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Hexagon (target/hexagon) Change subtract from zero to change sign

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The F2_sffms instruction [r0 -= sfmpy(r1, r2)] doesn't properly
handle -0.  Previously we would negate the input operand by subtracting
from zero.  Instead, we negate by changing the sign bit.

Test case added to tests/tcg/hexagon/fpstuff.c

Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Anton Johansson <anjo@rev.ng>
Message-Id: <20230307025828.1612809-12-tsimpson@quicinc.com>
This commit is contained in:
Taylor Simpson 2023-03-06 18:58:25 -08:00
parent 1c629814f7
commit 1a442c0931
2 changed files with 31 additions and 2 deletions
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2
target/hexagon/op_helper.c
View File

@ -1169,7 +1169,7 @@ float32 HELPER(sffms)(CPUHexagonState *env, float32 RxV,
{
float32 neg_RsV;
arch_fpop_start(env);
neg_RsV = float32_sub(float32_zero, RsV, &env->fp_status);
neg_RsV = float32_set_sign(RsV, float32_is_neg(RsV) ? 0 : 1);
RxV = internal_fmafx(neg_RsV, RtV, RxV, 0, &env->fp_status);
arch_fpop_end(env);
return RxV;

31
tests/tcg/hexagon/fpstuff.c
View File

@ -1,5 +1,5 @@
/*
* Copyright(c) 2020-2022 Qualcomm Innovation Center, Inc. All Rights Reserved.
* Copyright(c) 2020-2023 Qualcomm Innovation Center, Inc. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@ -40,6 +40,7 @@ const int SF_HEX_NAN = 0xffffffff;
const int SF_small_neg = 0xab98fba8;
const int SF_denorm = 0x00000001;
const int SF_random = 0x346001d6;
const int SF_neg_zero = 0x80000000;
const long long DF_QNaN = 0x7ff8000000000000ULL;
const long long DF_SNaN = 0x7ff7000000000000ULL;
@ -536,6 +537,33 @@ static void check_sffixupd(void)
check32(result, 0x146001d6);
}
static void check_sffms(void)
{
int result;
/* Check that sffms properly deals with -0 */
result = SF_neg_zero;
asm ("%0 -= sfmpy(%1 , %2)\n\t"
: "+r"(result)
: "r"(SF_ZERO), "r"(SF_ZERO)
: "r12", "r8");
check32(result, SF_neg_zero);
result = SF_ZERO;
asm ("%0 -= sfmpy(%1 , %2)\n\t"
: "+r"(result)
: "r"(SF_neg_zero), "r"(SF_ZERO)
: "r12", "r8");
check32(result, SF_ZERO);
result = SF_ZERO;
asm ("%0 -= sfmpy(%1 , %2)\n\t"
: "+r"(result)
: "r"(SF_ZERO), "r"(SF_neg_zero)
: "r12", "r8");
check32(result, SF_ZERO);
}
static void check_float2int_convs()
{
int res32;
@ -688,6 +716,7 @@ int main()
check_invsqrta();
check_sffixupn();
check_sffixupd();
check_sffms();
check_float2int_convs();
puts(err ? "FAIL" : "PASS");