DWARFExpression: Fix implementation of DW_OP_pick
Summary:
The DWARF spec states that the DWARF stack arguments are numbered from
the top. Our implementation of DW_OP_pick was counting them from the
bottom.
This bug probably wasn't noticed because nobody (except my upcoming
postfix-to-DWARF converter) uses DW_OP_pick, but I've cross-checked with
gdb to confirm that counting from the top is the expected behavior.
This patch fixes the implementation to match the spec and gdb behavior
and adds a test.
Reviewers: jasonmolenda, clayborg
Subscribers: mgorny, aprantl, lldb-commits
Differential Revision: https://reviews.llvm.org/D61182
llvm-svn: 359436
diff --git a/lldb/include/lldb/Utility/Scalar.h b/lldb/include/lldb/Utility/Scalar.h
index 633bfeb..8f921b2 100644
--- a/lldb/include/lldb/Utility/Scalar.h
+++ b/lldb/include/lldb/Utility/Scalar.h
@@ -339,6 +339,8 @@
bool operator>(const Scalar &lhs, const Scalar &rhs);
bool operator>=(const Scalar &lhs, const Scalar &rhs);
+llvm::raw_ostream &operator<<(llvm::raw_ostream &os, const Scalar &scalar);
+
} // namespace lldb_private
#endif // LLDB_UTILITY_SCALAR_H
diff --git a/lldb/source/Expression/DWARFExpression.cpp b/lldb/source/Expression/DWARFExpression.cpp
index 17841bb..5250e4d 100644
--- a/lldb/source/Expression/DWARFExpression.cpp
+++ b/lldb/source/Expression/DWARFExpression.cpp
@@ -1751,7 +1751,7 @@
case DW_OP_pick: {
uint8_t pick_idx = opcodes.GetU8(&offset);
if (pick_idx < stack.size())
- stack.push_back(stack[pick_idx]);
+ stack.push_back(stack[stack.size() - 1 - pick_idx]);
else {
if (error_ptr)
error_ptr->SetErrorStringWithFormat(
diff --git a/lldb/source/Utility/Scalar.cpp b/lldb/source/Utility/Scalar.cpp
index 2b5753e..7658ac8 100644
--- a/lldb/source/Utility/Scalar.cpp
+++ b/lldb/source/Utility/Scalar.cpp
@@ -12,6 +12,7 @@
#include "lldb/Utility/Endian.h"
#include "lldb/Utility/Status.h"
#include "lldb/Utility/Stream.h"
+#include "lldb/Utility/StreamString.h"
#include "lldb/lldb-types.h"
#include "llvm/ADT/SmallString.h"
@@ -2844,3 +2845,9 @@
}
return false;
}
+
+llvm::raw_ostream &lldb_private::operator<<(llvm::raw_ostream &os, const Scalar &scalar) {
+ StreamString s;
+ scalar.GetValue(&s, /*show_type*/ true);
+ return os << s.GetString();
+}
diff --git a/lldb/unittests/Expression/CMakeLists.txt b/lldb/unittests/Expression/CMakeLists.txt
index bad090d..fbb314b 100644
--- a/lldb/unittests/Expression/CMakeLists.txt
+++ b/lldb/unittests/Expression/CMakeLists.txt
@@ -1,4 +1,5 @@
add_lldb_unittest(ExpressionTests
+ DWARFExpressionTest.cpp
ClangParserTest.cpp
LINK_LIBS
@@ -6,4 +7,5 @@
lldbPluginExpressionParserClang
lldbUtility
lldbUtilityHelpers
+ LLVMTestingSupport
)
diff --git a/lldb/unittests/Expression/DWARFExpressionTest.cpp b/lldb/unittests/Expression/DWARFExpressionTest.cpp
new file mode 100644
index 0000000..6ce7ce8
--- /dev/null
+++ b/lldb/unittests/Expression/DWARFExpressionTest.cpp
@@ -0,0 +1,42 @@
+//===-- DWARFExpressionTest.cpp ----------------------------------*- C++-*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "lldb/Expression/DWARFExpression.h"
+#include "lldb/Core/Value.h"
+#include "lldb/Core/dwarf.h"
+#include "lldb/Utility/StreamString.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Testing/Support/Error.h"
+#include "gtest/gtest.h"
+
+using namespace lldb_private;
+
+static llvm::Expected<Scalar> Evaluate(llvm::ArrayRef<uint8_t> expr) {
+ DataExtractor extractor(expr.data(), expr.size(), lldb::eByteOrderLittle,
+ /*addr_size*/ 4);
+
+ Value result;
+ Status status;
+ if (!DWARFExpression::Evaluate(
+ /*exe_ctx*/ nullptr, /*reg_ctx*/ nullptr, /*opcode_ctx*/ nullptr,
+ extractor, /*dwarf_cu*/ nullptr, /*offset*/ 0, expr.size(),
+ lldb::eRegisterKindLLDB, /*initial_value_ptr*/ nullptr,
+ /*object_address_ptr*/ nullptr, result, &status))
+ return status.ToError();
+
+ return result.GetScalar();
+}
+
+TEST(DWARFExpression, DW_OP_pick) {
+ EXPECT_THAT_EXPECTED(Evaluate({DW_OP_lit1, DW_OP_lit0, DW_OP_pick, 0}),
+ llvm::HasValue(0));
+ EXPECT_THAT_EXPECTED(Evaluate({DW_OP_lit1, DW_OP_lit0, DW_OP_pick, 1}),
+ llvm::HasValue(1));
+ EXPECT_THAT_EXPECTED(Evaluate({DW_OP_lit1, DW_OP_lit0, DW_OP_pick, 2}),
+ llvm::Failed());
+}