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Re: how to compile glibc to pure arm instructions?
- From: Roland McGrath <roland at hack dot frob dot com>
- To: Zheng Junling <zhengjunling at huawei dot com>
- Cc: Liu hua <sdu dot liu at huawei dot com>, <libc-help at sourceware dot org>, <wangnan0 at huawei dot com>, <peifeiyue at huawei dot com>, <david dot gilbert at linaro dot org>
- Date: Tue, 3 Jun 2014 10:44:27 -0700 (PDT)
- Subject: Re: how to compile glibc to pure arm instructions?
- Authentication-results: sourceware.org; auth=none
- References: <5387F66C dot 7000401 at huawei dot com> <20140530162734 dot 91BA52C39BC at topped-with-meat dot com> <538DBC12 dot 6040300 at huawei dot com>
You'll have to ask the ARM maintainers and/or the people who wrote that
code. My impression is that Thumb-2 has certain instructions not available
in ARM mode that can be used to produce better performance in some of these
hand-tuned assembly situations. It's certainly the case that it is widely
assumed in userland that if the hardware supports Thumb-2 (e.g. any ARMv7
configuration), then the code is free to use it.