DIEHash: Use DW_FORM_sdata for integers, per spec.
This allows us to produce the same hash as GCC for at least some simple
examples.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192855 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/AsmPrinter/DIEHash.cpp b/lib/CodeGen/AsmPrinter/DIEHash.cpp
index bf02daa..9a26e72 100644
--- a/lib/CodeGen/AsmPrinter/DIEHash.cpp
+++ b/lib/CodeGen/AsmPrinter/DIEHash.cpp
@@ -68,6 +68,20 @@
} while (Value != 0);
}
+void DIEHash::addSLEB128(int64_t Value) {
+ DEBUG(dbgs() << "Adding ULEB128 " << Value << " to hash.\n");
+ bool More;
+ do {
+ uint8_t Byte = Value & 0x7f;
+ Value >>= 7;
+ More = !((((Value == 0 ) && ((Byte & 0x40) == 0)) ||
+ ((Value == -1) && ((Byte & 0x40) != 0))));
+ if (More)
+ Byte |= 0x80; // Mark this byte to show that more bytes will follow.
+ Hash.update(Byte);
+ } while (More);
+}
+
/// \brief Including \p Parent adds the context of Parent to the hash..
void DIEHash::addParentContext(DIE *Parent) {
@@ -277,15 +291,20 @@
// Add the letter A to the hash.
addULEB128('A');
- // Then the attribute code and form.
+ // Then the attribute code.
addULEB128(Desc->getAttribute());
- addULEB128(Desc->getForm());
+
+ // To ensure reproducibility of the signature, the set of forms used in the
+ // signature computation is limited to the following: DW_FORM_sdata,
+ // DW_FORM_flag, DW_FORM_string, and DW_FORM_block.
// TODO: Add support for additional forms.
switch (Desc->getForm()) {
- // TODO: We'll want to add DW_FORM_string here if we start emitting them
- // again.
+ case dwarf::DW_FORM_string:
+ llvm_unreachable(
+ "Add support for DW_FORM_string if we ever start emitting them again");
case dwarf::DW_FORM_strp:
+ addULEB128(dwarf::DW_FORM_string);
addString(cast<DIEString>(Value)->getString());
break;
case dwarf::DW_FORM_data1:
@@ -293,7 +312,8 @@
case dwarf::DW_FORM_data4:
case dwarf::DW_FORM_data8:
case dwarf::DW_FORM_udata:
- addULEB128(cast<DIEInteger>(Value)->getValue());
+ addULEB128(dwarf::DW_FORM_sdata);
+ addSLEB128((int64_t)cast<DIEInteger>(Value)->getValue());
break;
}
}
diff --git a/lib/CodeGen/AsmPrinter/DIEHash.h b/lib/CodeGen/AsmPrinter/DIEHash.h
index b792aea..78238e1 100644
--- a/lib/CodeGen/AsmPrinter/DIEHash.h
+++ b/lib/CodeGen/AsmPrinter/DIEHash.h
@@ -106,6 +106,9 @@
/// \brief Encodes and adds \param Value to the hash as a ULEB128.
void addULEB128(uint64_t Value);
+ /// \brief Encodes and adds \param Value to the hash as a SLEB128.
+ void addSLEB128(int64_t Value);
+
/// \brief Adds \param Str to the hash and includes a NULL byte.
void addString(StringRef Str);