[DebugInfo] Generate fixups as emitting DWARF .debug_frame/.eh_frame.

It is necessary to generate fixups in .debug_frame or .eh_frame as
relaxation is enabled due to the address delta may be changed after
relaxation.

There is an opcode with 6-bits data in debug frame encoding. So, we
also need 6-bits fixup types.

Differential Revision: https://reviews.llvm.org/D58335

llvm-svn: 366524

8 files changed, 99 insertions, 38 deletions

diff --git a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
index 5ede9bf5961..b7bb9c2347a 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
@@ -402,11 +402,11 @@ void DWARFContext::dump(
   }
 
   if (const auto *Off = shouldDump(Explicit, ".debug_frame", DIDT_ID_DebugFrame,
-                                   DObj->getDebugFrameSection()))
+                                   DObj->getDebugFrameSection().Data))
     getDebugFrame()->dump(OS, getRegisterInfo(), *Off);
 
   if (const auto *Off = shouldDump(Explicit, ".eh_frame", DIDT_ID_DebugFrame,
-                                   DObj->getEHFrameSection()))
+                                   DObj->getEHFrameSection().Data))
     getEHFrame()->dump(OS, getRegisterInfo(), *Off);
 
   if (DumpType & DIDT_DebugMacro) {
@@ -766,7 +766,7 @@ const DWARFDebugFrame *DWARFContext::getDebugFrame() {
   // provides this information). This problem is fixed in DWARFv4
   // See this dwarf-discuss discussion for more details:
   // http://lists.dwarfstd.org/htdig.cgi/dwarf-discuss-dwarfstd.org/2011-December/001173.html
-  DWARFDataExtractor debugFrameData(DObj->getDebugFrameSection(),
+  DWARFDataExtractor debugFrameData(*DObj, DObj->getDebugFrameSection(),
                                     isLittleEndian(), DObj->getAddressSize());
   DebugFrame.reset(new DWARFDebugFrame(getArch(), false /* IsEH */));
   DebugFrame->parse(debugFrameData);
@@ -777,8 +777,8 @@ const DWARFDebugFrame *DWARFContext::getEHFrame() {
   if (EHFrame)
     return EHFrame.get();
 
-  DWARFDataExtractor debugFrameData(DObj->getEHFrameSection(), isLittleEndian(),
-                                    DObj->getAddressSize());
+  DWARFDataExtractor debugFrameData(*DObj, DObj->getEHFrameSection(),
+                                    isLittleEndian(), DObj->getAddressSize());
   DebugFrame.reset(new DWARFDebugFrame(getArch(), true /* IsEH */));
   DebugFrame->parse(debugFrameData);
   return DebugFrame.get();
@@ -1385,6 +1385,8 @@ class DWARFObjInMemory final : public DWARFObject {
   DWARFSectionMap RnglistsSection;
   DWARFSectionMap StringOffsetSection;
   DWARFSectionMap LineDWOSection;
+  DWARFSectionMap DebugFrameSection;
+  DWARFSectionMap EHFrameSection;
   DWARFSectionMap LocDWOSection;
   DWARFSectionMap StringOffsetDWOSection;
   DWARFSectionMap RangeDWOSection;
@@ -1405,6 +1407,8 @@ class DWARFObjInMemory final : public DWARFObject {
         .Case("debug_loc", &LocSection)
         .Case("debug_loclists", &LocListsSection)
         .Case("debug_line", &LineSection)
+        .Case("debug_frame", &DebugFrameSection)
+        .Case("eh_frame", &EHFrameSection)
         .Case("debug_str_offsets", &StringOffsetSection)
         .Case("debug_ranges", &RangeSection)
         .Case("debug_rnglists", &RnglistsSection)
@@ -1428,8 +1432,6 @@ class DWARFObjInMemory final : public DWARFObject {
 
