[clang] d4bcb45 - [MC][re-land] Omit DWARF unwind info if compact unwind is present where eligible
Jez Ng via cfe-commits
cfe-commits at lists.llvm.org
Sun Jun 12 14:24:32 PDT 2022
Author: Jez Ng
Date: 2022-06-12T17:24:19-04:00
New Revision: d4bcb45db78dc7ca371224cb01bea8dcb14e0698
URL: https://github.com/llvm/llvm-project/commit/d4bcb45db78dc7ca371224cb01bea8dcb14e0698
DIFF: https://github.com/llvm/llvm-project/commit/d4bcb45db78dc7ca371224cb01bea8dcb14e0698.diff
LOG: [MC][re-land] Omit DWARF unwind info if compact unwind is present where eligible
This reverts commit d941d597837d9e1405086f008c9bd6a71e7263c9.
Differential Revision: https://reviews.llvm.org/D122258
Added:
clang/test/Driver/femit-dwarf-unwind.c
clang/test/Driver/femit-dwarf-unwind.s
llvm/test/MC/MachO/AArch64/emit-dwarf-unwind.s
llvm/test/MC/X86/compact-unwind-mode-dwarf.s
Modified:
clang/include/clang/Basic/CodeGenOptions.def
clang/include/clang/Driver/Options.td
clang/lib/CodeGen/BackendUtil.cpp
clang/lib/Driver/ToolChains/Clang.cpp
clang/tools/driver/cc1as_main.cpp
llvm/include/llvm/MC/MCContext.h
llvm/include/llvm/MC/MCTargetOptions.h
llvm/include/llvm/MC/MCTargetOptionsCommandFlags.h
llvm/lib/CodeGen/LLVMTargetMachine.cpp
llvm/lib/CodeGen/MachineModuleInfo.cpp
llvm/lib/ExecutionEngine/MCJIT/MCJIT.cpp
llvm/lib/ExecutionEngine/Orc/CompileUtils.cpp
llvm/lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp
llvm/lib/MC/MCContext.cpp
llvm/lib/MC/MCDwarf.cpp
llvm/lib/MC/MCObjectFileInfo.cpp
llvm/lib/MC/MCTargetOptions.cpp
llvm/lib/MC/MCTargetOptionsCommandFlags.cpp
llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
Removed:
################################################################################
diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def
index d8f667dc387bb..8e89106993c26 100644
--- a/clang/include/clang/Basic/CodeGenOptions.def
+++ b/clang/include/clang/Basic/CodeGenOptions.def
@@ -114,6 +114,10 @@ CODEGENOPT(StackSizeSection , 1, 0) ///< Set when -fstack-size-section is enabl
CODEGENOPT(ForceDwarfFrameSection , 1, 0) ///< Set when -fforce-dwarf-frame is
///< enabled.
+///< Set when -femit-dwarf-unwind is passed.
+ENUM_CODEGENOPT(EmitDwarfUnwind, llvm::EmitDwarfUnwindType, 2,
+ llvm::EmitDwarfUnwindType::Default)
+
///< Set when -fxray-always-emit-customevents is enabled.
CODEGENOPT(XRayAlwaysEmitCustomEvents , 1, 0)
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 95840760f7746..002cd6cc8cb17 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -3044,6 +3044,13 @@ def fmacro_prefix_map_EQ
defm force_dwarf_frame : BoolFOption<"force-dwarf-frame",
CodeGenOpts<"ForceDwarfFrameSection">, DefaultFalse,
PosFlag<SetTrue, [CC1Option], "Always emit a debug frame section">, NegFlag<SetFalse>>;
+def femit_dwarf_unwind_EQ : Joined<["-"], "femit-dwarf-unwind=">,
+ Group<f_Group>, Flags<[CC1Option, CC1AsOption]>,
+ HelpText<"When to emit DWARF unwind (EH frame) info">,
+ Values<"always,no-compact-unwind,default">,
+ NormalizedValues<["Always", "NoCompactUnwind", "Default"]>,
+ NormalizedValuesScope<"llvm::EmitDwarfUnwindType">,
+ MarshallingInfoEnum<CodeGenOpts<"EmitDwarfUnwind">, "Default">;
def g_Flag : Flag<["-"], "g">, Group<g_Group>,
HelpText<"Generate source-level debug information">;
def gline_tables_only : Flag<["-"], "gline-tables-only">, Group<gN_Group>,
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 0de15b1e48078..4b294c254e476 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -453,6 +453,7 @@ static bool initTargetOptions(DiagnosticsEngine &Diags,
}
Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
+ Options.MCOptions.EmitDwarfUnwind = CodeGenOpts.getEmitDwarfUnwind();
Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;
Options.MCOptions.MCUseDwarfDirectory =
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index ceac142653ebe..62e891ce38c49 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2518,6 +2518,8 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
DefaultIncrementalLinkerCompatible))
CmdArgs.push_back("-mincremental-linker-compatible");
+ Args.AddLastArg(CmdArgs, options::OPT_femit_dwarf_unwind_EQ);
+
// If you add more args here, also add them to the block below that
// starts with "// If CollectArgsForIntegratedAssembler() isn't called below".
