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Re: [PATCH] S/390: Hardware transactional memory support
- From: Torvald Riegel <triegel at redhat dot com>
- To: Andreas Krebbel <krebbel at linux dot vnet dot ibm dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Fri, 02 Aug 2013 13:31:54 +0200
- Subject: Re: [PATCH] S/390: Hardware transactional memory support
- References: <20130621102314 dot GA753 at bart>
On Fri, 2013-06-21 at 12:23 +0200, Andreas Krebbel wrote:
> Index: libitm/config/s390/target.h
> ===================================================================
> *** libitm/config/s390/target.h.orig
> --- libitm/config/s390/target.h
> ***************
[...]
> + static inline uint32_t
> + htm_begin ()
> + {
> + return __builtin_tbegin_nofloat (NULL);
> + }
I'm not quite sure I understand why the nofloat variant is sufficient;
is this because we don't use FPRs in the abort/restart code of libitm
(and the FPRs are known to be clobbered after starting a txn)?
There is a bit in the properties passed to _ITM_beginTransaction which
states whether the txn has floating point update code
(pr_hasNoFloatUpdate). Would this be useful?
(BTW, sorry for the late response. I don't read gcc-patches frequently,
so please CC me on libitm-related things.)