;; ARM 1020E & ARM 1022E Pipeline Description
;; Copyright (C) 2005 Free Software Foundation, Inc.
;; Contributed by Richard Earnshaw (richard.earnshaw@arm.com)
;;
;; This file is part of GCC.
;;
;; GCC is free software; you can redistribute it and/or modify it
;; under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.
;;
;; GCC is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;; General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with GCC; see the file COPYING. If not, write to the Free
;; Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
;; 02110-1301, USA. */
;; These descriptions are based on the information contained in the
;; ARM1020E Technical Reference Manual, Copyright (c) 2003 ARM
;; Limited.
;;
;; This automaton provides a pipeline description for the ARM
;; 1020E core.
;;
;; The model given here assumes that the condition for all conditional
;; instructions is "true", i.e., that all of the instructions are
;; actually executed.
(define_automaton "arm1020e")
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Pipelines
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; There are two pipelines:
;;
;; - An Arithmetic Logic Unit (ALU) pipeline.
;;
;; The ALU pipeline has fetch, issue, decode, execute, memory, and
;; write stages. We only need to model the execute, memory and write
;; stages.
;;
;; - A Load-Store Unit (LSU) pipeline.
;;
;; The LSU pipeline has decode, execute, memory, and write stages.
;; We only model the execute, memory and write stages.
(define_cpu_unit "1020a_e,1020a_m,1020a_w" "arm1020e")
(define_cpu_unit "1020l_e,1020l_m,1020l_w" "arm1020e")
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; ALU Instructions
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; ALU instructions require three cycles to execute, and use the ALU
;; pipeline in each of the three stages. The results are available
;; after the execute stage stage has finished.
;;
;; If the destination register is the PC, the pipelines are stalled
;; for several cycles. That case is not modeled here.
;; ALU operations with no shifted operand
(define_insn_reservation "1020alu_op" 1
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "type" "alu"))
"1020a_e,1020a_m,1020a_w")
;; ALU operations with a shift-by-constant operand
(define_insn_reservation "1020alu_shift_op" 1
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "type" "alu_shift"))
"1020a_e,1020a_m,1020a_w")
;; ALU operations with a shift-by-register operand
;; These really stall in the decoder, in order to read
;; the shift value in a second cycle. Pretend we take two cycles in
;; the execute stage.
(define_insn_reservation "1020alu_shift_reg_op" 2
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "type" "alu_shift_reg"))
"1020a_e*2,1020a_m,1020a_w")
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Multiplication Instructions
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Multiplication instructions loop in the execute stage until the
;; instruction has been passed through the multiplier array enough
;; times.
;; The result of the "smul" and "smulw" instructions is not available
;; until after the memory stage.
(define_insn_reservation "1020mult1" 2
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "insn" "smulxy,smulwy"))
"1020a_e,1020a_m,1020a_w")
;; The "smlaxy" and "smlawx" instructions require two iterations through
;; the execute stage; the result is available immediately following
;; the execute stage.
(define_insn_reservation "1020mult2" 2
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "insn" "smlaxy,smlalxy,smlawx"))
"1020a_e*2,1020a_m,1020a_w")
;; The "smlalxy", "mul", and "mla" instructions require two iterations
;; through the execute stage; the result is not available until after
;; the memory stage.
(define_insn_reservation "1020mult3" 3
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "insn" "smlalxy,mul,mla"))
"1020a_e*2,1020a_m,1020a_w")
;; The "muls" and "mlas" instructions loop in the execute stage for
;; four iterations in order to set the flags. The value result is
;; available after three iterations.
(define_insn_reservation "1020mult4" 3
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "insn" "muls,mlas"))
"1020a_e*4,1020a_m,1020a_w")
;; Long multiply instructions that produce two registers of
;; output (such as umull) make their results available in two cycles;
;; the least significant word is available before the most significant
;; word. That fact is not modeled; instead, the instructions are
;; described.as if the entire result was available at the end of the
;; cycle in which both words are available.
;; The "umull", "umlal", "smull", and "smlal" instructions all take
;; three iterations through the execute cycle, and make their results
;; available after the memory cycle.
(define_insn_reservation "1020mult5" 4
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "insn" "umull,umlal,smull,smlal"))
"1020a_e*3,1020a_m,1020a_w")
;; The "umulls", "umlals", "smulls", and "smlals" instructions loop in
;; the execute stage for five iterations in order to set the flags.
;; The value result is available after four iterations.
(define_insn_reservation "1020mult6" 4
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "insn" "umulls,umlals,smulls,smlals"))
"1020a_e*5,1020a_m,1020a_w")
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Load/Store Instructions
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; The models for load/store instructions do not accurately describe
;; the difference between operations with a base register writeback
;; (such as "ldm!"). These models assume that all memory references
;; hit in dcache.
;; LSU instructions require six cycles to execute. They use the ALU
;; pipeline in all but the 5th cycle, and the LSU pipeline in cycles
;; three through six.
;; Loads and stores which use a scaled register offset or scaled
;; register pre-indexed addressing mode take three cycles EXCEPT for
;; those that are base + offset with LSL of 0 or 2, or base - offset
;; with LSL of zero. The remainder take 1 cycle to execute.
;; For 4byte loads there is a bypass from the load stage
(define_insn_reservation "1020load1_op" 2
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "type" "load_byte,load1"))
"1020a_e+1020l_e,1020l_m,1020l_w")
(define_insn_reservation "1020store1_op" 0
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "type" "store1"))
"1020a_e+1020l_e,1020l_m,1020l_w")
;; A load's result can be stored by an immediately following store
(define_bypass 1 "1020load1_op" "1020store1_op" "arm_no_early_store_addr_dep")
;; On a LDM/STM operation, the LSU pipeline iterates until all of the
;; registers have been processed.
;;
;; The time it takes to load the data depends on whether or not the
;; base address is 64-bit aligned; if it is not, an additional cycle
;; is required. This model assumes that the address is always 64-bit
;; aligned. Because the processor can load two registers per cycle,
;; that assumption means that we use the same instruction reservations
;; for loading 2k and 2k - 1 registers.
;;
;; The ALU pipeline is decoupled after the first cycle unless there is
;; a register dependency; the dependency is cleared as soon as the LDM/STM
;; has dealt with the corresponding register. So for example,
;; stmia sp, {r0-r3}
;; add r0, r0, #4
;; will have one fewer stalls than
;; stmia sp, {r0-r3}
;; add r3, r3, #4
;;
;; As with ALU operations, if one of the destination registers is the
;; PC, there are additional stalls; that is not modeled.
(define_insn_reservation "1020load2_op" 2
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "type" "load2"))
"1020a_e+1020l_e,1020l_m,1020l_w")
(define_insn_reservation "1020store2_op" 0
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "type" "store2"))
"1020a_e+1020l_e,1020l_m,1020l_w")
(define_insn_reservation "1020load34_op" 3
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "type" "load3,load4"))
"1020a_e+1020l_e,1020l_e+1020l_m,1020l_m,1020l_w")
(define_insn_reservation "1020store34_op" 0
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "type" "store3,store4"))
"1020a_e+1020l_e,1020l_e+1020l_m,1020l_m,1020l_w")
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Branch and Call Instructions
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Branch instructions are difficult to model accurately. The ARM
;; core can predict most branches. If the branch is predicted
;; correctly, and predicted early enough, the branch can be completely
;; eliminated from the instruction stream. Some branches can
;; therefore appear to require zero cycles to execute. We assume that
;; all branches are predicted correctly, and that the latency is
;; therefore the minimum value.
(define_insn_reservation "1020branch_op" 0
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "type" "branch"))
"1020a_e")
;; The latency for a call is not predictable. Therefore, we use 32 as
;; roughly equivalent to positive infinity.
(define_insn_reservation "1020call_op" 32
(and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "type" "call"))
"1020a_e*32")
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; VFP
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define_cpu_unit "v10_fmac" "arm1020e")
(define_cpu_unit "v10_ds" "arm1020e")
(define_cpu_unit "v10_fmstat" "arm1020e")
(define_cpu_unit "v10_ls1,v10_ls2,v10_ls3" "arm1020e")
;; fmstat is a serializing instruction. It will stall the core until
;; the mac and ds units have completed.
(exclusion_set "v10_fmac,v10_ds" "v10_fmstat")
(define_attr "vfp10" "yes,no"
(const (if_then_else (and (eq_attr "tune" "arm1020e,arm1022e")
(eq_attr "fpu" "vfp"))
(const_string "yes") (const_string "no"))))
;; The VFP "type" attributes differ from those used in the FPA model.
;; ffarith Fast floating point insns, e.g. abs, neg, cpy, cmp.
;; farith Most arithmetic insns.
;; fmul Double precision multiply.
;; fdivs Single precision sqrt or division.
;; fdivd Double precision sqrt or division.
;; f_flag fmstat operation
;; f_load Floating point load from memory.
;; f_store Floating point store to memory.
;; f_2_r Transfer vfp to arm reg.
