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[DebugInfo][DWARF] Allow memory locations in DW_AT_call_target expressions (#171183)

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Fixes #70949. Prior to PR #151378 memory locations were incorrect; that
patch prevented the emission of the incorrect locations.

This patch fixes the underlying issue.
This commit is contained in:
Orlando Cazalet-Hyams 2025-12-13 17:37:35 +00:00 committed by GitHub
parent f721a3965c
commit fa1dceb67f
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GPG Key ID: B5690EEEBB952194
5 changed files with 173 additions and 37 deletions
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42
llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
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@ -1321,15 +1321,22 @@ DwarfCompileUnit::getDwarf5OrGNULocationAtom(dwarf::LocationAtom Loc) const {
DIE &DwarfCompileUnit::constructCallSiteEntryDIE(
DIE &ScopeDIE, const DISubprogram *CalleeSP, const Function *CalleeF,
bool IsTail, const MCSymbol *PCAddr, const MCSymbol *CallAddr,
unsigned CallReg, DIType *AllocSiteTy) {
MachineLocation CallTarget, int64_t Offset, DIType *AllocSiteTy) {
// Insert a call site entry DIE within ScopeDIE.
DIE &CallSiteDIE = createAndAddDIE(getDwarf5OrGNUTag(dwarf::DW_TAG_call_site),
ScopeDIE, nullptr);
if (CallReg) {
// Indirect call.
addAddress(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_target),
MachineLocation(CallReg));
// A valid register in CallTarget indicates an indirect call.
if (CallTarget.getReg()) {
// CallTarget is the location of the address of an indirect call. The
// location may be indirect, modified by Offset.
if (CallTarget.isIndirect())
addMemoryLocation(CallSiteDIE,
getDwarf5OrGNUAttr(dwarf::DW_AT_call_target),
CallTarget, Offset);
else
addAddress(CallSiteDIE, getDwarf5OrGNUAttr(dwarf::DW_AT_call_target),
CallTarget);
} else if (CalleeSP) {
DIE *CalleeDIE = getOrCreateSubprogramDIE(CalleeSP, CalleeF);
assert(CalleeDIE && "Could not create DIE for call site entry origin");
@ -1642,15 +1649,15 @@ void DwarfCompileUnit::addVariableAddress(const DbgVariable &DV, DIE &Die,
addAddress(Die, dwarf::DW_AT_location, Location);
}
/// Add an address attribute to a die based on the location provided.
void DwarfCompileUnit::addAddress(DIE &Die, dwarf::Attribute Attribute,
const MachineLocation &Location) {
void DwarfCompileUnit::addLocationWithExpr(DIE &Die, dwarf::Attribute Attribute,
const MachineLocation &Location,
ArrayRef<uint64_t> Expr) {
DIELoc *Loc = new (DIEValueAllocator) DIELoc;
DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
if (Location.isIndirect())
DwarfExpr.setMemoryLocationKind();
DIExpressionCursor Cursor({});
DIExpressionCursor Cursor(Expr);
const TargetRegisterInfo &TRI = *Asm->MF->getSubtarget().getRegisterInfo();
if (!DwarfExpr.addMachineRegExpression(TRI, Cursor, Location.getReg()))
return;
@ -1664,6 +1671,23 @@ void DwarfCompileUnit::addAddress(DIE &Die, dwarf::Attribute Attribute,
*DwarfExpr.TagOffset);
}
/// Add an address attribute to a die based on the location provided.
void DwarfCompileUnit::addAddress(DIE &Die, dwarf::Attribute Attribute,
const MachineLocation &Location) {
addLocationWithExpr(Die, Attribute, Location, {});
}
/// Add a memory location exprloc to \p DIE with attribute \p Attribute
/// at \p Location + \p Offset.
void DwarfCompileUnit::addMemoryLocation(DIE &Die, dwarf::Attribute Attribute,
const MachineLocation &Location,
int64_t Offset) {
assert(Location.isIndirect() && "Memory loc should be indirect");
SmallVector<uint64_t, 3> Ops;
DIExpression::appendOffset(Ops, Offset);
addLocationWithExpr(Die, Attribute, Location, Ops);
}
/// Start with the address based on the location provided, and generate the
/// DWARF information necessary to find the actual variable given the extra
/// address information encoded in the DbgVariable, starting from the starting

