1 ;; ARM 926EJ-S Pipeline Description
2 ;; Copyright (C) 2003-2013 Free Software Foundation, Inc.
3 ;; Written by CodeSourcery, LLC.
5 ;; This file is part of GCC.
7 ;; GCC is free software; you can redistribute it and/or modify it
8 ;; under the terms of the GNU General Public License as published by
9 ;; the Free Software Foundation; either version 3, or (at your option)
12 ;; GCC is distributed in the hope that it will be useful, but
13 ;; WITHOUT ANY WARRANTY; without even the implied warranty of
14 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 ;; General Public License for more details.
17 ;; You should have received a copy of the GNU General Public License
18 ;; along with GCC; see the file COPYING3. If not see
19 ;; <http://www.gnu.org/licenses/>. */
21 ;; These descriptions are based on the information contained in the
22 ;; ARM926EJ-S Technical Reference Manual, Copyright (c) 2002 ARM
26 ;; This automaton provides a pipeline description for the ARM
29 ;; The model given here assumes that the condition for all conditional
30 ;; instructions is "true", i.e., that all of the instructions are
33 (define_automaton "arm926ejs")
35 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
37 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
39 ;; There is a single pipeline
41 ;; The ALU pipeline has fetch, decode, execute, memory, and
42 ;; write stages. We only need to model the execute, memory and write
45 (define_cpu_unit "e,m,w" "arm926ejs")
47 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
49 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
51 ;; ALU instructions require three cycles to execute, and use the ALU
52 ;; pipeline in each of the three stages. The results are available
53 ;; after the execute stage stage has finished.
55 ;; If the destination register is the PC, the pipelines are stalled
56 ;; for several cycles. That case is not modeled here.
58 ;; ALU operations with no shifted operand
59 (define_insn_reservation "9_alu_op" 1
60 (and (eq_attr "tune" "arm926ejs")
61 (eq_attr "type" "alu_reg,simple_alu_imm,simple_alu_shift,alu_shift"))
64 ;; ALU operations with a shift-by-register operand
65 ;; These really stall in the decoder, in order to read
66 ;; the shift value in a second cycle. Pretend we take two cycles in
68 (define_insn_reservation "9_alu_shift_reg_op" 2
69 (and (eq_attr "tune" "arm926ejs")
70 (eq_attr "type" "alu_shift_reg"))
73 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
74 ;; Multiplication Instructions
75 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
77 ;; Multiplication instructions loop in the execute stage until the
78 ;; instruction has been passed through the multiplier array enough
79 ;; times. Multiply operations occur in both the execute and memory
80 ;; stages of the pipeline
82 (define_insn_reservation "9_mult1" 3
83 (and (eq_attr "tune" "arm926ejs")
84 (eq_attr "insn" "smlalxy,mul,mla"))
87 (define_insn_reservation "9_mult2" 4
88 (and (eq_attr "tune" "arm926ejs")
89 (eq_attr "insn" "muls,mlas"))
92 (define_insn_reservation "9_mult3" 4
93 (and (eq_attr "tune" "arm926ejs")
94 (eq_attr "insn" "umull,umlal,smull,smlal"))
97 (define_insn_reservation "9_mult4" 5
98 (and (eq_attr "tune" "arm926ejs")
99 (eq_attr "insn" "umulls,umlals,smulls,smlals"))
102 (define_insn_reservation "9_mult5" 2
103 (and (eq_attr "tune" "arm926ejs")
104 (eq_attr "insn" "smulxy,smlaxy,smlawx"))
107 (define_insn_reservation "9_mult6" 3
108 (and (eq_attr "tune" "arm926ejs")
109 (eq_attr "insn" "smlalxy"))
112 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
113 ;; Load/Store Instructions
114 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
116 ;; The models for load/store instructions do not accurately describe
117 ;; the difference between operations with a base register writeback
118 ;; (such as "ldm!"). These models assume that all memory references
121 ;; Loads with a shifted offset take 3 cycles, and are (a) probably the
122 ;; most common and (b) the pessimistic assumption will lead to fewer stalls.
123 (define_insn_reservation "9_load1_op" 3
124 (and (eq_attr "tune" "arm926ejs")
125 (eq_attr "type" "load1,load_byte"))
128 (define_insn_reservation "9_store1_op" 0
129 (and (eq_attr "tune" "arm926ejs")
130 (eq_attr "type" "store1"))
133 ;; multiple word loads and stores
134 (define_insn_reservation "9_load2_op" 3
135 (and (eq_attr "tune" "arm926ejs")
136 (eq_attr "type" "load2"))
139 (define_insn_reservation "9_load3_op" 4
140 (and (eq_attr "tune" "arm926ejs")
141 (eq_attr "type" "load3"))
144 (define_insn_reservation "9_load4_op" 5
145 (and (eq_attr "tune" "arm926ejs")
146 (eq_attr "type" "load4"))
149 (define_insn_reservation "9_store2_op" 0
150 (and (eq_attr "tune" "arm926ejs")
151 (eq_attr "type" "store2"))
154 (define_insn_reservation "9_store3_op" 0
155 (and (eq_attr "tune" "arm926ejs")
156 (eq_attr "type" "store3"))
159 (define_insn_reservation "9_store4_op" 0
160 (and (eq_attr "tune" "arm926ejs")
161 (eq_attr "type" "store4"))
164 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
165 ;; Branch and Call Instructions
166 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
168 ;; Branch instructions are difficult to model accurately. The ARM
169 ;; core can predict most branches. If the branch is predicted
170 ;; correctly, and predicted early enough, the branch can be completely
171 ;; eliminated from the instruction stream. Some branches can
172 ;; therefore appear to require zero cycles to execute. We assume that
173 ;; all branches are predicted correctly, and that the latency is
174 ;; therefore the minimum value.
176 (define_insn_reservation "9_branch_op" 0
177 (and (eq_attr "tune" "arm926ejs")
178 (eq_attr "type" "branch"))
181 ;; The latency for a call is not predictable. Therefore, we use 32 as
182 ;; roughly equivalent to positive infinity.
184 (define_insn_reservation "9_call_op" 32
185 (and (eq_attr "tune" "arm926ejs")
186 (eq_attr "type" "call"))