On Sat, 26 Feb 2022 03:02:51 GMT, Sandhya Viswanathan <sviswanat...@openjdk.org> wrote:
>> src/hotspot/cpu/x86/x86.ad line 7263: >> >>> 7261: __ vector_round_float_avx($dst$$XMMRegister, $src$$XMMRegister, >>> $xtmp1$$XMMRegister, >>> 7262: $xtmp2$$XMMRegister, >>> $xtmp3$$XMMRegister, $xtmp4$$XMMRegister, >>> 7263: >>> ExternalAddress(vector_float_signflip()), new_mxcsr, $scratch$$Register, >>> vlen_enc); >> >> The vector_float_signflip() here should be replaced by vector_all_bits_set(). >> cvtps2dq description: >> If a converted result cannot be represented in the destination >> format, the floating-point invalid exception is raised, and if this >> exception is masked, the indefinite integer value >> (2w-1, where w represents the number of bits in the destination format) is >> returned. > > Clarification, the number in my comments above is (2^w - 1). This is from > Intel SDM > (https://www.intel.com/content/www/us/en/developer/articles/technical/intel-sdm.html). > Also you will need to take care when the valid unoverflowed result is -1 i.e. > 0xFFFFFFFF (2^32 - 1). I believe the indefinite value should be 2^(w - 1) (a.k.a 0x80000000) and the documentation is typoed. If you look at `cvtss2si`, the indefinite value is also written as 2^w - 1 but yet in `MacroAssembler::convert_f2i` we compare it with 0x80000000. In addition, choosing -1 as an indefinite value is weird enough and to complicate it as 2^w - 1 is really unusual. ------------- PR: https://git.openjdk.java.net/jdk/pull/7094
