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DWARF type hashing: pointers to members

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Includes a test case/FIXME demonstrating a bug/limitation in pointer to
member hashing. To be honest I'm not sure why we don't just always use
summary hashing for referenced types... but perhaps I'm missing
something.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193175 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Blaikie 2013-10-22 18:14:41 +00:00
parent 51ec77d880
commit f196208900
2 changed files with 192 additions and 11 deletions
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25
lib/CodeGen/AsmPrinter/DIEHash.cpp
View File

@ -192,6 +192,7 @@ void DIEHash::collectAttributes(DIE *Die, DIEAttrs &Attrs) {
void DIEHash::hashAttribute(AttrEntry Attr, dwarf::Tag Tag) {
const DIEValue *Value = Attr.Val;
const DIEAbbrevData *Desc = Attr.Desc;
dwarf::Attribute Attribute = Desc->getAttribute();
// 7.27 Step 3
// ... An attribute that refers to another type entry T is processed as
@ -200,14 +201,16 @@ void DIEHash::hashAttribute(AttrEntry Attr, dwarf::Tag Tag) {
DIE *Entry = EntryAttr->getEntry();
// Step 5
// If the tag in Step 3 is one of ...
if (Tag == dwarf::DW_TAG_pointer_type ||
Tag == dwarf::DW_TAG_reference_type ||
Tag == dwarf::DW_TAG_rvalue_reference_type) {
// ... and the referenced type (via the DW_AT_type or DW_AT_friend
// attribute) ...
assert(Desc->getAttribute() == dwarf::DW_AT_type ||
Desc->getAttribute() == dwarf::DW_AT_friend);
// If the tag in Step 3 is one of [the below tags]
if ((Tag == dwarf::DW_TAG_pointer_type ||
Tag == dwarf::DW_TAG_reference_type ||
Tag == dwarf::DW_TAG_rvalue_reference_type ||
Tag == dwarf::DW_TAG_ptr_to_member_type) &&
// and the referenced type (via the [below attributes])
// FIXME: This seems overly restrictive, and causes hash mismatches
// there's a decl/def difference in the containing type of a
// ptr_to_member_type.
Attribute == dwarf::DW_AT_type) {
// [FIXME] ... has a DW_AT_name attribute,
// append the letter 'N'
addULEB128('N');
@ -238,7 +241,7 @@ void DIEHash::hashAttribute(AttrEntry Attr, dwarf::Tag Tag) {
// 'R' as the marker
addULEB128('R');
addULEB128(Desc->getAttribute());
addULEB128(Attribute);
// and use the unsigned LEB128 encoding of [the index of T in the
// list] as the attribute value;
@ -249,7 +252,7 @@ void DIEHash::hashAttribute(AttrEntry Attr, dwarf::Tag Tag) {
// otherwise, b) use the letter 'T' as a the marker, ...
addULEB128('T');
addULEB128(Desc->getAttribute());
addULEB128(Attribute);
// ... process the type T recursively by performing Steps 2 through 7, and
// use the result as the attribute value.
@ -261,7 +264,7 @@ void DIEHash::hashAttribute(AttrEntry Attr, dwarf::Tag Tag) {
// Other attribute values use the letter 'A' as the marker, ...
