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Peter Anvin" , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt References: <20240905170356.260300-1-andriy.shevchenko@linux.intel.com> <20241016192011.GY17263@noisy.programming.kicks-ass.net> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzUVEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gKEludGVsIFdvcmsgQWRkcmVzcykgPGRhdmUuaGFuc2VuQGludGVs LmNvbT7CwXgEEwECACIFAlQ+9J0CGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEGg1 lTBwyZKwLZUP/0dnbhDc229u2u6WtK1s1cSd9WsflGXGagkR6liJ4um3XCfYWDHvIdkHYC1t MNcVHFBwmQkawxsYvgO8kXT3SaFZe4ISfB4K4CL2qp4JO+nJdlFUbZI7cz/Td9z8nHjMcWYF IQuTsWOLs/LBMTs+ANumibtw6UkiGVD3dfHJAOPNApjVr+M0P/lVmTeP8w0uVcd2syiaU5jB aht9CYATn+ytFGWZnBEEQFnqcibIaOrmoBLu2b3fKJEd8Jp7NHDSIdrvrMjYynmc6sZKUqH2 I1qOevaa8jUg7wlLJAWGfIqnu85kkqrVOkbNbk4TPub7VOqA6qG5GCNEIv6ZY7HLYd/vAkVY E8Plzq/NwLAuOWxvGrOl7OPuwVeR4hBDfcrNb990MFPpjGgACzAZyjdmYoMu8j3/MAEW4P0z F5+EYJAOZ+z212y1pchNNauehORXgjrNKsZwxwKpPY9qb84E3O9KYpwfATsqOoQ6tTgr+1BR CCwP712H+E9U5HJ0iibN/CDZFVPL1bRerHziuwuQuvE0qWg0+0SChFe9oq0KAwEkVs6ZDMB2 P16MieEEQ6StQRlvy2YBv80L1TMl3T90Bo1UUn6ARXEpcbFE0/aORH/jEXcRteb+vuik5UGY 5TsyLYdPur3TXm7XDBdmmyQVJjnJKYK9AQxj95KlXLVO38lczsFNBFRjzmoBEACyAxbvUEhd GDGNg0JhDdezyTdN8C9BFsdxyTLnSH31NRiyp1QtuxvcqGZjb2trDVuCbIzRrgMZLVgo3upr MIOx1CXEgmn23Zhh0EpdVHM8IKx9Z7V0r+rrpRWFE8/wQZngKYVi49PGoZj50ZEifEJ5qn/H Nsp2+Y+bTUjDdgWMATg9DiFMyv8fvoqgNsNyrrZTnSgoLzdxr89FGHZCoSoAK8gfgFHuO54B lI8QOfPDG9WDPJ66HCodjTlBEr/Cwq6GruxS5i2Y33YVqxvFvDa1tUtl+iJ2SWKS9kCai2DR 3BwVONJEYSDQaven/EHMlY1q8Vln3lGPsS11vSUK3QcNJjmrgYxH5KsVsf6PNRj9mp8Z1kIG qjRx08+nnyStWC0gZH6NrYyS9rpqH3j+hA2WcI7De51L4Rv9pFwzp161mvtc6eC/GxaiUGuH BNAVP0PY0fqvIC68p3rLIAW3f97uv4ce2RSQ7LbsPsimOeCo/5vgS6YQsj83E+AipPr09Caj 0hloj+hFoqiticNpmsxdWKoOsV0PftcQvBCCYuhKbZV9s5hjt9qn8CE86A5g5KqDf83Fxqm/ vXKgHNFHE5zgXGZnrmaf6resQzbvJHO0Fb0CcIohzrpPaL3YepcLDoCCgElGMGQjdCcSQ+Ci FCRl0Bvyj1YZUql+ZkptgGjikQARAQABwsFfBBgBAgAJBQJUY85qAhsMAAoJEGg1lTBwyZKw l4IQAIKHs/9po4spZDFyfDjunimEhVHqlUt7ggR1Hsl/tkvTSze8pI1P6dGp2XW6AnH1iayn yRcoyT0ZJ+Zmm4xAH1zqKjWplzqdb/dO28qk0bPso8+1oPO8oDhLm1+tY+cOvufXkBTm+whm +AyNTjaCRt6aSMnA/QHVGSJ8grrTJCoACVNhnXg/R0g90g8iV8Q+IBZyDkG0tBThaDdw1B2l asInUTeb9EiVfL/Zjdg5VWiF9LL7iS+9hTeVdR09vThQ/DhVbCNxVk+DtyBHsjOKifrVsYep WpRGBIAu3bK8eXtyvrw1igWTNs2wazJ71+0z2jMzbclKAyRHKU9JdN6Hkkgr2nPb561yjcB8 sIq1pFXKyO+nKy6SZYxOvHxCcjk2fkw6UmPU6/j/nQlj2lfOAgNVKuDLothIxzi8pndB8Jju KktE5HJqUUMXePkAYIxEQ0mMc8Po7tuXdejgPMwgP7x65xtfEqI0RuzbUioFltsp1jUaRwQZ MTsCeQDdjpgHsj+P2ZDeEKCbma4m6Ez/YWs4+zDm1X8uZDkZcfQlD9NldbKDJEXLIjYWo1PH hYepSffIWPyvBMBTW2W5FRjJ4vLRrJSUoEfJuPQ3vW9Y73foyo/qFoURHO48AinGPZ7PC7TF vUaNOTjKedrqHkaOcqB185ahG2had0xnFsDPlx5y In-Reply-To: <20241016192011.GY17263@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: ytmm5drq1xokx3zp7g1hhuzqxnnrhqri X-Rspamd-Queue-Id: 3336D1C0017 X-Rspamd-Server: rspam11 X-HE-Tag: 1729107849-894974 X-HE-Meta: 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 UVMuVSI7 5gEjc2kKhd2VLbQO7Qbcg4do9QMO12rIK6bck2jWcAaq+9+IbWAZCcfg5sic3Df4hGzBUc5WDiY7FbFQmDBoiCvDQMnV9c5eotZl4PEwB22P7izBRLdGKy1ijPDRS49oQaW2d+ZQIAITx5bFUDHupgBhdcs717pEl93VPc0exEZE2lF5SjIt9QcsahOKhb9KZzNZ5oztIzbBtBbcZ2B57LOvQOawWgGuFfYk+oqvdnbAea/2SMsL71dh+xaYmK6ESG3VL X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/16/24 12:20, Peter Zijlstra wrote: > The code as is, is wrong, I don't think we'll ever end up in the dec > case for 'short' unsigned types. Clang is just clever enough to realize > this and issues a warning. Ahhh, that's the key to it. Thanks, Peter. > Something like so might work: > > const int pao_ID__ = __builtin_constant_p(val) ? > ((typeof(var))(val) == 1 ? 1 : > ((typeof(var))(val) == (typeof(var))-1 ? -1 : 0 )) : 0; Would anybody hate if we broke this up a bit, like: const typeof(var) _val = val; const int paoconst = __builtin_constant_p(val); const int paoinc = paoconst && ((_val) == 1); const int paodec = paoconst && ((_val) == (typeof(var))-1); and then did if (paoinc) percpu_unary_op(size, qual, "inc", var); ... Or even: #define PAOINC 1234 const int pao_ID__ = __builtin_constant_p(val) ? ((typeof(var))(val) == 1 ? PAOINC : ... if (PAOINC) percpu_unary_op(size, qual, "inc", var); Since the 1 and -1 ternary results end up just being magic numbers anyway. Otherwise that pao_ID__ expression is pretty gnarly.