Move hash computation code into a separate class and file.

No functional change intended.

llvm-svn: 188028

lib/CodeGen/AsmPrinter/DIEHash.cpp

@@ -0,0 +1,136 @@
+//===-- llvm/CodeGen/DIEHash.cpp - Dwarf Hashing Framework ----------------===//
+//
+//                     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 DWARF4 hashing of DIEs.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "dwarfdebug"
+
+#include "DIE.h"
+#include "DIEHash.h"
+#include "DwarfCompileUnit.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/Dwarf.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/MD5.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+
+/// \brief Grabs the string in whichever attribute is passed in and returns
+/// a reference to it.
+static StringRef getDIEStringAttr(DIE *Die, uint16_t Attr) {
+  const SmallVectorImpl<DIEValue *> &Values = Die->getValues();
+  const DIEAbbrev &Abbrevs = Die->getAbbrev();
+
+  // Iterate through all the attributes until we find the one we're
+  // looking for, if we can't find it return an empty string.
+  for (size_t i = 0; i < Values.size(); ++i) {
+    if (Abbrevs.getData()[i].getAttribute() == Attr) {
+      DIEValue *V = Values[i];
+      assert(isa<DIEString>(V) && "String requested. Not a string.");
+      DIEString *S = cast<DIEString>(V);
+      return S->getString();
+    }
+  }
+  return StringRef("");
+}
+
+/// \brief Adds the string in \p Str to the hash. This also hashes
+/// a trailing NULL with the string.
+void DIEHash::addString(StringRef Str) {
+  DEBUG(dbgs() << "Adding string " << Str << " to hash.\n");
+  Hash.update(Str);
+  Hash.update(makeArrayRef((uint8_t)'\0'));
+}
+
+// FIXME: The LEB128 routines are copied and only slightly modified out of
+// LEB128.h.
+
+/// \brief Adds the unsigned in \p Value to the hash encoded as a ULEB128.
+void DIEHash::addULEB128(uint64_t Value) {
+  DEBUG(dbgs() << "Adding ULEB128 " << Value << " to hash.\n");
+  do {
+    uint8_t Byte = Value & 0x7f;
+    Value >>= 7;
+    if (Value != 0)
+      Byte |= 0x80; // Mark this byte to show that more bytes will follow.
+    Hash.update(Byte);
+  } while (Value != 0);
+}
+
+/// \brief Including \p Parent adds the context of Parent to the hash..
+void DIEHash::addParentContext(DIE *Parent) {
+
+  DEBUG(dbgs() << "Adding parent context to hash...\n");
+
+  // [7.27.2] For each surrounding type or namespace beginning with the
+  // outermost such construct...
+  SmallVector<DIE *, 1> Parents;
+  while (Parent->getTag() != dwarf::DW_TAG_compile_unit) {
+    Parents.push_back(Parent);
+    Parent = Parent->getParent();
+  }
+
+  // Reverse iterate over our list to go from the outermost construct to the
+  // innermost.
+  for (SmallVectorImpl<DIE *>::reverse_iterator I = Parents.rbegin(),
+                                                E = Parents.rend();
+       I != E; ++I) {
+    DIE *Die = *I;
+
+    // ... Append the letter "C" to the sequence...
+    addULEB128('C');
+
+    // ... Followed by the DWARF tag of the construct...
+    addULEB128(Die->getTag());
+
+    // ... Then the name, taken from the DW_AT_name attribute.
+    StringRef Name = getDIEStringAttr(Die, dwarf::DW_AT_name);
+    DEBUG(dbgs() << "... adding context: " << Name << "\n");
+    if (!Name.empty())
+      addString(Name);
+  }
+}
+
+/// This is based on the type signature computation given in section 7.27 of the
+/// DWARF4 standard. It is the md5 hash of a flattened description of the DIE
+/// with
+/// the exception that we are hashing only the context and the name of the type.
+uint64_t DIEHash::computeDIEODRSignature(DIE *Die) {
+
+  // Add the contexts to the hash. We won't be computing the ODR hash for
+  // function local types so it's safe to use the generic context hashing
+  // algorithm here.
+  // FIXME: If we figure out how to account for linkage in some way we could
+  // actually do this with a slight modification to the parent hash algorithm.
+  DIE *Parent = Die->getParent();
+  if (Parent)
+    addParentContext(Parent);
+
+  // Add the current DIE information.
+
+  // Add the DWARF tag of the DIE.
+  addULEB128(Die->getTag());
+
+  // Add the name of the type to the hash.
+  addString(getDIEStringAttr(Die, dwarf::DW_AT_name));
+
+  // Now get the result.
+  MD5::MD5Result Result;
+  Hash.final(Result);
+
+  // ... take the least significant 8 bytes and return those. Our MD5
+  // implementation always returns its results in little endian, swap bytes
+  // appropriately.
+  return *reinterpret_cast<support::ulittle64_t *>(Result + 8);
+}

