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;; ARM 1136J[F]-S Pipeline Description
;; Copyright (C) 2003, 2007 Free Software Foundation, Inc.
;; Written by CodeSourcery, LLC.
;;
;; 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 3, 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 COPYING3. If not see
;; <http://www.gnu.org/licenses/>. */
;; These descriptions are based on the information contained in the
;; ARM1136JF-S Technical Reference Manual, Copyright (c) 2003 ARM
;; Limited.
;;
;; This automaton provides a pipeline description for the ARM
;; 1136J-S and 1136JF-S cores.
;;
;; 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 "arm1136jfs")
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Pipelines
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; There are three distinct pipelines (page 1-26 and following):
;;
;; - A 4-stage decode pipeline, shared by all three. It has fetch (1),
;; fetch (2), decode, and issue stages. Since this is always involved,
;; we do not model it in the scheduler.
;;
;; - A 4-stage ALU pipeline. It has shifter, ALU (main integer operations),
;; and saturation stages. The fourth stage is writeback; see below.
;;
;; - A 4-stage multiply-accumulate pipeline. It has three stages, called
;; MAC1 through MAC3, and a fourth writeback stage.
;;
;; The 4th-stage writeback is shared between the ALU and MAC pipelines,
;; which operate in lockstep. Results from either pipeline will be
;; moved into the writeback stage. Because the two pipelines operate
;; in lockstep, we schedule them as a single "execute" pipeline.
;;
;; - A 4-stage LSU pipeline. It has address generation, data cache (1),
;; data cache (2), and writeback stages. (Note that this pipeline,
;; including the writeback stage, is independent from the ALU & LSU pipes.)
(define_cpu_unit "e_1,e_2,e_3,e_wb" "arm1136jfs") ; ALU and MAC
; e_1 = Sh/Mac1, e_2 = ALU/Mac2, e_3 = SAT/Mac3
(define_cpu_unit "l_a,l_dc1,l_dc2,l_wb" "arm1136jfs") ; Load/Store
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; ALU Instructions
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; ALU instructions require eight cycles to execute, and use the ALU
;; pipeline in each of the eight stages. The results are available
;; after the alu stage has finished.
;;
;; If the destination register is the PC, the pipelines are stalled
;; for several cycles. That case is not modelled here.
;; ALU operations with no shifted operand
(define_insn_reservation "11_alu_op" 2
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "type" "alu"))
"e_1,e_2,e_3,e_wb")
;; ALU operations with a shift-by-constant operand
(define_insn_reservation "11_alu_shift_op" 2
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "type" "alu_shift"))
"e_1,e_2,e_3,e_wb")
;; 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 shift stage.
(define_insn_reservation "11_alu_shift_reg_op" 3
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "type" "alu_shift_reg"))
"e_1*2,e_2,e_3,e_wb")
;; alu_ops can start sooner, if there is no shifter dependency
(define_bypass 1 "11_alu_op,11_alu_shift_op"
"11_alu_op")
(define_bypass 1 "11_alu_op,11_alu_shift_op"
"11_alu_shift_op"
"arm_no_early_alu_shift_value_dep")
(define_bypass 1 "11_alu_op,11_alu_shift_op"
"11_alu_shift_reg_op"
"arm_no_early_alu_shift_dep")
(define_bypass 2 "11_alu_shift_reg_op"
"11_alu_op")
(define_bypass 2 "11_alu_shift_reg_op"
"11_alu_shift_op"
"arm_no_early_alu_shift_value_dep")
(define_bypass 2 "11_alu_shift_reg_op"
"11_alu_shift_reg_op"
"arm_no_early_alu_shift_dep")
(define_bypass 1 "11_alu_op,11_alu_shift_op"
"11_mult1,11_mult2,11_mult3,11_mult4,11_mult5,11_mult6,11_mult7"
"arm_no_early_mul_dep")
(define_bypass 2 "11_alu_shift_reg_op"
"11_mult1,11_mult2,11_mult3,11_mult4,11_mult5,11_mult6,11_mult7"
"arm_no_early_mul_dep")
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Multiplication Instructions
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Multiplication instructions loop in the first two execute stages until
;; the instruction has been passed through the multiplier array enough
;; times.
;; Multiply and multiply-accumulate results are available after four stages.
(define_insn_reservation "11_mult1" 4
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "insn" "mul,mla"))
"e_1*2,e_2,e_3,e_wb")
;; The *S variants set the condition flags, which requires three more cycles.
