vsk created this revision.
vsk added reviewers: jingham, aprantl.
Value::GetValueByteSize() assumes that the size of a Value is always
equal to the size of the underlying variable's CompilerType. However,
llvm's DWARF generator doesn't appear to create fresh types with new
sizes when emitting fragments / DW_OP_piece. It seems like there's a
faulty assumption in lldb (although it's plausible that llvm is just
generating weird DWARF).
This patch teaches GetValueByteSize() to report the size of a Value as
the size of its data buffer if it's a host address.
I'm not sure whether this is an exhaustive fix. This does fix an ASan
error in lldb seen when debugging a clang binary.
ASan report: F11233245: asan-report-rdar58665925.txt
<https://reviews.llvm.org/F11233245>
rdar://58665925
https://reviews.llvm.org/D73148
Files:
lldb/source/Core/Value.cpp
lldb/unittests/Expression/DWARFExpressionTest.cpp
Index: lldb/unittests/Expression/DWARFExpressionTest.cpp
===================================================================
--- lldb/unittests/Expression/DWARFExpressionTest.cpp
+++ lldb/unittests/Expression/DWARFExpressionTest.cpp
@@ -360,4 +360,16 @@
// Note that the "00" should really be "undef", but we can't
// represent that yet.
llvm::HasValue(GetScalar(16, 0xff00, true)));
+
+ for (unsigned char ByteSize = 1; ByteSize <= 8; ++ByteSize) {
+ llvm::Expected<Scalar> empty = Evaluate({DW_OP_piece, ByteSize});
+ // Note that the "00" should really be "undef", but we can't
+ // represent that yet.
+ EXPECT_THAT_EXPECTED(empty,
+ llvm::HasValue(GetScalar(ByteSize * 8, 0, true)));
+
+ Value pieces;
+ ASSERT_EQ(pieces.AppendDataToHostBuffer(empty.get()), ByteSize);
+ ASSERT_EQ(pieces.GetValueByteSize(nullptr, nullptr), ByteSize);
+ }
}
Index: lldb/source/Core/Value.cpp
===================================================================
--- lldb/source/Core/Value.cpp
+++ lldb/source/Core/Value.cpp
@@ -222,6 +222,11 @@
case eContextTypeLLDBType: // Type *
case eContextTypeVariable: // Variable *
{
+ // The size of this Value may be less than the size of the type of its
+ // source variable due to truncating operations such as DW_OP_piece.
+ if (m_value_type == eValueTypeHostAddress)
+ return GetBuffer().GetByteSize();
+
auto *scope = exe_ctx ? exe_ctx->GetBestExecutionContextScope() : nullptr;
if (llvm::Optional<uint64_t> size = GetCompilerType().GetByteSize(scope)) {
if (error_ptr)
Index: lldb/unittests/Expression/DWARFExpressionTest.cpp
===================================================================
--- lldb/unittests/Expression/DWARFExpressionTest.cpp
+++ lldb/unittests/Expression/DWARFExpressionTest.cpp
@@ -360,4 +360,16 @@
// Note that the "00" should really be "undef", but we can't
// represent that yet.
llvm::HasValue(GetScalar(16, 0xff00, true)));
+
+ for (unsigned char ByteSize = 1; ByteSize <= 8; ++ByteSize) {
+ llvm::Expected<Scalar> empty = Evaluate({DW_OP_piece, ByteSize});
+ // Note that the "00" should really be "undef", but we can't
+ // represent that yet.
+ EXPECT_THAT_EXPECTED(empty,
+ llvm::HasValue(GetScalar(ByteSize * 8, 0, true)));
+
+ Value pieces;
+ ASSERT_EQ(pieces.AppendDataToHostBuffer(empty.get()), ByteSize);
+ ASSERT_EQ(pieces.GetValueByteSize(nullptr, nullptr), ByteSize);
+ }
}
Index: lldb/source/Core/Value.cpp
===================================================================
--- lldb/source/Core/Value.cpp
+++ lldb/source/Core/Value.cpp
@@ -222,6 +222,11 @@
case eContextTypeLLDBType: // Type *
case eContextTypeVariable: // Variable *
{
+ // The size of this Value may be less than the size of the type of its
+ // source variable due to truncating operations such as DW_OP_piece.
+ if (m_value_type == eValueTypeHostAddress)
+ return GetBuffer().GetByteSize();
+
auto *scope = exe_ctx ? exe_ctx->GetBestExecutionContextScope() : nullptr;
if (llvm::Optional<uint64_t> size = GetCompilerType().GetByteSize(scope)) {
if (error_ptr)
_______________________________________________
lldb-commits mailing list
lldb-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
