On Mon, 14 Nov 2022, Joshi, Tejas Sanjay wrote:
> [Public] > > Hi, Hi. I'm still waiting for feedback on fixes for existing models: https://inbox.sourceware.org/gcc-patches/5ae6fc21-edc6-133-aee2-a41e16eb...@ispras.ru/T/#t did you have a chance to look at those? > PFA the patch which adds znver4 instruction reservations separately from older > znver versions: > * This also models separate div, fdiv and ssediv units accordingly. Why are you modeling 'fdiv' and 'ssediv' separately? When preparing the above patches, I checked that x87 and SSE divisions use the same hardware unit, and I don't see a strong reason to artificially clone it in the model. (integer divider is a separate unit from the floating-point divider) > * Does not blow-up the insn-automata.cc size (it grew from 201502 to 206141 > for me.) > * The patch successfully builds, bootstraps, and passes make check. > * I have also run spec, showing no regressions for 1-copy 3-iteration runs. > However, I observe 1.5% gain for 507.cactuBSSN_r. I have a question on AVX512 modeling in your patch: > +;; AVX instructions > +(define_insn_reservation "znver4_sse_log" 1 > + (and (eq_attr "cpu" "znver4") > + (and (eq_attr "type" "sselog,sselog1") > + (and (eq_attr "mode" "V4SF,V8SF,V2DF,V4DF") > + (eq_attr "memory" "none")))) > + "znver4-direct,znver4-fpu") > + > +(define_insn_reservation "znver4_sse_log_evex" 1 > + (and (eq_attr "cpu" "znver4") > + (and (eq_attr "type" "sselog,sselog1") > + (and (eq_attr "mode" "V16SF,V8DF") > + (eq_attr "memory" "none")))) > + > "znver4-direct,znver4-fpu0+znver4-fpu1|znver4-fpu2+znver4-fpu3") > + This is an AVX512 instruction, and you're modeling that it occupies two ports at once and thus has half throughput, but later in the AVX512 section: > +;; AVX512 instructions > +(define_insn_reservation "znver4_sse_mul_evex" 3 > + (and (eq_attr "cpu" "znver4") > + (and (eq_attr "type" "ssemul") > + (and (eq_attr "mode" "V16SF,V8DF") > + (eq_attr "memory" "none")))) > + "znver4-double,znver4-fpu0|znver4-fpu3") none of the instructions are modeled this way. If that's on purpose, can you add a comment? It's surprising, since generally AVX512 has half throughput compared to AVX256 on Zen 4, but the model doesn't seem to reflect that. Alexander
