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Re: [PATCH] ieee754/dbl-64: Reduce the scope of temporary storage variables
- From: Joseph Myers <joseph at codesourcery dot com>
- To: Vineet Gupta <Vineet dot Gupta1 at synopsys dot com>
- Cc: <libc-alpha at sourceware dot org>, <linux-snps-arc at lists dot infradead dot org>
- Date: Mon, 11 Nov 2019 22:33:46 +0000
- Subject: Re: [PATCH] ieee754/dbl-64: Reduce the scope of temporary storage variables
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- References: <20191111194349.21813-1-vgupta@synopsys.com>
On Mon, 11 Nov 2019, Vineet Gupta wrote:
> Functionally it should not result in code gen changes and if at all
> those would be better since the scope of those temporaries is greatly
> reduced now
This feels like the sort of thing where "should not result in code gen
changes" should be tested by running build-many-glibcs.py --strip with
unmodified glibc sources to build a full set of stripped glibc binaries,
saving those binaries and then running build-many-glibcs.py --strip again
and comparing the two sets of shared libraries (something I did a lot of
when reworking how libm function aliases were defined; static libraries
are expected to change because of timestamps, but shared library binaries
can be usefully compared like this). If the two sets of stripped binaries
are indeed identical, that is strong evidence that the patch is safe;
otherwise, review of the patch will require more detailed inspection of
the types of the arguments to these macros, and the uses of the temporary
variables, at every call site, to make sure that semantics aren't being
changed.
(In any case, please specify when submitting a patch how it was tested.)
--
Joseph S. Myers
joseph@codesourcery.com