Split stuff as a preparation for CFI directives-based frame information emission
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123473 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/AsmPrinter/DwarfTableException.cpp b/lib/CodeGen/AsmPrinter/DwarfTableException.cpp
new file mode 100644
index 0000000..ccf8f9a
--- /dev/null
+++ b/lib/CodeGen/AsmPrinter/DwarfTableException.cpp
@@ -0,0 +1,349 @@
+//===-- CodeGen/AsmPrinter/DwarfTableException.cpp - Dwarf Exception Impl --==//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for writing DWARF exception info into asm files.
+// The implementation emits all the necessary tables "by hands".
+//
+//===----------------------------------------------------------------------===//
+
+#include "DwarfException.h"
+#include "llvm/Module.h"
+#include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineLocation.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCSection.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/Target/Mangler.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetFrameLowering.h"
+#include "llvm/Target/TargetLoweringObjectFile.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetOptions.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Support/Dwarf.h"
+#include "llvm/Support/FormattedStream.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/Twine.h"
+using namespace llvm;
+
+DwarfTableException::DwarfTableException(AsmPrinter *A)
+ : DwarfException(A),
+ shouldEmitTable(false), shouldEmitMoves(false),
+ shouldEmitTableModule(false), shouldEmitMovesModule(false) {}
+
+DwarfTableException::~DwarfTableException() {}
+
+/// EmitCIE - Emit a Common Information Entry (CIE). This holds information that
+/// is shared among many Frame Description Entries. There is at least one CIE
+/// in every non-empty .debug_frame section.
+void DwarfTableException::EmitCIE(const Function *PersonalityFn, unsigned Index) {
+ // Size and sign of stack growth.
+ int stackGrowth = Asm->getTargetData().getPointerSize();
+ if (Asm->TM.getFrameLowering()->getStackGrowthDirection() ==
+ TargetFrameLowering::StackGrowsDown)
+ stackGrowth *= -1;
+
+ const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
+
+ // Begin eh frame section.
+ Asm->OutStreamer.SwitchSection(TLOF.getEHFrameSection());
+
+ MCSymbol *EHFrameSym;
+ if (TLOF.isFunctionEHFrameSymbolPrivate())
+ EHFrameSym = Asm->GetTempSymbol("EH_frame", Index);
+ else
+ EHFrameSym = Asm->OutContext.GetOrCreateSymbol(Twine("EH_frame") +
+ Twine(Index));
+ Asm->OutStreamer.EmitLabel(EHFrameSym);
+
+ Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("section_eh_frame", Index));
+
+ // Define base labels.
+ Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_frame_common", Index));
+
+ // Define the eh frame length.
+ Asm->OutStreamer.AddComment("Length of Common Information Entry");
+ Asm->EmitLabelDifference(Asm->GetTempSymbol("eh_frame_common_end", Index),
+ Asm->GetTempSymbol("eh_frame_common_begin", Index),
+ 4);
+
+ // EH frame header.
+ Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_frame_common_begin",Index));
+ Asm->OutStreamer.AddComment("CIE Identifier Tag");
+ Asm->OutStreamer.EmitIntValue(0, 4/*size*/, 0/*addrspace*/);
+ Asm->OutStreamer.AddComment("DW_CIE_VERSION");
+ Asm->OutStreamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1/*size*/, 0/*addr*/);
+
+ // The personality presence indicates that language specific information will
+ // show up in the eh frame. Find out how we are supposed to lower the
+ // personality function reference:
+
+ unsigned LSDAEncoding = TLOF.getLSDAEncoding();
+ unsigned FDEEncoding = TLOF.getFDEEncoding();
+ unsigned PerEncoding = TLOF.getPersonalityEncoding();
+
+ char Augmentation[6] = { 0 };
+ unsigned AugmentationSize = 0;
+ char *APtr = Augmentation + 1;
+
+ if (PersonalityFn) {
+ // There is a personality function.
