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159fd7b8d3
Writes to ZCR_EL1 are self-synchronising, and so may be expensive in typical implementations. This patch adopts the approach used for costly system register writes elsewhere in the kernel: the system register write is suppressed if it would not change the stored value. Since the common case will be that of switching between tasks that use the same vector length as one another, prediction hit rates on the conditional branch should be reasonably good, with lower expected amortised cost than the unconditional execution of a heavyweight self-synchronising instruction. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
227 lines
5.7 KiB
C
227 lines
5.7 KiB
C
/*
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* FP/SIMD state saving and restoring macros
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*
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* Copyright (C) 2012 ARM Ltd.
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* Author: Catalin Marinas <catalin.marinas@arm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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.macro fpsimd_save state, tmpnr
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stp q0, q1, [\state, #16 * 0]
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stp q2, q3, [\state, #16 * 2]
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stp q4, q5, [\state, #16 * 4]
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stp q6, q7, [\state, #16 * 6]
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stp q8, q9, [\state, #16 * 8]
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stp q10, q11, [\state, #16 * 10]
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stp q12, q13, [\state, #16 * 12]
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stp q14, q15, [\state, #16 * 14]
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stp q16, q17, [\state, #16 * 16]
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stp q18, q19, [\state, #16 * 18]
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stp q20, q21, [\state, #16 * 20]
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stp q22, q23, [\state, #16 * 22]
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stp q24, q25, [\state, #16 * 24]
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stp q26, q27, [\state, #16 * 26]
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stp q28, q29, [\state, #16 * 28]
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stp q30, q31, [\state, #16 * 30]!
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mrs x\tmpnr, fpsr
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str w\tmpnr, [\state, #16 * 2]
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mrs x\tmpnr, fpcr
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str w\tmpnr, [\state, #16 * 2 + 4]
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.endm
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.macro fpsimd_restore_fpcr state, tmp
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/*
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* Writes to fpcr may be self-synchronising, so avoid restoring
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* the register if it hasn't changed.
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*/
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mrs \tmp, fpcr
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cmp \tmp, \state
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b.eq 9999f
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msr fpcr, \state
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9999:
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.endm
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/* Clobbers \state */
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.macro fpsimd_restore state, tmpnr
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ldp q0, q1, [\state, #16 * 0]
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ldp q2, q3, [\state, #16 * 2]
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ldp q4, q5, [\state, #16 * 4]
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ldp q6, q7, [\state, #16 * 6]
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ldp q8, q9, [\state, #16 * 8]
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ldp q10, q11, [\state, #16 * 10]
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ldp q12, q13, [\state, #16 * 12]
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ldp q14, q15, [\state, #16 * 14]
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ldp q16, q17, [\state, #16 * 16]
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ldp q18, q19, [\state, #16 * 18]
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ldp q20, q21, [\state, #16 * 20]
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ldp q22, q23, [\state, #16 * 22]
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ldp q24, q25, [\state, #16 * 24]
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ldp q26, q27, [\state, #16 * 26]
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ldp q28, q29, [\state, #16 * 28]
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ldp q30, q31, [\state, #16 * 30]!
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ldr w\tmpnr, [\state, #16 * 2]
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msr fpsr, x\tmpnr
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ldr w\tmpnr, [\state, #16 * 2 + 4]
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fpsimd_restore_fpcr x\tmpnr, \state
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.endm
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/* Sanity-check macros to help avoid encoding garbage instructions */
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.macro _check_general_reg nr
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.if (\nr) < 0 || (\nr) > 30
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.error "Bad register number \nr."
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.endif
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.endm
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.macro _sve_check_zreg znr
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.if (\znr) < 0 || (\znr) > 31
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.error "Bad Scalable Vector Extension vector register number \znr."
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.endif
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.endm
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.macro _sve_check_preg pnr
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.if (\pnr) < 0 || (\pnr) > 15
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.error "Bad Scalable Vector Extension predicate register number \pnr."
