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[DebugInfo][ARM] Fix incorrect debug information for RWPI accessed globals 

When compiling for the RWPI relocation model the debug information is wrong:

* the debug location is described as { DW_OP_addr Var }
  instead of { DW_OP_constNu Var DW_OP_bregX 0 DW_OP_plus }
* the relocation type is R_ARM_ABS32 instead of R_ARM_SBREL32

Differential Revision: https://reviews.llvm.org/D111404
This commit is contained in:
Alexandros Lamprineas 2021-10-18 19:24:05 +01:00
parent b8ce97372d
commit 04dc68710a
5 changed files with 79 additions and 3 deletions
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9
llvm/include/llvm/Target/TargetLoweringObjectFile.h
View File

@ -15,6 +15,7 @@
#define LLVM_TARGET_TARGETLOWERINGOBJECTFILE_H
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCRegister.h"
#include <cstdint>
namespace llvm {
@ -219,6 +220,14 @@ public:
return SupportDebugThreadLocalLocation;
}
/// Returns the register used as static base in RWPI variants.
virtual const MCRegister getStaticBase() const { return MCRegister::NoRegister; }
/// Get the target specific RWPI relocation.
virtual const MCExpr *getIndirectSymViaRWPI(const MCSymbol *Sym) const {
return nullptr;
}
/// Get the target specific PC relative GOT entry relocation
virtual const MCExpr *getIndirectSymViaGOTPCRel(const GlobalValue *GV,
const MCSymbol *Sym,

24
llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
View File

@ -262,14 +262,14 @@ void DwarfCompileUnit::addLocationAttribute(
if (Global) {
const MCSymbol *Sym = Asm->getSymbol(Global);
unsigned PointerSize = Asm->getDataLayout().getPointerSize();
assert((PointerSize == 4 || PointerSize == 8) &&
"Add support for other sizes if necessary");
if (Global->isThreadLocal()) {
if (Asm->TM.useEmulatedTLS()) {
// TODO: add debug info for emulated thread local mode.
} else {
// FIXME: Make this work with -gsplit-dwarf.
unsigned PointerSize = Asm->getDataLayout().getPointerSize();
assert((PointerSize == 4 || PointerSize == 8) &&
"Add support for other sizes if necessary");
// Based on GCC's support for TLS:
if (!DD->useSplitDwarf()) {
// 1) Start with a constNu of the appropriate pointer size
@ -292,6 +292,24 @@ void DwarfCompileUnit::addLocationAttribute(
DD->useGNUTLSOpcode() ? dwarf::DW_OP_GNU_push_tls_address
: dwarf::DW_OP_form_tls_address);
}
} else if (Asm->TM.getRelocationModel() == Reloc::RWPI ||
Asm->TM.getRelocationModel() == Reloc::ROPI_RWPI) {
// Constant
addUInt(*Loc, dwarf::DW_FORM_data1,
PointerSize == 4 ? dwarf::DW_OP_const4u
: dwarf::DW_OP_const8u);
// Relocation offset
addExpr(*Loc, PointerSize == 4 ? dwarf::DW_FORM_data4
: dwarf::DW_FORM_data8,
Asm->getObjFileLowering().getIndirectSymViaRWPI(Sym));
// Base register
Register BaseReg = Asm->getObjFileLowering().getStaticBase();
BaseReg = Asm->TM.getMCRegisterInfo()->getDwarfRegNum(BaseReg, false);
addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_breg0 + BaseReg);
// Offset from base register
addSInt(*Loc, dwarf::DW_FORM_sdata, 0);
// Operation
addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_plus);
} else {
DD->addArangeLabel(SymbolCU(this, Sym));
addOpAddress(*Loc, Sym);

10
llvm/lib/Target/ARM/ARMTargetObjectFile.cpp
View File

@ -54,6 +54,16 @@ void ARMElfTargetObjectFile::Initialize(MCContext &Ctx,
}
}
const MCRegister ARMElfTargetObjectFile::getStaticBase() const {
return ARM::R9;
}
const MCExpr *ARMElfTargetObjectFile::
getIndirectSymViaRWPI(const MCSymbol *Sym) const {
return MCSymbolRefExpr::create(Sym, MCSymbolRefExpr::VK_ARM_SBREL,
getContext());
}
const MCExpr *ARMElfTargetObjectFile::getTTypeGlobalReference(
const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM,
MachineModuleInfo *MMI, MCStreamer &Streamer) const {

5
llvm/lib/Target/ARM/ARMTargetObjectFile.h
View File

@ -11,6 +11,7 @@
#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCRegister.h"
namespace llvm {
@ -23,6 +24,10 @@ public:
void Initialize(MCContext &Ctx, const TargetMachine &TM) override;
const MCRegister getStaticBase() const override;
const MCExpr *getIndirectSymViaRWPI(const MCSymbol *Sym) const override;
const MCExpr *getTTypeGlobalReference(const GlobalValue *GV,
unsigned Encoding,
const TargetMachine &TM,

34
llvm/test/DebugInfo/ARM/rwpi.ll Normal file
View File

@ -0,0 +1,34 @@
; RUN: llc -mtriple armv7-linux -relocation-model=rwpi -o - %s | FileCheck %s
; RUN: llc -mtriple armv7-linux -relocation-model=ropi-rwpi -o - %s | FileCheck %s
@global = global i32 5, align 4, !dbg !0
; 8 bytes of data
; CHECK: .byte 8 @ DW_AT_location
; DW_OP_const4u
; CHECK-NEXT: .byte 12
; relocation offset
; CHECK-NEXT: .long global(sbrel)
; DW_OP_breg9
; CHECK-NEXT: .byte 121
; offset from breg9
; CHECK-NEXT: .byte 0
; DW_OP_plus
; CHECK-NEXT: .byte 34
!llvm.dbg.cu = !{!2}
!llvm.module.flags = !{!6, !7, !8, !9, !10}
!llvm.ident = !{!11}
!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
!1 = distinct !DIGlobalVariable(name: "global", scope: !2, file: !3, line: 1, type: !5, isLocal: false, isDefinition: true)
!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 14.0.0 (https://github.com/llvm/llvm-project.git 9f5c70c7ad404f0cb52416a0574d9e48d520be5d)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, globals: !4, splitDebugInlining: false, nameTableKind: None)
!3 = !DIFile(filename: "rwpi.c", directory: "/tmp")
!4 = !{!0}
!5 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!6 = !{i32 7, !"Dwarf Version", i32 4}
!7 = !{i32 2, !"Debug Info Version", i32 3}
!8 = !{i32 1, !"wchar_size", i32 4}
!9 = !{i32 1, !"min_enum_size", i32 4}
!10 = !{i32 7, !"frame-pointer", i32 2}
!11 = !{!"clang version 14.0.0 (https://github.com/llvm/llvm-project.git 9f5c70c7ad404f0cb52416a0574d9e48d520be5d)"}