@@ -4622,6 +4624,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
}
Args.ClaimAllArgs(options::OPT_Wa_COMMA);
Args.ClaimAllArgs(options::OPT_Xassembler);
+ Args.ClaimAllArgs(options::OPT_femit_dwarf_unwind_EQ);
}
if (isa<AnalyzeJobAction>(JA)) {
diff --git a/clang/test/Driver/femit-dwarf-unwind.c b/clang/test/Driver/femit-dwarf-unwind.c
new file mode 100644
index 0000000000000..6057c5e0e5348
--- /dev/null
+++ b/clang/test/Driver/femit-dwarf-unwind.c
@@ -0,0 +1,14 @@
+// REQUIRES: x86-registered-target
+
+// RUN: rm -rf %t; mkdir %t
+// RUN: %clang -target x86_64-apple-macos11.0 -c %s -o %t/x86_64.o
+// RUN: %clang -target x86_64-apple-macos11.0 -femit-dwarf-unwind=no-compact-unwind -c %s -o %t/x86_64-no-dwarf.o
+// RUN: llvm-objdump --macho --dwarf=frames %t/x86_64.o | FileCheck %s --check-prefix=WITH-FDE
+// RUN: llvm-objdump --macho --dwarf=frames %t/x86_64-no-dwarf.o | FileCheck %s --check-prefix=NO-FDE
+
+// WITH-FDE: FDE
+// NO-FDE-NOT: FDE
+
+int foo() {
+ return 1;
+}
diff --git a/clang/test/Driver/femit-dwarf-unwind.s b/clang/test/Driver/femit-dwarf-unwind.s
new file mode 100644
index 0000000000000..f2aa821b0cd5a
--- /dev/null
+++ b/clang/test/Driver/femit-dwarf-unwind.s
@@ -0,0 +1,17 @@
+// REQUIRES: x86-registered-target
+
+// RUN: rm -rf %t; mkdir %t
+// RUN: %clang -target x86_64-apple-macos11.0 -c %s -o %t/x86_64.o
+// RUN: %clang -target x86_64-apple-macos11.0 -femit-dwarf-unwind=no-compact-unwind -c %s -o %t/x86_64-no-dwarf.o
+// RUN: llvm-objdump --macho --dwarf=frames %t/x86_64.o | FileCheck %s --check-prefix=WITH-FDE
+// RUN: llvm-objdump --macho --dwarf=frames %t/x86_64-no-dwarf.o | FileCheck %s --check-prefix=NO-FDE
+
+// WITH-FDE: FDE
+// NO-FDE-NOT: FDE
+
+.text
+_foo:
+ .cfi_startproc
+ .cfi_def_cfa_offset 8
+ ret
+ .cfi_endproc
diff --git a/clang/tools/driver/cc1as_main.cpp b/clang/tools/driver/cc1as_main.cpp
index 6a11c25553ba3..264f747d6d740 100644
--- a/clang/tools/driver/cc1as_main.cpp
+++ b/clang/tools/driver/cc1as_main.cpp
@@ -137,6 +137,9 @@ struct AssemblerInvocation {
unsigned IncrementalLinkerCompatible : 1;
unsigned EmbedBitcode : 1;
+ /// Whether to emit DWARF unwind info.