;; r_2_f Transfer arm to vfp reg.
;; Note, no instruction can issue to the VFP if the core is stalled in the
;; first execute state. We model this by using 1020a_e in the first cycle.
(define_insn_reservation "v10_ffarith" 5
(and (eq_attr "vfp10" "yes")
(eq_attr "type" "ffarith"))
"1020a_e+v10_fmac")
(define_insn_reservation "v10_farith" 5
(and (eq_attr "vfp10" "yes")
(eq_attr "type" "farith"))
"1020a_e+v10_fmac")
(define_insn_reservation "v10_cvt" 5
(and (eq_attr "vfp10" "yes")
(eq_attr "type" "f_cvt"))
"1020a_e+v10_fmac")
(define_insn_reservation "v10_fmul" 6
(and (eq_attr "vfp10" "yes")
(eq_attr "type" "fmul"))
"1020a_e+v10_fmac*2")
(define_insn_reservation "v10_fdivs" 18
(and (eq_attr "vfp10" "yes")
(eq_attr "type" "fdivs"))
"1020a_e+v10_ds*14")
(define_insn_reservation "v10_fdivd" 32
(and (eq_attr "vfp10" "yes")
(eq_attr "type" "fdivd"))
"1020a_e+v10_fmac+v10_ds*28")
(define_insn_reservation "v10_floads" 4
(and (eq_attr "vfp10" "yes")
(eq_attr "type" "f_loads"))
"1020a_e+1020l_e+v10_ls1,v10_ls2")
;; We model a load of a double as needing all the vfp ls* stage in cycle 1.
;; This gives the correct mix between single-and double loads where a flds
;; followed by and fldd will stall for one cycle, but two back-to-back fldd
;; insns stall for two cycles.
(define_insn_reservation "v10_floadd" 5
(and (eq_attr "vfp10" "yes")
(eq_attr "type" "f_loadd"))
"1020a_e+1020l_e+v10_ls1+v10_ls2+v10_ls3,v10_ls2+v10_ls3,v10_ls3")
;; Moves to/from arm regs also use the load/store pipeline.
(define_insn_reservation "v10_c2v" 4
(and (eq_attr "vfp10" "yes")
(eq_attr "type" "r_2_f"))
"1020a_e+1020l_e+v10_ls1,v10_ls2")
(define_insn_reservation "v10_fstores" 1
(and (eq_attr "vfp10" "yes")
(eq_attr "type" "f_stores"))
"1020a_e+1020l_e+v10_ls1,v10_ls2")
(define_insn_reservation "v10_fstored" 1
(and (eq_attr "vfp10" "yes")
(eq_attr "type" "f_stored"))
"1020a_e+1020l_e+v10_ls1+v10_ls2+v10_ls3,v10_ls2+v10_ls3,v10_ls3")
(define_insn_reservation "v10_v2c" 1
(and (eq_attr "vfp10" "yes")
(eq_attr "type" "f_2_r"))
"1020a_e+1020l_e,1020l_m,1020l_w")
(define_insn_reservation "v10_to_cpsr" 2
(and (eq_attr "vfp10" "yes")
(eq_attr "type" "f_flag"))
"1020a_e+v10_fmstat,1020a_e+1020l_e,1020l_m,1020l_w")
;; VFP bypasses
;; There are bypasses for most operations other than store
(define_bypass 3
"v10_c2v,v10_floads"
"v10_ffarith,v10_farith,v10_fmul,v10_fdivs,v10_fdivd,v10_cvt")
(define_bypass 4
"v10_floadd"
"v10_ffarith,v10_farith,v10_fmul,v10_fdivs,v10_fdivd")
;; Arithmetic to other arithmetic saves a cycle due to forwarding
(define_bypass 4
"v10_ffarith,v10_farith"
"v10_ffarith,v10_farith,v10_fmul,v10_fdivs,v10_fdivd")
(define_bypass 5
"v10_fmul"
"v10_ffarith,v10_farith,v10_fmul,v10_fdivs,v10_fdivd")
(define_bypass 17
"v10_fdivs"
"v10_ffarith,v10_farith,v10_fmul,v10_fdivs,v10_fdivd")
(define_bypass 31
"v10_fdivd"
"v10_ffarith,v10_farith,v10_fmul,v10_fdivs,v10_fdivd")
;; VFP anti-dependencies.
;; There is one anti-dependence in the following case (not yet modelled):
;; - After a store: one extra cycle for both fsts and fstd
;; Note, back-to-back fstd instructions will overload the load/store datapath
;; causing a two-cycle stall.