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Re: Debugger support for __float128 type?
- From: Joseph Myers <joseph at codesourcery dot com>
- To: Ulrich Weigand <uweigand at de dot ibm dot com>
- Cc: <gcc at gcc dot gnu dot org>, <gdb at sourceware dot org>
- Date: Wed, 30 Sep 2015 20:12:17 +0000
- Subject: Re: Debugger support for __float128 type?
- Authentication-results: sourceware.org; auth=none
- References: <20150930173344 dot 9D78513CC at oc7340732750 dot ibm dot com>
On Wed, 30 Sep 2015, Ulrich Weigand wrote:
> - Extend the official DWARF standard in some way
I think you should do this.
Note that TS 18661-4 will be coming out very soon, and includes (optional)
* _FloatN, where N is 16, 32, 64 or >= 128 and a multiple of 32;
* _DecimalN, where N >= 32 and a multiple of 32;
* _Float32x, _Float64x, _Float128x, _Decimal64x, _Decimal128x
so this is not simply a matter of supporting a GNU extension (not that
it's simply a GNU extension on x86_64 anyway - __float128 is explicitly
mentioned in the x86_64 ABI document), but of supporting an ISO C
extension, in any case where one of the above types is the same size and
radix as float / double / long double but has a different representation.
(All the above are distinct types in C, and distinct from float, double,
long double even if the representations are the same. But I don't think
DWARF needs to distinguish e.g. float and _Float32 other than by their
name - it's only the case of different representations that needs
distinguishing. The _Float* and _Float*x types have corresponding complex
types, but nothing further should be needed in DWARF for those once you
can represent _Float*.)
Joseph S. Myers