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rnkrnk
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Generate native unwind info on Win64
This patch enables LLVM to emit Win64-native unwind info rather than DWARF CFI. It handles all corner cases (I hope), including stack realignment. Because the unwind info is not flexible enough to describe stack frames with a gap of unknown size in the middle, such as the one caused by stack realignment, I modified register spilling code to place all spills into the fixed frame slots, so that they can be accessed relative to the frame pointer. Patch by Vadim Chugunov! Reviewed By: rnk Differential Revision: http://reviews.llvm.org/D4081 llvm-svn: 211399
1 parent 4a4b357 commit 4a01230

19 files changed

Lines changed: 645 additions & 228 deletions

‎llvm/include/llvm/CodeGen/MachineFrameInfo.h‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -484,6 +484,9 @@ class MachineFrameInfo {
484484
///
485485
int CreateFixedObject(uint64_t Size, int64_t SPOffset, bool Immutable);
486486

487+
/// CreateFixedSpillStackObject - Create a spill slot at a fixed location
488+
/// on the stack. Returns an index with a negative value.
489+
int CreateFixedSpillStackObject(uint64_t Size, int64_t SPOffset);
487490

488491
/// isFixedObjectIndex - Returns true if the specified index corresponds to a
489492
/// fixed stack object.

‎llvm/include/llvm/MC/MCAsmInfo.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -481,6 +481,7 @@ class MCAsmInfo {
481481
bool isExceptionHandlingDwarf() const {
482482
return (ExceptionsType == ExceptionHandling::DwarfCFI ||
483483
ExceptionsType == ExceptionHandling::ARM ||
484+
// Win64 handler data still uses DWARF LSDA encoding.
484485
ExceptionsType == ExceptionHandling::Win64);
485486
}
486487
bool doesDwarfUseRelocationsAcrossSections() const {

‎llvm/include/llvm/Target/TargetFrameLowering.h‎

Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -93,6 +93,19 @@ class TargetFrameLowering {
9393
/// stack pointer.
9494
virtual bool isFPCloseToIncomingSP() const { return true; }
9595

96+
/// assignCalleeSavedSpillSlots - Allows target to override spill slot
97+
/// assignment logic. If implemented, assignCalleeSavedSpillSlots() should
98+
/// assign frame slots to all CSI entries and return true. If this method
99+
/// returns false, spill slots will be assigned using generic implementation.
100+
/// assignCalleeSavedSpillSlots() may add, delete or rearrange elements of
101+
/// CSI.
102+
virtual bool
103+
assignCalleeSavedSpillSlots(MachineFunction &MF,
104+
const TargetRegisterInfo *TRI,
105+
std::vector<CalleeSavedInfo> &CSI) const {
106+
return false;
107+
}
108+
96109
/// getCalleeSavedSpillSlots - This method returns a pointer to an array of
97110
/// pairs, that contains an entry for each callee saved register that must be
98111
/// spilled to a particular stack location if it is spilled.

‎llvm/lib/CodeGen/AsmPrinter/Win64Exception.cpp‎

Lines changed: 3 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -77,9 +77,9 @@ void Win64Exception::beginFunction(const MachineFunction *MF) {
7777
if (!shouldEmitPersonality)
7878
return;
7979

80-
MCSymbol *GCCHandlerSym =
81-
Asm->GetExternalSymbolSymbol("_GCC_specific_handler");
82-
Asm->OutStreamer.EmitWin64EHHandler(GCCHandlerSym, true, true);
80+
const MCSymbol *PersHandlerSym =
81+
TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI);
82+
Asm->OutStreamer.EmitWin64EHHandler(PersHandlerSym, true, true);
8383

8484
Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_begin",
8585
Asm->getFunctionNumber()));
@@ -98,15 +98,8 @@ void Win64Exception::endFunction(const MachineFunction *) {
9898
MMI->TidyLandingPads();
9999

100100
if (shouldEmitPersonality) {
101-
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
102-
const Function *Per = MMI->getPersonalities()[MMI->getPersonalityIndex()];
103-
const MCSymbol *Sym =
104-
TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI);
105-
106101
Asm->OutStreamer.PushSection();
107102
Asm->OutStreamer.EmitWin64EHHandlerData();
108-
Asm->OutStreamer.EmitValue(MCSymbolRefExpr::Create(Sym, Asm->OutContext),
109-
4);
110103
emitExceptionTable();
111104
Asm->OutStreamer.PopSection();
112105
}

