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target/arm: Implement SVE predicate test

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Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180516223007.10256-6-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Richard Henderson 2018-05-18 17:48:08 +01:00 • committed by Peter Maydell
parent d1822297f6
commit 9e18d7a67f
6 changed files with 171 additions and 1 deletions
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78
target/arm/sve_helper.c Normal file
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/*
* ARM SVE Operations
*
* Copyright (c) 2018 Linaro, Ltd.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "cpu.h"
#include "exec/exec-all.h"
#include "exec/cpu_ldst.h"
#include "exec/helper-proto.h"
#include "tcg/tcg-gvec-desc.h"
/* Return a value for NZCV as per the ARM PredTest pseudofunction.
*
* The return value has bit 31 set if N is set, bit 1 set if Z is clear,
* and bit 0 set if C is set. Compare the definitions of these variables
* within CPUARMState.
*/
/* For no G bits set, NZCV = C. */
#define PREDTEST_INIT 1
/* This is an iterative function, called for each Pd and Pg word
* moving forward.
*/
static uint32_t iter_predtest_fwd(uint64_t d, uint64_t g, uint32_t flags)
{
if (likely(g)) {
/* Compute N from first D & G.
Use bit 2 to signal first G bit seen. */
if (!(flags & 4)) {
flags |= ((d & (g & -g)) != 0) << 31;
flags |= 4;
}
/* Accumulate Z from each D & G. */
flags |= ((d & g) != 0) << 1;
/* Compute C from last !(D & G). Replace previous. */
flags = deposit32(flags, 0, 1, (d & pow2floor(g)) == 0);
}
return flags;
}
/* The same for a single word predicate. */
uint32_t HELPER(sve_predtest1)(uint64_t d, uint64_t g)
{
return iter_predtest_fwd(d, g, PREDTEST_INIT);
}
/* The same for a multi-word predicate. */
uint32_t HELPER(sve_predtest)(void *vd, void *vg, uint32_t words)
{
uint32_t flags = PREDTEST_INIT;
uint64_t *d = vd, *g = vg;
uintptr_t i = 0;
do {
flags = iter_predtest_fwd(d[i], g[i], flags);
} while (++i < words);
return flags;
}