rsmith added inline comments.
================
Comment at: clang/lib/CodeGen/CGCall.cpp:2082
+ const Type *RetTyPtr = RetTy.getTypePtr();
+ if (!RetTy->isVoidType() && !RetTyPtr->isRecordType() &&
+ RetAI.getKind() != ABIArgInfo::Indirect) {
----------------
Other types that we should think about from a padding perspective:
* `nullptr_t` (which has the same size and alignment as `void*` but is all
padding)
* 80-bit `long double` and `_Complex long double` (I don't know whether we
guarantee to initialize the 6 padding bytes)
* member pointers might contain padding under some ABI rules -- under the MS
ABI, you get a struct containing N pointers followed by M ints, which could
have 4 bytes of tail padding on 64-bit targets
* vector types with tail padding (eg, a vector of 3 `char`s is sometimes
passed as an `i32` with one byte `undef`)
* matrix types (presumably the same concerns as for vector types apply here)
* maybe Obj-C object types?
* `_ExtInt` types (eg, returning an `_ExtInt(65)` initialized to 0 produces an
`{i64, i64}` containing 7 bytes of `undef`)
It would be safer to list exactly those types for which we know this assumption
is correct rather than assuming that it's correct by default -- I think more
than half of the `Type` subclasses for concrete canonical types can have undef
bits in their IR representation.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D81678/new/
https://reviews.llvm.org/D81678
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