+ EmitDwarfUnwindType EmitDwarfUnwind;
+
/// The name of the relocation model to use.
std::string RelocationModel;
@@ -317,6 +320,14 @@ bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
.Default(0);
}
+ if (auto *A = Args.getLastArg(OPT_femit_dwarf_unwind_EQ)) {
+ Opts.EmitDwarfUnwind =
+ llvm::StringSwitch<EmitDwarfUnwindType>(A->getValue())
+ .Case("always", EmitDwarfUnwindType::Always)
+ .Case("no-compact-unwind", EmitDwarfUnwindType::NoCompactUnwind)
+ .Case("default", EmitDwarfUnwindType::Default);
+ }
+
return Success;
}
@@ -367,6 +378,8 @@ static bool ExecuteAssemblerImpl(AssemblerInvocation &Opts,
assert(MRI && "Unable to create target register info!");
MCTargetOptions MCOptions;
+ MCOptions.EmitDwarfUnwind = Opts.EmitDwarfUnwind;
+
std::unique_ptr<MCAsmInfo> MAI(
TheTarget->createMCAsmInfo(*MRI, Opts.Triple, MCOptions));
assert(MAI && "Unable to create target asm info!");
diff --git a/llvm/include/llvm/MC/MCContext.h b/llvm/include/llvm/MC/MCContext.h
index 5b81ba31b83c5..c3a4e57fdd753 100644
--- a/llvm/include/llvm/MC/MCContext.h
+++ b/llvm/include/llvm/MC/MCContext.h
@@ -67,6 +67,7 @@ template <typename T> class SmallVectorImpl;
class SMDiagnostic;
class SMLoc;
class SourceMgr;
+enum class EmitDwarfUnwindType;
/// Context object for machine code objects. This class owns all of the
/// sections that it creates.
@@ -772,6 +773,7 @@ class MCContext {
bool getGenDwarfForAssembly() { return GenDwarfForAssembly; }
void setGenDwarfForAssembly(bool Value) { GenDwarfForAssembly = Value; }
unsigned getGenDwarfFileNumber() { return GenDwarfFileNumber; }
+ EmitDwarfUnwindType emitDwarfUnwindInfo() const;
void setGenDwarfFileNumber(unsigned FileNumber) {
GenDwarfFileNumber = FileNumber;
diff --git a/llvm/include/llvm/MC/MCTargetOptions.h b/llvm/include/llvm/MC/MCTargetOptions.h
index 93712a6b7d44b..9c906cdc90d02 100644
--- a/llvm/include/llvm/MC/MCTargetOptions.h
+++ b/llvm/include/llvm/MC/MCTargetOptions.h
@@ -31,6 +31,12 @@ enum class DebugCompressionType {
Z, ///< zlib style complession
};
+enum class EmitDwarfUnwindType {
+ Always, // Always emit dwarf unwind
+ NoCompactUnwind, // Only emit if compact unwind isn't available
+ Default, // Default behavior is based on the target
+};
+
class StringRef;
class MCTargetOptions {
@@ -56,6 +62,9 @@ class MCTargetOptions {
bool PreserveAsmComments : 1;
bool Dwarf64 : 1;
+
+ EmitDwarfUnwindType EmitDwarfUnwind;
+
int DwarfVersion = 0;
enum DwarfDirectory {
diff --git a/llvm/include/llvm/MC/MCTargetOptionsCommandFlags.h b/llvm/include/llvm/MC/MCTargetOptionsCommandFlags.h
index 1894841989166..d51e740177f77 100644
--- a/llvm/include/llvm/MC/MCTargetOptionsCommandFlags.h
+++ b/llvm/include/llvm/MC/MCTargetOptionsCommandFlags.h
@@ -20,6 +20,7 @@
namespace llvm {
class MCTargetOptions;
+enum class EmitDwarfUnwindType;
namespace mc {
@@ -32,6 +33,8 @@ int getDwarfVersion();
bool getDwarf64();
+EmitDwarfUnwindType getEmitDwarfUnwind();
+
bool getShowMCInst();
bool getFatalWarnings();
diff --git a/llvm/lib/CodeGen/LLVMTargetMachine.cpp b/llvm/lib/CodeGen/LLVMTargetMachine.cpp
index af05dbced04e1..3192dcadb5f5e 100644
--- a/llvm/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/llvm/lib/CodeGen/LLVMTargetMachine.cpp
@@ -264,6 +264,9 @@ bool LLVMTargetMachine::addPassesToEmitMC(PassManagerBase &PM, MCContext *&Ctx,
"Cannot emit MC with limited codegen pipeline");
Ctx = &MMIWP->getMMI().getContext();
+ // libunwind is unable to load compact unwind dynamically, so we must generate
+ // DWARF unwind info for the JIT.
