| Issue |
147528
|
| Summary |
Bytecode Interpreter: Primtive arrays do not have per-element lifetime information
|
| Labels |
clang:frontend,
clang:bytecode
|
| Assignees |
|
| Reporter |
tbaederr
|
Similar to their `InitMap`.
To see this in action, we have to apply
```diff
--- i/clang/lib/AST/ByteCode/Compiler.cpp
+++ w/clang/lib/AST/ByteCode/Compiler.cpp
@@ -5008,7 +5008,8 @@ bool Compiler<Emitter>::VisitCallExpr(const CallExpr *E) {
if (!this->emitCheckPseudoDtor(E))
return false;
const Expr *Base = PD->getBase();
- if (!Base->isGLValue())
+ // if (!Base->isGLValue())
+ if (classify(Base) != PT_Ptr)
return this->discard(Base);
if (!this->visit(Base))
return false;
```
See:
```c++
#define assert_alive(l) if (!__builtin_is_within_lifetime(&l)) (void)(1/0);
#define assert_dead(l) if ( __builtin_is_within_lifetime(&l)) (void)(1/0);
consteval bool partial_arrays() {
int arr[2];
assert_alive(arr);
assert_alive(arr[0]);
assert_alive(arr[1]);
std::construct_at(&arr[0]);
assert_alive(arr);
assert_alive(arr[0]);
assert_alive(arr[1]);
std::destroy_at(&arr[0]);
assert_alive(arr);
assert_dead(arr[0]);
assert_alive(arr[1]);
std::construct_at(&arr[0]);
return true;
}
static_assert(partial_arrays());
```
The call to `std::destroy_at(&arr[0])` will mark the entire array as dead, because that's where the base offset points at the time of calling it.
After this call, the `assert_alive(arr)` and the `assert_alive(array[1])` both fail.
To properly support this, we need so ave the lifetime information for primitive array elements somewhere.
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