Based off the worse case numbers generated by D103695, the AVX2/512 bit reversing/counting costs were higher than necessary (based off instruction counts instead of actual throughput).
Add specific scalar costs for CTLZ instructions, we can't discriminate between CTLZ and CTLZ_ZERO_UNDEF so we have to assume the worst. Given how BSR is often a microcoded nightmare on some older targets we might still be underestimating it.
For targets supporting LZCNT (Intel Haswell+ or AMD Fam10+), we provide overrides that assume 1cy costs.
llvm-svn: 374786
Based on the names of the check lines, features seems more appropriate that cpu.
Spotted while prototyping my patch to make 512-bit vectors illegal on SKX sometimes.
llvm-svn: 320959
Simon Pilgrim