+ Options.MCOptions.EmitDwarfUnwind = EmitDwarfUnwindType::Always;
if (Options.MCOptions.MCSaveTempLabels)
Ctx->setAllowTemporaryLabels(false);
diff --git a/llvm/lib/CodeGen/MachineModuleInfo.cpp b/llvm/lib/CodeGen/MachineModuleInfo.cpp
index 07ada255eb83d..23d55a5df9f57 100644
--- a/llvm/lib/CodeGen/MachineModuleInfo.cpp
+++ b/llvm/lib/CodeGen/MachineModuleInfo.cpp
@@ -60,7 +60,7 @@ MachineModuleInfo::MachineModuleInfo(MachineModuleInfo &&MMI)
: TM(std::move(MMI.TM)),
Context(MMI.TM.getTargetTriple(), MMI.TM.getMCAsmInfo(),
MMI.TM.getMCRegisterInfo(), MMI.TM.getMCSubtargetInfo(), nullptr,
- nullptr, false),
+ &MMI.TM.Options.MCOptions, false),
MachineFunctions(std::move(MMI.MachineFunctions)) {
Context.setObjectFileInfo(MMI.TM.getObjFileLowering());
ObjFileMMI = MMI.ObjFileMMI;
@@ -72,7 +72,7 @@ MachineModuleInfo::MachineModuleInfo(MachineModuleInfo &&MMI)
MachineModuleInfo::MachineModuleInfo(const LLVMTargetMachine *TM)
: TM(*TM), Context(TM->getTargetTriple(), TM->getMCAsmInfo(),
TM->getMCRegisterInfo(), TM->getMCSubtargetInfo(),
- nullptr, nullptr, false) {
+ nullptr, &TM->Options.MCOptions, false) {
Context.setObjectFileInfo(TM->getObjFileLowering());
initialize();
}
@@ -81,7 +81,7 @@ MachineModuleInfo::MachineModuleInfo(const LLVMTargetMachine *TM,
MCContext *ExtContext)
: TM(*TM), Context(TM->getTargetTriple(), TM->getMCAsmInfo(),
TM->getMCRegisterInfo(), TM->getMCSubtargetInfo(),
- nullptr, nullptr, false),
+ nullptr, &TM->Options.MCOptions, false),
ExternalContext(ExtContext) {
Context.setObjectFileInfo(TM->getObjFileLowering());
initialize();
diff --git a/llvm/lib/ExecutionEngine/MCJIT/MCJIT.cpp b/llvm/lib/ExecutionEngine/MCJIT/MCJIT.cpp
index ed912280ac826..4ac901daa5c83 100644
--- a/llvm/lib/ExecutionEngine/MCJIT/MCJIT.cpp
+++ b/llvm/lib/ExecutionEngine/MCJIT/MCJIT.cpp
@@ -19,6 +19,7 @@
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Module.h"
+#include "llvm/MC/MCContext.h"
#include "llvm/Object/Archive.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/DynamicLibrary.h"
diff --git a/llvm/lib/ExecutionEngine/Orc/CompileUtils.cpp b/llvm/lib/ExecutionEngine/Orc/CompileUtils.cpp
index f342470052581..fad7428e1f906 100644
--- a/llvm/lib/ExecutionEngine/Orc/CompileUtils.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/CompileUtils.cpp
@@ -12,6 +12,7 @@
#include "llvm/ExecutionEngine/ObjectCache.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Module.h"
+#include "llvm/MC/MCContext.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/ErrorHandling.h"
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp
index 820d1dbad8f20..bc42eebf3fec9 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RTDyldMemoryManager.cpp
@@ -95,18 +95,16 @@ void RTDyldMemoryManager::registerEHFramesInProcess(uint8_t *Addr,
// and projects/libunwind/src/UnwindLevel1-gcc-ext.c.
