Add a hashing routine that handles hashing types. Add a test for

hashing the contents of DW_FORM_data1 on top of a type with attributes.

llvm-svn: 189862

2 files changed, 23 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp b/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
index 1581c9682da..519c8a00685 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp
@@ -422,6 +422,7 @@ uint64_t DIEHash::computeDIEODRSignature(DIE *Die) {
 /// This is based on the type signature computation given in section 7.27 of the
 /// DWARF4 standard. It is an md5 hash of the flattened description of the DIE
 /// with the inclusion of the full CU and all top level CU entities.
+// TODO: Initialize the type chain at 0 instead of 1 for CU signatures.
 uint64_t DIEHash::computeCUSignature(DIE *Die) {
 
   // Hash the DIE.
@@ -436,3 +437,22 @@ uint64_t DIEHash::computeCUSignature(DIE *Die) {
   // appropriately.
   return *reinterpret_cast<support::ulittle64_t *>(Result + 8);
 }
+
+/// This is based on the type signature computation given in section 7.27 of the
+/// DWARF4 standard. It is an md5 hash of the flattened description of the DIE
+/// with the inclusion of additional forms not specifically called out in the
+/// standard.
+uint64_t DIEHash::computeTypeSignature(DIE *Die) {
+
+  // Hash the DIE.
+  computeHash(Die);
+
+  // Now return 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);
+}
diff --git a/llvm/lib/CodeGen/AsmPrinter/DIEHash.h b/llvm/lib/CodeGen/AsmPrinter/DIEHash.h
index f98b56dd73b..b792aeab6ce 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DIEHash.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DIEHash.h
@@ -87,6 +87,9 @@ public:
   /// \brief Computes the CU signature.
   uint64_t computeCUSignature(DIE *Die);
 
+  /// \brief Computes the type signature.
+  uint64_t computeTypeSignature(DIE *Die);
+
   // Helper routines to process parts of a DIE.
 private:
   /// \brief Adds the parent context of \param Die to the hash.