https://github.com/Michael137 created https://github.com/llvm/llvm-project/pull/96932
Adds test that checks that LLDB correctly infers the alignment of packed structures. Specifically, the `InferAlignment` code-path of the `ItaniumRecordLayoutBuilder` where it assumes that overlapping field offsets imply a packed structure and thus sets alignment to `1`. See discussion in https://github.com/llvm/llvm-project/pull/93809. Also adds two XFAIL-ed tests: 1. where LLDB doesn't correctly infer the alignment of a derived class whose base has an explicit `DW_AT_alignment. See https://github.com/llvm/llvm-project/issues/73623. 2. where the aforementioned `InferAlignment` kicks in for overlapping fields (but in this case incorrectly since the structure isn't actually packed). >From 2113f052dd69cc1773f642e06339e5a13599090c Mon Sep 17 00:00:00 2001 From: Michael Buch <michaelbuc...@gmail.com> Date: Thu, 27 Jun 2024 17:16:50 +0100 Subject: [PATCH] [lldb][test] Add test-cases for packed structures Adds test that checks that LLDB correctly infers the alignment of packed structures. Specifically, the `InferAlignment` code-path of the `ItaniumRecordLayoutBuilder` where it assumes that overlapping field offsets imply a packed structure and thus sets alignment to `1`. See discussion in https://github.com/llvm/llvm-project/pull/93809. Also adds two XFAIL-ed tests: 1. where LLDB doesn't correctly infer the alignment of a derived class whose base has an explicit `DW_AT_alignment. See https://github.com/llvm/llvm-project/issues/73623. 2. where the aforementioned `InferAlignment` kicks in for overlapping fields (but in this case incorrectly since the structure isn't actually packed). --- .../TestAlignAsBaseClass.py | 8 +++++ .../API/lang/cpp/alignas_base_class/main.cpp | 6 ++++ .../DWARF/no_unique_address-alignment.cpp | 25 +++++++++++++ lldb/test/Shell/SymbolFile/DWARF/packed.cpp | 36 +++++++++++++++++++ 4 files changed, 75 insertions(+) create mode 100644 lldb/test/Shell/SymbolFile/DWARF/no_unique_address-alignment.cpp create mode 100644 lldb/test/Shell/SymbolFile/DWARF/packed.cpp diff --git a/lldb/test/API/lang/cpp/alignas_base_class/TestAlignAsBaseClass.py b/lldb/test/API/lang/cpp/alignas_base_class/TestAlignAsBaseClass.py index 7d97b0c42b7e1..f9c99d15e5891 100644 --- a/lldb/test/API/lang/cpp/alignas_base_class/TestAlignAsBaseClass.py +++ b/lldb/test/API/lang/cpp/alignas_base_class/TestAlignAsBaseClass.py @@ -16,3 +16,11 @@ def test(self): # Verify specified class alignments. self.expect_expr("alignof(B2)", result_value="8") self.expect_expr("alignof(EmptyClassAlign8)", result_value="8") + + @no_debug_info_test + @expectedFailureAll(bugnumber="https://github.com/llvm/llvm-project/issues/73623";) + def test(self): + self.build() + self.dbg.CreateTarget(self.getBuildArtifact("a.out")) + + self.expect_expr("alignof(Derived)", result_value="8") diff --git a/lldb/test/API/lang/cpp/alignas_base_class/main.cpp b/lldb/test/API/lang/cpp/alignas_base_class/main.cpp index 9d37554957ba3..fb922c42edfc3 100644 --- a/lldb/test/API/lang/cpp/alignas_base_class/main.cpp +++ b/lldb/test/API/lang/cpp/alignas_base_class/main.cpp @@ -13,4 +13,10 @@ D d3g; struct alignas(8) EmptyClassAlign8 { } t; +struct alignas(8) __attribute__((packed)) AlignedAndPackedBase {} foo; + +struct Derived : AlignedAndPackedBase { +} bar; +static_assert(alignof(Derived) == 8); + int main() {} diff --git a/lldb/test/Shell/SymbolFile/DWARF/no_unique_address-alignment.cpp b/lldb/test/Shell/SymbolFile/DWARF/no_unique_address-alignment.cpp new file mode 100644 index 0000000000000..79199a9237a63 --- /dev/null +++ b/lldb/test/Shell/SymbolFile/DWARF/no_unique_address-alignment.cpp @@ -0,0 +1,25 @@ +// XFAIL: * + +// RUN: %clangxx_host -gdwarf -o %t %s +// RUN: %lldb %t \ +// RUN: -o "b main" \ +// RUN: -o "expr alignof(OverlappingFields)" \ +// RUN: -o "expr sizeof(OverlappingFields)" \ +// RUN: -o exit | FileCheck %s + +// CHECK: (lldb) expr alignof(OverlappingFields) +// CHECK-NEXT: ${{.*}} = 4 +// CHECK: (lldb) expr sizeof(OverlappingFields) +// CHECK-NEXT: ${{.*}} = 8 + +struct Empty {}; + +struct OverlappingFields { + char y; + [[no_unique_address]] Empty e; + int z; +} g_packed_struct; +static_assert(alignof(OverlappingFields) == 4); +static_assert(sizeof(OverlappingFields) == 8); + +int main() {} diff --git a/lldb/test/Shell/SymbolFile/DWARF/packed.cpp b/lldb/test/Shell/SymbolFile/DWARF/packed.cpp new file mode 100644 index 0000000000000..53b5ee624472c --- /dev/null +++ b/lldb/test/Shell/SymbolFile/DWARF/packed.cpp @@ -0,0 +1,36 @@ +// RUN: %clangxx_host -gdwarf -o %t %s +// RUN: %lldb %t \ +// RUN: -o "b main" \ +// RUN: -o "expr alignof(packed)" \ +// RUN: -o "expr sizeof(packed)" \ +// RUN: -o "expr alignof(packed_and_aligned)" \ +// RUN: -o "expr sizeof(packed_and_aligned)" \ +// RUN: -o exit | FileCheck %s + +// CHECK: (lldb) expr alignof(packed) +// CHECK-NEXT: ${{.*}} = 1 +// CHECK: (lldb) expr sizeof(packed) +// CHECK-NEXT: ${{.*}} = 9 + +// CHECK: (lldb) expr alignof(packed_and_aligned) +// CHECK-NEXT: ${{.*}} = 16 +// CHECK: (lldb) expr sizeof(packed_and_aligned) +// CHECK-NEXT: ${{.*}} = 16 + +struct __attribute__((packed)) packed { + int x; + char y; + int z; +} g_packed_struct; +static_assert(alignof(packed) == 1); +static_assert(sizeof(packed) == 9); + +struct __attribute__((packed, aligned(16))) packed_and_aligned { + int x; + char y; + int z; +} g_packed_and_aligned_struct; +static_assert(alignof(packed_and_aligned) == 16); +static_assert(sizeof(packed_and_aligned) == 16); + +int main() {} _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
