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Re: [PATCH 2/4] S390: Use own tbegin macro instead of __builtin_tbegin.

From: Florian Weimer <fweimer at redhat dot com>
To: Stefan Liebler <stli at linux dot vnet dot ibm dot com>, libc-alpha at sourceware dot org
Date: Thu, 22 Dec 2016 13:54:31 +0100
Subject: Re: [PATCH 2/4] S390: Use own tbegin macro instead of __builtin_tbegin.
Authentication-results: sourceware.org; auth=none
References: <1481032315-12420-1-git-send-email-stli@linux.vnet.ibm.com> <1481032315-12420-2-git-send-email-stli@linux.vnet.ibm.com>

On 12/06/2016 02:51 PM, Stefan Liebler wrote:

The used inline assembly does not clobber the fprs / vrs!
Clobbering the latter ones would force the compiler to save / restore
the call saved fprs as those overlap with the vrs, but they only
need to be restored if the transaction fails.  Thus the user of the
tbegin macros has to compile the file / function with -msoft-float.
It prevents gcc from using fprs / vrs.

Is it possible to disable the new macros if the file is not compiledwith -msoft-float?


Thanks,
Florian

References:
- [PATCH 1/4] S390: Use C11-like atomics instead of plain memory accesses in lock elision code.
  - From: Stefan Liebler
- [PATCH 2/4] S390: Use own tbegin macro instead of __builtin_tbegin.
  - From: Stefan Liebler

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