(define_insn_reservation "11_mult2" 4
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "insn" "muls,mlas"))
"e_1*2,e_2,e_3,e_wb")
(define_bypass 3 "11_mult1,11_mult2"
"11_mult1,11_mult2,11_mult3,11_mult4,11_mult5,11_mult6,11_mult7"
"arm_no_early_mul_dep")
(define_bypass 3 "11_mult1,11_mult2"
"11_alu_op")
(define_bypass 3 "11_mult1,11_mult2"
"11_alu_shift_op"
"arm_no_early_alu_shift_value_dep")
(define_bypass 3 "11_mult1,11_mult2"
"11_alu_shift_reg_op"
"arm_no_early_alu_shift_dep")
(define_bypass 3 "11_mult1,11_mult2"
"11_store1"
"arm_no_early_store_addr_dep")
;; Signed and unsigned multiply long results are available across two cycles;
;; the less significant word is available one cycle before the more significant
;; word. Here we conservatively wait until both are available, which is
;; after three iterations and the memory cycle. The same is also true of
;; the two multiply-accumulate instructions.
(define_insn_reservation "11_mult3" 5
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "insn" "smull,umull,smlal,umlal"))
"e_1*3,e_2,e_3,e_wb*2")
;; The *S variants set the condition flags, which requires three more cycles.
(define_insn_reservation "11_mult4" 5
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "insn" "smulls,umulls,smlals,umlals"))
"e_1*3,e_2,e_3,e_wb*2")
(define_bypass 4 "11_mult3,11_mult4"
"11_mult1,11_mult2,11_mult3,11_mult4,11_mult5,11_mult6,11_mult7"
"arm_no_early_mul_dep")
(define_bypass 4 "11_mult3,11_mult4"
"11_alu_op")
(define_bypass 4 "11_mult3,11_mult4"
"11_alu_shift_op"
"arm_no_early_alu_shift_value_dep")
(define_bypass 4 "11_mult3,11_mult4"
"11_alu_shift_reg_op"
"arm_no_early_alu_shift_dep")
(define_bypass 4 "11_mult3,11_mult4"
"11_store1"
"arm_no_early_store_addr_dep")
;; Various 16x16->32 multiplies and multiply-accumulates, using combinations
;; of high and low halves of the argument registers. They take a single
;; pass through the pipeline and make the result available after three
;; cycles.
(define_insn_reservation "11_mult5" 3
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "insn" "smulxy,smlaxy,smulwy,smlawy,smuad,smuadx,smlad,smladx,smusd,smusdx,smlsd,smlsdx"))
"e_1,e_2,e_3,e_wb")
(define_bypass 2 "11_mult5"
"11_mult1,11_mult2,11_mult3,11_mult4,11_mult5,11_mult6,11_mult7"
"arm_no_early_mul_dep")
(define_bypass 2 "11_mult5"
"11_alu_op")
(define_bypass 2 "11_mult5"
"11_alu_shift_op"
"arm_no_early_alu_shift_value_dep")
(define_bypass 2 "11_mult5"
"11_alu_shift_reg_op"
"arm_no_early_alu_shift_dep")
(define_bypass 2 "11_mult5"
"11_store1"
"arm_no_early_store_addr_dep")
;; The same idea, then the 32-bit result is added to a 64-bit quantity.
(define_insn_reservation "11_mult6" 4
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "insn" "smlalxy"))
"e_1*2,e_2,e_3,e_wb*2")
;; Signed 32x32 multiply, then the most significant 32 bits are extracted
;; and are available after the memory stage.
(define_insn_reservation "11_mult7" 4
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "insn" "smmul,smmulr"))
"e_1*2,e_2,e_3,e_wb")
(define_bypass 3 "11_mult6,11_mult7"
"11_mult1,11_mult2,11_mult3,11_mult4,11_mult5,11_mult6,11_mult7"
"arm_no_early_mul_dep")
(define_bypass 3 "11_mult6,11_mult7"
"11_alu_op")
(define_bypass 3 "11_mult6,11_mult7"
"11_alu_shift_op"
"arm_no_early_alu_shift_value_dep")
(define_bypass 3 "11_mult6,11_mult7"
"11_alu_shift_reg_op"
"arm_no_early_alu_shift_dep")
(define_bypass 3 "11_mult6,11_mult7"
"11_store1"
"arm_no_early_store_addr_dep")
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Branch Instructions
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; These vary greatly depending on their arguments and the results of
;; stat prediction. Cycle count ranges from zero (unconditional branch,
;; folded dynamic prediction) to seven (incorrect predictions, etc). We
;; assume an optimal case for now, because the cost of a cache miss
;; overwhelms the cost of everything else anyhow.
