friss created this revision.
friss added reviewers: jingham, labath.
Using enumerators as flags is standard practice. This patch adds
support to LLDB to display such enum values symbolically, eg:
(E) e1 = A | B
If enumerators don't cover the whole value, the remaining bits are
displayed as hexadecimal:
(E) e4 = A | 0x10
Detecting whether an enum is used as a bitfield or not is
complicated. This patch implements a heuristic that assumes that such
enumerators will either have only 1 bit set or will be a combination
of previous values.
This patch doesn't change the way we currently display enums which the
above heuristic would not consider as bitfields.
https://reviews.llvm.org/D67520
Files:
lit/SymbolFile/DWARF/debug-types-missing-signature.test
packages/Python/lldbsuite/test/lang/c/enum_types/TestEnumTypes.py
packages/Python/lldbsuite/test/lang/c/enum_types/main.c
source/Symbol/ClangASTContext.cpp
Index: source/Symbol/ClangASTContext.cpp
===================================================================
--- source/Symbol/ClangASTContext.cpp
+++ source/Symbol/ClangASTContext.cpp
@@ -9471,6 +9471,82 @@
}
}
+static bool DumpEnumValue(const clang::QualType &qual_type, Stream *s,
+ const DataExtractor &data, lldb::offset_t byte_offset,
+ size_t byte_size, uint32_t bitfield_bit_offset,
+ uint32_t bitfield_bit_size) {
+ const clang::EnumType *enutype =
+ llvm::cast<clang::EnumType>(qual_type.getTypePtr());
+ const clang::EnumDecl *enum_decl = enutype->getDecl();
+ assert(enum_decl);
+ lldb::offset_t offset = byte_offset;
+ const uint64_t enum_svalue = data.GetMaxS64Bitfield(
+ &offset, byte_size, bitfield_bit_size, bitfield_bit_offset);
+ bool can_be_bitfield = true;
+ uint64_t covered_bits = 0;
+ int num_enumerators = 0;
+
+ // Try to find an exact match for the value.
+ // At the same time, we're applying a heuristic to determine whether we want
+ // to print this enum as a bitfield. We're likely dealing with a bitfield if
+ // every enumrator is either a one bit value or a superset of the previous
+ // enumerators. Also 0 doesn't make sense when the enumerators are used as
+ // flags.
+ for (auto enumerator : enum_decl->enumerators()) {
+ uint64_t val = enumerator->getInitVal().getSExtValue();
+ if ((llvm::countPopulation(val) != 1 && (val & ~covered_bits) != 0) ||
+ val == 0)
+ can_be_bitfield = false;
+ covered_bits |= val;
+ ++num_enumerators;
+ if (val == enum_svalue) {
+ s->PutCString(enumerator->getNameAsString());
+ return true;
+ }
+ }
+
+ // No exact match, but we don't think this is a bitfield. Print the value as
+ // decimal.
+ if (!can_be_bitfield) {
+ s->Printf("%" PRIi64, enum_svalue);
+ return true;
+ }
+
+ // Unsigned values make more sense for flags.
+ offset = byte_offset;
+ const uint64_t enum_uvalue = data.GetMaxU64Bitfield(
+ &offset, byte_size, bitfield_bit_size, bitfield_bit_offset);
+
+ uint64_t remaining_value = enum_uvalue;
+ std::vector<std::pair<uint64_t, llvm::StringRef>> values;
+ values.reserve(num_enumerators);
+ for (auto enumerator : enum_decl->enumerators())
+ values.emplace_back(enumerator->getInitVal().getZExtValue(),
+ enumerator->getName());
+
+ // Sort in reverse order of the number of set bits. This is so that
+ // in `enum {A, B, ALL = A|B }` we visit ALL first.
+ std::stable_sort(
+ values.begin(), values.end(), [](const auto &a, const auto &b) {
+ return llvm::countPopulation(a.first) > llvm::countPopulation(b.first);
+ });
+
+ for (const auto &val : values) {
+ if ((remaining_value & val.first) != val.first)
+ continue;
+ remaining_value &= ~val.first;
+ s->PutCString(val.second);
+ if (remaining_value)
+ s->PutCString(" | ");
+ }
+
+ // If there is a remainder that is not covered by the value, print it as hex.
+ if (remaining_value)
+ s->Printf("0x%" PRIx64, remaining_value);
+
+ return true;
+}
+
bool ClangASTContext::DumpTypeValue(
lldb::opaque_compiler_type_t type, Stream *s, lldb::Format format,
const DataExtractor &data, lldb::offset_t byte_offset, size_t byte_size,
@@ -9514,45 +9590,9 @@
// If our format is enum or default, show the enumeration value as its
// enumeration string value, else just display it as requested.