const char *P = (const char *)Addr;
const char *End = P + Size;
- do {
+ while (P != End)
P = processFDE(P, false);
- } while(P != End);
}
void RTDyldMemoryManager::deregisterEHFramesInProcess(uint8_t *Addr,
size_t Size) {
const char *P = (const char *)Addr;
const char *End = P + Size;
- do {
+ while (P != End)
P = processFDE(P, true);
- } while(P != End);
}
#else
diff --git a/llvm/lib/MC/MCContext.cpp b/llvm/lib/MC/MCContext.cpp
index 887969fcd8410..52bf48b6d242b 100644
--- a/llvm/lib/MC/MCContext.cpp
+++ b/llvm/lib/MC/MCContext.cpp
@@ -877,6 +877,12 @@ void MCContext::RemapDebugPaths() {
// Dwarf Management
//===----------------------------------------------------------------------===//
+EmitDwarfUnwindType MCContext::emitDwarfUnwindInfo() const {
+ if (!TargetOptions)
+ return EmitDwarfUnwindType::Default;
+ return TargetOptions->EmitDwarfUnwind;
+}
+
void MCContext::setGenDwarfRootFile(StringRef InputFileName, StringRef Buffer) {
// MCDwarf needs the root file as well as the compilation directory.
// If we find a '.file 0' directive that will supersede these values.
diff --git a/llvm/lib/MC/MCDwarf.cpp b/llvm/lib/MC/MCDwarf.cpp
index 6152b3e5210e2..d151b8b3f89a6 100644
--- a/llvm/lib/MC/MCDwarf.cpp
+++ b/llvm/lib/MC/MCDwarf.cpp
@@ -1842,8 +1842,6 @@ template <> struct DenseMapInfo<CIEKey> {
void MCDwarfFrameEmitter::Emit(MCObjectStreamer &Streamer, MCAsmBackend *MAB,
bool IsEH) {
- Streamer.generateCompactUnwindEncodings(MAB);
-
MCContext &Context = Streamer.getContext();
const MCObjectFileInfo *MOFI = Context.getObjectFileInfo();
const MCAsmInfo *AsmInfo = Context.getAsmInfo();
@@ -1853,6 +1851,7 @@ void MCDwarfFrameEmitter::Emit(MCObjectStreamer &Streamer, MCAsmBackend *MAB,
// Emit the compact unwind info if available.
bool NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame();
if (IsEH && MOFI->getCompactUnwindSection()) {
+ Streamer.generateCompactUnwindEncodings(MAB);
bool SectionEmitted = false;
for (const MCDwarfFrameInfo &Frame : FrameArray) {
if (Frame.CompactUnwindEncoding == 0) continue;
diff --git a/llvm/lib/MC/MCObjectFileInfo.cpp b/llvm/lib/MC/MCObjectFileInfo.cpp
index 0d08976d98942..bb39e5aaad7f4 100644
--- a/llvm/lib/MC/MCObjectFileInfo.cpp
+++ b/llvm/lib/MC/MCObjectFileInfo.cpp
@@ -64,8 +64,18 @@ void MCObjectFileInfo::initMachOMCObjectFileInfo(const Triple &T) {
(T.getArch() == Triple::aarch64 || T.getArch() == Triple::aarch64_32))
SupportsCompactUnwindWithoutEHFrame = true;
- if (T.isWatchABI())
+ switch (Ctx->emitDwarfUnwindInfo()) {
+ case EmitDwarfUnwindType::Always:
+ OmitDwarfIfHaveCompactUnwind = false;
+ break;
+ case EmitDwarfUnwindType::NoCompactUnwind:
OmitDwarfIfHaveCompactUnwind = true;
+ break;
+ case EmitDwarfUnwindType::Default:
+ OmitDwarfIfHaveCompactUnwind =
+ T.isWatchABI() || SupportsCompactUnwindWithoutEHFrame;
+ break;
+ }
FDECFIEncoding = dwarf::DW_EH_PE_pcrel;
diff --git a/llvm/lib/MC/MCTargetOptions.cpp b/llvm/lib/MC/MCTargetOptions.cpp
index bb48182c6622b..c2946da3ee66f 100644
--- a/llvm/lib/MC/MCTargetOptions.cpp