   StringRef AbbrevSection;
   StringRef ARangeSection;
-  StringRef DebugFrameSection;
-  StringRef EHFrameSection;
   StringRef StringSection;
   StringRef MacinfoSection;
   StringRef AbbrevDWOSection;
@@ -1449,8 +1451,6 @@ class DWARFObjInMemory final : public DWARFObject {
     return StringSwitch<StringRef *>(Name)
         .Case("debug_abbrev", &AbbrevSection)
         .Case("debug_aranges", &ARangeSection)
-        .Case("debug_frame", &DebugFrameSection)
-        .Case("eh_frame", &EHFrameSection)
         .Case("debug_str", &StringSection)
         .Case("debug_macinfo", &MacinfoSection)
         .Case("debug_abbrev.dwo", &AbbrevDWOSection)
@@ -1747,8 +1747,12 @@ public:
   const DWARFSection &getLocSection() const override { return LocSection; }
   const DWARFSection &getLoclistsSection() const override { return LocListsSection; }
   StringRef getARangeSection() const override { return ARangeSection; }
-  StringRef getDebugFrameSection() const override { return DebugFrameSection; }
-  StringRef getEHFrameSection() const override { return EHFrameSection; }
+  const DWARFSection &getDebugFrameSection() const override {
+    return DebugFrameSection;
+  }
+  const DWARFSection &getEHFrameSection() const override {
+    return EHFrameSection;
+  }
   const DWARFSection &getLineSection() const override { return LineSection; }
   StringRef getStringSection() const override { return StringSection; }
   const DWARFSection &getRangeSection() const override { return RangeSection; }
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
index b3f23366f2a..64336934d21 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
@@ -34,10 +34,10 @@ using namespace dwarf;
 const uint8_t DWARF_CFI_PRIMARY_OPCODE_MASK = 0xc0;
 const uint8_t DWARF_CFI_PRIMARY_OPERAND_MASK = 0x3f;
 
-Error CFIProgram::parse(DataExtractor Data, uint32_t *Offset,
+Error CFIProgram::parse(DWARFDataExtractor Data, uint32_t *Offset,
                         uint32_t EndOffset) {
   while (*Offset < EndOffset) {
-    uint8_t Opcode = Data.getU8(Offset);
+    uint8_t Opcode = Data.getRelocatedValue(1, Offset);
     // Some instructions have a primary opcode encoded in the top bits.
     uint8_t Primary = Opcode & DWARF_CFI_PRIMARY_OPCODE_MASK;
 
@@ -74,19 +74,19 @@ Error CFIProgram::parse(DataExtractor Data, uint32_t *Offset,
         break;
       case DW_CFA_set_loc:
         // Operands: Address
-        addInstruction(Opcode, Data.getAddress(Offset));
+        addInstruction(Opcode, Data.getRelocatedAddress(Offset));
         break;
       case DW_CFA_advance_loc1:
         // Operands: 1-byte delta
-        addInstruction(Opcode, Data.getU8(Offset));
+        addInstruction(Opcode, Data.getRelocatedValue(1, Offset));
         break;
       case DW_CFA_advance_loc2:
         // Operands: 2-byte delta
-        addInstruction(Opcode, Data.getU16(Offset));
+        addInstruction(Opcode, Data.getRelocatedValue(2, Offset));
         break;
       case DW_CFA_advance_loc4:
         // Operands: 4-byte delta
-        addInstruction(Opcode, Data.getU32(Offset));
+        addInstruction(Opcode, Data.getRelocatedValue(4, Offset));
         break;
       case DW_CFA_restore_extended:
       case DW_CFA_undefined:
@@ -361,7 +361,7 @@ void DWARFDebugFrame::parse(DWARFDataExtractor Data) {
     uint32_t StartOffset = Offset;
 
     bool IsDWARF64 = false;
-    uint64_t Length = Data.getU32(&Offset);
+    uint64_t Length = Data.getRelocatedValue(4, &Offset);
     uint64_t Id;
 
     if (Length == UINT32_MAX) {
@@ -369,7 +369,7 @@ void DWARFDebugFrame::parse(DWARFDataExtractor Data) {
       // field being 0xffffffff. Then, the next 64 bits are the actual entry
       // length.
       IsDWARF64 = true;
-      Length = Data.getU64(&Offset);
+      Length = Data.getRelocatedValue(8, &Offset);
     }
 
