]> granicus.if.org Git - llvm/commitdiff
DebugInfo: support for DW_FORM_implicit_const
authorVictor Leschuk <vleschuk@accesssoftek.com>
Tue, 10 Jan 2017 21:18:26 +0000 (21:18 +0000)
committerVictor Leschuk <vleschuk@accesssoftek.com>
Tue, 10 Jan 2017 21:18:26 +0000 (21:18 +0000)
Support for DW_FORM_implicit_const DWARFv5 feature.
When this form is used attribute value goes to .debug_abbrev section (as SLEB).
As this form would break any debug tool which doesn't support DWARFv5
it is guarded by dwarf version check. Attempt to use this form with
dwarf version <= 4 is considered a fatal error.

Differential Revision: https://reviews.llvm.org/D28456

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@291599 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/DIE.h
include/llvm/DebugInfo/DWARF/DWARFAbbreviationDeclaration.h
include/llvm/DebugInfo/DWARF/DWARFFormValue.h
lib/CodeGen/AsmPrinter/DIE.cpp
lib/CodeGen/AsmPrinter/DwarfUnit.cpp
lib/DebugInfo/DWARF/DWARFAbbreviationDeclaration.cpp
lib/DebugInfo/DWARF/DWARFDebugInfoEntry.cpp
lib/DebugInfo/DWARF/DWARFFormValue.cpp
test/DebugInfo/Inputs/implicit-const-test.o [new file with mode: 0644]
test/DebugInfo/dwarfdump-implicit-const.test [new file with mode: 0644]
unittests/DebugInfo/DWARF/DWARFDebugInfoTest.cpp

index 09c3bf6a1b56c60bd2e70858b417ebd171861d7f..95c4b4248bbd0dcd091f67f5a44f4134953f103b 100644 (file)
@@ -52,13 +52,20 @@ class DIEAbbrevData {
   /// Dwarf form code.
   dwarf::Form Form;
 
+  /// Dwarf attribute value for DW_FORM_implicit_const
+  int64_t Value;
+
 public:
-  DIEAbbrevData(dwarf::Attribute A, dwarf::Form F) : Attribute(A), Form(F) {}
+  DIEAbbrevData(dwarf::Attribute A, dwarf::Form F)
+      : Attribute(A), Form(F), Value(0) {}
+  DIEAbbrevData(dwarf::Attribute A, int64_t V)
+      : Attribute(A), Form(dwarf::DW_FORM_implicit_const), Value(V) {}
 
   /// Accessors.
   /// @{
   dwarf::Attribute getAttribute() const { return Attribute; }
   dwarf::Form getForm() const { return Form; }
+  int64_t getValue() const { return Value; }
   /// @}
 
   /// Used to gather unique data for the abbreviation folding set.
@@ -102,6 +109,11 @@ public:
     Data.push_back(DIEAbbrevData(Attribute, Form));
   }
 
+  /// Adds attribute with DW_FORM_implicit_const value
+  void AddImplicitConstAttribute(dwarf::Attribute Attribute, int64_t Value) {
+    Data.push_back(DIEAbbrevData(Attribute, Value));
+  }
+
   /// Used to gather unique data for the abbreviation folding set.
   void Profile(FoldingSetNodeID &ID) const;
 