addULEB128('A');
addULEB128(Desc->getAttribute());
addULEB128(Attribute);
// ... and the value consists of the form code (encoded as an unsigned LEB128
// value) followed by the encoding of the value according to the form code. To

178
unittests/CodeGen/DIEHashTest.cpp
View File

@ -264,4 +264,182 @@ TEST(DIEHashTest, RValueReference) {
ASSERT_EQ(0xad211c8c3b31e57ULL, MD5Res);
}
// struct foo { foo foo::*mem; };
TEST(DIEHashTest, PtrToMember) {
DIE Foo(dwarf::DW_TAG_structure_type);
DIEInteger Eight(8);
Foo.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Eight);
DIEString FooStr(&Eight, "foo");
Foo.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &FooStr);
DIE *Mem = new DIE(dwarf::DW_TAG_member);
DIEString MemStr(&Eight, "mem");
Mem->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &MemStr);
DIEInteger Zero(0);
Mem->addValue(dwarf::DW_AT_data_member_location, dwarf::DW_FORM_data1, &Zero);
DIE PtrToFooMem(dwarf::DW_TAG_ptr_to_member_type);
DIEEntry FooEntry(&Foo);
PtrToFooMem.addValue(dwarf::DW_AT_type, dwarf::DW_FORM_ref4, &FooEntry);
PtrToFooMem.addValue(dwarf::DW_AT_containing_type, dwarf::DW_FORM_ref4, &FooEntry);
DIEEntry PtrToFooMemRef(&PtrToFooMem);
Mem->addValue(dwarf::DW_AT_type, dwarf::DW_FORM_ref4, &PtrToFooMemRef);
Foo.addChild(Mem);
uint64_t MD5Res = DIEHash().computeTypeSignature(&Foo);
ASSERT_EQ(0x852e0c9ff7c04ebULL, MD5Res);
}
// Check that the hash for a pointer-to-member matches regardless of whether the
// pointed-to type is a declaration or a definition.
//
// struct bar; // { };
// struct foo { bar foo::*mem; };
TEST(DIEHashTest, PtrToMemberDeclDefMatch) {
DIEInteger Zero(0);
DIEInteger One(1);
DIEInteger Eight(8);
DIEString FooStr(&Eight, "foo");
DIEString BarStr(&Eight, "bar");
DIEString MemStr(&Eight, "mem");
uint64_t MD5ResDecl;
{
DIE Bar(dwarf::DW_TAG_structure_type);
Bar.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &BarStr);
Bar.addValue(dwarf::DW_AT_declaration, dwarf::DW_FORM_flag_present, &One);
DIE Foo(dwarf::DW_TAG_structure_type);
Foo.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Eight);
Foo.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &FooStr);
DIE *Mem = new DIE(dwarf::DW_TAG_member);
Mem->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &MemStr);
Mem->addValue(dwarf::DW_AT_data_member_location, dwarf::DW_FORM_data1,
&Zero);
DIE PtrToFooMem(dwarf::DW_TAG_ptr_to_member_type);
DIEEntry BarEntry(&Bar);
PtrToFooMem.addValue(dwarf::DW_AT_type, dwarf::DW_FORM_ref4, &BarEntry);
DIEEntry FooEntry(&Foo);
PtrToFooMem.addValue(dwarf::DW_AT_containing_type, dwarf::DW_FORM_ref4,
&FooEntry);
DIEEntry PtrToFooMemRef(&PtrToFooMem);
Mem->addValue(dwarf::DW_AT_type, dwarf::DW_FORM_ref4, &PtrToFooMemRef);
Foo.addChild(Mem);
MD5ResDecl = DIEHash().computeTypeSignature(&Foo);
}
uint64_t MD5ResDef;
{
DIE Bar(dwarf::DW_TAG_structure_type);
Bar.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &BarStr);
Bar.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &One);
DIE Foo(dwarf::DW_TAG_structure_type);
Foo.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Eight);
Foo.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &FooStr);
DIE *Mem = new DIE(dwarf::DW_TAG_member);
Mem->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &MemStr);
Mem->addValue(dwarf::DW_AT_data_member_location, dwarf::DW_FORM_data1,
&Zero);
DIE PtrToFooMem(dwarf::DW_TAG_ptr_to_member_type);
DIEEntry BarEntry(&Bar);
PtrToFooMem.addValue(dwarf::DW_AT_type, dwarf::DW_FORM_ref4, &BarEntry);
DIEEntry FooEntry(&Foo);
PtrToFooMem.addValue(dwarf::DW_AT_containing_type, dwarf::DW_FORM_ref4,
&FooEntry);
DIEEntry PtrToFooMemRef(&PtrToFooMem);
Mem->addValue(dwarf::DW_AT_type, dwarf::DW_FORM_ref4, &PtrToFooMemRef);
Foo.addChild(Mem);
MD5ResDef = DIEHash().computeTypeSignature(&Foo);
}
ASSERT_EQ(MD5ResDef, MD5ResDecl);
}
// Check that the hash for a pointer-to-member matches regardless of whether the
// pointed-to type is a declaration or a definition.