+ *APtr++ = 'P';
+ AugmentationSize += 1 + Asm->GetSizeOfEncodedValue(PerEncoding);
+ }
+
+ if (UsesLSDA[Index]) {
+ // An LSDA pointer is in the FDE augmentation.
+ *APtr++ = 'L';
+ ++AugmentationSize;
+ }
+
+ if (FDEEncoding != dwarf::DW_EH_PE_absptr) {
+ // A non-default pointer encoding for the FDE.
+ *APtr++ = 'R';
+ ++AugmentationSize;
+ }
+
+ if (APtr != Augmentation + 1)
+ Augmentation[0] = 'z';
+
+ Asm->OutStreamer.AddComment("CIE Augmentation");
+ Asm->OutStreamer.EmitBytes(StringRef(Augmentation, strlen(Augmentation)+1),0);
+
+ // Round out reader.
+ Asm->EmitULEB128(1, "CIE Code Alignment Factor");
+ Asm->EmitSLEB128(stackGrowth, "CIE Data Alignment Factor");
+ Asm->OutStreamer.AddComment("CIE Return Address Column");
+
+ const TargetRegisterInfo *RI = Asm->TM.getRegisterInfo();
+ const TargetFrameLowering *TFI = Asm->TM.getFrameLowering();
+ Asm->EmitInt8(RI->getDwarfRegNum(RI->getRARegister(), true));
+
+ if (Augmentation[0]) {
+ Asm->EmitULEB128(AugmentationSize, "Augmentation Size");
+
+ // If there is a personality, we need to indicate the function's location.
+ if (PersonalityFn) {
+ Asm->EmitEncodingByte(PerEncoding, "Personality");
+ Asm->OutStreamer.AddComment("Personality");
+ Asm->EmitReference(PersonalityFn, PerEncoding);
+ }
+ if (UsesLSDA[Index])
+ Asm->EmitEncodingByte(LSDAEncoding, "LSDA");
+ if (FDEEncoding != dwarf::DW_EH_PE_absptr)
+ Asm->EmitEncodingByte(FDEEncoding, "FDE");
+ }
+
+ // Indicate locations of general callee saved registers in frame.
+ std::vector<MachineMove> Moves;
+ TFI->getInitialFrameState(Moves);
+ Asm->EmitFrameMoves(Moves, 0, true);
+
+ // On Darwin the linker honors the alignment of eh_frame, which means it must
+ // be 8-byte on 64-bit targets to match what gcc does. Otherwise you get
+ // holes which confuse readers of eh_frame.
+ Asm->EmitAlignment(Asm->getTargetData().getPointerSize() == 4 ? 2 : 3);
+ Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_frame_common_end", Index));
+}
+
+/// EmitFDE - Emit the Frame Description Entry (FDE) for the function.
+void DwarfTableException::EmitFDE(const FunctionEHFrameInfo &EHFrameInfo) {
+ assert(!EHFrameInfo.function->hasAvailableExternallyLinkage() &&
+ "Should not emit 'available externally' functions at all");
+
+ const Function *TheFunc = EHFrameInfo.function;
+ const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
+
+ unsigned LSDAEncoding = TLOF.getLSDAEncoding();
+ unsigned FDEEncoding = TLOF.getFDEEncoding();
+
+ Asm->OutStreamer.SwitchSection(TLOF.getEHFrameSection());
+
+ // Externally visible entry into the functions eh frame info. If the
+ // corresponding function is static, this should not be externally visible.
+ if (!TheFunc->hasLocalLinkage() && TLOF.isFunctionEHSymbolGlobal())
+ Asm->OutStreamer.EmitSymbolAttribute(EHFrameInfo.FunctionEHSym,MCSA_Global);
+
+ // If corresponding function is weak definition, this should be too.
+ if (TheFunc->isWeakForLinker() && Asm->MAI->getWeakDefDirective())
+ Asm->OutStreamer.EmitSymbolAttribute(EHFrameInfo.FunctionEHSym,
+ MCSA_WeakDefinition);
+
+ // If corresponding function is hidden, this should be too.
