Sketch out a DWARF parser.

This introduces a new library to LLVM: libDebugInfo. It will provide debug information
parsing to LLVM. Much of the design and some of the code is taken from the LLDB project.

It also contains an llvm-dwarfdump tool that can dump the abbrevs and DIEs from an
object file. It can be used to write tests for DWARF input and output easily.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139627 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 410 insertions, 0 deletions

diff --git a/lib/DebugInfo/DWARFDebugInfoEntry.cpp b/lib/DebugInfo/DWARFDebugInfoEntry.cpp
new file mode 100644
index 0000000000..5813a55f2f
--- /dev/null
+++ b/lib/DebugInfo/DWARFDebugInfoEntry.cpp
@@ -0,0 +1,410 @@
+//===-- DWARFDebugInfoEntry.cpp --------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "DWARFDebugInfoEntry.h"
+#include "DWARFCompileUnit.h"
+#include "DWARFContext.h"
+#include "DWARFDebugAbbrev.h"
+#include "DWARFFormValue.h"
+#include "llvm/Support/Dwarf.h"
+#include "llvm/Support/Format.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+using namespace dwarf;
+
+void DWARFDebugInfoEntryMinimal::dump(raw_ostream &OS,
+                                      const DWARFCompileUnit *cu,
+                                      unsigned recurseDepth,
+                                      unsigned indent) const {
+  DataExtractor debug_info_data = cu->getDebugInfoExtractor();
+  uint32_t offset = Offset;
+
+  if (debug_info_data.isValidOffset(offset)) {
+    uint64_t abbrCode = debug_info_data.getULEB128(&offset);
+
+    OS.indent(indent) << format("\n0x%8.8x: ", Offset);
+    if (abbrCode) {
+      if (AbbrevDecl) {
+        OS << TagString(AbbrevDecl->getTag())
+           << format(" [%u] %c\n", abbrCode,
+                                   AbbrevDecl->hasChildren() ? '*': ' ');
+
+        // Dump all data in the .debug_info for the attributes
+        const uint32_t numAttributes = AbbrevDecl->getNumAttributes();
+        for (uint32_t i = 0; i != numAttributes; ++i) {
+          uint16_t attr = AbbrevDecl->getAttrByIndex(i);
+          uint16_t form = AbbrevDecl->getFormByIndex(i);
+          dumpAttribute(OS, cu, &offset, attr, form, indent);
+        }
+
+        const DWARFDebugInfoEntryMinimal *child = getFirstChild();
+        if (recurseDepth > 0 && child) {
+          indent += 2;
+          while (child) {
+            child->dump(OS, cu, recurseDepth-1, indent);
+            child = child->getSibling();
+          }
+          indent -= 2;
+        }
+      } else {
+        OS << "Abbreviation code not found in 'debug_abbrev' class for code: "
+           << abbrCode << '\n';
+      }
+    } else {
+      OS << "NULL\n";
+    }
+  }
+}
+
+void DWARFDebugInfoEntryMinimal::dumpAttribute(raw_ostream &OS,
+                                               const DWARFCompileUnit *cu,
+                                               uint32_t* offset_ptr,
+                                               uint16_t attr,
+                                               uint16_t form,
+                                               unsigned indent) const {
+  OS.indent(indent) << format("0x%8.8x: ", *offset_ptr)
+                    << AttributeString(attr)
+                    << " [" << FormEncodingString(form) << ']';
+
+  DWARFFormValue formValue(form);
+
+  if (!formValue.extractValue(cu->getDebugInfoExtractor(), offset_ptr, cu))
+    return;
+
+  OS << "\t(";
+  formValue.dump(OS, 0, cu);
+  OS << ")\n";
+}
+
+bool DWARFDebugInfoEntryMinimal::extractFast(const DWARFCompileUnit *cu,
+                                             const uint8_t *fixed_form_sizes,
+                                             uint32_t *offset_ptr) {
+  Offset = *offset_ptr;
+
+  DataExtractor debug_info_data = cu->getDebugInfoExtractor();
+  uint64_t abbrCode = debug_info_data.getULEB128(offset_ptr);
+
+  assert (fixed_form_sizes); // For best performance this should be specified!
+
+  if (abbrCode) {
+    uint32_t offset = *offset_ptr;
+
+    AbbrevDecl = cu->getAbbreviations()->getAbbreviationDeclaration(abbrCode);
+
+    // Skip all data in the .debug_info for the attributes
+    const uint32_t numAttributes = AbbrevDecl->getNumAttributes();
+    uint32_t i;
+    uint16_t form;
+    for (i=0; i<numAttributes; ++i) {
+      form = AbbrevDecl->getFormByIndex(i);
+
+      const uint8_t fixed_skip_size = fixed_form_sizes[form];
+      if (fixed_skip_size)
+        offset += fixed_skip_size;
+      else {
+        bool form_is_indirect = false;
+        do {
+          form_is_indirect = false;
+          uint32_t form_size = 0;
+          switch (form) {
+          // Blocks if inlined data that have a length field and the data bytes
+          // inlined in the .debug_info.