index 778817f57bf5773facb47ecc0bdf394862487c38..db9bd506be8979cb474112b54d649bee062d78f4 100644 (file)
@@ -23,21 +23,32 @@ class raw_ostream;
 class DWARFAbbreviationDeclaration {
 public:
   struct AttributeSpec {
-    AttributeSpec(dwarf::Attribute A, dwarf::Form F, Optional<uint8_t> S)
-        : Attr(A), Form(F), ByteSize(S) {}
+    AttributeSpec(dwarf::Attribute A, dwarf::Form F, Optional<int64_t> V)
+        : Attr(A), Form(F), ByteSizeOrValue(V) {}
     dwarf::Attribute Attr;
     dwarf::Form Form;
-    /// If ByteSize has a value, then it contains the fixed size in bytes for
-    /// the Form in this object. If ByteSize doesn't have a value, then the
-    /// byte size of Form either varies according to the DWARFUnit that it is
-    /// contained in or the value size varies and must be decoded from the
-    /// debug information in order to determine its size.
-    Optional<uint8_t> ByteSize;
+    /// The following field is used for ByteSize for non-implicit_const
+    /// attributes and as value for implicit_const ones, indicated by
+    /// Form == DW_FORM_implicit_const.
+    /// The following cases are distinguished:
+    /// * Form != DW_FORM_implicit_const and ByteSizeOrValue has a value:
+    ///     ByteSizeOrValue contains the fixed size in bytes
+    ///     for the Form in this object.
+    /// * Form != DW_FORM_implicit_const and ByteSizeOrValue is None:
+    ///     byte size of Form either varies according to the DWARFUnit
+    ///     that it is contained in or the value size varies and must be
+    ///     decoded from the debug information in order to determine its size.
+    /// * Form == DW_FORM_implicit_const:
+    ///     ByteSizeOrValue contains value for the implicit_const attribute.
+    Optional<int64_t> ByteSizeOrValue;
+    bool isImplicitConst() const {
+      return Form == dwarf::DW_FORM_implicit_const;
+    }
     /// Get the fixed byte size of this Form if possible. This function might
     /// use the DWARFUnit to calculate the size of the Form, like for
     /// DW_AT_address and DW_AT_ref_addr, so this isn't just an accessor for
     /// the ByteSize member.
-    Optional<uint8_t> getByteSize(const DWARFUnit &U) const;
+    Optional<int64_t> getByteSize(const DWARFUnit &U) const;
   };
   typedef SmallVector<AttributeSpec, 8> AttributeSpecVector;
 
index 920880cea10caeded9b4bc9bc72e7b0d467b7e5b..1b7659dfb04ac41ee28b8520e793a0072215bdfb 100644 (file)
@@ -57,6 +57,9 @@ public:
   DWARFFormValue(dwarf::Form F = dwarf::Form(0)) : Form(F), U(nullptr) {}
   dwarf::Form getForm() const { return Form; }
   void setForm(dwarf::Form F) { Form = F; }
+  void setUValue(uint64_t V) { Value.uval = V; }
+  void setSValue(int64_t V) { Value.sval = V; }
+  void setPValue(const char *V) { Value.cstr = V; }
   bool isFormClass(FormClass FC) const;
   const DWARFUnit *getUnit() const { return U; }
   void dump(raw_ostream &OS) const;
index 8ae2f2487cadedf53a2cece681a75898e0540c6c..a8a3b30d5b603016623da94ba83c75b9eb2e96dc 100644 (file)
@@ -79,6 +79,13 @@ void DIEAbbrev::Emit(const AsmPrinter *AP) const {
     // Emit form type.
     AP->EmitULEB128(AttrData.getForm(),
                     dwarf::FormEncodingString(AttrData.getForm()).data());
+
+    // Emit value for DW_FORM_implicit_const.
+    if (AttrData.getForm() == dwarf::DW_FORM_implicit_const) {
+      assert(AP->getDwarfVersion() >= 5 &&
+            "DW_FORM_implicit_const is supported starting from DWARFv5");
+      AP->EmitSLEB128(AttrData.getValue());
+    }
   }
 
   // Mark end of abbreviation.
@@ -160,7 +167,11 @@ DIE *DIE::getParent() const {
 DIEAbbrev DIE::generateAbbrev() const {
   DIEAbbrev Abbrev(Tag, hasChildren());
   for (const DIEValue &V : values())
-    Abbrev.AddAttribute(V.getAttribute(), V.getForm());
+    if (V.getForm() == dwarf::DW_FORM_implicit_const)
+      Abbrev.AddImplicitConstAttribute(V.getAttribute(),
+                                       V.getDIEInteger().getValue());
+    else
+      Abbrev.AddAttribute(V.getAttribute(), V.getForm());
   return Abbrev;
 }
 