+ if (TheFunc->hasHiddenVisibility())
+ if (MCSymbolAttr HiddenAttr = Asm->MAI->getHiddenVisibilityAttr())
+ Asm->OutStreamer.EmitSymbolAttribute(EHFrameInfo.FunctionEHSym,
+ HiddenAttr);
+
+ // If there are no calls then you can't unwind. This may mean we can omit the
+ // EH Frame, but some environments do not handle weak absolute symbols. If
+ // UnwindTablesMandatory is set we cannot do this optimization; the unwind
+ // info is to be available for non-EH uses.
+ if (!EHFrameInfo.adjustsStack && !UnwindTablesMandatory &&
+ (!TheFunc->isWeakForLinker() ||
+ !Asm->MAI->getWeakDefDirective() ||
+ TLOF.getSupportsWeakOmittedEHFrame())) {
+ Asm->OutStreamer.EmitAssignment(EHFrameInfo.FunctionEHSym,
+ MCConstantExpr::Create(0, Asm->OutContext));
+ // This name has no connection to the function, so it might get
+ // dead-stripped when the function is not, erroneously. Prohibit
+ // dead-stripping unconditionally.
+ if (Asm->MAI->hasNoDeadStrip())
+ Asm->OutStreamer.EmitSymbolAttribute(EHFrameInfo.FunctionEHSym,
+ MCSA_NoDeadStrip);
+ } else {
+ Asm->OutStreamer.EmitLabel(EHFrameInfo.FunctionEHSym);
+
+ // EH frame header.
+ Asm->OutStreamer.AddComment("Length of Frame Information Entry");
+ Asm->EmitLabelDifference(
+ Asm->GetTempSymbol("eh_frame_end", EHFrameInfo.Number),
+ Asm->GetTempSymbol("eh_frame_begin", EHFrameInfo.Number), 4);
+
+ Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_frame_begin",
+ EHFrameInfo.Number));
+
+ Asm->OutStreamer.AddComment("FDE CIE offset");
+ Asm->EmitLabelDifference(
+ Asm->GetTempSymbol("eh_frame_begin", EHFrameInfo.Number),
+ Asm->GetTempSymbol("eh_frame_common",
+ EHFrameInfo.PersonalityIndex), 4);
+
+ MCSymbol *EHFuncBeginSym =
+ Asm->GetTempSymbol("eh_func_begin", EHFrameInfo.Number);
+
+ Asm->OutStreamer.AddComment("FDE initial location");
+ Asm->EmitReference(EHFuncBeginSym, FDEEncoding);
+
+ Asm->OutStreamer.AddComment("FDE address range");
+ Asm->EmitLabelDifference(Asm->GetTempSymbol("eh_func_end",
+ EHFrameInfo.Number),
+ EHFuncBeginSym,
+ Asm->GetSizeOfEncodedValue(FDEEncoding));
+
+ // If there is a personality and landing pads then point to the language
+ // specific data area in the exception table.
+ if (MMI->getPersonalities()[0] != NULL) {
+ unsigned Size = Asm->GetSizeOfEncodedValue(LSDAEncoding);
+
+ Asm->EmitULEB128(Size, "Augmentation size");
+ Asm->OutStreamer.AddComment("Language Specific Data Area");
+ if (EHFrameInfo.hasLandingPads)
+ Asm->EmitReference(Asm->GetTempSymbol("exception", EHFrameInfo.Number),
+ LSDAEncoding);
+ else
+ Asm->OutStreamer.EmitIntValue(0, Size/*size*/, 0/*addrspace*/);
+
+ } else {
+ Asm->EmitULEB128(0, "Augmentation size");
+ }
+
+ // Indicate locations of function specific callee saved registers in frame.