+          case DW_FORM_block:
+            form_size = debug_info_data.getULEB128(&offset);
+            break;
+          case DW_FORM_block1:
+            form_size = debug_info_data.getU8(&offset);
+            break;
+          case DW_FORM_block2:
+            form_size = debug_info_data.getU16(&offset);
+            break;
+          case DW_FORM_block4:
+            form_size = debug_info_data.getU32(&offset);
+            break;
+
+          // Inlined NULL terminated C-strings
+          case DW_FORM_string:
+            debug_info_data.getCStr(&offset);
+            break;
+
+          // Compile unit address sized values
+          case DW_FORM_addr:
+          case DW_FORM_ref_addr:
+            form_size = cu->getAddressByteSize();
+            break;
+
+          // 1 byte values
+          case DW_FORM_data1:
+          case DW_FORM_flag:
+          case DW_FORM_ref1:
+            form_size = 1;
+            break;
+
+          // 2 byte values
+          case DW_FORM_data2:
+          case DW_FORM_ref2:
+            form_size = 2;
+            break;
+
+          // 4 byte values
+          case DW_FORM_strp:
+          case DW_FORM_data4:
+          case DW_FORM_ref4:
+            form_size = 4;
+            break;
+
+          // 8 byte values
+          case DW_FORM_data8:
+          case DW_FORM_ref8:
+            form_size = 8;
+            break;
+
+          // signed or unsigned LEB 128 values
+          case DW_FORM_sdata:
+          case DW_FORM_udata:
+          case DW_FORM_ref_udata:
+            debug_info_data.getULEB128(&offset);
+            break;
+
+          case DW_FORM_indirect:
+            form_is_indirect = true;
+            form = debug_info_data.getULEB128(&offset);
+            break;
+
+          default:
+            *offset_ptr = Offset;
+            return false;
+          }
+          offset += form_size;
+
+        } while (form_is_indirect);
+      }
+    }
+    *offset_ptr = offset;
+    return true;
+  } else {
+    AbbrevDecl = NULL;
+    return true; // NULL debug tag entry
+  }
+
+  return false;
+}
+
+bool
+DWARFDebugInfoEntryMinimal::extract(const DWARFCompileUnit *cu,
+                                    uint32_t *offset_ptr) {
+  DataExtractor debug_info_data = cu->getDebugInfoExtractor();
+  const uint32_t cu_end_offset = cu->getNextCompileUnitOffset();
+  const uint8_t cu_addr_size = cu->getAddressByteSize();
+  uint32_t offset = *offset_ptr;
+  if ((offset < cu_end_offset) && debug_info_data.isValidOffset(offset)) {
+    Offset = offset;
+
+    uint64_t abbrCode = debug_info_data.getULEB128(&offset);
+
+    if (abbrCode) {
+      AbbrevDecl = cu->getAbbreviations()->getAbbreviationDeclaration(abbrCode);
+
+      if (AbbrevDecl) {
+        uint16_t tag = AbbrevDecl->getTag();
+
+        bool isCompileUnitTag = tag == DW_TAG_compile_unit;
+        if(cu && isCompileUnitTag)
+          const_cast<DWARFCompileUnit*>(cu)->setBaseAddress(0);
+
+        // Skip all data in the .debug_info for the attributes
+        const uint32_t numAttributes = AbbrevDecl->getNumAttributes();
+        for (uint32_t i = 0; i != numAttributes; ++i) {
+          uint16_t attr = AbbrevDecl->getAttrByIndex(i);
+          uint16_t form = AbbrevDecl->getFormByIndex(i);
+
+          if (isCompileUnitTag &&
+              ((attr == DW_AT_entry_pc) || (attr == DW_AT_low_pc))) {
+            DWARFFormValue form_value(form);
+            if (form_value.extractValue(debug_info_data, &offset, cu)) {
+              if (attr == DW_AT_low_pc || attr == DW_AT_entry_pc)
+                const_cast<DWARFCompileUnit*>(cu)
+                  ->setBaseAddress(form_value.getUnsigned());
+            }
+          } else {
+            bool form_is_indirect = false;
+            do {
+              form_is_indirect = false;
+              register uint32_t form_size = 0;
+              switch (form) {
+              // Blocks if inlined data that have a length field and the data
+              // bytes // inlined in the .debug_info
+              case DW_FORM_block:
+                form_size = debug_info_data.getULEB128(&offset);
+                break;
+              case DW_FORM_block1:
+                form_size = debug_info_data.getU8(&offset);
+                break;
+              case DW_FORM_block2:
+                form_size = debug_info_data.getU16(&offset);
+                break;
+              case DW_FORM_block4:
+                form_size = debug_info_data.getU32(&offset);
+                break;
+
+              // Inlined NULL terminated C-strings