@@ -342,6 +353,8 @@ void DIEValue::dump() const {
 ///
 void DIEInteger::EmitValue(const AsmPrinter *Asm, dwarf::Form Form) const {
   switch (Form) {
+  case dwarf::DW_FORM_implicit_const:
+    LLVM_FALLTHROUGH;
   case dwarf::DW_FORM_flag_present:
     // Emit something to keep the lines and comments in sync.
     // FIXME: Is there a better way to do this?
@@ -406,6 +419,7 @@ void DIEInteger::EmitValue(const AsmPrinter *Asm, dwarf::Form Form) const {
 ///
 unsigned DIEInteger::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
   switch (Form) {
+  case dwarf::DW_FORM_implicit_const: LLVM_FALLTHROUGH;
   case dwarf::DW_FORM_flag_present: return 0;
   case dwarf::DW_FORM_flag:  LLVM_FALLTHROUGH;
   case dwarf::DW_FORM_ref1:  LLVM_FALLTHROUGH;
index 4f90245c6d49e85bea1e386a02d5037c1050aef8..2a866c071f5935fbd86cc74acc68b09408ec446b 100644 (file)
@@ -200,6 +200,8 @@ void DwarfUnit::addUInt(DIEValueList &Die, dwarf::Attribute Attribute,
                         Optional<dwarf::Form> Form, uint64_t Integer) {
   if (!Form)
     Form = DIEInteger::BestForm(false, Integer);
+  assert(Form != dwarf::DW_FORM_implicit_const &&
+         "DW_FORM_implicit_const is used only for signed integers");
   Die.addValue(DIEValueAllocator, Attribute, *Form, DIEInteger(Integer));
 }
 
index 6126470aa099da5e1754eec4b611f6d56771309a..08bc74a81e9afea1f21607f5e264cc5e04650f88 100644 (file)
@@ -56,13 +56,20 @@ DWARFAbbreviationDeclaration::extract(DataExtractor Data,
     auto A = static_cast<Attribute>(Data.getULEB128(OffsetPtr));
     auto F = static_cast<Form>(Data.getULEB128(OffsetPtr));
     if (A && F) {
-      auto FixedFormByteSize = DWARFFormValue::getFixedByteSize(F);
-      AttributeSpecs.push_back(AttributeSpec(A, F, FixedFormByteSize));
+      Optional<int64_t> V;
+      bool IsImplicitConst = (F == DW_FORM_implicit_const);
+      if (IsImplicitConst)
+        V = Data.getSLEB128(OffsetPtr);
+      else if (auto Size = DWARFFormValue::getFixedByteSize(F))
+        V = *Size;
+      AttributeSpecs.push_back(AttributeSpec(A, F, V));
+      if (IsImplicitConst)
+        continue;
       // If this abbrevation still has a fixed byte size, then update the
       // FixedAttributeSize as needed.
       if (FixedAttributeSize) {
-        if (FixedFormByteSize)
-          FixedAttributeSize->NumBytes += *FixedFormByteSize;
+        if (V)
+          FixedAttributeSize->NumBytes += *V;
         else {
           switch (F) {
           case DW_FORM_addr:
@@ -129,6 +136,8 @@ void DWARFAbbreviationDeclaration::dump(raw_ostream &OS) const {
       OS << formString;
     else
       OS << format("DW_FORM_Unknown_%x", Spec.Form);
+    if (Spec.isImplicitConst())
+      OS << '\t' << *Spec.ByteSizeOrValue;
     OS << '\n';
   }
   OS << '\n';
@@ -160,11 +169,15 @@ Optional<DWARFFormValue> DWARFAbbreviationDeclaration::getAttributeValue(
     if (*MatchAttrIndex == AttrIndex) {
       // We have arrived at the attribute to extract, extract if from Offset.
       DWARFFormValue FormValue(Spec.Form);
+      if (Spec.isImplicitConst()) {
+        FormValue.setSValue(*Spec.ByteSizeOrValue);
+        return FormValue;
+      }
       if (FormValue.extractValue(DebugInfoData, &Offset, &U))
         return FormValue;
     }
     // March Offset along until we get to the attribute we want.
-    if (Optional<uint8_t> FixedSize = Spec.getByteSize(U))
+    if (auto FixedSize = Spec.getByteSize(U))
       Offset += *FixedSize;
     else
       DWARFFormValue::skipValue(Spec.Form, DebugInfoData, &Offset, &U);
@@ -185,9 +198,17 @@ size_t DWARFAbbreviationDeclaration::FixedSizeInfo::getByteSize(
   return ByteSize;
 }
 