‎llvm/lib/CodeGen/MachineFunction.cpp‎

Lines changed: 28 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -457,7 +457,7 @@ unsigned MachineFunction::addLiveIn(unsigned PReg,
457457
/// getJTISymbol - Return the MCSymbol for the specified non-empty jump table.
458458
/// If isLinkerPrivate is specified, an 'l' label is returned, otherwise a
459459
/// normal 'L' label is returned.
460-
MCSymbol *MachineFunction::getJTISymbol(unsigned JTI, MCContext &Ctx,
460+
MCSymbol *MachineFunction::getJTISymbol(unsigned JTI, MCContext &Ctx,
461461
bool isLinkerPrivate) const {
462462
const DataLayout *DL = getTarget().getDataLayout();
463463
assert(JumpTableInfo && "No jump tables");
@@ -530,10 +530,9 @@ int MachineFrameInfo::CreateStackObject(uint64_t Size, unsigned Alignment,
530530
///
531531
int MachineFrameInfo::CreateSpillStackObject(uint64_t Size,
532532
unsigned Alignment) {
533-
Alignment =
534-
clampStackAlignment(!getFrameLowering()->isStackRealignable() ||
535-
!RealignOption,
536-
Alignment, getFrameLowering()->getStackAlignment());
533+
Alignment = clampStackAlignment(
534+
!getFrameLowering()->isStackRealignable() || !RealignOption, Alignment,
535+
getFrameLowering()->getStackAlignment());
537536
CreateStackObject(Size, Alignment, true);
538537
int Index = (int)Objects.size() - NumFixedObjects - 1;
539538
ensureMaxAlignment(Alignment);
@@ -548,10 +547,9 @@ int MachineFrameInfo::CreateSpillStackObject(uint64_t Size,
548547
int MachineFrameInfo::CreateVariableSizedObject(unsigned Alignment,
549548
const AllocaInst *Alloca) {
550549
HasVarSizedObjects = true;
551-
Alignment =
552-
clampStackAlignment(!getFrameLowering()->isStackRealignable() ||
553-
!RealignOption,
554-
Alignment, getFrameLowering()->getStackAlignment());
550+
Alignment = clampStackAlignment(
551+
!getFrameLowering()->isStackRealignable() || !RealignOption, Alignment,
552+
getFrameLowering()->getStackAlignment());
555553
Objects.push_back(StackObject(0, Alignment, 0, false, false, Alloca));
556554
ensureMaxAlignment(Alignment);
557555
return (int)Objects.size()-NumFixedObjects-1;
@@ -571,16 +569,30 @@ int MachineFrameInfo::CreateFixedObject(uint64_t Size, int64_t SPOffset,
571569
// object is 16-byte aligned.
572570
unsigned StackAlign = getFrameLowering()->getStackAlignment();
573571
unsigned Align = MinAlign(SPOffset, StackAlign);
574-
Align =
575-
clampStackAlignment(!getFrameLowering()->isStackRealignable() ||
576-
!RealignOption,
577-
Align, getFrameLowering()->getStackAlignment());
572+
Align = clampStackAlignment(!getFrameLowering()->isStackRealignable() ||
573+
!RealignOption,
574+
Align, getFrameLowering()->getStackAlignment());
578575
Objects.insert(Objects.begin(), StackObject(Size, Align, SPOffset, Immutable,
579576
/*isSS*/ false,
580577
/*Alloca*/ nullptr));
581578
return -++NumFixedObjects;
582579
}
583580

581+
/// CreateFixedSpillStackObject - Create a spill slot at a fixed location
582+
/// on the stack. Returns an index with a negative value.
583+
int MachineFrameInfo::CreateFixedSpillStackObject(uint64_t Size,
584+
int64_t SPOffset) {
585+
unsigned StackAlign = getFrameLowering()->getStackAlignment();
586+
unsigned Align = MinAlign(SPOffset, StackAlign);
587+
Align = clampStackAlignment(!getFrameLowering()->isStackRealignable() ||
588+
!RealignOption,
589+
Align, getFrameLowering()->getStackAlignment());
590+
Objects.insert(Objects.begin(), StackObject(Size, Align, SPOffset,
591+
/*Immutable*/ true,
592+
/*isSS*/ true,
593+
/*Alloca*/ nullptr));
594+
return -++NumFixedObjects;
595+
}
584596

585597
BitVector
586598
MachineFrameInfo::getPristineRegs(const MachineBasicBlock *MBB) const {
@@ -849,11 +861,10 @@ static bool CanShareConstantPoolEntry(const Constant *A, const Constant *B,
849861
if (isa<StructType>(A->getType()) || isa<ArrayType>(A->getType()) ||
850862
isa<StructType>(B->getType()) || isa<ArrayType>(B->getType()))
851863
return false;
852-
864+
853865
// For now, only support constants with the same size.
854866
uint64_t StoreSize = TD->getTypeStoreSize(A->getType());
855-
if (StoreSize != TD->getTypeStoreSize(B->getType()) ||
856-
StoreSize > 128)
867+
if (StoreSize != TD->getTypeStoreSize(B->getType()) || StoreSize > 128)
857868
return false;
858869