+++ b/llvm/lib/MC/MCTargetOptions.cpp
@@ -17,6 +17,7 @@ MCTargetOptions::MCTargetOptions()
MCSaveTempLabels(false), MCIncrementalLinkerCompatible(false),
ShowMCEncoding(false), ShowMCInst(false), AsmVerbose(false),
PreserveAsmComments(true), Dwarf64(false),
+ EmitDwarfUnwind(EmitDwarfUnwindType::Default),
MCUseDwarfDirectory(DefaultDwarfDirectory) {}
StringRef MCTargetOptions::getABIName() const {
diff --git a/llvm/lib/MC/MCTargetOptionsCommandFlags.cpp b/llvm/lib/MC/MCTargetOptionsCommandFlags.cpp
index 762c8d43063c7..a310dc894021f 100644
--- a/llvm/lib/MC/MCTargetOptionsCommandFlags.cpp
+++ b/llvm/lib/MC/MCTargetOptionsCommandFlags.cpp
@@ -1,5 +1,4 @@
-//===-- MCTargetOptionsCommandFlags.cpp --------------------------*- C++
-//-*-===//
+//===-- MCTargetOptionsCommandFlags.cpp -----------------------*- C++ //-*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
@@ -39,6 +38,7 @@ MCOPT_EXP(bool, RelaxAll)
MCOPT(bool, IncrementalLinkerCompatible)
MCOPT(int, DwarfVersion)
MCOPT(bool, Dwarf64)
+MCOPT(EmitDwarfUnwindType, EmitDwarfUnwind)
MCOPT(bool, ShowMCInst)
MCOPT(bool, FatalWarnings)
MCOPT(bool, NoWarn)
@@ -73,6 +73,19 @@ llvm::mc::RegisterMCTargetOptionsFlags::RegisterMCTargetOptionsFlags() {
cl::desc("Generate debugging info in the 64-bit DWARF format"));
MCBINDOPT(Dwarf64);
+ static cl::opt<EmitDwarfUnwindType> EmitDwarfUnwind(
+ "emit-dwarf-unwind", cl::desc("Whether to emit DWARF EH frame entries."),
+ cl::init(EmitDwarfUnwindType::Default),
+ cl::values(clEnumValN(EmitDwarfUnwindType::Always, "always",
+ "Always emit EH frame entries"),
+ clEnumValN(EmitDwarfUnwindType::NoCompactUnwind,
+ "no-compact-unwind",
+ "Only emit EH frame entries when compact unwind is "
+ "not available"),
+ clEnumValN(EmitDwarfUnwindType::Default, "default",
+ "Use target platform default")));
+ MCBINDOPT(EmitDwarfUnwind);
+
static cl::opt<bool> ShowMCInst(
"asm-show-inst",
cl::desc("Emit internal instruction representation to assembly file"));
@@ -116,5 +129,7 @@ MCTargetOptions llvm::mc::InitMCTargetOptionsFromFlags() {
Options.MCNoWarn = getNoWarn();
Options.MCNoDeprecatedWarn = getNoDeprecatedWarn();
Options.MCNoTypeCheck = getNoTypeCheck();
+ Options.EmitDwarfUnwind = getEmitDwarfUnwind();
+
return Options;
}
diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
index f09c3b36ff3a8..2d92b8d5b574b 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
@@ -1377,7 +1377,7 @@ class DarwinX86AsmBackend : public X86AsmBackend {
default:
// Any other CFI directives indicate a frame that we aren't prepared
// to represent via compact unwind, so just bail out.
- return 0;
+ return CU::UNWIND_MODE_DWARF;
case MCCFIInstruction::OpDefCfaRegister: {
// Defines a frame pointer. E.g.
//
@@ -1391,7 +1391,7 @@ class DarwinX86AsmBackend : public X86AsmBackend {
// generate a compact unwinding representation, so bail out.
if (*MRI.getLLVMRegNum(Inst.getRegister(), true) !=
(Is64Bit ? X86::RBP : X86::EBP))
- return 0;
+ return CU::UNWIND_MODE_DWARF;
// Reset the counts.
