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Mon, 27 May 2024 06:44:41 -0700 (PDT) Message-ID: <1cf28a31-976f-45dc-8dfb-ceecdc60cac7@suse.com> Date: Mon, 27 May 2024 15:44:40 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 12/13] xen/bitops: Clean up ffs64()/fls64() definitions Content-Language: en-US To: Andrew Cooper Cc: =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , Wei Liu , Stefano Stabellini , Julien Grall , Volodymyr Babchuk , Bertrand Marquis , Michal Orzel , Oleksii Kurochko , Shawn Anastasio , "consulting @ bugseng . com" , Simone Ballarin , Federico Serafini , Nicola Vetrini , Xen-devel References: <20240524200338.1232391-1-andrew.cooper3@citrix.com> <20240524200338.1232391-13-andrew.cooper3@citrix.com> From: Jan Beulich Autocrypt: addr=jbeulich@suse.com; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: <20240524200338.1232391-13-andrew.cooper3@citrix.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 24.05.2024 22:03, Andrew Cooper wrote: > Implement ffs64() and fls64() as plain static inlines, dropping the ifdefary > and intermediate generic_f?s64() forms. > > Add tests for all interesting bit positions at 32bit boundaries. > > No functional change. > > Signed-off-by: Andrew Cooper Reviewed-by: Jan Beulich with two remarks: > --- a/xen/common/bitops.c > +++ b/xen/common/bitops.c > @@ -24,6 +24,22 @@ static void __init test_ffs(void) > CHECK(ffsl, 1UL << 32, 33); > CHECK(ffsl, 1UL << 63, 64); > #endif > + > + /* > + * unsigned int ffs64(uint64_t) > + * > + * 32-bit builds of Xen have to split this into two adjacent operations, > + * so test all interesting bit positions across the divide. > + */ > + CHECK(ffs64, 0, 0); > + CHECK(ffs64, 1, 1); > + CHECK(ffs64, 3, 1); > + CHECK(ffs64, 7, 1); > + CHECK(ffs64, 6, 2); > + > + CHECK(ffs64, 0x8000000080000000ULL, 32); > + CHECK(ffs64, 0x8000000100000000ULL, 33); > + CHECK(ffs64, 0x8000000000000000ULL, 64); With the intermediate blank line, the respective part of the comment doesn't look to be related to these 3 lines. Could I talk you into moving that part down? > --- a/xen/include/xen/bitops.h > +++ b/xen/include/xen/bitops.h > @@ -60,6 +60,14 @@ static always_inline __pure unsigned int ffsl(unsigned long x) > #endif > } > > +static always_inline __pure unsigned int ffs64(uint64_t x) > +{ > + if ( BITS_PER_LONG == 64 ) In principle >= 64 would be okay here, and hence I'd prefer if we used that less strict form. Yet I'm not going to insist. Jan