[ObjectYAML] NFC. Refactor DWARFYAML CompileUnit dump code

Summary: This patch refactors the DWARFYAML code for dumping compile units to use a visitor pattern. Using this design will, in the future, enable the DWARF YAML code to perform analysis and mutations of the DWARF DIEs. An example of such mutations would be calculating the length of a compile unit and updating the CU's Length field before writing the DIE. This support will make it easier to craft or modify DWARF tests by hand.

Reviewers: lhames

Subscribers: mgorny, fhahn, jgosnell, aprantl, llvm-commits

Differential Revision: https://reviews.llvm.org/D30357

llvm-svn: 297067

1 files changed, 167 insertions, 0 deletions

diff --git a/llvm/lib/ObjectYAML/DWARFVisitor.cpp b/llvm/lib/ObjectYAML/DWARFVisitor.cpp
new file mode 100644
index 00000000000..8135b8bd651
--- /dev/null
+++ b/llvm/lib/ObjectYAML/DWARFVisitor.cpp
@@ -0,0 +1,167 @@
+//===--- DWARFVisitor.cpp ---------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//===----------------------------------------------------------------------===//
+
+#include "DWARFVisitor.h"
+#include "llvm/ObjectYAML/DWARFYAML.h"
+
+using namespace llvm;
+
+template <typename T>
+void DWARFYAML::VisitorImpl<T>::onVariableSizeValue(uint64_t U, unsigned Size) {
+  switch (Size) {
+  case 8:
+    onValue((uint64_t)U);
+    break;
+  case 4:
+    onValue((uint32_t)U);
+    break;
+  case 2:
+    onValue((uint16_t)U);
+    break;
+  case 1:
+    onValue((uint8_t)U);
+    break;
+  default:
+    llvm_unreachable("Invalid integer write size.");
+  }
+}
+
+unsigned getRefSize(const DWARFYAML::Unit &Unit) {
+  if (Unit.Version == 2)
+    return Unit.AddrSize;
+  return Unit.Length.isDWARF64() ? 8 : 4;
+}
+
+template <typename T> void DWARFYAML::VisitorImpl<T>::traverseDebugInfo() {
+  for (auto &Unit : DebugInfo.CompileUnits) {
+    onStartCompileUnit(Unit);
+    auto FirstAbbrevCode = Unit.Entries[0].AbbrCode;
+
+    for (auto &Entry : Unit.Entries) {
+      onStartDIE(Unit, Entry);
+      if (Entry.AbbrCode == 0u)
+        continue;
+      auto &Abbrev = DebugInfo.AbbrevDecls[Entry.AbbrCode - FirstAbbrevCode];
+      auto FormVal = Entry.Values.begin();
+      auto AbbrForm = Abbrev.Attributes.begin();
+      for (;
+           FormVal != Entry.Values.end() && AbbrForm != Abbrev.Attributes.end();
+           ++FormVal, ++AbbrForm) {
+        onForm(*AbbrForm, *FormVal);
+        dwarf::Form Form = AbbrForm->Form;
+        bool Indirect;
+        do {
+          Indirect = false;
+          switch (Form) {
+          case dwarf::DW_FORM_addr:
+            onVariableSizeValue(FormVal->Value, Unit.AddrSize);
+            break;
+          case dwarf::DW_FORM_ref_addr:
+            onVariableSizeValue(FormVal->Value, getRefSize(Unit));
+            break;
+          case dwarf::DW_FORM_exprloc:
+          case dwarf::DW_FORM_block:
+            onValue((uint64_t)FormVal->BlockData.size(), true);
+            onValue(
+                MemoryBufferRef(StringRef((const char *)&FormVal->BlockData[0],
+                                          FormVal->BlockData.size()),
+                                ""));
+            break;
+          case dwarf::DW_FORM_block1: {
+            auto writeSize = FormVal->BlockData.size();
+            onValue((uint8_t)writeSize);
+            onValue(
+                MemoryBufferRef(StringRef((const char *)&FormVal->BlockData[0],
+                                          FormVal->BlockData.size()),
+                                ""));
+            break;
+          }
+          case dwarf::DW_FORM_block2: {
+            auto writeSize = FormVal->BlockData.size();
+            onValue((uint16_t)writeSize);
+            onValue(
+                MemoryBufferRef(StringRef((const char *)&FormVal->BlockData[0],
+                                          FormVal->BlockData.size()),
+                                ""));
+            break;
+          }
+          case dwarf::DW_FORM_block4: {
+            auto writeSize = FormVal->BlockData.size();
+            onValue((uint32_t)writeSize);
+            onValue(
+                MemoryBufferRef(StringRef((const char *)&FormVal->BlockData[0],
+                                          FormVal->BlockData.size()),
+                                ""));
+            break;
+          }
+          case dwarf::DW_FORM_data1:
+          case dwarf::DW_FORM_ref1:
+          case dwarf::DW_FORM_flag:
+            onValue((uint8_t)FormVal->Value);
+            break;
+          case dwarf::DW_FORM_data2:
+          case dwarf::DW_FORM_ref2:
+            onValue((uint16_t)FormVal->Value);
+            break;
+          case dwarf::DW_FORM_data4:
+          case dwarf::DW_FORM_ref4:
+            onValue((uint32_t)FormVal->Value);
+            break;
+          case dwarf::DW_FORM_data8:
+          case dwarf::DW_FORM_ref8:
+            onValue((uint64_t)FormVal->Value);
+            break;
+          case dwarf::DW_FORM_sdata:
+            onValue((int64_t)FormVal->Value, true);
+            break;
+          case dwarf::DW_FORM_udata:
+          case dwarf::DW_FORM_ref_udata:
+            onValue((uint64_t)FormVal->Value, true);
+            break;
+          case dwarf::DW_FORM_string:
+            onValue(FormVal->CStr);
+            break;
+          case dwarf::DW_FORM_indirect:
+            onValue((uint64_t)FormVal->Value, true);
+            Indirect = true;
+            Form = static_cast<dwarf::Form>((uint64_t)FormVal->Value);
+            ++FormVal;
+            break;
+          case dwarf::DW_FORM_strp:
+          case dwarf::DW_FORM_sec_offset:
+          case dwarf::DW_FORM_GNU_ref_alt:
+          case dwarf::DW_FORM_GNU_strp_alt:
+          case dwarf::DW_FORM_line_strp:
+          case dwarf::DW_FORM_strp_sup:
+          case dwarf::DW_FORM_ref_sup:
+            onVariableSizeValue(FormVal->Value, getRefSize(Unit));
+            break;
+          case dwarf::DW_FORM_ref_sig8:
+            onValue((uint64_t)FormVal->Value);
+            break;
+          case dwarf::DW_FORM_GNU_addr_index:
+          case dwarf::DW_FORM_GNU_str_index:
+            onValue((uint64_t)FormVal->Value, true);
+            break;
+          default:
+            break;
+          }
+        } while (Indirect);
+      }
+      onEndDIE(Unit, Entry);
+    }
+    onEndCompileUnit(Unit);
+  }
+}
+
+// Explicitly instantiate the two template expansions.
+template class DWARFYAML::VisitorImpl<DWARFYAML::Data>;
+template class DWARFYAML::VisitorImpl<const DWARFYAML::Data>;