18
llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
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@ -160,6 +160,12 @@ class DwarfCompileUnit final : public DwarfUnit {
DIE &createAbstractSubprogramDIE(const DISubprogram *SP, DIE *ContextDIE,
DwarfCompileUnit *ContextCU);
/// Add a location exprloc to \p DIE with attribute \p Attribute at
/// for \p Location modified by raw DIExpression \p Expr.
void addLocationWithExpr(DIE &Die, dwarf::Attribute Attribute,
const MachineLocation &Location,
ArrayRef<uint64_t> Expr);
public:
DwarfCompileUnit(unsigned UID, const DICompileUnit *Node, AsmPrinter *A,
DwarfDebug *DW, DwarfFile *DWU,
@ -309,12 +315,14 @@ public:
/// \p IsTail specifies whether the call is a tail call.
/// \p PCAddr points to the PC value after the call instruction.
/// \p CallAddr points to the PC value at the call instruction (or is null).
/// \p CallReg is a register location for an indirect call. For direct calls
/// the \p CallReg is set to 0.
/// \p CallTarget a location holding the target address for an indirect call.
/// For direct calls \p CallTarget register is set to 0.
/// \p Offset from \p CallTarget register value if the location is indirect.
DIE &constructCallSiteEntryDIE(DIE &ScopeDIE, const DISubprogram *CalleeSP,
const Function *CalleeF, bool IsTail,
const MCSymbol *PCAddr,
const MCSymbol *CallAddr, unsigned CallReg,
const MCSymbol *CallAddr,
MachineLocation CallTarget, int64_t Offset,
DIType *AllocSiteTy);
/// Construct call site parameter DIEs for the \p CallSiteDIE. The \p Params
/// were collected by the \ref collectCallSiteParameters.
@ -385,6 +393,10 @@ public:
void addAddress(DIE &Die, dwarf::Attribute Attribute,
const MachineLocation &Location);
/// Add a memory location exprloc to \p DIE with attribute \p Attribute
/// at \p Location + \p Offset.
void addMemoryLocation(DIE &Die, dwarf::Attribute Attribute,
const MachineLocation &Location, int64_t Offset);
/// Start with the address based on the location provided, and generate the
/// DWARF information necessary to find the actual variable (navigating the
/// extra location information encoded in the type) based on the starting