+              case DW_FORM_string:
+                debug_info_data.getCStr(&offset);
+                break;
+
+              // Compile unit address sized values
+              case DW_FORM_addr:
+              case DW_FORM_ref_addr:
+                form_size = cu_addr_size;
+                break;
+
+              // 1 byte values
+              case DW_FORM_data1:
+              case DW_FORM_flag:
+              case DW_FORM_ref1:
+                form_size = 1;
+                break;
+
+              // 2 byte values
+              case DW_FORM_data2:
+              case DW_FORM_ref2:
+                form_size = 2;
+                break;
+
+                // 4 byte values
+              case DW_FORM_strp:
+                form_size = 4;
+                break;
+
+              case DW_FORM_data4:
+              case DW_FORM_ref4:
+                form_size = 4;
+                break;
+
+              // 8 byte values
+              case DW_FORM_data8:
+              case DW_FORM_ref8:
+                form_size = 8;
+                break;
+
+              // signed or unsigned LEB 128 values
+              case DW_FORM_sdata:
+              case DW_FORM_udata:
+              case DW_FORM_ref_udata:
+                debug_info_data.getULEB128(&offset);
+                break;
+
+              case DW_FORM_indirect:
+                form = debug_info_data.getULEB128(&offset);
+                form_is_indirect = true;
+                break;
+
+              default:
+                *offset_ptr = offset;
+                return false;
+              }
+
+              offset += form_size;
+            } while (form_is_indirect);
+          }
+        }
+        *offset_ptr = offset;
+        return true;
+      }
+    } else {
+      AbbrevDecl = NULL;
+      *offset_ptr = offset;
+      return true;    // NULL debug tag entry
+    }
+  }
+
+  return false;
+}
+
+uint32_t
+DWARFDebugInfoEntryMinimal::getAttributeValue(const DWARFCompileUnit *cu,
+                                              const uint16_t attr,
+                                              DWARFFormValue &form_value,
+                                              uint32_t *end_attr_offset_ptr)
+                                              const {
+  if (AbbrevDecl) {
+    uint32_t attr_idx = AbbrevDecl->findAttributeIndex(attr);
+
+    if (attr_idx != -1U) {
+      uint32_t offset = getOffset();
+
+      DataExtractor debug_info_data = cu->getDebugInfoExtractor();
+
+      // Skip the abbreviation code so we are at the data for the attributes
+      debug_info_data.getULEB128(&offset);
+
+      uint32_t idx = 0;
+      while (idx < attr_idx)
+        DWARFFormValue::skipValue(AbbrevDecl->getFormByIndex(idx++),
+                                  debug_info_data, &offset, cu);
+
+      const uint32_t attr_offset = offset;
+      form_value = DWARFFormValue(AbbrevDecl->getFormByIndex(idx));
+      if (form_value.extractValue(debug_info_data, &offset, cu))
+      {
+        if (end_attr_offset_ptr)
+          *end_attr_offset_ptr = offset;
+        return attr_offset;
+      }
+    }
+  }
+
+  return 0;
+}
+
+const char*
+DWARFDebugInfoEntryMinimal::getAttributeValueAsString(
+    const DWARFCompileUnit* cu,
+    const uint16_t attr,
+    const char* fail_value) const {
+  DWARFFormValue form_value;
+  if (getAttributeValue(cu, attr, form_value)) {
+    DataExtractor stringExtractor(cu->getContext().getStringSection(),
+        false, 0);
+    return form_value.getAsCString(&stringExtractor);
+  }
+  return fail_value;
+}
+
+uint64_t
+DWARFDebugInfoEntryMinimal::getAttributeValueAsUnsigned(
+    const DWARFCompileUnit* cu,
+    const uint16_t attr,
+    uint64_t fail_value) const {
+  DWARFFormValue form_value;
+  if (getAttributeValue(cu, attr, form_value))
+      return form_value.getUnsigned();
+  return fail_value;
+}
+
+int64_t
+DWARFDebugInfoEntryMinimal::getAttributeValueAsSigned(
+    const DWARFCompileUnit* cu,
+    const uint16_t attr,
+    int64_t fail_value) const {
+  DWARFFormValue form_value;
+  if (getAttributeValue(cu, attr, form_value))
+      return form_value.getSigned();
+  return fail_value;
+}
+
+uint64_t
+DWARFDebugInfoEntryMinimal::getAttributeValueAsReference(const DWARFCompileUnit* cu,
+                                                  const uint16_t attr,
+                                                  uint64_t fail_value) const {
+  DWARFFormValue form_value;
+  if (getAttributeValue(cu, attr, form_value))
+      return form_value.getReference(cu);
+  return fail_value;
+}