if ((format == eFormatEnum || format == eFormatDefault) &&
- GetCompleteType(type)) {
- const clang::EnumType *enutype =
- llvm::cast<clang::EnumType>(qual_type.getTypePtr());
- const clang::EnumDecl *enum_decl = enutype->getDecl();
- assert(enum_decl);
- clang::EnumDecl::enumerator_iterator enum_pos, enum_end_pos;
- const bool is_signed = qual_type->isSignedIntegerOrEnumerationType();
- lldb::offset_t offset = byte_offset;
- if (is_signed) {
- const int64_t enum_svalue = data.GetMaxS64Bitfield(
- &offset, byte_size, bitfield_bit_size, bitfield_bit_offset);
- for (enum_pos = enum_decl->enumerator_begin(),
- enum_end_pos = enum_decl->enumerator_end();
- enum_pos != enum_end_pos; ++enum_pos) {
- if (enum_pos->getInitVal().getSExtValue() == enum_svalue) {
- s->PutCString(enum_pos->getNameAsString());
- return true;
- }
- }
- // If we have gotten here we didn't get find the enumerator in the
- // enum decl, so just print the integer.
- s->Printf("%" PRIi64, enum_svalue);
- } else {
- const uint64_t enum_uvalue = data.GetMaxU64Bitfield(
- &offset, byte_size, bitfield_bit_size, bitfield_bit_offset);
- for (enum_pos = enum_decl->enumerator_begin(),
- enum_end_pos = enum_decl->enumerator_end();
- enum_pos != enum_end_pos; ++enum_pos) {
- if (enum_pos->getInitVal().getZExtValue() == enum_uvalue) {
- s->PutCString(enum_pos->getNameAsString());
- return true;
- }
- }
- // If we have gotten here we didn't get find the enumerator in the
- // enum decl, so just print the integer.
- s->Printf("%" PRIu64, enum_uvalue);
- }
- return true;
- }
+ GetCompleteType(type))
+ return DumpEnumValue(qual_type, s, data, byte_offset, byte_size,
+ bitfield_bit_offset, bitfield_bit_size);
// format was not enum, just fall through and dump the value as
// requested....
LLVM_FALLTHROUGH;
Index: packages/Python/lldbsuite/test/lang/c/enum_types/main.c
===================================================================
--- packages/Python/lldbsuite/test/lang/c/enum_types/main.c
+++ packages/Python/lldbsuite/test/lang/c/enum_types/main.c
@@ -18,6 +18,17 @@
int main (int argc, char const *argv[])
{
+ enum bitfield {
+ A = 1 << 0,
+ B = 1 << 1,
+ C = 1 << 2,
+ AB = A | B,
+ ALL = A | B | C,
+ };
+
+ enum bitfield a = A, b = B, c = C, ab = AB, ac = A | C, all = ALL;
+ int nonsense = a + b + c + ab + ac + all; // Breakpoint for bitfield
+
enum days {
Monday = -3,
Tuesday,
Index: packages/Python/lldbsuite/test/lang/c/enum_types/TestEnumTypes.py
===================================================================
--- packages/Python/lldbsuite/test/lang/c/enum_types/TestEnumTypes.py
+++ packages/Python/lldbsuite/test/lang/c/enum_types/TestEnumTypes.py
@@ -25,11 +25,26 @@
exe = self.getBuildArtifact("a.out")
self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
+ lldbutil.run_to_source_breakpoint(
+ self, '// Breakpoint for bitfield', lldb.SBFileSpec("main.c"))
+
+ self.expect("fr var a", DATA_TYPES_DISPLAYED_CORRECTLY,
+ patterns=[' = A$'])
+ self.expect("fr var b", DATA_TYPES_DISPLAYED_CORRECTLY,
+ patterns=[' = B$'])
+ self.expect("fr var c", DATA_TYPES_DISPLAYED_CORRECTLY,
+ patterns=[' = C$'])
+ self.expect("fr var ab", DATA_TYPES_DISPLAYED_CORRECTLY,
+ patterns=[' = AB$'])
+ self.expect("fr var ac", DATA_TYPES_DISPLAYED_CORRECTLY,
+ patterns=[' = A | C$'])
+ self.expect("fr var all", DATA_TYPES_DISPLAYED_CORRECTLY,
+ patterns=[' = ALL$'])
+
# Break inside the main.
bkpt_id = lldbutil.run_break_set_by_file_and_line(
self, "main.c", self.line, num_expected_locations=1, loc_exact=True)
-
- self.runCmd("run", RUN_SUCCEEDED)
+ self.runCmd("c", RUN_SUCCEEDED)
# The stop reason of the thread should be breakpoint.
self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT,
Index: lit/SymbolFile/DWARF/debug-types-missing-signature.test
===================================================================
--- lit/SymbolFile/DWARF/debug-types-missing-signature.test
+++ lit/SymbolFile/DWARF/debug-types-missing-signature.test
@@ -22,5 +22,5 @@
RUN: %lldb %t -b -o "target variable a e ec" | FileCheck --check-prefix=VARS %s
VARS: (const (anonymous struct)) a = {}
-VARS: (const (anonymous enum)) e = 1
-VARS: (const (anonymous enum)) ec = 1
+VARS: (const (anonymous enum)) e = 0x1
+VARS: (const (anonymous enum)) ec = 0x1
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