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.endif
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.endm
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.macro _check_num n, min, max
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.if (\n) < (\min) || (\n) > (\max)
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.error "Number \n out of range [\min,\max]"
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.endif
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.endm
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/* SVE instruction encodings for non-SVE-capable assemblers */
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/* STR (vector): STR Z\nz, [X\nxbase, #\offset, MUL VL] */
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.macro _sve_str_v nz, nxbase, offset=0
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_sve_check_zreg \nz
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_check_general_reg \nxbase
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_check_num (\offset), -0x100, 0xff
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.inst 0xe5804000 \
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| (\nz) \
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| ((\nxbase) << 5) \
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| (((\offset) & 7) << 10) \
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| (((\offset) & 0x1f8) << 13)
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.endm
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/* LDR (vector): LDR Z\nz, [X\nxbase, #\offset, MUL VL] */
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.macro _sve_ldr_v nz, nxbase, offset=0
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_sve_check_zreg \nz
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_check_general_reg \nxbase
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_check_num (\offset), -0x100, 0xff
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.inst 0x85804000 \
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| (\nz) \
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| ((\nxbase) << 5) \
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| (((\offset) & 7) << 10) \
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| (((\offset) & 0x1f8) << 13)
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.endm
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/* STR (predicate): STR P\np, [X\nxbase, #\offset, MUL VL] */
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.macro _sve_str_p np, nxbase, offset=0
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_sve_check_preg \np
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_check_general_reg \nxbase
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_check_num (\offset), -0x100, 0xff
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.inst 0xe5800000 \
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| (\np) \
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| ((\nxbase) << 5) \
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| (((\offset) & 7) << 10) \
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| (((\offset) & 0x1f8) << 13)
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.endm
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/* LDR (predicate): LDR P\np, [X\nxbase, #\offset, MUL VL] */
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.macro _sve_ldr_p np, nxbase, offset=0
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_sve_check_preg \np
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_check_general_reg \nxbase
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_check_num (\offset), -0x100, 0xff
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.inst 0x85800000 \
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| (\np) \
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| ((\nxbase) << 5) \
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| (((\offset) & 7) << 10) \
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| (((\offset) & 0x1f8) << 13)
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.endm
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/* RDVL X\nx, #\imm */
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.macro _sve_rdvl nx, imm
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_check_general_reg \nx
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_check_num (\imm), -0x20, 0x1f
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.inst 0x04bf5000 \
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| (\nx) \
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| (((\imm) & 0x3f) << 5)
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.endm
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/* RDFFR (unpredicated): RDFFR P\np.B */
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.macro _sve_rdffr np
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_sve_check_preg \np
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.inst 0x2519f000 \
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| (\np)
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.endm
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/* WRFFR P\np.B */
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.macro _sve_wrffr np
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_sve_check_preg \np
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.inst 0x25289000 \
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| ((\np) << 5)
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.endm
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.macro __for from:req, to:req
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.if (\from) == (\to)
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_for__body \from
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.else
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__for \from, (\from) + ((\to) - (\from)) / 2
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__for (\from) + ((\to) - (\from)) / 2 + 1, \to
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.endif
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.endm
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.macro _for var:req, from:req, to:req, insn:vararg
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.macro _for__body \var:req
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\insn
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.endm
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__for \from, \to
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.purgem _for__body
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.endm
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.macro sve_save nxbase, xpfpsr, nxtmp
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_for n, 0, 31, _sve_str_v \n, \nxbase, \n - 34
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_for n, 0, 15, _sve_str_p \n, \nxbase, \n - 16
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_sve_rdffr 0
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_sve_str_p 0, \nxbase
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_sve_ldr_p 0, \nxbase, -16
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mrs x\nxtmp, fpsr
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str w\nxtmp, [\xpfpsr]
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mrs x\nxtmp, fpcr
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str w\nxtmp, [\xpfpsr, #4]
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.endm
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.macro sve_load nxbase, xpfpsr, xvqminus1, nxtmp, xtmp2
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mrs_s x\nxtmp, SYS_ZCR_EL1
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bic \xtmp2, x\nxtmp, ZCR_ELx_LEN_MASK
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orr \xtmp2, \xtmp2, \xvqminus1
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cmp \xtmp2, x\nxtmp
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b.eq 921f
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msr_s SYS_ZCR_EL1, \xtmp2 // self-synchronising
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921:
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_for n, 0, 31, _sve_ldr_v \n, \nxbase, \n - 34
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_sve_ldr_p 0, \nxbase
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_sve_wrffr 0
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_for n, 0, 15, _sve_ldr_p \n, \nxbase, \n - 16
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ldr w\nxtmp, [\xpfpsr]
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msr fpsr, x\nxtmp
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ldr w\nxtmp, [\xpfpsr, #4]
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msr fpcr, x\nxtmp
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.endm
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