859870
Type *IntTy = IntegerType::get(A->getContext(), StoreSize*8);
@@ -882,7 +893,7 @@ static bool CanShareConstantPoolEntry(const Constant *A, const Constant *B,
882893
/// an existing one. User must specify the log2 of the minimum required
883894
/// alignment for the object.
884895
///
885-
unsigned MachineConstantPool::getConstantPoolIndex(const Constant *C,
896+
unsigned MachineConstantPool::getConstantPoolIndex(const Constant *C,
886897
unsigned Alignment) {
887898
assert(Alignment && "Alignment must be specified!");
888899
if (Alignment > PoolAlignment) PoolAlignment = Alignment;

‎llvm/lib/CodeGen/PrologEpilogInserter.cpp‎

Lines changed: 46 additions & 41 deletions
Original file line numberDiff line numberDiff line change
@@ -268,51 +268,56 @@ void PEI::calculateCalleeSavedRegisters(MachineFunction &F) {
268268
}
269269
}
270270

271-
if (CSI.empty())
272-
return; // Early exit if no callee saved registers are modified!
273-
274-
unsigned NumFixedSpillSlots;
275-
const TargetFrameLowering::SpillSlot *FixedSpillSlots =
276-
TFI->getCalleeSavedSpillSlots(NumFixedSpillSlots);
277-
278-
// Now that we know which registers need to be saved and restored, allocate
279-
// stack slots for them.
280-
for (std::vector<CalleeSavedInfo>::iterator
281-
I = CSI.begin(), E = CSI.end(); I != E; ++I) {
282-
unsigned Reg = I->getReg();
283-
const TargetRegisterClass *RC = RegInfo->getMinimalPhysRegClass(Reg);
284-
285-
int FrameIdx;
286-
if (RegInfo->hasReservedSpillSlot(F, Reg, FrameIdx)) {
287-
I->setFrameIdx(FrameIdx);
288-
continue;
289-
}
271+
if (!TFI->assignCalleeSavedSpillSlots(F, RegInfo, CSI)) {
272+
// If target doesn't implement this, use generic code.
273+
274+
if (CSI.empty())
275+
return; // Early exit if no callee saved registers are modified!
276+
277+
unsigned NumFixedSpillSlots;
278+
const TargetFrameLowering::SpillSlot *FixedSpillSlots =
279+
TFI->getCalleeSavedSpillSlots(NumFixedSpillSlots);
280+
281+
// Now that we know which registers need to be saved and restored, allocate
282+
// stack slots for them.
283+
for (std::vector<CalleeSavedInfo>::iterator I = CSI.begin(), E = CSI.end();
284+
I != E; ++I) {
285+
unsigned Reg = I->getReg();
286+
const TargetRegisterClass *RC = RegInfo->getMinimalPhysRegClass(Reg);
287+
288+
int FrameIdx;
289+
if (RegInfo->hasReservedSpillSlot(F, Reg, FrameIdx)) {
290+
I->setFrameIdx(FrameIdx);
291+
continue;
292+
}
290293

291-
// Check to see if this physreg must be spilled to a particular stack slot
292-
// on this target.
293-
const TargetFrameLowering::SpillSlot *FixedSlot = FixedSpillSlots;
294-
while (FixedSlot != FixedSpillSlots+NumFixedSpillSlots &&
295-
FixedSlot->Reg != Reg)
296-
++FixedSlot;
297-
298-
if (FixedSlot == FixedSpillSlots + NumFixedSpillSlots) {
299-
// Nope, just spill it anywhere convenient.
300-
unsigned Align = RC->getAlignment();
301-
unsigned StackAlign = TFI->getStackAlignment();
302-
303-
// We may not be able to satisfy the desired alignment specification of
304-
// the TargetRegisterClass if the stack alignment is smaller. Use the
305-
// min.
306-
Align = std::min(Align, StackAlign);
307-
FrameIdx = MFI->CreateStackObject(RC->getSize(), Align, true);
294+
// Check to see if this physreg must be spilled to a particular stack slot
295+
// on this target.
296+
const TargetFrameLowering::SpillSlot *FixedSlot = FixedSpillSlots;
297+
while (FixedSlot != FixedSpillSlots + NumFixedSpillSlots &&
298+
FixedSlot->Reg != Reg)
299+
++FixedSlot;
300+
301+
if (FixedSlot == FixedSpillSlots + NumFixedSpillSlots) {
302+
// Nope, just spill it anywhere convenient.
303+
unsigned Align = RC->getAlignment();
304+
unsigned StackAlign = TFI->getStackAlignment();
305+
306+
// We may not be able to satisfy the desired alignment specification of
307+
// the TargetRegisterClass if the stack alignment is smaller. Use the
308+
// min.
309+
Align = std::min(Align, StackAlign);
310+
FrameIdx = MFI->CreateStackObject(RC->getSize(), Align, true);
308311
if ((unsigned)FrameIdx < MinCSFrameIndex) MinCSFrameIndex = FrameIdx;
309312
if ((unsigned)FrameIdx > MaxCSFrameIndex) MaxCSFrameIndex = FrameIdx;
310-
} else {
311-
// Spill it to the stack where we must.
312-
FrameIdx = MFI->CreateFixedObject(RC->getSize(), FixedSlot->Offset, true);
313-
}
313+
} else {
314+
// Spill it to the stack where we must.
315+
FrameIdx =
316+
MFI->CreateFixedSpillStackObject(RC->getSize(), FixedSlot->Offset);
317+
}
314318