//
// struct bar; // { };
// struct foo { bar bar::*mem; };
TEST(DIEHashTest, PtrToMemberDeclDefMisMatch) {
DIEInteger Zero(0);
DIEInteger One(1);
DIEInteger Eight(8);
DIEString FooStr(&Eight, "foo");
DIEString BarStr(&Eight, "bar");
DIEString MemStr(&Eight, "mem");
uint64_t MD5ResDecl;
{
DIE Bar(dwarf::DW_TAG_structure_type);
Bar.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &BarStr);
Bar.addValue(dwarf::DW_AT_declaration, dwarf::DW_FORM_flag_present, &One);
DIE Foo(dwarf::DW_TAG_structure_type);
Foo.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Eight);
Foo.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &FooStr);
DIE *Mem = new DIE(dwarf::DW_TAG_member);
Mem->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &MemStr);
Mem->addValue(dwarf::DW_AT_data_member_location, dwarf::DW_FORM_data1,
&Zero);
DIE PtrToFooMem(dwarf::DW_TAG_ptr_to_member_type);
DIEEntry BarEntry(&Bar);
PtrToFooMem.addValue(dwarf::DW_AT_type, dwarf::DW_FORM_ref4, &BarEntry);
PtrToFooMem.addValue(dwarf::DW_AT_containing_type, dwarf::DW_FORM_ref4,
&BarEntry);
DIEEntry PtrToFooMemRef(&PtrToFooMem);
Mem->addValue(dwarf::DW_AT_type, dwarf::DW_FORM_ref4, &PtrToFooMemRef);
Foo.addChild(Mem);
MD5ResDecl = DIEHash().computeTypeSignature(&Foo);
}
uint64_t MD5ResDef;
{
DIE Bar(dwarf::DW_TAG_structure_type);
Bar.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &BarStr);
Bar.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &One);
DIE Foo(dwarf::DW_TAG_structure_type);
Foo.addValue(dwarf::DW_AT_byte_size, dwarf::DW_FORM_data1, &Eight);
Foo.addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &FooStr);
DIE *Mem = new DIE(dwarf::DW_TAG_member);
Mem->addValue(dwarf::DW_AT_name, dwarf::DW_FORM_strp, &MemStr);
Mem->addValue(dwarf::DW_AT_data_member_location, dwarf::DW_FORM_data1,
&Zero);
DIE PtrToFooMem(dwarf::DW_TAG_ptr_to_member_type);
DIEEntry BarEntry(&Bar);
PtrToFooMem.addValue(dwarf::DW_AT_type, dwarf::DW_FORM_ref4, &BarEntry);
PtrToFooMem.addValue(dwarf::DW_AT_containing_type, dwarf::DW_FORM_ref4,
&BarEntry);
DIEEntry PtrToFooMemRef(&PtrToFooMem);
Mem->addValue(dwarf::DW_AT_type, dwarf::DW_FORM_ref4, &PtrToFooMemRef);
Foo.addChild(Mem);
MD5ResDef = DIEHash().computeTypeSignature(&Foo);
}
// FIXME: This seems to be a bug in the DWARF type hashing specification that
// only uses the brief name hashing for types referenced via DW_AT_type. In
// this case the type is referenced via DW_AT_containing_type and full hashing
// causes a hash to differ when the containing type is a declaration in one TU
// and a definition in another.
ASSERT_NE(MD5ResDef, MD5ResDecl);
}
}