     // At this point, Offset points to the next field after Length.
@@ -512,8 +512,8 @@ void DWARFDebugFrame::parse(DWARFDataExtractor Data) {
             ReportError(StartOffset, "Parsing augmentation data at %lx failed");
         }
       } else {
-        InitialLocation = Data.getAddress(&Offset);
-        AddressRange = Data.getAddress(&Offset);
+        InitialLocation = Data.getRelocatedAddress(&Offset);
+        AddressRange = Data.getRelocatedAddress(&Offset);
       }
 
       Entries.emplace_back(new FDE(StartOffset, Length, CIEPointer,
diff --git a/llvm/lib/MC/MCAsmBackend.cpp b/llvm/lib/MC/MCAsmBackend.cpp
index 9b1102cbe7d..b800e9caee2 100644
--- a/llvm/lib/MC/MCAsmBackend.cpp
+++ b/llvm/lib/MC/MCAsmBackend.cpp
@@ -73,6 +73,7 @@ const MCFixupKindInfo &MCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
       {"FK_Data_2", 0, 16, 0},
       {"FK_Data_4", 0, 32, 0},
       {"FK_Data_8", 0, 64, 0},
+      {"FK_Data_6b", 0, 6, 0},
       {"FK_PCRel_1", 0, 8, MCFixupKindInfo::FKF_IsPCRel},
       {"FK_PCRel_2", 0, 16, MCFixupKindInfo::FKF_IsPCRel},
       {"FK_PCRel_4", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
@@ -93,10 +94,12 @@ const MCFixupKindInfo &MCAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
       {"FK_Data_Add_2", 0, 16, 0},
       {"FK_Data_Add_4", 0, 32, 0},
       {"FK_Data_Add_8", 0, 64, 0},
+      {"FK_Data_Add_6b", 0, 6, 0},
       {"FK_Data_Sub_1", 0, 8, 0},
       {"FK_Data_Sub_2", 0, 16, 0},
       {"FK_Data_Sub_4", 0, 32, 0},
-      {"FK_Data_Sub_8", 0, 64, 0}};
+      {"FK_Data_Sub_8", 0, 64, 0},
+      {"FK_Data_Sub_6b", 0, 6, 0}};
 
   assert((size_t)Kind <= array_lengthof(Builtins) && "Unknown fixup kind");
   return Builtins[Kind];
diff --git a/llvm/lib/MC/MCAssembler.cpp b/llvm/lib/MC/MCAssembler.cpp
index c4f4d4c2870..22a8e73e4af 100644
--- a/llvm/lib/MC/MCAssembler.cpp
+++ b/llvm/lib/MC/MCAssembler.cpp
@@ -840,6 +840,10 @@ void MCAssembler::layout(MCAsmLayout &Layout) {
           getBackend().shouldInsertFixupForCodeAlign(*this, Layout, *AF);
         }
         continue;
+      } else if (auto *FragWithFixups =
+                     dyn_cast<MCDwarfCallFrameFragment>(&Frag)) {
+        Fixups = FragWithFixups->getFixups();
+        Contents = FragWithFixups->getContents();
       } else
         llvm_unreachable("Unknown fragment with fixups!");
       for (const MCFixup &Fixup : Fixups) {
@@ -969,13 +973,9 @@ bool MCAssembler::relaxDwarfLineAddr(MCAsmLayout &Layout,
   MCContext &Context = Layout.getAssembler().getContext();
   uint64_t OldSize = DF.getContents().size();
   int64_t AddrDelta;
-  bool Abs;
-  if (getBackend().requiresDiffExpressionRelocations())
-    Abs = DF.getAddrDelta().evaluateAsAbsolute(AddrDelta, Layout);
-  else {
-    Abs = DF.getAddrDelta().evaluateKnownAbsolute(AddrDelta, Layout);
-    assert(Abs && "We created a line delta with an invalid expression");
-  }
+  bool Abs = DF.getAddrDelta().evaluateKnownAbsolute(AddrDelta, Layout);
+  assert(Abs && "We created a line delta with an invalid expression");
+  (void)Abs;
   int64_t LineDelta;
   LineDelta = DF.getLineDelta();
   SmallVectorImpl<char> &Data = DF.getContents();
@@ -983,7 +983,7 @@ bool MCAssembler::relaxDwarfLineAddr(MCAsmLayout &Layout,
   raw_svector_ostream OSE(Data);
   DF.getFixups().clear();
 
