[Lldb-commits] [lldb] [lldb][test] Add test-cases for packed/aligned structures (PR #96932)
Michael Buch via lldb-commits
lldb-commits at lists.llvm.org
Fri Jun 28 01:08:34 PDT 2024
https://github.com/Michael137 updated https://github.com/llvm/llvm-project/pull/96932
>From d2c28706769f89bf9f0b53071726bb59c6205ce8 Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12 at gmail.com>
Date: Thu, 27 Jun 2024 17:16:50 +0100
Subject: [PATCH 1/2] [lldb][test] Add test-cases for packed structures
Adds test that checks whether 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.
While here, also added a test-case where we check alignment of
a class whose base has an explicit `DW_AT_alignment
(those don't get transitively propagated in DWARF, but don't seem
like a problem for LLDB).
Lastly, also added an XFAIL-ed tests where the aforementioned
`InferAlignment` kicks in for overlapping fields (but in this
case incorrectly since the structure isn't actually packed).
---
.../TestAlignAsBaseClass.py | 1 +
.../API/lang/cpp/alignas_base_class/main.cpp | 7 ++++
.../DWARF/no_unique_address-alignment.cpp | 25 +++++++++++++
lldb/test/Shell/SymbolFile/DWARF/packed.cpp | 36 +++++++++++++++++++
4 files changed, 69 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..362fc2740bf52 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 +16,4 @@ def test(self):
# Verify specified class alignments.
self.expect_expr("alignof(B2)", result_value="8")
self.expect_expr("alignof(EmptyClassAlign8)", result_value="8")
+ 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..a37919deaebdc 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 +13,11 @@ 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..6e544f40625df
--- /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..fb94a834d48a6
--- /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() {}
>From a7b91858c8f9e09b455a581469155152f2dea11e Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12 at gmail.com>
Date: Fri, 28 Jun 2024 09:08:20 +0100
Subject: [PATCH 2/2] fixup! don't set redundant breakpoints
---
.../Shell/SymbolFile/DWARF/no_unique_address-alignment.cpp | 3 +--
lldb/test/Shell/SymbolFile/DWARF/packed.cpp | 1 -
2 files changed, 1 insertion(+), 3 deletions(-)
diff --git a/lldb/test/Shell/SymbolFile/DWARF/no_unique_address-alignment.cpp b/lldb/test/Shell/SymbolFile/DWARF/no_unique_address-alignment.cpp
index 6e544f40625df..1488199a3ad2d 100644
--- a/lldb/test/Shell/SymbolFile/DWARF/no_unique_address-alignment.cpp
+++ b/lldb/test/Shell/SymbolFile/DWARF/no_unique_address-alignment.cpp
@@ -2,7 +2,6 @@
// 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
@@ -18,7 +17,7 @@ struct OverlappingFields {
char y;
[[no_unique_address]] Empty e;
int z;
-} g_packed_struct;
+} g_overlapping_struct;
static_assert(alignof(OverlappingFields) == 4);
static_assert(sizeof(OverlappingFields) == 8);
diff --git a/lldb/test/Shell/SymbolFile/DWARF/packed.cpp b/lldb/test/Shell/SymbolFile/DWARF/packed.cpp
index fb94a834d48a6..640a2e0454c92 100644
--- a/lldb/test/Shell/SymbolFile/DWARF/packed.cpp
+++ b/lldb/test/Shell/SymbolFile/DWARF/packed.cpp
@@ -1,6 +1,5 @@
// 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)" \
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