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arch-arm: Do not increment exponent if FPSCR.FZ in fplib

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If flushing to zero, the exponent shouldn't be incremented since
we are supposed to produce a 0 value and not a denormal number

Change-Id: Ib6dd594a6555b2fd9a20a52b59cbf1f5f94c2eb5
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/28107
Reviewed-by: Jordi Vaquero <jordi.vaquero@metempsy.com>
Tested-by: kokoro <noreply+kokoro@google.com>
This commit is contained in:
Giacomo Travaglini
2020-04-22 14:50:15 +01:00
parent da21567d2c
commit b089163b72
1 changed files with 25 additions and 15 deletions
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40
src/arch/arm/insts/fplib.cc
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@@ -1,5 +1,5 @@
/*
* Copyright (c) 2012-2013, 2017-2018 ARM Limited
* Copyright (c) 2012-2013, 2017-2018, 2020 ARM Limited
* Copyright (c) 2020 Metempsy Technology Consulting
* All rights reserved
*
@@ -393,14 +393,18 @@ fp16_unpack(int *sgn, int *exp, uint16_t *mnt, uint16_t x, int mode,
*exp = FP16_EXP(x);
*mnt = FP16_MANT(x);
// Handle subnormals:
if (*exp) {
*mnt |= 1ULL << FP16_MANT_BITS;
} else {
++*exp;
// Handle subnormals:
// IDC (Input Denormal) is not set in this case.
if (mode & FPLIB_FZ16)
*mnt = 0;
if (*mnt) {
if (mode & FPLIB_FZ16) {
*mnt = 0;
} else {
++*exp;
}
}
}
}
@@ -412,14 +416,17 @@ fp32_unpack(int *sgn, int *exp, uint32_t *mnt, uint32_t x, int mode,
*exp = FP32_EXP(x);
*mnt = FP32_MANT(x);
// Handle subnormals:
if (*exp) {
*mnt |= 1ULL << FP32_MANT_BITS;
} else {
++*exp;
if ((mode & FPLIB_FZ) && *mnt) {
*flags |= FPLIB_IDC;
*mnt = 0;
// Handle subnormals:
if (*mnt) {
if (mode & FPLIB_FZ) {
*flags |= FPLIB_IDC;
*mnt = 0;
} else {
++*exp;
}
}
}
}
@@ -434,14 +441,17 @@ fp64_unpack(int *sgn, int *exp, uint64_t *mnt, uint64_t x, int mode,
*exp = FP64_EXP(x);
*mnt = FP64_MANT(x);
// Handle subnormals:
if (*exp) {
*mnt |= 1ULL << FP64_MANT_BITS;
} else {
++*exp;
if ((mode & FPLIB_FZ) && *mnt) {
*flags |= FPLIB_IDC;
*mnt = 0;
// Handle subnormals:
if (*mnt) {
if (mode & FPLIB_FZ) {
*flags |= FPLIB_IDC;
*mnt = 0;
} else {
++*exp;
}
}
}
}