-  if (Abs) {
+  if (!getBackend().requiresDiffExpressionRelocations()) {
     MCDwarfLineAddr::Encode(Context, getDWARFLinetableParams(), LineDelta,
                             AddrDelta, OSE);
   } else {
@@ -1017,10 +1017,25 @@ bool MCAssembler::relaxDwarfCallFrameFragment(MCAsmLayout &Layout,
   bool Abs = DF.getAddrDelta().evaluateKnownAbsolute(AddrDelta, Layout);
   assert(Abs && "We created call frame with an invalid expression");
   (void) Abs;
-  SmallString<8> &Data = DF.getContents();
+  SmallVectorImpl<char> &Data = DF.getContents();
   Data.clear();
   raw_svector_ostream OSE(Data);
-  MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OSE);
+  DF.getFixups().clear();
+
+  if (getBackend().requiresDiffExpressionRelocations()) {
+    uint32_t Offset;
+    uint32_t Size;
+    MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OSE, &Offset,
+                                          &Size);
+    if (Size) {
+      DF.getFixups().push_back(MCFixup::create(
+          Offset, &DF.getAddrDelta(),
+          MCFixup::getKindForSizeInBits(Size /*In bits.*/, false /*isPCRel*/)));
+    }
+  } else {
+    MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OSE);
+  }
+
   return OldSize != Data.size();
 }
 
diff --git a/llvm/lib/MC/MCDwarf.cpp b/llvm/lib/MC/MCDwarf.cpp
index aae6fdf9093..8456b3421bc 100644
--- a/llvm/lib/MC/MCDwarf.cpp
+++ b/llvm/lib/MC/MCDwarf.cpp
@@ -1897,26 +1897,54 @@ void MCDwarfFrameEmitter::EmitAdvanceLoc(MCObjectStreamer &Streamer,
 }
 
 void MCDwarfFrameEmitter::EncodeAdvanceLoc(MCContext &Context,
-                                           uint64_t AddrDelta,
-                                           raw_ostream &OS) {
+                                           uint64_t AddrDelta, raw_ostream &OS,
+                                           uint32_t *Offset, uint32_t *Size) {
   // Scale the address delta by the minimum instruction length.
   AddrDelta = ScaleAddrDelta(Context, AddrDelta);
 
