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DIEHash: Use DW_FORM_sdata for integers, per spec.

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This allows us to produce the same hash as GCC for at least some simple
examples.

llvm-svn: 192855
This commit is contained in:
David Blaikie 2013-10-16 23:36:20 +00:00
parent d991bcf46c
commit 9599400c07
4 changed files with 47 additions and 8 deletions
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30
lib/CodeGen/AsmPrinter/DIEHash.cpp
View File

@ -68,6 +68,20 @@ void DIEHash::addULEB128(uint64_t Value) {
} 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 @@ void DIEHash::hashAttribute(AttrEntry Attr) {
// 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 @@ void DIEHash::hashAttribute(AttrEntry Attr) {
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;
}
}

3
lib/CodeGen/AsmPrinter/DIEHash.h
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@ -106,6 +106,9 @@ private:
/// \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);

4
test/DebugInfo/X86/fission-hash.ll
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@ -3,8 +3,8 @@
; The source is an empty file.
; CHECK: DW_AT_GNU_dwo_id [DW_FORM_data8] (0x2410f0bbc44241ed)
; CHECK: DW_AT_GNU_dwo_id [DW_FORM_data8] (0x2410f0bbc44241ed)
; CHECK: DW_AT_GNU_dwo_id [DW_FORM_data8] (0x63fc20b98dd69e2d)
; CHECK: DW_AT_GNU_dwo_id [DW_FORM_data8] (0x63fc20b98dd69e2d)
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3}

18
unittests/CodeGen/DIEHashTest.cpp
View File

@ -23,6 +23,22 @@ TEST(DIEHashData1Test, DIEHash) {
DIEInteger Size(4);
Die.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Size);
uint64_t MD5Res = Hash.computeTypeSignature(&Die);
ASSERT_EQ(0x4F68EF1039F8D2BULL, MD5Res);
ASSERT_EQ(0x1AFE116E83701108ULL, MD5Res);
}
TEST(DIEHashTrivialTypeTest, DIEHash) {
// A complete, but simple, type containing no members and defined on the first
// line of a file.
DIE FooType(dwarf::DW_TAG_structure_type);
DIEInteger One(1);
FooType.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &One);
// Line and file number are ignored.
FooType.addValue(dwarf::DW_AT_decl_file, dwarf::DW_FORM_data1, &One);
FooType.addValue(dwarf::DW_AT_decl_line, dwarf::DW_FORM_data1, &One);
uint64_t MD5Res = DIEHash().computeTypeSignature(&FooType);
// The exact same hash GCC produces for this DIE.
ASSERT_EQ(0x715305ce6cfd9ad1ULL, MD5Res);
}
}