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Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.11.2 Subject: Re: wishlist: support for shorter pointers Content-Language: en-GB To: =?UTF-8?Q?Rafa=c5=82_Pietrak?= , Martin Uecker , Ian Lance Taylor Cc: "Richard Earnshaw (lists)" , "gcc@gcc.gnu.org" References: <439affd4-11fe-de80-94c8-6fc64cbf76ec@ztk-rp.eu> <112e711791835d56cca38654f83a009cb46707d4.camel@gwdg.de> <940e9ae5-8649-5a28-e29f-06f0b2982892@ztk-rp.eu> <6c881d3fc76d112d52ec668d05b68394ae792f30.camel@gwdg.de> <1eeef918-80d0-12a3-e7e9-5a75b25fb769@ztk-rp.eu> <8825a11f-e462-8d97-3cdf-a5015250f3c1@westcontrol.com> <45292545-b4e1-a2c8-38d0-a7773f309ca5@ztk-rp.eu> <25afc1cb-3a62-135d-3206-2d9eb6216944@westcontrol.com> <701a38b8-9e90-36ce-9357-8b648f04a4d8@ztk-rp.eu> From: David Brown In-Reply-To: <701a38b8-9e90-36ce-9357-8b648f04a4d8@ztk-rp.eu> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: SV0P279CA0007.NORP279.PROD.OUTLOOK.COM (2603:10a6:f10:11::12) To SV0P279MB0233.NORP279.PROD.OUTLOOK.COM (2603:10a6:f10:b::13) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SV0P279MB0233:EE_|OS6P279MB0621:EE_ X-MS-Office365-Filtering-Correlation-Id: d121d2e8-5238-4540-8aec-08db7d5768d2 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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Isn't it so? >>> >> >> Not really, no - I would rather see better ways to handle allocation >> and section control than more named address spaces. > > Doesn't it call for "something" that a c-source (through the compiler) > can express to the linker programmers' intention? > Yes, I think that is fair to say. And that "something" should be more advanced and flexible than the limited "section" attribute we have today. But I don't think it should be "named address spaces". My objection to named address spaces stem from two points: 1. They are compiler implementations, not user code (or library code), which means development is inevitably much slower and less flexible. 2. They mix two concepts that are actually quite separate - how objects are allocated, and how they are accessed. Access to different types of object in different sorts of memory can be done today. In C, you can use inline functions or macros. For target-specific stuff you can use inline assembly, and GCC might have builtins for some target-specific features. In C++, you can also wrap things in classes if that makes more sense. Allocation is currently controlled by "section" attributes. This is where we I believe GCC could do better, and give the user more control. (It may be possible to develop a compiler-independent syntax here that could become part of future C and C++ standards, but I think it will unavoidably be heavily implementation dependent.) All we really need is a way to combine these with types to improve user convenience and reduce the risk of mistakes. And I believe that allowing allocation control attributes to be attached to types would give us that in GCC. Then it would all be user code - typedefs, macros, functions, classes, whatever suits. David