51
llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
View File

@ -942,25 +942,27 @@ void DwarfDebug::constructCallSiteEntryDIEs(const DISubprogram &SP,
DIType *AllocSiteTy = dyn_cast_or_null<DIType>(MI.getHeapAllocMarker());
// If this is a direct call, find the callee's subprogram.
// In the case of an indirect call find the register that holds
// the callee.
// In the case of an indirect call find the register or memory location
// that holds the callee address.
const MachineOperand &CalleeOp = TII->getCalleeOperand(MI);
bool PhysRegCalleeOperand =
CalleeOp.isReg() && CalleeOp.getReg().isPhysical();
// Hack: WebAssembly CALL instructions have MCInstrDesc that does not
// describe the call target operand.
if (CalleeOp.getOperandNo() < MI.getDesc().operands().size()) {
const MCOperandInfo &MCOI =
MI.getDesc().operands()[CalleeOp.getOperandNo()];
PhysRegCalleeOperand =
PhysRegCalleeOperand && MCOI.OperandType == MCOI::OPERAND_REGISTER;
}
unsigned CallReg = 0;
MachineLocation CallTarget{0};
int64_t Offset = 0;
const DISubprogram *CalleeSP = nullptr;
const Function *CalleeDecl = nullptr;
if (PhysRegCalleeOperand) {
CallReg = CalleeOp.getReg(); // might be zero
bool Scalable = false;
const MachineOperand *BaseOp = nullptr;
const TargetRegisterInfo &TRI =
*Asm->MF->getSubtarget().getRegisterInfo();
if (TII->getMemOperandWithOffset(MI, BaseOp, Offset, Scalable, &TRI)) {
if (BaseOp && BaseOp->isReg() && !Scalable)
CallTarget = MachineLocation(BaseOp->getReg(), /*Indirect*/ true);
}
if (!CallTarget.isIndirect())
CallTarget = MachineLocation(CalleeOp.getReg()); // Might be zero.
} else if (CalleeOp.isGlobal()) {
CalleeDecl = dyn_cast<Function>(CalleeOp.getGlobal());
if (CalleeDecl)
@ -969,7 +971,8 @@ void DwarfDebug::constructCallSiteEntryDIEs(const DISubprogram &SP,
// Omit DIE if we can't tell where the call goes *and* we don't want to
// add metadata to it.
if (CalleeSP == nullptr && CallReg == 0 && AllocSiteTy == nullptr)
if (CalleeSP == nullptr && CallTarget.getReg() == 0 &&
AllocSiteTy == nullptr)
continue;
// TODO: Omit call site entries for runtime calls (objc_msgSend, etc).
@ -997,16 +1000,18 @@ void DwarfDebug::constructCallSiteEntryDIEs(const DISubprogram &SP,
assert((IsTail || PCAddr) && "Non-tail call without return PC");
LLVM_DEBUG(dbgs() << "CallSiteEntry: " << MF.getName() << " -> "
<< (CalleeDecl ? CalleeDecl->getName()
: StringRef(MF.getSubtarget()
.getRegisterInfo()
->getName(CallReg)))
<< (IsTail ? " [IsTail]" : "") << "\n");
LLVM_DEBUG(
dbgs() << "CallSiteEntry: " << MF.getName() << " -> "
<< (CalleeDecl
? CalleeDecl->getName()
: StringRef(
MF.getSubtarget().getRegisterInfo()->getName(
CallTarget.getReg())))
<< (IsTail ? " [IsTail]" : "") << "\n");
DIE &CallSiteDIE =
CU.constructCallSiteEntryDIE(ScopeDIE, CalleeSP, CalleeDecl, IsTail,
PCAddr, CallAddr, CallReg, AllocSiteTy);
DIE &CallSiteDIE = CU.constructCallSiteEntryDIE(
ScopeDIE, CalleeSP, CalleeDecl, IsTail, PCAddr, CallAddr, CallTarget,
Offset, AllocSiteTy);
// Optionally emit call-site-param debug info.
if (emitDebugEntryValues()) {

