DwarfCFI;
diff --git a/llvm/test/CodeGen/AArch64/tls-dtprel64.ll b/llvm/test/CodeGen/AArch64/tls-dtprel64.ll
index c481980354905..b025c8c9331fd 100644
--- a/llvm/test/CodeGen/AArch64/tls-dtprel64.ll
+++ b/llvm/test/CodeGen/AArch64/tls-dtprel64.ll
@@ -1,7 +1,7 @@
; RUN: llc -O0 -mtriple=aarch64-linux-gnu -filetype=obj < %s \
-; RUN: | llvm-objdump -r - | FileCheck %s
+; RUN: | llvm-objdump -r - | FileCheck %s
-; CHECK: R_AARCH64_TLS_DTPREL64
+; CHECK: R_AARCH64_TLS_DTPREL64 var
@var = thread_local global i32 0, align 4, !dbg !0
diff --git a/llvm/test/DebugInfo/AArch64/tls-at-location.ll b/llvm/test/DebugInfo/AArch64/tls-at-location.ll
index d619962ccbf69..13bdad20032be 100644
--- a/llvm/test/DebugInfo/AArch64/tls-at-location.ll
+++ b/llvm/test/DebugInfo/AArch64/tls-at-location.ll
@@ -1,5 +1,5 @@
; RUN: llc -O0 -mtriple=aarch64-non-linux-gnu -filetype=obj < %s \
-; RUN: | llvm-dwarfdump - | FileCheck %s
+; RUN: | llvm-dwarfdump - | FileCheck %s
; CHECK: .debug_info contents:
; CHECK: DW_TAG_variable
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