dcandler updated this revision to Diff 224581.
dcandler retitled this revision from "[cfi] Add flag to always generate call
frame information" to "[cfi] Add flag to always generate .debug_frame".
dcandler edited the summary of this revision.
dcandler added reviewers: rengolin, joerg.
dcandler added a comment.
Herald added subscribers: jsji, MaskRay, kbarton, nemanjai.
I've modified the patch so that the new flag will ensure the cfi instructions
are actually present to be emitted as well. I went ahead and renamed the flag
-gdwarf-frame too, to better reflect that it's dealing with the debug
information you'd otherwise get with -g, and is meant to specifically put the
information in a .debug_frame section and not .eh_frame.
Currently, two things signal for need for cfi: exceptions (via the function's
needsUnwindTableEntry()), and debug (via the machine module information's
hasDebugInfo()). At frame lowering, both trigger the same thing. But when the
assembly printer decides on which section to use, needsUnwindTableEntry() is
checked first and triggers the need for .eh_frame, while hasDebugInfo() is
checked afterwards for whether .debug_frame is needed. So .debug_frame is only
present when any level of debug is requested, and no functions need unwinding
for exceptions.
It wouldn't be appropriate to change either needsUnwindTableEntry() or
hasDebugInfo(), so I've added a check for my flag alongside them. Because the
same logic is used in multiple places, I've wrapped all three checks into one
function to try and clean things up slightly. When deciding on which section to
emit, the new flag means .debug_frame is produced instead of nothing. If
.eh_frame would have been needed, rather than replace it, the new flag simply
emits both .debug_frame and .eh_frame.
The end result is that -gdwarf-frame should only provide a .debug_frame section
as additional information, without otherwise modifying anything. The existing
-funwind-tables (and -fasynchronous-unwind-tables) flag can be used to provide
similar information, but because it takes the exception angle, it alters
function attributes and ultimately produces .eh_frame instead.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D67216/new/
https://reviews.llvm.org/D67216
Files:
clang/include/clang/Basic/CodeGenOptions.def
clang/include/clang/Driver/Options.td
clang/lib/CodeGen/BackendUtil.cpp
clang/lib/Driver/ToolChains/Clang.cpp
clang/lib/Frontend/CompilerInvocation.cpp
clang/test/Driver/gdwarf-frame.c
llvm/include/llvm/CodeGen/CommandFlags.inc
llvm/include/llvm/CodeGen/MachineFunction.h
llvm/include/llvm/Target/TargetOptions.h
llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
llvm/lib/CodeGen/CFIInstrInserter.cpp
llvm/lib/CodeGen/MachineFunction.cpp
llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
llvm/lib/Target/ARC/ARCRegisterInfo.cpp
llvm/lib/Target/Hexagon/HexagonFrameLowering.cpp
llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
llvm/lib/Target/X86/X86FrameLowering.cpp
llvm/lib/Target/X86/X86InstrInfo.cpp
llvm/lib/Target/XCore/XCoreRegisterInfo.cpp
llvm/test/CodeGen/ARM/dwarf-frame.ll
Index: llvm/test/CodeGen/ARM/dwarf-frame.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/ARM/dwarf-frame.ll
@@ -0,0 +1,38 @@
+; RUN: llc -mtriple armv7-unknown -frame-pointer=all -filetype=asm -o - %s | FileCheck %s --check-prefix=CHECK-NO-CFI
+; RUN: llc -mtriple armv7-unknown -frame-pointer=all -filetype=asm -dwarf-frame-section -o - %s | FileCheck %s --check-prefix=CHECK-ALWAYS-CFI
+
+declare void @dummy_use(i32*, i32)
+
+define void @test_basic() #0 {
+ %mem = alloca i32, i32 10
+ call void @dummy_use (i32* %mem, i32 10)
+ ret void
+}
+
+; CHECK-NO-CFI-LABEL: test_basic:
+; CHECK-NO-CFI: .fnstart
+; CHECK-NO-CFI-NOT: .cfi_sections .debug_frame
+; CHECK-NO-CFI-NOT: .cfi_startproc
+; CHECK-NO-CFI: @ %bb.0:
+; CHECK-NO-CFI: push {r11, lr}
+; CHECK-NO-CFI-NOT: .cfi_def_cfa_offset 8
+; CHECK-NO-CFI-NOT: .cfi_offset lr, -4
+; CHECK-NO-CFI-NOT: .cfi_offset r11, -8
