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AlignmentCalc: Mark as packed if members are not aligned

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We previously only marked as packed if there was no tail padding, which
was not a sufficient condition.

The new AlignmentCalcTest.PackedMembers test case is an example which
would previously not have been marked as packed.
This commit is contained in:
Alastair Robertson 2023-08-01 08:08:46 -07:00 committed by Alastair Robertson
parent ececbe0a99
commit 0612159121
2 changed files with 55 additions and 19 deletions
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6
oi/type_graph/AlignmentCalc.cpp
View File

@ -67,11 +67,17 @@ void AlignmentCalc::visit(Class& c) {
member.align = member.type().align();
}
alignment = std::max(alignment, member.align);
if (member.align != 0 && (member.bitOffset / 8) % member.align != 0) {
// Mark as packed if members are not aligned
c.setPacked();
}
}
c.setAlign(alignment);
if (c.size() % c.align() != 0) {
// Mark as packed if there is no tail padding
c.setPacked();
}
}

68
test/test_alignment_calc.cpp
View File

@ -66,19 +66,49 @@ TEST(AlignmentCalcTest, StructInContainer) {
)");
}
TEST(AlignmentCalcTest, Packed) {
auto mystruct = Class{0, Class::Kind::Struct, "MyStruct", 9};
auto myint8 = Primitive{Primitive::Kind::Int8};
auto myint64 = Primitive{Primitive::Kind::Int64};
mystruct.members.push_back(Member{myint8, "n1", 0});
mystruct.members.push_back(Member{myint64, "n2", 1 * 8});
test(AlignmentCalc::createPass(), {mystruct}, R"(
[0] Struct: MyStruct (size: 9, align: 8, packed)
TEST(AlignmentCalcTest, PackedMembers) {
test(AlignmentCalc::createPass(), R"(
[0] Struct: MyStruct (size: 8)
Member: n1 (offset: 0)
Primitive: int8_t
Member: n2 (offset: 1)
Primitive: int32_t
Member: n3 (offset: 5)
Primitive: int8_t
Member: n4 (offset: 6)
Primitive: int8_t
Member: n5 (offset: 7)
Primitive: int8_t
)",
R"(
[0] Struct: MyStruct (size: 8, align: 4, packed)
Member: n1 (offset: 0, align: 1)
Primitive: int8_t
Member: n2 (offset: 1, align: 8)
Primitive: int64_t
Member: n2 (offset: 1, align: 4)
Primitive: int32_t
Member: n3 (offset: 5, align: 1)
Primitive: int8_t
Member: n4 (offset: 6, align: 1)
Primitive: int8_t
Member: n5 (offset: 7, align: 1)
Primitive: int8_t
)");
}
TEST(AlignmentCalcTest, PackedTailPadding) {
test(AlignmentCalc::createPass(), R"(
[0] Struct: MyStruct (size: 5)
Member: n1 (offset: 0)
Primitive: int32_t
Member: n2 (offset: 4)
Primitive: int8_t
)",
R"(
[0] Struct: MyStruct (size: 5, align: 4, packed)
Member: n1 (offset: 0, align: 4)
Primitive: int32_t
Member: n2 (offset: 4, align: 1)
Primitive: int8_t
)");
}
@ -89,7 +119,7 @@ TEST(AlignmentCalcTest, RecurseClassParam) {
[1] Class: ClassA (size: 16)
Member: a (offset: 0)
Primitive: int8_t
Member: b (offset: 4)
Member: b (offset: 8)
Primitive: int64_t
)",
R"(
@ -98,7 +128,7 @@ TEST(AlignmentCalcTest, RecurseClassParam) {
[1] Class: ClassA (size: 16, align: 8)
Member: a (offset: 0, align: 1)
Primitive: int8_t
Member: b (offset: 4, align: 8)
Member: b (offset: 8, align: 8)
Primitive: int64_t
)");
}
@ -110,7 +140,7 @@ TEST(AlignmentCalcTest, RecurseClassParent) {
[1] Class: ClassA (size: 16)
Member: a (offset: 0)
Primitive: int8_t
Member: b (offset: 4)
Member: b (offset: 8)
Primitive: int64_t
)",
R"(
@ -119,7 +149,7 @@ TEST(AlignmentCalcTest, RecurseClassParent) {
[1] Class: ClassA (size: 16, align: 8)
Member: a (offset: 0, align: 1)
Primitive: int8_t
Member: b (offset: 4, align: 8)
Member: b (offset: 8, align: 8)
Primitive: int64_t
)");
}
@ -131,7 +161,7 @@ TEST(AlignmentCalcTest, RecurseClassMember) {
[1] Class: ClassA (size: 16)
Member: a (offset: 0)
Primitive: int8_t
Member: b (offset: 4)
Member: b (offset: 8)
Primitive: int64_t
)",
R"(
@ -140,7 +170,7 @@ TEST(AlignmentCalcTest, RecurseClassMember) {
[1] Class: ClassA (size: 16, align: 8)
Member: a (offset: 0, align: 1)
Primitive: int8_t
Member: b (offset: 4, align: 8)
Member: b (offset: 8, align: 8)
Primitive: int64_t
)");
}
@ -152,7 +182,7 @@ TEST(AlignmentCalcTest, RecurseClassChild) {
[1] Class: ClassA (size: 16)
Member: a (offset: 0)
Primitive: int8_t
Member: b (offset: 4)
Member: b (offset: 8)
Primitive: int64_t
)",
R"(
@ -161,7 +191,7 @@ TEST(AlignmentCalcTest, RecurseClassChild) {
[1] Class: ClassA (size: 16, align: 8)
Member: a (offset: 0, align: 1)
Primitive: int8_t
Member: b (offset: 4, align: 8)
Member: b (offset: 8, align: 8)
Primitive: int64_t
)");
}