https://bugs.kde.org/show_bug.cgi?id=413330
Bug ID: 413330 Summary: avx-1 test fails on AMD EPYC 7401P 24-Core Processor Product: valgrind Version: unspecified Platform: Other OS: Linux Status: REPORTED Severity: normal Priority: NOR Component: general Assignee: jsew...@acm.org Reporter: ahajk...@redhat.com Target Milestone: --- SUMMARY avx-1 test fails on AMD EPYC 7401P 24-Core Processor due to slightly different RSQRTPS implementation rsqrtps may produce slighly different results on different CPU families because the results of instructions like reciprocal square root estimate are not defined by the IEEE standard (https://randomascii.wordpress.com/2013/07/16/floating-point-determinism/) I tried to run this simple code on AMD EPYC 7401P 24-Core Processor (dell) and Intel(R) Core(TM) i7-7600U CPU @ 2.80GHz (intel) code: #include<stdio.h> int main() { float arr_in[4], arr_out[4]; arr_in[0] = 1; arr_in[1] = 2; arr_in[2] = 3; arr_in[3] = 4; arr_out[0] = 0; arr_out[1] = 0; arr_out[2] = 0; arr_out[3] = 0; __asm__ __volatile__( "movups %0, %%xmm0; \n\t" "rsqrtss %%xmm0, %%xmm1; \n\t" "movups %%xmm1, %1; \n\t" : "=m" (arr_in) : "m" (arr_out) : ); printf("arr_out: "); for (int i = 0; i < 4; i++) printf("%lf ", arr_out[i]); printf("\n"); return 0; } the results: dell: arr_out: 0.999878 0.707031 0.577271 0.499939 intel: arr_out: 0.999756 0.706909 0.577271 0.499878 avx-1 test always expects exactly the same output which causes its failure on some CPU's -- You are receiving this mail because: You are watching all bug changes.