-Optional<uint8_t> DWARFAbbreviationDeclaration::AttributeSpec::getByteSize(
+Optional<int64_t> DWARFAbbreviationDeclaration::AttributeSpec::getByteSize(
     const DWARFUnit &U) const {
-  return ByteSize ? ByteSize : DWARFFormValue::getFixedByteSize(Form, &U);
+  if (isImplicitConst())
+    return 0;
+  if (ByteSizeOrValue)
+    return ByteSizeOrValue;
+  Optional<int64_t> S;
+  auto FixedByteSize = DWARFFormValue::getFixedByteSize(Form, &U);
+  if (FixedByteSize)
+    S = *FixedByteSize;
+  return S;
 }
 
 Optional<size_t> DWARFAbbreviationDeclaration::getFixedAttributesByteSize(
index 9f623e4954c82ef0475631d3fc9e224b5742dfc5..c487e1dca7c6a9e2bf5451b600f0d6d9613530e1 100644 (file)
@@ -57,7 +57,7 @@ bool DWARFDebugInfoEntry::extractFast(const DWARFUnit &U, uint32_t *OffsetPtr,
   // Skip all data in the .debug_info for the attributes
   for (const auto &AttrSpec : AbbrevDecl->attributes()) {
     // Check if this attribute has a fixed byte size.
-    if (Optional<uint8_t> FixedSize = AttrSpec.getByteSize(U)) {
+    if (auto FixedSize = AttrSpec.getByteSize(U)) {
       // Attribute byte size if fixed, just add the size to the offset.
       *OffsetPtr += *FixedSize;
     } else if (!DWARFFormValue::skipValue(AttrSpec.Form, DebugInfoData,
index e48a6f0981b7210d1c3dae394447bfd29b1df82a..dc9310dc4e89b8093dbf3b6f5e545ace42b697a2 100644 (file)
@@ -153,7 +153,7 @@ static Optional<uint8_t> getFixedByteSize(dwarf::Form Form, const T *U) {
       return 16;
 
     case DW_FORM_implicit_const:
-      // The implicit value is stored in the abbreviation as a ULEB128, any
+      // The implicit value is stored in the abbreviation as a SLEB128, and
       // there no data in debug info.
       return 0;
 