memset(SavedRegs, 0, sizeof(SavedRegs));
diff --git a/llvm/test/MC/MachO/AArch64/emit-dwarf-unwind.s b/llvm/test/MC/MachO/AArch64/emit-dwarf-unwind.s
new file mode 100644
index 0000000000000..89dc56b8aa87f
--- /dev/null
+++ b/llvm/test/MC/MachO/AArch64/emit-dwarf-unwind.s
@@ -0,0 +1,33 @@
+// RUN: rm -rf %t; mkdir %t
+// RUN: llvm-mc -triple x86_64-apple-macos11.0 %s -filetype=obj -o %t/x86_64.o
+// RUN: llvm-objdump --macho --dwarf=frames %t/x86_64.o | FileCheck %s --check-prefix TWO-FDES
+// RUN: llvm-mc -triple arm64-apple-macos11.0 %s -filetype=obj -o %t/arm64.o
+// RUN: llvm-objdump --macho --dwarf=frames %t/arm64.o | FileCheck %s --check-prefix ONE-FDE
+// RUN: llvm-mc -triple x86_64-apple-macos11.0 %s -filetype=obj --emit-dwarf-unwind no-compact-unwind -o %t/x86_64-no-dwarf.o
+// RUN: llvm-objdump --macho --dwarf=frames %t/x86_64-no-dwarf.o | FileCheck %s --check-prefix ONE-FDE
+// RUN: llvm-mc -triple arm64-apple-macos11.0 %s -filetype=obj --emit-dwarf-unwind always -o %t/arm64-dwarf.o
+// RUN: llvm-objdump --macho --dwarf=frames %t/arm64-dwarf.o | FileCheck %s --check-prefix TWO-FDES
+
+// TWO-FDES: FDE
+// TWO-FDES: FDE
+
+// ONE-FDE-NOT: FDE
+// ONE-FDE: FDE
+// ONE-FDE-NOT: FDE
+
+_main:
+ .cfi_startproc
+ .cfi_def_cfa_offset 16
+ ret
+ .cfi_endproc
+
+_foo:
+ .cfi_startproc
+ .cfi_def_cfa_offset 16
+ /// This encodes DW_CFA_GNU_args_size which cannot be expressed using compact
+ /// unwind, so we must use DWARf unwind for this function.
+ .cfi_escape 0x2e, 0x10
+ ret
+ .cfi_endproc
+
+.subsections_via_symbols
diff --git a/llvm/test/MC/X86/compact-unwind-mode-dwarf.s b/llvm/test/MC/X86/compact-unwind-mode-dwarf.s
new file mode 100644
index 0000000000000..ca051b07b59ef
--- /dev/null
+++ b/llvm/test/MC/X86/compact-unwind-mode-dwarf.s
@@ -0,0 +1,50 @@
+// RUN: llvm-mc -triple x86_64-apple-macos10.6 -filetype=obj %s -o %t.o
+// RUN: llvm-objdump --macho --unwind-info --dwarf=frames %t.o | FileCheck %s
+
+/// For functions whose unwind info cannot be encoded with compact unwind, make
+/// sure that we encode them using DWARF unwind, and make sure we emit a compact
+/// unwind entry that indicates that a DWARF encoding is being used.
+
+_f:
+ .cfi_startproc
+ ## This encodes DW_CFA_GNU_args_size which cannot be expressed using compact
+ ## unwind, so we must use DWARF unwind instead.
+ .cfi_escape 0x2e, 0x10
+ ret
+ .cfi_endproc
+
+_g:
+ .cfi_startproc
+ ## This encodes DW_CFA_GNU_args_size which cannot be expressed using compact
+ ## unwind, so we must use DWARF unwind instead.
+ .cfi_escape 0x2e, 0x10
+ ret
+ .cfi_endproc
+
+// CHECK: Contents of __compact_unwind section:
+// CHECK: Entry at offset 0x0:
+// CHECK: start: 0x[[#%x,F:]] _f
+// CHECK: length: 0x1
+// CHECK: compact encoding: 0x04000000
+// CHECK: Entry at offset 0x20:
+// CHECK: start: 0x[[#%x,G:]] _g
+// CHECK: length: 0x1
+// CHECK: compact encoding: 0x04000000
+
+// CHECK: .eh_frame contents:
+// CHECK: 00000000 00000014 00000000 CIE
+// CHECK: Format: DWARF32
+// CHECK: Version: 1
+// CHECK: Augmentation: "zR"
+// CHECK: Code alignment factor: 1
+// CHECK: Data alignment factor: -8
+// CHECK: Return address column: 16
+// CHECK: Augmentation data: 10
+
+// CHECK: FDE cie=00000000 pc=[[#%.8x,F]]...
+// CHECK: Format: DWARF32
+// CHECK: DW_CFA_GNU_args_size: +16
+
+// CHECK: FDE cie=00000000 pc=[[#%.8x,G]]...
+// CHECK: Format: DWARF32
+// CHECK: DW_CFA_GNU_args_size: +16
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