+; CHECK-NO-CFI: mov r11, sp
+; CHECK-NO-CFI-NOT: .cfi_def_cfa_register r11
+; CHECK-NO-CFI-NOT: .cfi_endproc
+; CHECK-NO-CFI: .fnend
+
+; CHECK-ALWAYS-CFI-LABEL: test_basic:
+; CHECK-ALWAYS-CFI: .fnstart
+; CHECK-ALWAYS-CFI: .cfi_sections .debug_frame
+; CHECK-ALWAYS-CFI: .cfi_startproc
+; CHECK-ALWAYS-CFI: @ %bb.0:
+; CHECK-ALWAYS-CFI: push {r11, lr}
+; CHECK-ALWAYS-CFI: .cfi_def_cfa_offset 8
+; CHECK-ALWAYS-CFI: .cfi_offset lr, -4
+; CHECK-ALWAYS-CFI: .cfi_offset r11, -8
+; CHECK-ALWAYS-CFI: mov r11, sp
+; CHECK-ALWAYS-CFI: .cfi_def_cfa_register r11
+; CHECK-ALWAYS-CFI: .cfi_endproc
+; CHECK-ALWAYS-CFI: .fnend
Index: llvm/lib/Target/XCore/XCoreRegisterInfo.cpp
===================================================================
--- llvm/lib/Target/XCore/XCoreRegisterInfo.cpp
+++ llvm/lib/Target/XCore/XCoreRegisterInfo.cpp
@@ -203,7 +203,7 @@
}
bool XCoreRegisterInfo::needsFrameMoves(const MachineFunction &MF) {
- return MF.getMMI().hasDebugInfo() || MF.getFunction().needsUnwindTableEntry();
+ return MF.needsFrameMoves();
}
const MCPhysReg *
Index: llvm/lib/Target/X86/X86InstrInfo.cpp
===================================================================
--- llvm/lib/Target/X86/X86InstrInfo.cpp
+++ llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -3963,9 +3963,7 @@
MachineFunction &MF = *MBB.getParent();
const X86FrameLowering *TFL = Subtarget.getFrameLowering();
bool IsWin64Prologue = MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
- bool NeedsDwarfCFI =
- !IsWin64Prologue &&
- (MF.getMMI().hasDebugInfo() || MF.getFunction().needsUnwindTableEntry());
+ bool NeedsDwarfCFI = !IsWin64Prologue && MF.needsFrameMoves();
bool EmitCFI = !TFL->hasFP(MF) && NeedsDwarfCFI;
if (EmitCFI) {
TFL->BuildCFI(MBB, I, DL,
Index: llvm/lib/Target/X86/X86FrameLowering.cpp
===================================================================
--- llvm/lib/Target/X86/X86FrameLowering.cpp
+++ llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -993,8 +993,7 @@
bool NeedsWinFPO =
!IsFunclet && STI.isTargetWin32() && MMI.getModule()->getCodeViewFlag();
bool NeedsWinCFI = NeedsWin64CFI || NeedsWinFPO;
- bool NeedsDwarfCFI =
- !IsWin64Prologue && (MMI.hasDebugInfo() || Fn.needsUnwindTableEntry());
+ bool NeedsDwarfCFI = !IsWin64Prologue && MF.needsFrameMoves();
Register FramePtr = TRI->getFrameRegister(MF);
const Register MachineFramePtr =
STI.isTarget64BitILP32()
@@ -1614,10 +1613,9 @@
bool HasFP = hasFP(MF);
uint64_t NumBytes = 0;
- bool NeedsDwarfCFI =
- (!MF.getTarget().getTargetTriple().isOSDarwin() &&
- !MF.getTarget().getTargetTriple().isOSWindows()) &&
- (MF.getMMI().hasDebugInfo() || MF.getFunction().needsUnwindTableEntry());
+ bool NeedsDwarfCFI = (!MF.getTarget().getTargetTriple().isOSDarwin() &&
+ !MF.getTarget().getTargetTriple().isOSWindows()) &&
+ MF.needsFrameMoves();
if (IsFunclet) {
assert(HasFP && "EH funclets without FP not yet implemented");
@@ -2812,11 +2810,9 @@
unsigned StackAlign = getStackAlignment();
Amount = alignTo(Amount, StackAlign);
- MachineModuleInfo &MMI = MF.getMMI();
const Function &F = MF.getFunction();
bool WindowsCFI = MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
- bool DwarfCFI = !WindowsCFI &&
- (MMI.hasDebugInfo() || F.needsUnwindTableEntry());
+ bool DwarfCFI = !WindowsCFI && MF.needsFrameMoves();
// If we have any exception handlers in this function, and we adjust
// the SP before calls, we may need to indicate this to the unwinder
Index: llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
===================================================================
--- llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
+++ llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
@@ -782,8 +782,7 @@
MachineModuleInfo &MMI = MF.getMMI();
const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo();
DebugLoc dl;
- bool needsCFI = MMI.hasDebugInfo() ||
- MF.getFunction().needsUnwindTableEntry();
+ bool needsCFI = MF.needsFrameMoves();
// Get processor type.
