On 11/30/22 03:51, Iain Sandoe wrote:
Hi Adrian,
On 28 Nov 2022, at 20:44, Iain Sandoe <i...@sandoe.co.uk> wrote:
Bootstrapping and running the testsuite on x86_64 was successfull. No
regression occured.
This looks resonable to me, as said in the PR. I’d like to test a little wider
with some larger
codebases, if you could bear with me for a few days.
So wider testing (in this case folly) reveals that, although the analysis seems
reasonable, this is not quite the right patch to fix the issue. It can be that
CONSTRUCTORS contain nested await expressions, so we cannot simply punt on
seeing one.
My hunch is that the real solution lies in (correctly) deciding whether to
promote the temporary or not. Jason recently made a change that identifies
whether a target expression is expected to be elided (i.e. it is a direct
intializer for another object) - I think this might help in this case. My
concern is whether I should read “expected to be elided” to be a guarantee
(“expected” to me could also be read “but it might not be”).
You should be able to rely on that flag. I believe all TARGET_EXPRs
with TARGET_EXPR_ELIDING_P set are indeed elided. As an optimization,
occasionally TARGET_EXPRs without the flag are elided anyway, but it's
still safe to promote them; the optimization just won't happen then.
Jason
