rjmccall accepted this revision.
rjmccall added a comment.
This revision is now accepted and ready to land.
Thanks. Some minor changes and then LGTM.
I'm currently wondering if a better solution might be to just teach the
Bypasses analysis about the C lifetime rule. But we don't need to do that
right now.
================
Comment at: lib/CodeGen/CGDecl.cpp:1031
+ // Skip emitting lifetime intrinsics when a label was seen in the
+ // current block and we are compiling for C.
+ if (!Bypasses.IsBypassed(&D) &&
----------------
It's probably appropriate to just rework this entire comment at this point.
Suggestion:
If there's a jump into the lifetime of this variable, its lifetime gets broken
up into several regions in IR, which requires more work to handle correctly.
For now, just omit the intrinsics; this is a rare case, and it's better to
just be
conservatively correct. PR28267.
We have to do this in all language modes if there's a jump past the
declaration.
We also have to do it in C if there's a jump to an earlier point in the
current
block because non-VLA lifetimes begin as soon as the containing block is
entered, not when its variables actually come into scope; suppressing the
lifetime annotations completely in this case is unnecessarily pessimistic, but
again, this is rare.
================
Comment at: lib/CodeGen/CodeGenFunction.h:216
+ /// Return true if a label was seen in the current block.
+ bool labelSeen() const {
+ if (CurLexicalScope)
----------------
It seems reasonable to give this a more descriptive name, like
hasLabelBeenSeenInCurrentScope().
https://reviews.llvm.org/D27680
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