[Lldb-commits] [lldb] [lldb] Reject mixed typed DWARF binary operands (PR #201288)
via lldb-commits
lldb-commits at lists.llvm.org
Fri Jun 5 08:34:08 PDT 2026
https://github.com/firmiana402 updated https://github.com/llvm/llvm-project/pull/201288
>From f1b02e03761213e92d2e782c0b367d9d56cd240a Mon Sep 17 00:00:00 2001
From: firmiana402 <firmiana402 at gmail.com>
Date: Wed, 3 Jun 2026 11:31:09 +0800
Subject: [PATCH 1/3] [lldb] Reject mixed typed DWARF binary operands
---
lldb/source/Expression/DWARFExpression.cpp | 90 ++++++++++++++++++++++
1 file changed, 90 insertions(+)
diff --git a/lldb/source/Expression/DWARFExpression.cpp b/lldb/source/Expression/DWARFExpression.cpp
index 106e3b4d59283..c04fcc34b7dfa 100644
--- a/lldb/source/Expression/DWARFExpression.cpp
+++ b/lldb/source/Expression/DWARFExpression.cpp
@@ -1291,6 +1291,32 @@ static llvm::Error Evaluate_DW_OP_call_frame_cfa(EvalContext &eval_ctx) {
return llvm::Error::success();
}
+static llvm::Error CheckScalarOperandsHaveSameType(const Scalar &lhs,
+ const Scalar &rhs,
+ LocationAtom opcode) {
+ // Scalar does not preserve the original DWARF DIE, but it does carry the
+ // pieces of base-type information used by the evaluator: kind, size, and
+ // integer signedness.
+ if (lhs.GetType() != rhs.GetType())
+ return llvm::createStringError(
+ "%s requires operands to have the same type",
+ DW_OP_value_to_name(opcode));
+
+ if (lhs.GetByteSize() != rhs.GetByteSize())
+ return llvm::createStringError(
+ "%s requires operands to have the same type",
+ DW_OP_value_to_name(opcode));
+
+ // Floating scalars do not have integer signedness, so only compare
+ // signedness after establishing that both operands are integers.
+ if (lhs.GetType() == Scalar::e_int && lhs.IsSigned() != rhs.IsSigned())
+ return llvm::createStringError(
+ "%s requires operands to have the same type",
+ DW_OP_value_to_name(opcode));
+
+ return llvm::Error::success();
+}
+
llvm::Expected<Value> DWARFExpression::Evaluate(
ExecutionContext *exe_ctx, RegisterContext *reg_ctx,
lldb::ModuleSP module_sp, const DataExtractor &opcodes,
@@ -1470,12 +1496,20 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
break;
case DW_OP_and:
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() & tmp.GetScalar();
break;
case DW_OP_div: {
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
if (tmp.GetScalar().IsZero())
return llvm::createStringError("divide by zero");
@@ -1493,12 +1527,20 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
} break;
case DW_OP_minus:
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() - tmp.GetScalar();
break;
case DW_OP_mod:
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() % tmp.GetScalar();
@@ -1521,12 +1563,20 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
break;
case DW_OP_or:
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() | tmp.GetScalar();
break;
case DW_OP_plus:
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() += tmp.GetScalar();
@@ -1541,12 +1591,20 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
} break;
case DW_OP_shl:
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() <<= tmp.GetScalar();
break;
case DW_OP_shr:
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
stack.pop_back();
if (!stack.back().GetScalar().ShiftRightLogical(tmp.GetScalar()))
@@ -1554,12 +1612,20 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
break;
case DW_OP_shra:
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() >>= tmp.GetScalar();
break;
case DW_OP_xor:
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() ^ tmp.GetScalar();
@@ -1601,36 +1667,60 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
} break;
case DW_OP_eq:
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() == tmp.GetScalar();
break;
case DW_OP_ge:
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() >= tmp.GetScalar();
break;
case DW_OP_gt:
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() > tmp.GetScalar();
break;
case DW_OP_le:
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() <= tmp.GetScalar();
break;
case DW_OP_lt:
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() < tmp.GetScalar();
break;
case DW_OP_ne:
+ if (llvm::Error err = CheckScalarOperandsHaveSameType(
+ stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
+ opcode))
+ return err;
tmp = stack.back();
stack.pop_back();
stack.back().GetScalar() = stack.back().GetScalar() != tmp.GetScalar();
>From dd117340160e242853d09b2c57477de6d762c243 Mon Sep 17 00:00:00 2001
From: firmiana402 <firmiana402 at gmail.com>
Date: Thu, 4 Jun 2026 11:00:50 +0800
Subject: [PATCH 2/3] [lldb] Test mixed typed DWARF binary operands
---
.../Expression/DWARFExpressionTest.cpp | 48 +++++++++++++++++++
1 file changed, 48 insertions(+)
diff --git a/lldb/unittests/Expression/DWARFExpressionTest.cpp b/lldb/unittests/Expression/DWARFExpressionTest.cpp
index 00ee6b13ad93c..ddbbdc91711ff 100644
--- a/lldb/unittests/Expression/DWARFExpressionTest.cpp
+++ b/lldb/unittests/Expression/DWARFExpressionTest.cpp
@@ -576,6 +576,54 @@ TEST(DWARFExpression, DW_OP_convert) {
llvm::Failed());
}
+TEST(DWARFExpression, TypedBinaryOpsRejectMismatchedTypes) {
+ class TypedDwarfDelegate : public MockDwarfDelegate {
+ public:
+ enum : uint8_t {
+ UnsignedChar = 1,
+ SignedChar = 2,
+ UnsignedShort = 3,
+ };
+
+ llvm::Expected<std::pair<uint64_t, bool>>
+ GetDIEBitSizeAndSign(uint64_t relative_die_offset) const override {
+ switch (relative_die_offset) {
+ case UnsignedChar:
+ return std::pair<uint64_t, bool>{8, false};
+ case SignedChar:
+ return std::pair<uint64_t, bool>{8, true};
+ case UnsignedShort:
+ return std::pair<uint64_t, bool>{16, false};
+ default:
+ return llvm::createStringError("unknown base type offset");
+ }
+ }
+ };
+
+ TypedDwarfDelegate unit;
+ constexpr uint8_t opcodes[] = {
+ DW_OP_plus, DW_OP_minus, DW_OP_div, DW_OP_mod, DW_OP_and, DW_OP_or,
+ DW_OP_xor, DW_OP_shl, DW_OP_shr, DW_OP_shra, DW_OP_lt, DW_OP_le,
+ DW_OP_gt, DW_OP_ge, DW_OP_eq, DW_OP_ne,
+ };
+
+ for (uint8_t opcode : opcodes) {
+ std::vector<uint8_t> expr = {
+ DW_OP_constu, 0xff, 0x01, DW_OP_convert,
+ TypedDwarfDelegate::UnsignedChar, DW_OP_lit1, DW_OP_convert,
+ TypedDwarfDelegate::UnsignedShort, opcode, DW_OP_stack_value};
+ EXPECT_THAT_EXPECTED(Evaluate(expr, {}, &unit), llvm::Failed())
+ << "opcode 0x" << llvm::utohexstr(opcode);
+ }
+
+ EXPECT_THAT_EXPECTED(
+ Evaluate({DW_OP_constu, 0xff, 0x01, DW_OP_convert,
+ TypedDwarfDelegate::UnsignedChar, DW_OP_lit1, DW_OP_convert,
+ TypedDwarfDelegate::SignedChar, DW_OP_plus, DW_OP_stack_value},
+ {}, &unit),
+ llvm::Failed());
+}
+
TEST(DWARFExpression, DW_OP_stack_value) {
EXPECT_THAT_EXPECTED(Evaluate({DW_OP_stack_value}), llvm::Failed());
}
>From 1749a4c867c632410cd8334ddddab65defb586af Mon Sep 17 00:00:00 2001
From: firmiana402 <firmiana402 at gmail.com>
Date: Fri, 5 Jun 2026 23:16:20 +0800
Subject: [PATCH 3/3] Relax generic DWARF operand checks and format code
---
lldb/source/Expression/DWARFExpression.cpp | 72 +++++++++++--------
.../Expression/DWARFExpressionTest.cpp | 32 +++++++--
2 files changed, 70 insertions(+), 34 deletions(-)
diff --git a/lldb/source/Expression/DWARFExpression.cpp b/lldb/source/Expression/DWARFExpression.cpp
index c04fcc34b7dfa..25d9f8ca38682 100644
--- a/lldb/source/Expression/DWARFExpression.cpp
+++ b/lldb/source/Expression/DWARFExpression.cpp
@@ -1293,26 +1293,40 @@ static llvm::Error Evaluate_DW_OP_call_frame_cfa(EvalContext &eval_ctx) {
static llvm::Error CheckScalarOperandsHaveSameType(const Scalar &lhs,
const Scalar &rhs,
- LocationAtom opcode) {
+ LocationAtom opcode,
+ size_t address_size) {
// Scalar does not preserve the original DWARF DIE, but it does carry the
// pieces of base-type information used by the evaluator: kind, size, and
// integer signedness.
if (lhs.GetType() != rhs.GetType())
- return llvm::createStringError(
- "%s requires operands to have the same type",
- DW_OP_value_to_name(opcode));
+ return llvm::createStringError("%s requires operands to have the same type",
+ DW_OP_value_to_name(opcode));
if (lhs.GetByteSize() != rhs.GetByteSize())
- return llvm::createStringError(
- "%s requires operands to have the same type",
- DW_OP_value_to_name(opcode));
+ return llvm::createStringError("%s requires operands to have the same type",
+ DW_OP_value_to_name(opcode));
- // Floating scalars do not have integer signedness, so only compare
- // signedness after establishing that both operands are integers.
- if (lhs.GetType() == Scalar::e_int && lhs.IsSigned() != rhs.IsSigned())
- return llvm::createStringError(
- "%s requires operands to have the same type",
- DW_OP_value_to_name(opcode));
+ // Only integer scalars have signedness, so non-integer operands have no
+ // further scalar type information to compare after kind and size match.
+ if (lhs.GetType() != Scalar::e_int)
+ return llvm::Error::success();
+
+ // DWARF generic values are address-sized integers with unspecified
+ // signedness. LLDB does not explicitly preserve genericness on the expression
+ // stack, so treat integers at least as wide as the generic type as
+ // potentially generic to keep existing expressions compatible. For example,
+ // DW_OP_constu and DW_OP_consts currently do not always use to_generic due to
+ // https://github.com/llvm/llvm-project/issues/47431. A precise fix would
+ // require tracking genericness directly, which is a larger type-system
+ // change, so do not use signedness to reject these operands here.
+ if (address_size != 0 && lhs.GetByteSize() >= address_size)
+ return llvm::Error::success();
+
+ // For non-generic integer operands, signedness is part of the base-type
+ // information preserved by Scalar, so require it to match.
+ if (lhs.IsSigned() != rhs.IsSigned())
+ return llvm::createStringError("%s requires operands to have the same type",
+ DW_OP_value_to_name(opcode));
return llvm::Error::success();
}
@@ -1498,7 +1512,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_and:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
@@ -1508,7 +1522,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_div: {
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
if (tmp.GetScalar().IsZero())
@@ -1529,7 +1543,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_minus:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
@@ -1539,7 +1553,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_mod:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
@@ -1565,7 +1579,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_or:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
@@ -1575,7 +1589,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_plus:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
@@ -1593,7 +1607,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_shl:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
@@ -1603,7 +1617,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_shr:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
@@ -1614,7 +1628,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_shra:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
@@ -1624,7 +1638,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_xor:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
@@ -1669,7 +1683,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_eq:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
@@ -1679,7 +1693,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_ge:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
@@ -1689,7 +1703,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_gt:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
@@ -1699,7 +1713,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_le:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
@@ -1709,7 +1723,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_lt:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
@@ -1719,7 +1733,7 @@ llvm::Expected<Value> DWARFExpression::Evaluate(
case DW_OP_ne:
if (llvm::Error err = CheckScalarOperandsHaveSameType(
stack[stack.size() - 2].GetScalar(), stack.back().GetScalar(),
- opcode))
+ opcode, address_size))
return err;
tmp = stack.back();
stack.pop_back();
diff --git a/lldb/unittests/Expression/DWARFExpressionTest.cpp b/lldb/unittests/Expression/DWARFExpressionTest.cpp
index ddbbdc91711ff..9a5c2a4258471 100644
--- a/lldb/unittests/Expression/DWARFExpressionTest.cpp
+++ b/lldb/unittests/Expression/DWARFExpressionTest.cpp
@@ -602,16 +602,22 @@ TEST(DWARFExpression, TypedBinaryOpsRejectMismatchedTypes) {
TypedDwarfDelegate unit;
constexpr uint8_t opcodes[] = {
- DW_OP_plus, DW_OP_minus, DW_OP_div, DW_OP_mod, DW_OP_and, DW_OP_or,
+ DW_OP_plus, DW_OP_minus, DW_OP_div, DW_OP_mod, DW_OP_and, DW_OP_or,
DW_OP_xor, DW_OP_shl, DW_OP_shr, DW_OP_shra, DW_OP_lt, DW_OP_le,
DW_OP_gt, DW_OP_ge, DW_OP_eq, DW_OP_ne,
};
for (uint8_t opcode : opcodes) {
- std::vector<uint8_t> expr = {
- DW_OP_constu, 0xff, 0x01, DW_OP_convert,
- TypedDwarfDelegate::UnsignedChar, DW_OP_lit1, DW_OP_convert,
- TypedDwarfDelegate::UnsignedShort, opcode, DW_OP_stack_value};
+ std::vector<uint8_t> expr = {DW_OP_constu,
+ 0xff,
+ 0x01,
+ DW_OP_convert,
+ TypedDwarfDelegate::UnsignedChar,
+ DW_OP_lit1,
+ DW_OP_convert,
+ TypedDwarfDelegate::UnsignedShort,
+ opcode,
+ DW_OP_stack_value};
EXPECT_THAT_EXPECTED(Evaluate(expr, {}, &unit), llvm::Failed())
<< "opcode 0x" << llvm::utohexstr(opcode);
}
@@ -624,6 +630,22 @@ TEST(DWARFExpression, TypedBinaryOpsRejectMismatchedTypes) {
llvm::Failed());
}
+TEST(DWARFExpression, GenericBinaryOpsAllowDifferentSignedness) {
+ // The DWARF generic type has unspecified signedness, so differently signed
+ // address-sized generic values are still compatible operands.
+ uint8_t expr[] = {DW_OP_lit8, DW_OP_consts, 4, DW_OP_minus,
+ DW_OP_stack_value};
+ DataExtractor extractor(expr, sizeof(expr), lldb::eByteOrderLittle,
+ /*addr_size*/ 8);
+ EXPECT_THAT_EXPECTED(
+ DWARFExpression::Evaluate(/*exe_ctx=*/nullptr, /*reg_ctx=*/nullptr,
+ /*module_sp=*/{}, extractor,
+ /*unit=*/nullptr, lldb::eRegisterKindLLDB,
+ /*initial_value_ptr=*/nullptr,
+ /*object_address_ptr=*/nullptr),
+ ExpectScalar(4));
+}
+
TEST(DWARFExpression, DW_OP_stack_value) {
EXPECT_THAT_EXPECTED(Evaluate({DW_OP_stack_value}), llvm::Failed());
}
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