Author: Michael Buch Date: 2022-09-23T12:27:08+02:00 New Revision: d5d90428500870107909fb8f90023ff608cd1ec2
URL: https://github.com/llvm/llvm-project/commit/d5d90428500870107909fb8f90023ff608cd1ec2 DIFF: https://github.com/llvm/llvm-project/commit/d5d90428500870107909fb8f90023ff608cd1ec2.diff LOG: [lldb][TypeSystemClang] Deduce lldb::eEncodingUint for unsigned enum types The motivating issue was the following: ``` $ cat main.cpp enum class EnumVals : uint16_t { VAL1 = 0 }; struct Foo { EnumVals b1 : 4; }; int main() { // Assign value out-of-range if // bit-field were signed Foo f{.b1 = (EnumVals)8}; return 0; // Break here } (lldb) script >>> lldb.frame.FindVariable("f").GetChildMemberWithName("b1").GetValueAsUnsigned() 4294967288 ``` In the above example we observe a unsigned integer wrap-around because we sign-extended the bit-fields underlying Scalar value before casting it to an unsigned. The sign extension occurs because we don't mark APSInt::IsUnsigned == true correctly when extracting the value from memory (in Value::ResolveValue). The reason why sign extension causes the wraparound is that the value we're assigning to the bit-field is out-of-range (if it were a signed bit-field), which causes `Scalar::sext` to left-fill the Scalar with 1s. This patch corrects GetEncoding to account for unsigned enum types. With this change the Scalar would be zero-extended instead. This is mainly a convenience fix which well-formed code wouldn't encounter. rdar://99785324 Differential Revision: https://reviews.llvm.org/D134493 Added: lldb/test/API/python_api/sbvalue_unsigned_enum_bitfield_value/TestSBValueUnsignedEnumBitField.py lldb/test/API/python_api/sbvalue_unsigned_enum_bitfield_value/main.cpp Modified: lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp Removed: ################################################################################ diff --git a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp index e298d7fee4214..6164b978f2f24 100644 --- a/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp +++ b/lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp @@ -5097,7 +5097,9 @@ lldb::Encoding TypeSystemClang::GetEncoding(lldb::opaque_compiler_type_t type, case clang::Type::Record: break; case clang::Type::Enum: - return lldb::eEncodingSint; + return qual_type->isUnsignedIntegerOrEnumerationType() + ? lldb::eEncodingUint + : lldb::eEncodingSint; case clang::Type::DependentSizedArray: case clang::Type::DependentSizedExtVector: case clang::Type::UnresolvedUsing: diff --git a/lldb/test/API/python_api/sbvalue_unsigned_enum_bitfield_value/TestSBValueUnsignedEnumBitField.py b/lldb/test/API/python_api/sbvalue_unsigned_enum_bitfield_value/TestSBValueUnsignedEnumBitField.py new file mode 100644 index 0000000000000..eb01fd6ee63a7 --- /dev/null +++ b/lldb/test/API/python_api/sbvalue_unsigned_enum_bitfield_value/TestSBValueUnsignedEnumBitField.py @@ -0,0 +1,18 @@ +""" +Test that SBValue doesn't incorrectly sign-extend +the Scalar value of a bitfield that has an unsigned +enum type. + +We test this by assigning to a bit-field a value +that is out-of-range of it's signed counterpart. +I.e., with a bit-field of width 4, assigning +8 to it would be out-of-range if we treated it +as a signed. If LLDB were to sign-extend the Scalar +(which shouldn't happen for unsigned bit-fields) +it would left-fill the result with 1s; we test +for this not to happen. +""" + +import lldbsuite.test.lldbinline as lldbinline + +lldbinline.MakeInlineTest(__file__, globals()) diff --git a/lldb/test/API/python_api/sbvalue_unsigned_enum_bitfield_value/main.cpp b/lldb/test/API/python_api/sbvalue_unsigned_enum_bitfield_value/main.cpp new file mode 100644 index 0000000000000..9859754d4973f --- /dev/null +++ b/lldb/test/API/python_api/sbvalue_unsigned_enum_bitfield_value/main.cpp @@ -0,0 +1,14 @@ +#include <stdint.h> + +enum class EnumVals : uint16_t { VAL0 = 0 }; + +struct Foo { + EnumVals b : 4; +}; + +int main(int argc, char const *argv[], char const *envp[]) { + Foo f{.b = static_cast<EnumVals>(8)}; + return 0; //% b = self.frame().FindVariable("f").GetChildMemberWithName("b") + //% val = b.GetValueAsUnsigned() + //% self.assertEqual(val, 8, "Bit-field not correctly extracted") +} _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