bool isPPC64 = Subtarget.isPPC64();
Index: llvm/lib/Target/Hexagon/HexagonFrameLowering.cpp
===================================================================
--- llvm/lib/Target/Hexagon/HexagonFrameLowering.cpp
+++ llvm/lib/Target/Hexagon/HexagonFrameLowering.cpp
@@ -223,8 +223,7 @@
bool HexagonCallFrameInformation::runOnMachineFunction(MachineFunction &MF) {
auto &HFI = *MF.getSubtarget<HexagonSubtarget>().getFrameLowering();
- bool NeedCFI = MF.getMMI().hasDebugInfo() ||
- MF.getFunction().needsUnwindTableEntry();
+ bool NeedCFI = MF.needsFrameMoves();
if (!NeedCFI)
return false;
Index: llvm/lib/Target/ARC/ARCRegisterInfo.cpp
===================================================================
--- llvm/lib/Target/ARC/ARCRegisterInfo.cpp
+++ llvm/lib/Target/ARC/ARCRegisterInfo.cpp
@@ -128,7 +128,7 @@
ARCRegisterInfo::ARCRegisterInfo() : ARCGenRegisterInfo(ARC::BLINK) {}
bool ARCRegisterInfo::needsFrameMoves(const MachineFunction &MF) {
- return MF.getMMI().hasDebugInfo() || MF.getFunction().needsUnwindTableEntry();
+ return MF.needsFrameMoves();
}
const MCPhysReg *
Index: llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -841,8 +841,8 @@
const TargetInstrInfo *TII = Subtarget.getInstrInfo();
MachineModuleInfo &MMI = MF.getMMI();
AArch64FunctionInfo *AFI = MF.getInfo<AArch64FunctionInfo>();
- bool needsFrameMoves = (MMI.hasDebugInfo() || F.needsUnwindTableEntry()) &&
- !MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
+ bool needsFrameMoves =
+ MF.needsFrameMoves() && !MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
bool HasFP = hasFP(MF);
bool NeedsWinCFI = needsWinCFI(MF);
bool HasWinCFI = false;
Index: llvm/lib/CodeGen/MachineFunction.cpp
===================================================================
--- llvm/lib/CodeGen/MachineFunction.cpp
+++ llvm/lib/CodeGen/MachineFunction.cpp
@@ -521,6 +521,12 @@
OS << "\n# End machine code for function " << getName() << ".\n\n";
}
+/// True if this function needs frame moves for debug or exceptions.