+  bool WithFixups = false;
+  if (Offset && Size)
+    WithFixups = true;
+
   support::endianness E =
       Context.getAsmInfo()->isLittleEndian() ? support::little : support::big;
   if (AddrDelta == 0) {
+    if (WithFixups) {
+      *Offset = 0;
+      *Size = 0;
+    }
   } else if (isUIntN(6, AddrDelta)) {
     uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta;
-    OS << Opcode;
+    if (WithFixups) {
+      *Offset = OS.tell();
+      *Size = 6;
+      OS << uint8_t(dwarf::DW_CFA_advance_loc);
+    } else
+      OS << Opcode;
   } else if (isUInt<8>(AddrDelta)) {
     OS << uint8_t(dwarf::DW_CFA_advance_loc1);
-    OS << uint8_t(AddrDelta);
+    if (WithFixups) {
+      *Offset = OS.tell();
+      *Size = 8;
+      OS.write_zeros(1);
+    } else
+      OS << uint8_t(AddrDelta);
   } else if (isUInt<16>(AddrDelta)) {
     OS << uint8_t(dwarf::DW_CFA_advance_loc2);
-    support::endian::write<uint16_t>(OS, AddrDelta, E);
+    if (WithFixups) {
+      *Offset = OS.tell();
+      *Size = 16;
+      OS.write_zeros(2);
+    } else
+      support::endian::write<uint16_t>(OS, AddrDelta, E);
   } else {
     assert(isUInt<32>(AddrDelta));
     OS << uint8_t(dwarf::DW_CFA_advance_loc4);
-    support::endian::write<uint32_t>(OS, AddrDelta, E);
+    if (WithFixups) {
+      *Offset = OS.tell();
+      *Size = 32;
+      OS.write_zeros(4);
+    } else
+      support::endian::write<uint32_t>(OS, AddrDelta, E);
   }
 }
diff --git a/llvm/lib/Object/RelocationResolver.cpp b/llvm/lib/Object/RelocationResolver.cpp
index 0a243f32e12..8738e2e9f3b 100644
--- a/llvm/lib/Object/RelocationResolver.cpp
+++ b/llvm/lib/Object/RelocationResolver.cpp
@@ -335,6 +335,8 @@ static bool supportsRISCV(uint64_t Type) {
   case ELF::R_RISCV_NONE:
   case ELF::R_RISCV_32:
   case ELF::R_RISCV_64:
+  case ELF::R_RISCV_SET6:
+  case ELF::R_RISCV_SUB6:
   case ELF::R_RISCV_ADD8:
   case ELF::R_RISCV_SUB8:
   case ELF::R_RISCV_ADD16:
@@ -358,6 +360,10 @@ static uint64_t resolveRISCV(RelocationRef R, uint64_t S, uint64_t A) {
     return (S + RA) & 0xFFFFFFFF;
   case ELF::R_RISCV_64:
     return S + RA;
+  case ELF::R_RISCV_SET6:
+    return (A + (S + RA)) & 0xFF;
+  case ELF::R_RISCV_SUB6:
+    return (A - (S + RA)) & 0xFF;
   case ELF::R_RISCV_ADD8:
     return (A + (S + RA)) & 0xFF;
   case ELF::R_RISCV_SUB8:
diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVAsmBackend.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVAsmBackend.cpp
index ee5f760ebcb..9d94be12635 100644
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVAsmBackend.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVAsmBackend.cpp
@@ -186,6 +186,7 @@ static uint64_t adjustFixupValue(const MCFixup &Fixup, uint64_t Value,
   case FK_Data_2:
   case FK_Data_4:
   case FK_Data_8:
+  case FK_Data_6b:
     return Value;
   case RISCV::fixup_riscv_lo12_i:
   case RISCV::fixup_riscv_pcrel_lo12_i:
diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVELFObjectWriter.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVELFObjectWriter.cpp
index 3ccbc86d261..c5d4b1f8ac1 100644
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVELFObjectWriter.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVELFObjectWriter.cpp
@@ -98,6 +98,8 @@ unsigned RISCVELFObjectWriter::getRelocType(MCContext &Ctx,
     return ELF::R_RISCV_ADD32;
   case FK_Data_Add_8:
     return ELF::R_RISCV_ADD64;
+  case FK_Data_Add_6b:
+    return ELF::R_RISCV_SET6;
   case FK_Data_Sub_1:
     return ELF::R_RISCV_SUB8;
   case FK_Data_Sub_2:
@@ -106,6 +108,8 @@ unsigned RISCVELFObjectWriter::getRelocType(MCContext &Ctx,
     return ELF::R_RISCV_SUB32;
   case FK_Data_Sub_8:
     return ELF::R_RISCV_SUB64;
+  case FK_Data_Sub_6b:
+    return ELF::R_RISCV_SUB6;
   case RISCV::fixup_riscv_hi20:
     return ELF::R_RISCV_HI20;
   case RISCV::fixup_riscv_lo12_i: