Subversion Repositories openrisc_me

;; .........................

;;

;; DFA-based pipeline description for Sandcraft SR3 (MIPS64 based)

;;

;; The SR3 is described as:

;;     - nine-stage pipeline, insn buffering with out-of-order issue to

;;       multiple function units, with an average dispatch rate of 2

;;       insn.s per cycle (max 6 insns: 2 fpu, 4 cpu).

;;

;;  The details on this are scant except for a diagram in

;;  Chap. 6 of Rev. 1.0 SR3 Spec.

;;

;;  The model employed below is designed to closely approximate the

;;  published latencies. Emulation of out-of-order issue and the insn

;;  buffering is done via a VLIW dispatch style (with a packing of 6 insns);

;;  the function unit reservations restrictions (define_*_set) are

;;  contrived to support published timings.

;;

;; Reference:

;;   "SR3 Microprocessor Specification, System development information,"

;;   Revision 1.0, 13 December 2000.

;;

;;

;; Reservation model is based on:

;;   1) Figure 6-1, from the 1.0 specification.

;;   2) Chapter 19, from the 1.0 specification.

;;   3) following questions(Red Hat)/answers(Sandcraft):

;;     RH> From Section 19.1

;;     RH>      1) In terms of figure 6-1, are all the instructions in

;;     RH>         table 19-1 restricted

;;     RH>         to ALUx? When ALUx is not in use for an instruction in table;;     RH>          19-1 is

;;     RH>         it fully compatible with all insns that issue to ALUy?

;;

;;     Yes, all the instructions in Table 19-1 only go to ALUX, and all the

;;     instructions that can be issued to ALUY can also be issued to ALUX.

;;

;;

;;     RH> From Section 19.2

;;     RH>      2) Explain conditional moves execution path (in terms of

;;     RH>      figure 6-1)

;;

;;     Conditional move of integer registers (based on floating point condition

;;     codes or integer register value) go to ALUX or ALUY.

;;

;;     RH>      3) Explain floating point store execution path (in terms of

;;     RH>      figure 6-1)

;;

;;     Floating point stores go to Ld/St and go to MOV in the floating point

;;     pipeline.

;;

;;     Floating point loads go to Ld/St and go to LOAD in the floating point

;;     pipeline.

;;

;;     RH>      4) Explain branch on floating condition (in terms of figure 6-1);;

;;     Branch on floating condition go to BRU.

;;

;;     RH>      5) Is the column for single RECIP instruction latency correct?

;;     RH>      What about for RSQRT single and double?

;;

;;     The latency/repeat for RECIP and RSQRT are correct.

;;

;;

;; Use four automata to isolate long latency operations, and to

;; reduce the complexity of cpu+fpu, reducing space.

;;

(define_automaton "sr71_cpu, sr71_cpu1, sr71_cp1, sr71_cp2, sr71_fextra, sr71_imacc")

;;  feeders for CPU function units and feeders for fpu (CP1 interface)

(define_cpu_unit "sr_iss0,sr_iss1,sr_iss2,sr_iss3,sr_iss4,sr_iss5" "sr71_cpu")

;; CPU function units

(define_cpu_unit "ipu_bru"       "sr71_cpu1")

(define_cpu_unit "ipu_alux"      "sr71_cpu1")

(define_cpu_unit "ipu_aluy"      "sr71_cpu1")

(define_cpu_unit "ipu_ldst"      "sr71_cpu1")

(define_cpu_unit "ipu_macc_iter" "sr71_imacc")

;; Floating-point unit (Co-processor interface 1).

(define_cpu_unit "fpu_mov"          "sr71_cp1")

(define_cpu_unit "fpu_load"         "sr71_cp1")

(define_cpu_unit "fpu_fpu"          "sr71_cp2")

;; fictitous unit to track long float insns with separate automaton

(define_cpu_unit "fpu_iter"         "sr71_fextra")

;;

;; Define common execution path (reservation) combinations

;;

;;

(define_reservation "cpu_iss"         "sr_iss0|sr_iss1|sr_iss2|sr_iss3")

;; two cycles are used for instruction using the fpu as it runs

;; at half the clock speed of the cpu. By adding an extra cycle

;; to the issue units, the default/minimum "repeat" dispatch delay is

;; accounted for all insn.s

(define_reservation "cp1_iss"         "(sr_iss4*2)|(sr_iss5*2)")

(define_reservation "serial_dispatch" "sr_iss0+sr_iss1+sr_iss2+sr_iss3+sr_iss4+sr_iss5")

;; Simulate a 6 insn VLIW dispatch, 1 cycle in dispatch followed by

;; reservation of function unit.

(define_reservation "ri_insns"         "cpu_iss,(ipu_alux|ipu_aluy)")

(define_reservation "ri_mem"           "cpu_iss,ipu_ldst")

(define_reservation "ri_alux"          "cpu_iss,ipu_alux")

(define_reservation "ri_branch"        "cpu_iss,ipu_bru")

(define_reservation "rf_insn"          "cp1_iss,fpu_fpu")

(define_reservation "rf_ldmem"         "cp1_iss,fpu_load")

; simultaneous reservation of pseudo-unit keeps cp1 fpu tied

; up until long cycle insn is finished...

(define_reservation "rf_multi1"        "rf_insn+fpu_iter")

;;

;; The ordering of the instruction-execution-path/resource-usage

;; descriptions (also known as reservation RTL) is roughly ordered

;; based on the define attribute RTL for the "type" classification.

;; When modifying, remember that the first test that matches is the

;; reservation used!

;;

(define_insn_reservation "ir_sr70_unknown" 1

  (and (eq_attr "cpu" "sr71000")

       (eq_attr "type" "unknown"))

  "serial_dispatch")

;; Assume prediction fails.

(define_insn_reservation "ir_sr70_branch" 6

  (and (eq_attr "cpu" "sr71000")

       (eq_attr "type" "branch,jump,call"))

  "ri_branch")

(define_insn_reservation "ir_sr70_load" 2

  (and (eq_attr "cpu" "sr71000")

       (eq_attr "type" "load"))

  "ri_mem")

(define_insn_reservation "ir_sr70_store" 1

  (and (eq_attr "cpu" "sr71000")

       (eq_attr "type" "store"))

  "ri_mem")

;;

;; float loads/stores flow through both cpu and cp1...

;;

(define_insn_reservation "ir_sr70_fload" 9

  (and (eq_attr "cpu" "sr71000")

       (eq_attr "type" "fpload,fpidxload"))

  "(cpu_iss+cp1_iss),(ri_mem+rf_ldmem)")

(define_insn_reservation "ir_sr70_fstore" 1

  (and (eq_attr "cpu" "sr71000")

       (eq_attr "type" "fpstore,fpidxstore"))

  "(cpu_iss+cp1_iss),(fpu_mov+ri_mem)")

;; This reservation is for conditional move based on integer

;; or floating point CC.

(define_insn_reservation "ir_sr70_condmove" 4

  (and (eq_attr "cpu" "sr71000")

       (eq_attr "type" "condmove"))

  "ri_insns")

;; Try to discriminate move-from-cp1 versus move-to-cp1 as latencies

;; are different. Like float load/store, these insns use multiple

;; resources simultaneously

(define_insn_reservation "ir_sr70_xfer_from" 6

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "xfer")

            (eq_attr "mode" "!SF,DF,FPSW")))

  "(cpu_iss+cp1_iss),(fpu_mov+ri_mem)")

(define_insn_reservation "ir_sr70_xfer_to" 9

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "xfer")

            (eq_attr "mode" "SF,DF")))

  "(cpu_iss+cp1_iss),(ri_mem+rf_ldmem)")

(define_insn_reservation "ir_sr70_hilo" 1

  (and (eq_attr "cpu" "sr71000")

       (eq_attr "type" "mthilo,mfhilo"))

  "ri_insns")

(define_insn_reservation "ir_sr70_arith" 1

  (and (eq_attr "cpu" "sr71000")

       (eq_attr "type" "arith,shift,slt,clz,const,trap"))

  "ri_insns")

;; emulate repeat (dispatch stall) by spending extra cycle(s) in

;; in iter unit

(define_insn_reservation "ir_sr70_imul_si" 4

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "imul,imul3,imadd")

            (eq_attr "mode" "SI")))

  "ri_alux,ipu_alux,ipu_macc_iter")

(define_insn_reservation "ir_sr70_imul_di" 6

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "imul,imul3,imadd")

            (eq_attr "mode" "DI")))

  "ri_alux,ipu_alux,(ipu_macc_iter*3)")

;; Divide algorithm is early out with best latency of 7 pcycles.