lib/CodeGen/AsmPrinter/DIEHash.h

@@ -0,0 +1,46 @@
+//===-- llvm/CodeGen/DIEHash.h - Dwarf Hashing Framework -------*- C++ -*--===//
+//
+//                     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 DWARF4 hashing of DIEs.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/MD5.h"
+
+namespace llvm {
+
+class CompileUnit;
+
+/// \brief An object containing the capability of hashing and adding hash
+/// attributes onto a DIE.
+class DIEHash {
+public:
+  /// \brief Initializes. The hash is default initialized.
+  DIEHash() {}
+
+  /// \brief Computes the ODR signature
+  uint64_t computeDIEODRSignature(DIE *Die);
+
+  // Helper routines to process parts of a DIE.
+ private:
+  /// \brief Adds the parent context of \param Die to the hash.
+  void addParentContext(DIE *Die);
+  
+  // Routines that add DIEValues to the hash.
+private:
+  /// \brief Encodes and adds \param Value to the hash as a ULEB128.
+  void addULEB128(uint64_t Value);
+
+  /// \brief Adds \param Str to the hash and includes a NULL byte.
+  void addString(StringRef Str);
+  
+private:
+  MD5 Hash;
+};
+}

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -14,6 +14,7 @@
 #define DEBUG_TYPE "dwarfdebug"
 #include "DwarfDebug.h"
 #include "DIE.h"
+#include "DIEHash.h"
 #include "DwarfAccelTable.h"
 #include "DwarfCompileUnit.h"
 #include "llvm/ADT/STLExtras.h"
@@ -962,8 +963,7 @@ void DwarfDebug::collectDeadVariables() {
   DeleteContainerSeconds(DeadFnScopeMap);
 }
 
-// Type Signature [7.27] computation code.
+// Type Signature [7.27] and ODR Hash code.
-typedef ArrayRef<uint8_t> HashValue;
 
 /// \brief Grabs the string in whichever attribute is passed in and returns
 /// a reference to it. Returns "" if the attribute doesn't exist.
@@ -976,100 +976,6 @@ static StringRef getDIEStringAttr(DIE *Die, unsigned Attr) {
   return StringRef("");
 }
 