+bool MachineFunction::needsFrameMoves() const {
+ return getMMI().hasDebugInfo() || getTarget().Options.EmitDwarfFrameSection ||
+ F.needsUnwindTableEntry();
+}
+
namespace llvm {
template<>
Index: llvm/lib/CodeGen/CFIInstrInserter.cpp
===================================================================
--- llvm/lib/CodeGen/CFIInstrInserter.cpp
+++ llvm/lib/CodeGen/CFIInstrInserter.cpp
@@ -48,8 +48,7 @@
}
bool runOnMachineFunction(MachineFunction &MF) override {
- if (!MF.getMMI().hasDebugInfo() &&
- !MF.getFunction().needsUnwindTableEntry())
+ if (!MF.needsFrameMoves())
return false;
MBBVector.resize(MF.getNumBlockIDs());
Index: llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
+++ llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
@@ -29,6 +29,7 @@
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FormattedStream.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
+#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
using namespace llvm;
@@ -133,6 +134,8 @@
if (!hasEmittedCFISections) {
if (Asm->needsOnlyDebugCFIMoves())
Asm->OutStreamer->EmitCFISections(false, true);
+ else if (Asm->TM.Options.EmitDwarfFrameSection)
+ Asm->OutStreamer->EmitCFISections(true, true);
hasEmittedCFISections = true;
}
Index: llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -940,7 +940,7 @@
MF->getFunction().needsUnwindTableEntry())
return CFI_M_EH;
- if (MMI->hasDebugInfo())
+ if (MMI->hasDebugInfo() || MF->getTarget().Options.EmitDwarfFrameSection)
return CFI_M_Debug;
return CFI_M_None;
Index: llvm/include/llvm/Target/TargetOptions.h
===================================================================
--- llvm/include/llvm/Target/TargetOptions.h
+++ llvm/include/llvm/Target/TargetOptions.h
@@ -119,7 +119,7 @@
ExplicitEmulatedTLS(false), EnableIPRA(false),
EmitStackSizeSection(false), EnableMachineOutliner(false),
SupportsDefaultOutlining(false), EmitAddrsig(false),
- EnableDebugEntryValues(false) {}
+ EnableDebugEntryValues(false), EmitDwarfFrameSection(false) {}
/// PrintMachineCode - This flag is enabled when the -print-machineinstrs
/// option is specified on the command line, and should enable debugging
@@ -256,6 +256,9 @@
/// Emit debug info about parameter's entry values.
unsigned EnableDebugEntryValues : 1;
+ /// Emit Dwarf unwinding information.
+ unsigned EmitDwarfFrameSection : 1;
+
/// FloatABIType - This setting is set by -float-abi=xxx option is specfied
/// on the command line. This setting may either be Default, Soft, or Hard.
/// Default selects the target's default behavior. Soft selects the ABI for
Index: llvm/include/llvm/CodeGen/MachineFunction.h
===================================================================
--- llvm/include/llvm/CodeGen/MachineFunction.h
+++ llvm/include/llvm/CodeGen/MachineFunction.h
@@ -548,6 +548,9 @@
}
void setHasWinCFI(bool v) { HasWinCFI = v; }
+ /// True if this function needs frame moves for debug or exceptions.
+ bool needsFrameMoves() const;
+
/// Get the function properties
const MachineFunctionProperties &getProperties() const { return Properties; }
MachineFunctionProperties &getProperties() { return Properties; }
Index: llvm/include/llvm/CodeGen/CommandFlags.inc
===================================================================
--- llvm/include/llvm/CodeGen/CommandFlags.inc
+++ llvm/include/llvm/CodeGen/CommandFlags.inc
@@ -276,6 +276,8 @@
cl::desc("Emit debug info about parameter's entry values"),
cl::init(false));
+static cl::opt<bool> DwarfFrameSection("dwarf-frame-section", cl::desc("Emit debug frame section without generating other debug info"), cl::init(false));
+
// Common utility function tightly tied to the options listed here. Initializes
// a TargetOptions object with CodeGen flags and returns it.