91
llvm/test/DebugInfo/X86/dwarf-call-target-mem-loc.mir Normal file
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@ -0,0 +1,91 @@
# RUN: llc %s --start-after=livedebugvalues -o - --filetype=obj | llvm-dwarfdump - | FileCheck %s
## Check the memory location of the target address for the indirect call
## (virtual in this case) is described by a DW_AT_call_target expression.
# CHECK: DW_TAG_call_site
# CHECK-NEXT: DW_AT_call_target (DW_OP_breg0 RAX+8)
## Generated from this C++ with llc -stop-after=livedebugvalues -simplify-mir:
## struct Base {
## virtual int zz() { return x; }
## [[clang::noinline]]
## virtual int v() { return zz(); }
## int x;
## };
## struct Child: public Base {
## [[clang::noinline]]
## virtual int v() { return x * 2; }
## int x;
## };
##
## [[clang::noinline]]
## [[clang::disable_tail_calls]]
## int foo(Base* b) {
## return b->v();
## }
--- |
target triple = "x86_64-unknown-linux-gnu"
define dso_local noundef i32 @_Z3fooP4Base(ptr noundef %b) local_unnamed_addr !dbg !5 {
entry:
%vtable = load ptr, ptr %b, align 8, !dbg !12
%vfn = getelementptr inbounds nuw i8, ptr %vtable, i64 8, !dbg !12
%0 = load ptr, ptr %vfn, align 8, !dbg !12
%call = call noundef i32 %0(ptr noundef nonnull align 8 dereferenceable(12) %b), !dbg !12
ret i32 %call, !dbg !12
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!2, !3}
!llvm.ident = !{!4}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 22.0.0git", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
!1 = !DIFile(filename: "test.cpp", directory: "/")
!2 = !{i32 7, !"Dwarf Version", i32 5}
!3 = !{i32 2, !"Debug Info Version", i32 3}
!4 = !{!"clang version 22.0.0git"}
!5 = distinct !DISubprogram(name: "foo", linkageName: "_Z3fooP4Base", scope: !1, file: !1, line: 15, type: !6, scopeLine: 15, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11, keyInstructions: true)
!6 = !DISubroutineType(types: !7)
!7 = !{!8, !9}
!8 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!9 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !10, size: 64)
!10 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Base", file: !1, line: 1, size: 128, flags: DIFlagFwdDecl | DIFlagNonTrivial, identifier: "_ZTS4Base")
!11 = !{}
!12 = !DILocation(line: 16, scope: !5)
...
---
name: _Z3fooP4Base
alignment: 16
tracksRegLiveness: true
noPhis: true
isSSA: false
noVRegs: true
hasFakeUses: false
debugInstrRef: true
tracksDebugUserValues: true
liveins:
- { reg: '$rdi' }
frameInfo:
stackSize: 8
offsetAdjustment: -8
maxAlignment: 1
adjustsStack: true
hasCalls: true
maxCallFrameSize: 0
isCalleeSavedInfoValid: true
machineFunctionInfo:
amxProgModel: None
body: |
bb.0.entry:
liveins: $rdi
frame-setup PUSH64r undef $rax, implicit-def $rsp, implicit $rsp
frame-setup CFI_INSTRUCTION def_cfa_offset 16
renamable $rax = MOV64rm renamable $rdi, 1, $noreg, 0, $noreg, debug-location !12 :: (load (s64) from %ir.b)
CALL64m killed renamable $rax, 1, $noreg, 8, $noreg, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp, implicit-def $eax, debug-location !12 :: (load (s64) from %ir.vfn)
$rcx = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !12
frame-destroy CFI_INSTRUCTION def_cfa_offset 8, debug-location !12
RET64 $eax, debug-location !12
...

8
llvm/test/DebugInfo/X86/dwarf-callsite-related-attrs-indirect.ll
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@ -8,7 +8,7 @@
; RUN: llvm-dwarfdump -statistics %t.o | FileCheck %s -check-prefix=STATS
; VERIFY: No errors.
; STATS: "#call site DIEs": 1,
; STATS: "#call site DIEs": 2,
; OBJ: DW_TAG_subprogram
; OBJ: DW_AT_name ("call_reg")
@ -18,7 +18,7 @@ entry:
#dbg_value(ptr %f, !17, !DIExpression(), !18)
; OBJ: DW_TAG_call_site
; OBJ: DW_AT_call_target
; OBJ: DW_AT_call_target (DW_OP_reg[[#]] {{.*}})
; OBJ: DW_AT_call_return_pc
call void (...) %f() #1, !dbg !19
ret void, !dbg !20
@ -31,6 +31,10 @@ define dso_local void @call_mem(ptr noundef readonly captures(none) %f) local_un
entry:
#dbg_value(ptr %f, !26, !DIExpression(), !27)
%0 = load ptr, ptr %f, align 8, !dbg !28, !tbaa !29
; OBJ: DW_TAG_call_site
; OBJ: DW_AT_call_target (DW_OP_breg[[#]] {{.*}})
; OBJ: DW_AT_call_return_pc
call void (...) %0() #1, !dbg !28
ret void, !dbg !33
}