+ Asm->EmitFrameMoves(EHFrameInfo.Moves, EHFuncBeginSym, true);
+
+ // On Darwin the linker honors the alignment of eh_frame, which means it
+ // must be 8-byte on 64-bit targets to match what gcc does. Otherwise you
+ // get holes which confuse readers of eh_frame.
+ Asm->EmitAlignment(Asm->getTargetData().getPointerSize() == 4 ? 2 : 3);
+ Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_frame_end",
+ EHFrameInfo.Number));
+
+ // If the function is marked used, this table should be also. We cannot
+ // make the mark unconditional in this case, since retaining the table also
+ // retains the function in this case, and there is code around that depends
+ // on unused functions (calling undefined externals) being dead-stripped to
+ // link correctly. Yes, there really is.
+ if (MMI->isUsedFunction(EHFrameInfo.function))
+ if (Asm->MAI->hasNoDeadStrip())
+ Asm->OutStreamer.EmitSymbolAttribute(EHFrameInfo.FunctionEHSym,
+ MCSA_NoDeadStrip);
+ }
+ Asm->OutStreamer.AddBlankLine();
+}
+
+/// EndModule - Emit all exception information that should come after the
+/// content.
+void DwarfTableException::EndModule() {
+ if (Asm->MAI->getExceptionHandlingType() != ExceptionHandling::Dwarf)
+ return;
+
+ if (!shouldEmitMovesModule && !shouldEmitTableModule)
+ return;
+
+ const std::vector<const Function*> &Personalities = MMI->getPersonalities();
+
+ for (unsigned I = 0, E = Personalities.size(); I < E; ++I)
+ EmitCIE(Personalities[I], I);
+
+ for (std::vector<FunctionEHFrameInfo>::iterator
+ I = EHFrames.begin(), E = EHFrames.end(); I != E; ++I)
+ EmitFDE(*I);
+}
+
+/// BeginFunction - Gather pre-function exception information. Assumes it's
+/// being emitted immediately after the function entry point.
+void DwarfTableException::BeginFunction(const MachineFunction *MF) {
+ shouldEmitTable = shouldEmitMoves = false;
+
+ // If any landing pads survive, we need an EH table.
+ shouldEmitTable = !MMI->getLandingPads().empty();
+
+ // See if we need frame move info.
+ shouldEmitMoves =
+ !Asm->MF->getFunction()->doesNotThrow() || UnwindTablesMandatory;
+
+ if (shouldEmitMoves || shouldEmitTable)
+ // Assumes in correct section after the entry point.
+ Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_begin",
+ Asm->getFunctionNumber()));
+
+ shouldEmitTableModule |= shouldEmitTable;
+ shouldEmitMovesModule |= shouldEmitMoves;
+}
+
+/// EndFunction - Gather and emit post-function exception information.
+///
+void DwarfTableException::EndFunction() {
+ if (!shouldEmitMoves && !shouldEmitTable) return;
+
+ Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_end",
+ Asm->getFunctionNumber()));
+
+ // Record if this personality index uses a landing pad.
+ bool HasLandingPad = !MMI->getLandingPads().empty();
+ UsesLSDA[MMI->getPersonalityIndex()] |= HasLandingPad;
+
+ // Map all labels and get rid of any dead landing pads.
+ MMI->TidyLandingPads();
+
+ if (HasLandingPad)
+ EmitExceptionTable();
+
+ const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
+ MCSymbol *FunctionEHSym =
+ Asm->GetSymbolWithGlobalValueBase(Asm->MF->getFunction(), ".eh",
+ TLOF.isFunctionEHFrameSymbolPrivate());
+
+ // Save EH frame information
+ EHFrames.
+ push_back(FunctionEHFrameInfo(FunctionEHSym,
+ Asm->getFunctionNumber(),
+ MMI->getPersonalityIndex(),
+ Asm->MF->getFrameInfo()->adjustsStack(),
+ !MMI->getLandingPads().empty(),
+ MMI->getFrameMoves(),
+ Asm->MF->getFunction()));
+}