[Lldb-commits] [lldb] [lldb][ClangASTImporter] Import record layouts from origin if available (PR #83295)
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Wed Feb 28 09:06:10 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-lldb
Author: Michael Buch (Michael137)
<details>
<summary>Changes</summary>
Layout information for a record gets stored in the `ClangASTImporter` associated with the `DWARFASTParserClang` that originally parsed the record. LLDB sometimes moves clang types from one AST to another (in the reproducer the origin AST was a precompiled-header and the destination was the AST backing the executable). When clang then asks LLDB to `layoutRecordType`, it will do so with the help of the `ClangASTImporter` the type is associated with. If the type's origin is actually in a different LLDB module (and thus a different `DWARFASTParserClang` was used to set its layout info), we won't find the layout info in our local `ClangASTImporter`.
In the reproducer this meant we would drop the alignment info of the origin type and misread a variable's contents with `frame var` and `expr`.
There is logic in `ClangASTSource::layoutRecordType` to import an origin's layout info. This patch re-uses that infrastructure to import an origin's layout from one `ClangASTImporter` instance to another.
rdar://123274144
---
Full diff: https://github.com/llvm/llvm-project/pull/83295.diff
5 Files Affected:
- (modified) lldb/source/Plugins/ExpressionParser/Clang/ClangASTImporter.cpp (+16-7)
- (added) lldb/test/API/lang/cpp/gmodules/alignment/Makefile (+4)
- (added) lldb/test/API/lang/cpp/gmodules/alignment/TestPchAlignment.py (+60)
- (added) lldb/test/API/lang/cpp/gmodules/alignment/main.cpp (+10)
- (added) lldb/test/API/lang/cpp/gmodules/alignment/pch.h (+21)
``````````diff
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangASTImporter.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangASTImporter.cpp
index 62a30c14912bc9..754191ad83fe8a 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangASTImporter.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangASTImporter.cpp
@@ -527,7 +527,6 @@ bool ClangASTImporter::LayoutRecordType(
&vbase_offsets) {
RecordDeclToLayoutMap::iterator pos =
m_record_decl_to_layout_map.find(record_decl);
- bool success = false;
base_offsets.clear();
vbase_offsets.clear();
if (pos != m_record_decl_to_layout_map.end()) {
@@ -537,13 +536,23 @@ bool ClangASTImporter::LayoutRecordType(
base_offsets.swap(pos->second.base_offsets);
vbase_offsets.swap(pos->second.vbase_offsets);
m_record_decl_to_layout_map.erase(pos);
- success = true;
- } else {
- bit_size = 0;
- alignment = 0;
- field_offsets.clear();
+ return true;
}
- return success;
+
+ // It's possible that we calculated the layout in a different
+ // ClangASTImporter instance. Try to import such layout if
+ // our decl has an origin.
+ if (auto origin = GetDeclOrigin(record_decl); origin.Valid())
+ if (importRecordLayoutFromOrigin(record_decl, bit_size, alignment,
+ field_offsets, base_offsets,
+ vbase_offsets))
+ return true;
+
+ bit_size = 0;
+ alignment = 0;
+ field_offsets.clear();
+
+ return false;
}
void ClangASTImporter::SetRecordLayout(clang::RecordDecl *decl,
diff --git a/lldb/test/API/lang/cpp/gmodules/alignment/Makefile b/lldb/test/API/lang/cpp/gmodules/alignment/Makefile
new file mode 100644
index 00000000000000..a6c3e8ca84a3e4
--- /dev/null
+++ b/lldb/test/API/lang/cpp/gmodules/alignment/Makefile
@@ -0,0 +1,4 @@
+PCH_CXX_SOURCE = pch.h
+CXX_SOURCES = main.cpp
+
+include Makefile.rules
diff --git a/lldb/test/API/lang/cpp/gmodules/alignment/TestPchAlignment.py b/lldb/test/API/lang/cpp/gmodules/alignment/TestPchAlignment.py
new file mode 100644
index 00000000000000..535dd13d0ada48
--- /dev/null
+++ b/lldb/test/API/lang/cpp/gmodules/alignment/TestPchAlignment.py
@@ -0,0 +1,60 @@
+"""
+Tests that we correctly track AST layout info
+(specifically alignment) when moving AST nodes
+between ClangASTImporter instances (in this case,
+from pch to executable to expression AST).
+"""
+
+import lldb
+import os
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestPchAlignment(TestBase):
+ @add_test_categories(["gmodules"])
+ def test_expr(self):
+ self.build()
+ lldbutil.run_to_source_breakpoint(
+ self, "return data", lldb.SBFileSpec("main.cpp")
+ )
+
+ self.expect(
+ "frame variable data",
+ substrs=["row = 1", "col = 2", "row = 3", "col = 4", "stride = 5"],
+ )
+
+ @add_test_categories(["gmodules"])
+ def test_frame_var(self):
+ self.build()
+ lldbutil.run_to_source_breakpoint(
+ self, "return data", lldb.SBFileSpec("main.cpp")
+ )
+
+ self.expect_expr(
+ "data",
+ result_type="MatrixData",
+ result_children=[
+ ValueCheck(
+ name="section",
+ children=[
+ ValueCheck(
+ name="origin",
+ children=[
+ ValueCheck(name="row", value="1"),
+ ValueCheck(name="col", value="2"),
+ ],
+ ),
+ ValueCheck(
+ name="size",
+ children=[
+ ValueCheck(name="row", value="3"),
+ ValueCheck(name="col", value="4"),
+ ],
+ ),
+ ],
+ ),
+ ValueCheck(name="stride", value="5"),
+ ],
+ )
diff --git a/lldb/test/API/lang/cpp/gmodules/alignment/main.cpp b/lldb/test/API/lang/cpp/gmodules/alignment/main.cpp
new file mode 100644
index 00000000000000..5481f3fad1ff76
--- /dev/null
+++ b/lldb/test/API/lang/cpp/gmodules/alignment/main.cpp
@@ -0,0 +1,10 @@
+int main(int argc, const char *argv[]) {
+ struct MatrixData data = {0};
+ data.section.origin.row = 1;
+ data.section.origin.col = 2;
+ data.section.size.row = 3;
+ data.section.size.col = 4;
+ data.stride = 5;
+
+ return data.section.size.row;
+}
diff --git a/lldb/test/API/lang/cpp/gmodules/alignment/pch.h b/lldb/test/API/lang/cpp/gmodules/alignment/pch.h
new file mode 100644
index 00000000000000..f0be272aa601aa
--- /dev/null
+++ b/lldb/test/API/lang/cpp/gmodules/alignment/pch.h
@@ -0,0 +1,21 @@
+#ifndef PCH_H_IN
+#define PCH_H_IN
+
+static const int kAlignment = 64;
+
+struct [[gnu::aligned(kAlignment)]] RowCol {
+ unsigned row;
+ unsigned col;
+};
+
+struct [[gnu::aligned(kAlignment)]] Submatrix {
+ struct RowCol origin;
+ struct RowCol size;
+};
+
+struct [[gnu::aligned(kAlignment)]] MatrixData {
+ struct Submatrix section;
+ unsigned stride;
+};
+
+#endif // _H_IN
``````````
</details>
https://github.com/llvm/llvm-project/pull/83295
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