315-
I->setFrameIdx(FrameIdx);
319+
I->setFrameIdx(FrameIdx);
320+
}
316321
}
317322

318323
MFI->setCalleeSavedInfo(CSI);

‎llvm/lib/MC/MCObjectFileInfo.cpp‎

Lines changed: 10 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -632,11 +632,16 @@ void MCObjectFileInfo::InitCOFFMCObjectFileInfo(Triple T) {
632632
// though it contains relocatable pointers. In PIC mode, this is probably a
633633
// big runtime hit for C++ apps. Either the contents of the LSDA need to be
634634
// adjusted or this should be a data section.
635-
LSDASection =
636-
Ctx->getCOFFSection(".gcc_except_table",
637-
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
638-
COFF::IMAGE_SCN_MEM_READ,
639-
SectionKind::getReadOnly());
635+
assert(T.isOSWindows() && "Windows is the only supported COFF target");
636+
if (T.getArch() == Triple::x86_64) {
637+
// On Windows 64 with SEH, the LSDA is emitted into the .xdata section
638+
LSDASection = 0;
639+
} else {
640+
LSDASection = Ctx->getCOFFSection(".gcc_except_table",
641+
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
642+
COFF::IMAGE_SCN_MEM_READ,
643+
SectionKind::getReadOnly());
644+
}
640645

641646
// Debug info.
642647
COFFDebugSymbolsSection =

‎llvm/lib/MC/MCStreamer.cpp‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -526,6 +526,8 @@ void MCStreamer::EmitWin64EHSetFrame(unsigned Register, unsigned Offset) {
526526
report_fatal_error("Frame register and offset already specified!");
527527
if (Offset & 0x0F)
528528
report_fatal_error("Misaligned frame pointer offset!");
529+
if (Offset > 240)
530+
report_fatal_error("Frame offset must be less than or equal to 240!");
529531
MCSymbol *Label = getContext().CreateTempSymbol();
530532
MCWin64EHInstruction Inst(Win64EH::UOP_SetFPReg, Label, Register, Offset);
531533
EmitLabel(Label);

‎llvm/lib/Target/X86/MCTargetDesc/X86MCAsmInfo.cpp‎

Lines changed: 8 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -142,8 +142,11 @@ getNonexecutableStackSection(MCContext &Ctx) const {
142142
void X86MCAsmInfoMicrosoft::anchor() { }
143143

144144
X86MCAsmInfoMicrosoft::X86MCAsmInfoMicrosoft(const Triple &Triple) {
145-
if (Triple.getArch() == Triple::x86_64)
145+
if (Triple.getArch() == Triple::x86_64) {
146146
PrivateGlobalPrefix = ".L";
147+
PointerSize = 8;
148+
ExceptionsType = ExceptionHandling::Win64;
149+
}
147150

148151
AssemblerDialect = AsmWriterFlavor;
149152

@@ -157,17 +160,18 @@ X86MCAsmInfoMicrosoft::X86MCAsmInfoMicrosoft(const Triple &Triple) {
157160
void X86MCAsmInfoGNUCOFF::anchor() { }
158161

159162
X86MCAsmInfoGNUCOFF::X86MCAsmInfoGNUCOFF(const Triple &Triple) {
163+
assert(Triple.isOSWindows() && "Windows is the only supported COFF target");
160164
if (Triple.getArch() == Triple::x86_64) {
161165
PrivateGlobalPrefix = ".L";
162166
PointerSize = 8;
167+
ExceptionsType = ExceptionHandling::Win64;
168+
} else {
169+
ExceptionsType = ExceptionHandling::DwarfCFI;
163170
}
164171

165172
AssemblerDialect = AsmWriterFlavor;
166173

167174
TextAlignFillValue = 0x90;
168175

169-
// Exceptions handling
170-
ExceptionsType = ExceptionHandling::DwarfCFI;
171-
172176
UseIntegratedAssembler = true;
173177
}

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