@@ -280,6 +280,8 @@ bool DWARFFormValue::isFormClass(DWARFFormValue::FormClass FC) const {
   case DW_FORM_GNU_str_index:
   case DW_FORM_GNU_strp_alt:
     return (FC == FC_String);
+  case DW_FORM_implicit_const:
+    return (FC == FC_Constant);
   default:
     break;
   }
diff --git a/test/DebugInfo/Inputs/implicit-const-test.o b/test/DebugInfo/Inputs/implicit-const-test.o
new file mode 100644 (file)
index 0000000..e69de29
diff --git a/test/DebugInfo/dwarfdump-implicit-const.test b/test/DebugInfo/dwarfdump-implicit-const.test
new file mode 100644 (file)
index 0000000..5458ada
--- /dev/null
@@ -0,0 +1,2 @@
+RUN: llvm-dwarfdump -debug-dump=abbrev %p/Inputs/implicit-const-test.o | FileCheck %s
+CHECK: DW_FORM_implicit_const -9223372036854775808
index 4435b7942682526f869f74c45de5ec8478bbb53b..4ad9e22dba1546a08dfc48b61ab5ff90c4a2b827 100644 (file)
@@ -77,6 +77,7 @@ void TestAllForms() {
   const uint64_t Data8 = 0x0011223344556677ULL;
   const uint64_t Data8_2 = 0xAABBCCDDEEFF0011ULL;
   const int64_t SData = INT64_MIN;
+  const int64_t ICSData = INT64_MAX; // DW_FORM_implicit_const SData
   const uint64_t UData[] = {UINT64_MAX - 1, UINT64_MAX - 2, UINT64_MAX - 3,
                             UINT64_MAX - 4, UINT64_MAX - 5, UINT64_MAX - 6,
                             UINT64_MAX - 7, UINT64_MAX - 8, UINT64_MAX - 9};
@@ -181,6 +182,12 @@ void TestAllForms() {
   const auto Attr_DW_FORM_sdata = static_cast<dwarf::Attribute>(Attr++);
   CUDie.addAttribute(Attr_DW_FORM_sdata, DW_FORM_sdata, SData);
 
+  const auto Attr_DW_FORM_implicit_const =
+    static_cast<dwarf::Attribute>(Attr++);
+  if (Version >= 5)
+    CUDie.addAttribute(Attr_DW_FORM_implicit_const, DW_FORM_implicit_const,
+                       ICSData);
+
   //----------------------------------------------------------------------
   // Test ULEB128 based forms
   //----------------------------------------------------------------------
@@ -323,13 +330,14 @@ void TestAllForms() {
                 Attr_DW_FORM_flag_present, 0ULL),
             1ULL);
 
-  // TODO: test Attr_DW_FORM_implicit_const extraction
-
   //----------------------------------------------------------------------
   // Test SLEB128 based forms
   //----------------------------------------------------------------------
   EXPECT_EQ(DieDG.getAttributeValueAsSignedConstant(Attr_DW_FORM_sdata, 0),
             SData);
+  if (Version >= 5)
+    EXPECT_EQ(DieDG.getAttributeValueAsSignedConstant(
+              Attr_DW_FORM_implicit_const, 0), ICSData);
 
   //----------------------------------------------------------------------
   // Test ULEB128 based forms
@@ -408,6 +416,24 @@ TEST(DWARFDebugInfo, TestDWARF32Version4Addr8AllForms) {
   TestAllForms<4, AddrType, RefAddrType>();
 }
 
+TEST(DWARFDebugInfo, TestDWARF32Version5Addr4AllForms) {
+  // Test that we can decode all forms for DWARF32, version 5, with 4 byte
+  // addresses.
+  typedef uint32_t AddrType;
+  // DW_FORM_ref_addr are 4 bytes in DWARF32 for version 3 and later
+  typedef uint32_t RefAddrType;
+  TestAllForms<5, AddrType, RefAddrType>();
+}
+
+TEST(DWARFDebugInfo, TestDWARF32Version5Addr8AllForms) {
+  // Test that we can decode all forms for DWARF32, version 5, with 8 byte
+  // addresses.
+  typedef uint64_t AddrType;
+  // DW_FORM_ref_addr are 4 bytes in DWARF32 for version 3 and later
+  typedef uint32_t RefAddrType;
+  TestAllForms<5, AddrType, RefAddrType>();
+}
+
 template <uint16_t Version, class AddrType> void TestChildren() {
   // Test that we can decode DW_FORM_ref_addr values correctly in DWARF 2 with
   // 4 byte addresses. DW_FORM_ref_addr values should be 4 bytes when using