[PATCH] D66094: [CodeGen] Emit destructor calls for non-trivial C structs returned by function calls and loaded from volatile objects
John McCall via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Tue Aug 13 16:13:53 PDT 2019
rjmccall added inline comments.
Comment at: clang/lib/CodeGen/CGCall.h:372
+ REQUIRES_DESTRUCTION = 0x4,
Does `llvm::Value*` actually guarantee three bits? Presumably on 64-bit platforms, but we do support 32-bit hosts.
Fortunately, I don't actually think there's any reason to be space-conscious in this class; all the values are short-lived. Might as well pull all the fields out into a bit-field or something.
Comment at: clang/lib/CodeGen/CGCall.h:390
+ return Value.getInt() & REQUIRES_DESTRUCTION;
I think the "is externally destructed" semantics make more sense — that is, the *default* should be that a destructor needs to get pushed, and maybe specific contexts should suppress that. That will also let you avoid all the ugly code to compute whether destruction is required in a bunch of generic places.
Actually, "externally destructed" is a really problematic idea; we need to come up with a better solution for contexts that need to be careful about destructor ordering like this, and it should probably be based on passing around and deactivating destructors. But that's for later.
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