static TargetOptions InitTargetOptionsFromCodeGenFlags() {
@@ -306,6 +308,7 @@
Options.EmitStackSizeSection = EnableStackSizeSection;
Options.EmitAddrsig = EnableAddrsig;
Options.EnableDebugEntryValues = EnableDebugEntryValues;
+ Options.EmitDwarfFrameSection = DwarfFrameSection;
Options.MCOptions = InitMCTargetOptionsFromFlags();
Index: clang/test/Driver/gdwarf-frame.c
===================================================================
--- /dev/null
+++ clang/test/Driver/gdwarf-frame.c
@@ -0,0 +1,6 @@
+// RUN: %clang -target arm -c -### %s -gdwarf-frame 2>&1 | FileCheck --check-prefix=CHECK-ALWAYS %s
+// RUN: %clang -target arm -c -### %s -gno-dwarf-frame 2>&1 | FileCheck --check-prefix=CHECK-NO-ALWAYS %s
+// RUN: %clang -target arm -c -### %s 2>&1 | FileCheck --check-prefix=CHECK-NO-ALWAYS %s
+
+// CHECK-ALWAYS: -gdwarf-frame
+// CHECK-NO-ALWAYS-NOT: -gdwarf-frame
Index: clang/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- clang/lib/Frontend/CompilerInvocation.cpp
+++ clang/lib/Frontend/CompilerInvocation.cpp
@@ -766,6 +766,9 @@
Opts.DebugExplicitImport = Args.hasArg(OPT_dwarf_explicit_import);
Opts.DebugFwdTemplateParams = Args.hasArg(OPT_debug_forward_template_params);
Opts.EmbedSource = Args.hasArg(OPT_gembed_source);
+
+ Opts.DwarfFrameSection =
+ Args.hasFlag(OPT_gdwarf_frame, OPT_gno_dwarf_frame, false);
for (const auto &Arg : Args.getAllArgValues(OPT_fdebug_prefix_map_EQ))
Opts.DebugPrefixMap.insert(StringRef(Arg).split('='));
Index: clang/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Clang.cpp
+++ clang/lib/Driver/ToolChains/Clang.cpp
@@ -3429,6 +3429,10 @@
CmdArgs.push_back("-generate-arange-section");
}
+ if (Args.hasFlag(options::OPT_gdwarf_frame,
+ options::OPT_gno_dwarf_frame, false))
+ CmdArgs.push_back("-gdwarf-frame");
+
if (Args.hasFlag(options::OPT_fdebug_types_section,
options::OPT_fno_debug_types_section, false)) {
if (!T.isOSBinFormatELF()) {
Index: clang/lib/CodeGen/BackendUtil.cpp
===================================================================
--- clang/lib/CodeGen/BackendUtil.cpp
+++ clang/lib/CodeGen/BackendUtil.cpp
@@ -485,6 +485,7 @@
Options.EmitStackSizeSection = CodeGenOpts.StackSizeSection;
Options.EmitAddrsig = CodeGenOpts.Addrsig;
Options.EnableDebugEntryValues = CodeGenOpts.EnableDebugEntryValues;
+ Options.EmitDwarfFrameSection = CodeGenOpts.DwarfFrameSection;
Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -1972,6 +1972,10 @@
def gpubnames : Flag<["-"], "gpubnames">, Group<g_flags_Group>, Flags<[CC1Option]>;
def gno_pubnames : Flag<["-"], "gno-pubnames">, Group<g_flags_Group>, Flags<[CC1Option]>;
def gdwarf_aranges : Flag<["-"], "gdwarf-aranges">, Group<g_flags_Group>;
+def gdwarf_frame : Flag<["-"], "gdwarf-frame">, Group<g_flags_Group>, Flags<[CC1Option]>,
+ HelpText<"Emit debug frame section without generating other debug info">;
+def gno_dwarf_frame : Flag<["-"], "gno-dwarf-frame">, Group<g_flags_Group>, Flags<[CC1Option]>,
+ HelpText<"Don't emit debug frame section without generating other debug info">;
def gmodules : Flag <["-"], "gmodules">, Group<gN_Group>,
HelpText<"Generate debug info with external references to clang modules"
" or precompiled headers">;
Index: clang/include/clang/Basic/CodeGenOptions.def
===================================================================
--- clang/include/clang/Basic/CodeGenOptions.def
+++ clang/include/clang/Basic/CodeGenOptions.def
@@ -96,6 +96,7 @@
CODEGENOPT(XRayInstrumentFunctions , 1, 0) ///< Set when -fxray-instrument is
///< enabled.
CODEGENOPT(StackSizeSection , 1, 0) ///< Set when -fstack-size-section is enabled.
+CODEGENOPT(DwarfFrameSection , 1, 0) ///< Set when -gdwarf-frame is enabled.
///< Set when -fxray-always-emit-customevents is enabled.
CODEGENOPT(XRayAlwaysEmitCustomEvents , 1, 0)
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