;; Use worst case for scheduling purposes.

(define_insn_reservation "ir_sr70_idiv_si" 41

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "idiv")

            (eq_attr "mode" "SI")))

  "ri_alux,ipu_alux,(ipu_macc_iter*38)")

(define_insn_reservation "ir_sr70_idiv_di" 73

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "idiv")

            (eq_attr "mode" "DI")))

  "ri_alux,ipu_alux,(ipu_macc_iter*70)")

;; extra reservations of fpu_fpu are for repeat latency

(define_insn_reservation "ir_sr70_fadd_sf" 8

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "fadd")

            (eq_attr "mode" "SF")))

  "rf_insn,fpu_fpu")

(define_insn_reservation "ir_sr70_fadd_df" 10

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "fadd")

            (eq_attr "mode" "DF")))

  "rf_insn,fpu_fpu")

;; Latencies for MADD,MSUB, NMADD, NMSUB assume the Multiply is fused

;; with the sub or add.

(define_insn_reservation "ir_sr70_fmul_sf" 8

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "fmul,fmadd")

            (eq_attr "mode" "SF")))

  "rf_insn,fpu_fpu")

;; tie up the fpu unit to emulate the balance for the "repeat

;; rate" of 8 (2 are spent in the iss unit)

(define_insn_reservation "ir_sr70_fmul_df" 16

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "fmul,fmadd")

            (eq_attr "mode" "DF")))

  "rf_insn,fpu_fpu*6")

;; RECIP insn uses same type attr as div, and for SR3, has same

;; timings for double. However, single RECIP has a latency of

;; 28 -- only way to fix this is to introduce new insn attrs.

;; cycles spent in iter unit are designed to satisfy balance

;; of "repeat" latency after insn uses up rf_multi1 reservation

(define_insn_reservation "ir_sr70_fdiv_sf" 60

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "fdiv,frdiv")

            (eq_attr "mode" "SF")))

  "rf_multi1+(fpu_iter*51)")

(define_insn_reservation "ir_sr70_fdiv_df" 120

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "fdiv,frdiv")

            (eq_attr "mode" "DF")))

  "rf_multi1+(fpu_iter*109)")

(define_insn_reservation "ir_sr70_fabs" 4

  (and (eq_attr "cpu" "sr71000")

       (eq_attr "type" "fabs,fneg,fmove"))

  "rf_insn,fpu_fpu")

(define_insn_reservation "ir_sr70_fcmp" 10

  (and (eq_attr "cpu" "sr71000")

       (eq_attr "type" "fcmp"))

  "rf_insn,fpu_fpu")

;; "fcvt" type attribute covers a number of diff insns, most have the same

;; latency descriptions, a few vary. We use the

;; most common timing (which is also worst case).

(define_insn_reservation "ir_sr70_fcvt" 12

  (and (eq_attr "cpu" "sr71000")

       (eq_attr "type" "fcvt"))

  "rf_insn,fpu_fpu*4")

(define_insn_reservation "ir_sr70_fsqrt_sf" 62

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "fsqrt")

            (eq_attr "mode" "SF")))

  "rf_multi1+(fpu_iter*53)")

(define_insn_reservation "ir_sr70_fsqrt_df" 122

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "fsqrt")

            (eq_attr "mode" "DF")))

  "rf_multi1+(fpu_iter*111)")

(define_insn_reservation "ir_sr70_frsqrt_sf" 48

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "frsqrt")

            (eq_attr "mode" "SF")))

  "rf_multi1+(fpu_iter*39)")

(define_insn_reservation "ir_sr70_frsqrt_df" 240

  (and (eq_attr "cpu" "sr71000")

       (and (eq_attr "type" "frsqrt")

            (eq_attr "mode" "DF")))

  "rf_multi1+(fpu_iter*229)")

(define_insn_reservation "ir_sr70_multi" 1

  (and (eq_attr "cpu" "sr71000")

       (eq_attr "type" "multi"))

  "serial_dispatch")

(define_insn_reservation "ir_sr70_nop" 1

  (and (eq_attr "cpu" "sr71000")

       (eq_attr "type" "nop"))

  "ri_insns")