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[clang] Add bitint classification for __builtin_classify_type #72036

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Merged
merged 1 commit into from
Nov 17, 2023
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[clang] Add bitint classification for __builtin_classify_type #72036

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2 changes: 2 additions & 0 deletions clang/docs/ReleaseNotes.rst
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Expand Up @@ -219,6 +219,8 @@ Non-comprehensive list of changes in this release
determined at runtime.
* The ``__datasizeof`` keyword has been added. It is similar to ``sizeof``
except that it returns the size of a type ignoring tail padding.
* ``__builtin_classify_type()`` now classifies ``_BitInt`` values as the return value ``18``,
to match GCC 14's behavior.
Comment on lines +222 to +223
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We should mention that this fixes #71911

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I didn't add that because the issue also mentions some extensions to __builtin_classify_type. We should probably split that out into a separate issue where we also document the exact extensions, maybe with a link to the gcc commit and test cases.

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Okay, that's reasonable.


New Compiler Flags
------------------
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7 changes: 6 additions & 1 deletion clang/lib/AST/ExprConstant.cpp
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Expand Up @@ -11520,6 +11520,9 @@ enum class GCCTypeClass {
// decay to pointer. (Prior to version 6 it was only used in C++ mode).
// GCC reserves 15 for strings, but actually uses 5 (pointer) for string
// literals.
// Lang = 16,
// OpaqueType = 17,
BitInt = 18
};

/// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way
Expand Down Expand Up @@ -11652,11 +11655,13 @@ EvaluateBuiltinClassifyType(QualType T, const LangOptions &LangOpts) {
case Type::ObjCInterface:
case Type::ObjCObjectPointer:
case Type::Pipe:
case Type::BitInt:
// GCC classifies vectors as None. We follow its lead and classify all
// other types that don't fit into the regular classification the same way.
return GCCTypeClass::None;

case Type::BitInt:
return GCCTypeClass::BitInt;

case Type::LValueReference:
case Type::RValueReference:
llvm_unreachable("invalid type for expression");
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5 changes: 4 additions & 1 deletion clang/test/Sema/builtin-classify-type.c
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Expand Up @@ -11,7 +11,8 @@ enum gcc_type_class {
function_type_class, method_type_class,
record_type_class, union_type_class,
array_type_class, string_type_class,
lang_type_class
lang_type_class, opaque_type_class,
bitint_type_class
};

void foo(void) {
Expand Down Expand Up @@ -45,6 +46,7 @@ void foo(void) {
vint32_t3 vt5;
typedef _BitInt(64) vint64_t3 __attribute__((vector_size(16)));
vint64_t3 vt6;
_BitInt(16) bitint;

_Atomic int atomic_i;
_Atomic double atomic_d;
Expand All @@ -70,6 +72,7 @@ void foo(void) {
int a17[__builtin_classify_type(atomic_d) == real_type_class ? 1 : -1];
int a18[__builtin_classify_type(complex_i) == complex_type_class ? 1 : -1];
int a19[__builtin_classify_type(complex_d) == complex_type_class ? 1 : -1];
int a20[__builtin_classify_type(bitint) == bitint_type_class ? 1 : -1];
}

extern int (^p)(void);
Expand Down
5 changes: 4 additions & 1 deletion clang/test/SemaCXX/builtin-classify-type.cpp
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Expand Up @@ -11,7 +11,8 @@ enum gcc_type_class {
function_type_class, method_type_class,
record_type_class, union_type_class,
array_type_class, string_type_class,
lang_type_class
lang_type_class, opaque_type_class,
bitint_type_class
};

class cl {
Expand Down Expand Up @@ -42,6 +43,7 @@ void foo() {
_Atomic double atomic_d;
_Complex int complex_i;
_Complex double complex_d;
_BitInt(32) bitint;

int a1[__builtin_classify_type(f()) == void_type_class ? 1 : -1];
int a2[__builtin_classify_type(i) == integer_type_class ? 1 : -1];
Expand All @@ -65,5 +67,6 @@ void foo() {
int a20[__builtin_classify_type(atomic_d) == real_type_class ? 1 : -1];
int a21[__builtin_classify_type(complex_i) == complex_type_class ? 1 : -1];
int a22[__builtin_classify_type(complex_d) == complex_type_class ? 1 : -1];
int a23[__builtin_classify_type(bitint) == bitint_type_class ? 1 : -1];
}