(define_insn_reservation "11_branches" 0
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "type" "branch"))
"nothing")
;; Call latencies are not predictable. A semi-arbitrary very large
;; number is used as "positive infinity" so that everything should be
;; finished by the time of return.
(define_insn_reservation "11_call" 32
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "type" "call"))
"nothing")
;; Branches are predicted. A correctly predicted branch will be no
;; cost, but we're conservative here, and use the timings a
;; late-register would give us.
(define_bypass 1 "11_alu_op,11_alu_shift_op"
"11_branches")
(define_bypass 2 "11_alu_shift_reg_op"
"11_branches")
(define_bypass 2 "11_load1,11_load2"
"11_branches")
(define_bypass 3 "11_load34"
"11_branches")
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Load/Store Instructions
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; The models for load/store instructions do not accurately describe
;; the difference between operations with a base register writeback.
;; These models assume that all memory references hit in dcache. Also,
;; if the PC is one of the registers involved, there are additional stalls
;; not modelled here. Addressing modes are also not modelled.
(define_insn_reservation "11_load1" 3
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "type" "load1"))
"l_a+e_1,l_dc1,l_dc2,l_wb")
;; Load byte results are not available until the writeback stage, where
;; the correct byte is extracted.
(define_insn_reservation "11_loadb" 4
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "type" "load_byte"))
"l_a+e_1,l_dc1,l_dc2,l_wb")
(define_insn_reservation "11_store1" 0
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "type" "store1"))
"l_a+e_1,l_dc1,l_dc2,l_wb")
;; Load/store double words into adjacent registers. The timing and
;; latencies are different depending on whether the address is 64-bit
;; aligned. This model assumes that it is.
(define_insn_reservation "11_load2" 3
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "type" "load2"))
"l_a+e_1,l_dc1,l_dc2,l_wb")
(define_insn_reservation "11_store2" 0
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "type" "store2"))
"l_a+e_1,l_dc1,l_dc2,l_wb")
;; Load/store multiple registers. Two registers are stored per cycle.
;; Actual timing depends on how many registers are affected, so we
;; optimistically schedule a low latency.
(define_insn_reservation "11_load34" 4
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "type" "load3,load4"))
"l_a+e_1,l_dc1*2,l_dc2,l_wb")
(define_insn_reservation "11_store34" 0
(and (eq_attr "tune" "arm1136js,arm1136jfs")
(eq_attr "type" "store3,store4"))
"l_a+e_1,l_dc1*2,l_dc2,l_wb")
;; A store can start immediately after an alu op, if that alu op does
;; not provide part of the address to access.
(define_bypass 1 "11_alu_op,11_alu_shift_op"
"11_store1"
"arm_no_early_store_addr_dep")
(define_bypass 2 "11_alu_shift_reg_op"
"11_store1"
"arm_no_early_store_addr_dep")
;; An alu op can start sooner after a load, if that alu op does not
;; have an early register dependency on the load
(define_bypass 2 "11_load1"
"11_alu_op")
(define_bypass 2 "11_load1"
"11_alu_shift_op"
"arm_no_early_alu_shift_value_dep")
(define_bypass 2 "11_load1"
"11_alu_shift_reg_op"
"arm_no_early_alu_shift_dep")
(define_bypass 3 "11_loadb"
"11_alu_op")
(define_bypass 3 "11_loadb"
"11_alu_shift_op"
"arm_no_early_alu_shift_value_dep")
(define_bypass 3 "11_loadb"
"11_alu_shift_reg_op"
"arm_no_early_alu_shift_dep")
;; A mul op can start sooner after a load, if that mul op does not
;; have an early multiply dependency
(define_bypass 2 "11_load1"
"11_mult1,11_mult2,11_mult3,11_mult4,11_mult5,11_mult6,11_mult7"
"arm_no_early_mul_dep")
(define_bypass 3 "11_load34"
"11_mult1,11_mult2,11_mult3,11_mult4,11_mult5,11_mult6,11_mult7"
"arm_no_early_mul_dep")
(define_bypass 3 "11_loadb"
"11_mult1,11_mult2,11_mult3,11_mult4,11_mult5,11_mult6,11_mult7"
"arm_no_early_mul_dep")
;; A store can start sooner after a load, if that load does not
;; produce part of the address to access
(define_bypass 2 "11_load1"
"11_store1"
"arm_no_early_store_addr_dep")
(define_bypass 3 "11_loadb"
"11_store1"
"arm_no_early_store_addr_dep")
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