From: "Alex Bennée" <alex.bennee@linaro.org>
To: qemu-devel@nongnu.org
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
"David Hildenbrand" <david@redhat.com>,
"Richard Henderson" <richard.henderson@linaro.org>,
cota@braap.org, "Alex Bennée" <alex.bennee@linaro.org>,
"Aurelien Jarno" <aurelien@aurel32.net>
Subject: [RFC PATCH 2/8] softfloat: Use int128.h for some operations
Date: Tue, 20 Oct 2020 17:37:32 +0100 [thread overview]
Message-ID: <20201020163738.27700-3-alex.bennee@linaro.org> (raw)
In-Reply-To: <20201020163738.27700-1-alex.bennee@linaro.org>
From: Richard Henderson <richard.henderson@linaro.org>
Use our Int128, which wraps the compiler's __int128_t,
instead of open-coding left shifts and arithmetic.
We'd need to extend Int128 to have unsigned operations
to replace more than these three.
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200925152047.709901-3-richard.henderson@linaro.org>
---
include/fpu/softfloat-macros.h | 39 +++++++++++++++++-----------------
1 file changed, 20 insertions(+), 19 deletions(-)
diff --git a/include/fpu/softfloat-macros.h b/include/fpu/softfloat-macros.h
index 57845f8af0..95d88d05b8 100644
--- a/include/fpu/softfloat-macros.h
+++ b/include/fpu/softfloat-macros.h
@@ -84,6 +84,7 @@ this code that are retained.
#include "fpu/softfloat-types.h"
#include "qemu/host-utils.h"
+#include "qemu/int128.h"
/*----------------------------------------------------------------------------
| Shifts `a' right by the number of bits given in `count'. If any nonzero
@@ -352,13 +353,11 @@ static inline void shortShift128Left(uint64_t a0, uint64_t a1, int count,
static inline void shift128Left(uint64_t a0, uint64_t a1, int count,
uint64_t *z0Ptr, uint64_t *z1Ptr)
{
- if (count < 64) {
- *z1Ptr = a1 << count;
- *z0Ptr = count == 0 ? a0 : (a0 << count) | (a1 >> (-count & 63));
- } else {
- *z1Ptr = 0;
- *z0Ptr = a1 << (count - 64);
- }
+ Int128 a = int128_make128(a1, a0);
+ Int128 z = int128_lshift(a, count);
+
+ *z0Ptr = int128_gethi(z);
+ *z1Ptr = int128_getlo(z);
}
/*----------------------------------------------------------------------------
@@ -405,15 +404,15 @@ static inline void
*----------------------------------------------------------------------------*/
static inline void
- add128(
- uint64_t a0, uint64_t a1, uint64_t b0, uint64_t b1, uint64_t *z0Ptr, uint64_t *z1Ptr )
+add128(uint64_t a0, uint64_t a1, uint64_t b0, uint64_t b1,
+ uint64_t *z0Ptr, uint64_t *z1Ptr)
{
- uint64_t z1;
-
- z1 = a1 + b1;
- *z1Ptr = z1;
- *z0Ptr = a0 + b0 + ( z1 < a1 );
+ Int128 a = int128_make128(a1, a0);
+ Int128 b = int128_make128(b1, b0);
+ Int128 z = int128_add(a, b);
+ *z0Ptr = int128_gethi(z);
+ *z1Ptr = int128_getlo(z);
}
/*----------------------------------------------------------------------------
@@ -463,13 +462,15 @@ static inline void
*----------------------------------------------------------------------------*/
static inline void
- sub128(
- uint64_t a0, uint64_t a1, uint64_t b0, uint64_t b1, uint64_t *z0Ptr, uint64_t *z1Ptr )
+sub128(uint64_t a0, uint64_t a1, uint64_t b0, uint64_t b1,
+ uint64_t *z0Ptr, uint64_t *z1Ptr)
{
+ Int128 a = int128_make128(a1, a0);
+ Int128 b = int128_make128(b1, b0);
+ Int128 z = int128_sub(a, b);
- *z1Ptr = a1 - b1;
- *z0Ptr = a0 - b0 - ( a1 < b1 );
-
+ *z0Ptr = int128_gethi(z);
+ *z1Ptr = int128_getlo(z);
}
/*----------------------------------------------------------------------------
--
2.20.1
next prev parent reply other threads:[~2020-10-20 16:51 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-20 16:37 [RFC PATCH 0/8] fpu: experimental conversion of float128_addsub Alex Bennée
2020-10-20 16:37 ` [RFC PATCH 1/8] softfloat: Use mulu64 for mul64To128 Alex Bennée
2020-10-20 16:37 ` Alex Bennée [this message]
2020-10-20 16:37 ` [RFC PATCH 3/8] softfloat: Tidy a * b + inf return Alex Bennée
2020-10-20 16:37 ` [RFC PATCH 4/8] softfloat: Add float_cmask and constants Alex Bennée
2020-10-20 16:37 ` [RFC PATCH 5/8] softfloat: Inline pick_nan_muladd into its caller Alex Bennée
2020-10-20 16:37 ` [RFC PATCH 6/8] int128.h: add bunch of uint128 utility functions (INCOMPLETE) Alex Bennée
2020-10-20 16:37 ` [RFC PATCH 7/8] tests/fp: add quad support to the benchmark utility Alex Bennée
2020-10-20 16:37 ` [RFC PATCH 8/8] softfloat: implement addsub_floats128 using Uint128 and new style code Alex Bennée
2020-10-20 18:49 ` Richard Henderson
2020-10-20 17:03 ` [RFC PATCH 0/8] fpu: experimental conversion of float128_addsub no-reply
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