-/// \brief Adds the string in \p Str to the hash in \p Hash. This also hashes
-/// a trailing NULL with the string.
-static void addStringToHash(MD5 &Hash, StringRef Str) {
-  DEBUG(dbgs() << "Adding string " << Str << " to hash.\n");
-  Hash.update(Str);
-  Hash.update(makeArrayRef((uint8_t)'\0'));
-}
-
-// FIXME: These are copied and only slightly modified out of LEB128.h.
-
-/// \brief Adds the unsigned in \p N to the hash in \p Hash. This also encodes
-/// the unsigned as a ULEB128.
-static void addULEB128ToHash(MD5 &Hash, uint64_t Value) {
-  DEBUG(dbgs() << "Adding ULEB128 " << Value << " to hash.\n");
-  do {
-    uint8_t Byte = Value & 0x7f;
-    Value >>= 7;
-    if (Value != 0)
-      Byte |= 0x80; // Mark this byte to show that more bytes will follow.
-    Hash.update(Byte);
-  } while (Value != 0);
-}
-
-/// \brief Including \p Parent adds the context of Parent to \p Hash.
-static void addParentContextToHash(MD5 &Hash, DIE *Parent) {
-
-  DEBUG(dbgs() << "Adding parent context to hash...\n");
-
-  // [7.27.2] For each surrounding type or namespace beginning with the
-  // outermost such construct...
-  SmallVector<DIE *, 1> Parents;
-  while (Parent->getTag() != dwarf::DW_TAG_compile_unit) {
-    Parents.push_back(Parent);
-    Parent = Parent->getParent();
-  }
-
-  // Reverse iterate over our list to go from the outermost construct to the
-  // innermost.
-  for (SmallVectorImpl<DIE *>::reverse_iterator I = Parents.rbegin(),
-                                                E = Parents.rend();
-       I != E; ++I) {
-    DIE *Die = *I;
-
-    // ... Append the letter "C" to the sequence...
-    addULEB128ToHash(Hash, 'C');
-
-    // ... Followed by the DWARF tag of the construct...
-    addULEB128ToHash(Hash, Die->getTag());
-
-    // ... Then the name, taken from the DW_AT_name attribute.
-    StringRef Name = getDIEStringAttr(Die, dwarf::DW_AT_name);
-    DEBUG(dbgs() << "... adding context: " << Name << "\n");
-    if (!Name.empty())
-      addStringToHash(Hash, Name);
-  }
-}
-
-/// This is based on the type signature computation given in section 7.27 of the
-/// DWARF4 standard. It is the md5 hash of a flattened description of the DIE with
-/// the exception that we are hashing only the context and the name of the type.
-static void addDIEODRSignature(MD5 &Hash, CompileUnit *CU, DIE *Die) {
-
-  // Add the contexts to the hash. We won't be computing the ODR hash for
-  // function local types so it's safe to use the generic context hashing
-  // algorithm here.
-  // FIXME: If we figure out how to account for linkage in some way we could
-  // actually do this with a slight modification to the parent hash algorithm.
-  DIE *Parent = Die->getParent();
-  if (Parent)
-    addParentContextToHash(Hash, Parent);
-
-  // Add the current DIE information.
-
-  // Add the DWARF tag of the DIE.
-  addULEB128ToHash(Hash, Die->getTag());
-
-  // Add the name of the type to the hash.
-  addStringToHash(Hash, getDIEStringAttr(Die, dwarf::DW_AT_name));
-
-  // Now get the result.
-  MD5::MD5Result Result;
-  Hash.final(Result);
-
-  // ... take the least significant 8 bytes and store those as the attribute.
-  // Our MD5 implementation always returns its results in little endian, swap
-  // bytes appropriately.
-  uint64_t Signature = *reinterpret_cast<support::ulittle64_t *>(Result + 8);
-
-  // FIXME: This should be added onto the type unit, not the type, but this
-  // works as an intermediate stage.
-  CU->addUInt(Die, dwarf::DW_AT_GNU_odr_signature, dwarf::DW_FORM_data8,
-              Signature);
-}
-
 /// Return true if the current DIE is contained within an anonymous namespace.
 static bool isContainedInAnonNamespace(DIE *Die) {
   DIE *Parent = Die->getParent();
@@ -1090,7 +996,7 @@ static bool shouldAddODRHash(CompileUnit *CU, DIE *Die) {
   return CU->getLanguage() == dwarf::DW_LANG_C_plus_plus &&
          getDIEStringAttr(Die, dwarf::DW_AT_name) != "" &&
          !isContainedInAnonNamespace(Die);
- }
+}
 
 void DwarfDebug::finalizeModuleInfo() {
   // Collect info for variables that were optimized out.
@@ -1111,12 +1017,16 @@ void DwarfDebug::finalizeModuleInfo() {
   // out type.
   // FIXME: Do type splitting.
   for (unsigned i = 0, e = TypeUnits.size(); i != e; ++i) {
-    MD5 Hash;
     DIE *Die = TypeUnits[i];
+    DIEHash Hash;
     // If we've requested ODR hashes and it's applicable for an ODR hash then
     // add the ODR signature now.
+    // FIXME: This should be added onto the type unit, not the type, but this
+    // works as an intermediate stage.
     if (GenerateODRHash && shouldAddODRHash(CUMap.begin()->second, Die))
-      addDIEODRSignature(Hash, CUMap.begin()->second, Die);
+      CUMap.begin()->second->addUInt(Die, dwarf::DW_AT_GNU_odr_signature,
+                                     dwarf::DW_FORM_data8,
+                                     Hash.computeDIEODRSignature(Die));
   }
 
    // Compute DIE offsets and sizes.