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Subject: Meeting tomorrow, notes for March 25 meeting
From: Hans Boehm (boehm_at_[hidden])
Date: 2019-04-28 23:00:21


We are meeting tomorrow April 29th at noon PDT, usual coordinates:

Join Hangouts Meet
meet.google.com/sbj-cvgh-vnd
Join by phone
‪+1 208-925-0196‬ PIN: ‪255 542‬#

The topic will continue to be the TM-lite proposal.

Notes from March 25:
-----------------------------

Attendees: Jade Alglave, Hans Boehm, Michael Scott, Michael Spear, Victor
Luchangco

Discussed Victor's additions to

M Spear: Synchronized instead?

Victor: No, want atomic block.

M Spear: Want to be able to use STL, e.g. map in transaction.

Hans: trade-off, non constexpr makes it implementation defined

Victor: Want nested transactions

M Spear: Should allow proper software engineering in transactions.

Victor: Should look at what's really allowed in constexpr.

M Spear: Want everything visible in translation unit to be allowed.

Hans : trade-off against portability. Constexpr growing.

M Spear: Not for simplifying implementation. Single global lock always
works.

All: Aim for subset of atomic_noexcept.

Do we need to catch transaction-unsafe code that's never executed?

Hans: Previously decided on undefined behavior when executing
transaction-unsafe code.

M Scott: Is SGL with no checks conforming?

Allow either detection or simple SGL?

M Spear: Real challenge is getting users. This is simpler than existing
implementations.

M Scott: 2 possible implementations:
  HTM-centric plus diagnosis
  SGL with no diagnosis

M Scott: Should warn, but not for atomics

M Spear: Should prohibit volatile, atomics, inline assembly

Victor: What about IO?

M Scott: Don't want to require diagnosis for unexecuted code.

Jade: Lock-free?

Victor: Want to allow SGL for now

Meet next time as scheduled, on April 29.



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