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From: Richard Henderson <richard.henderson@linaro.org>
To: qemu-devel@nongnu.org
Cc: alex.bennee@linaro.org, david@redhat.com
Subject: [PATCH v2 24/28] softfloat: Convert float32_exp2 to FloatParts
Date: Tue, 25 May 2021 08:07:02 -0700	[thread overview]
Message-ID: <20210525150706.294968-25-richard.henderson@linaro.org> (raw)
In-Reply-To: <20210525150706.294968-1-richard.henderson@linaro.org>

Keep the intermediate results in FloatParts instead of
converting back and forth between float64.  Use muladd
instead of separate mul+add.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 fpu/softfloat.c | 53 +++++++++++++++++++++----------------------------
 1 file changed, 23 insertions(+), 30 deletions(-)

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index b86441d0c9..c778b96c37 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -5213,47 +5213,40 @@ static const float64 float32_exp2_coefficients[15] =
 
 float32 float32_exp2(float32 a, float_status *status)
 {
-    bool aSign;
-    int aExp;
-    uint32_t aSig;
-    float64 r, x, xn;
+    FloatParts64 xp, xnp, tp, rp;
     int i;
-    a = float32_squash_input_denormal(a, status);
 
-    aSig = extractFloat32Frac( a );
-    aExp = extractFloat32Exp( a );
-    aSign = extractFloat32Sign( a );
-
-    if ( aExp == 0xFF) {
-        if (aSig) {
-            return propagateFloat32NaN(a, float32_zero, status);
+    float32_unpack_canonical(&xp, a, status);
+    if (unlikely(xp.cls != float_class_normal)) {
+        switch (xp.cls) {
+        case float_class_snan:
+        case float_class_qnan:
+            parts_return_nan(&xp, status);
+            return float32_round_pack_canonical(&xp, status);
+        case float_class_inf:
+            return xp.sign ? float32_zero : a;
+        case float_class_zero:
+            return float32_one;
+        default:
+            break;
         }
-        return (aSign) ? float32_zero : a;
-    }
-    if (aExp == 0) {
-        if (aSig == 0) return float32_one;
+        g_assert_not_reached();
     }
 
     float_raise(float_flag_inexact, status);
 
-    /* ******************************* */
-    /* using float64 for approximation */
-    /* ******************************* */
-    x = float32_to_float64(a, status);
-    x = float64_mul(x, float64_ln2, status);
+    float64_unpack_canonical(&xnp, float64_ln2, status);
+    xp = *parts_mul(&xp, &tp, status);
+    xnp = xp;
 
-    xn = x;
-    r = float64_one;
+    float64_unpack_canonical(&rp, float64_one, status);
     for (i = 0 ; i < 15 ; i++) {
-        float64 f;
-
-        f = float64_mul(xn, float32_exp2_coefficients[i], status);
-        r = float64_add(r, f, status);
-
-        xn = float64_mul(xn, x, status);
+        float64_unpack_canonical(&tp, float32_exp2_coefficients[i], status);
+        rp = *parts_muladd(&tp, &xp, &rp, 0, status);
+        xnp = *parts_mul(&xnp, &xp, status);
     }
 
-    return float64_to_float32(r, status);
+    return float32_round_pack_canonical(&rp, status);
 }
 
 /*----------------------------------------------------------------------------
-- 
2.25.1



  parent reply	other threads:[~2021-05-25 16:22 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-25 15:06 [PATCH v2 00/28] Convert floatx80 and float128 " Richard Henderson
2021-05-25 15:06 ` [PATCH v2 01/28] softfloat: Move round_to_uint_and_pack to softfloat-parts.c.inc Richard Henderson
2021-06-02 11:12   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 02/28] softfloat: Move int_to_float " Richard Henderson
2021-05-26 13:34   ` David Hildenbrand
2021-06-02 11:14   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 03/28] softfloat: Move uint_to_float " Richard Henderson
2021-05-26 13:36   ` David Hildenbrand
2021-06-02 11:31   ` Alex Bennée
2021-06-02 16:28     ` Richard Henderson
2021-05-25 15:06 ` [PATCH v2 04/28] softfloat: Move minmax_flags " Richard Henderson
2021-05-26 13:45   ` David Hildenbrand
2021-06-02 20:36   ` Alex Bennée
2021-06-02 22:23     ` Richard Henderson
2021-06-02 22:29   ` Richard Henderson
2021-05-25 15:06 ` [PATCH v2 05/28] softfloat: Move compare_floats " Richard Henderson
2021-06-03  9:00   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 06/28] softfloat: Move scalbn_decomposed " Richard Henderson
2021-06-03  9:01   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 07/28] softfloat: Move sqrt_float " Richard Henderson
2021-06-03  9:17   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 08/28] softfloat: Split out parts_uncanon_normal Richard Henderson
2021-06-03  9:22   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 09/28] softfloat: Reduce FloatFmt Richard Henderson
2021-06-03  9:23   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 10/28] softfloat: Introduce Floatx80RoundPrec Richard Henderson
2021-06-03  9:26   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 11/28] softfloat: Adjust parts_uncanon_normal for floatx80 Richard Henderson
2021-06-03 11:58   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 12/28] tests/fp/fp-test: Reverse order of floatx80 precision tests Richard Henderson
2021-05-25 15:06 ` [PATCH v2 13/28] softfloat: Convert floatx80_add/sub to FloatParts Richard Henderson
2021-06-03 14:23   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 14/28] softfloat: Convert floatx80_mul " Richard Henderson
2021-06-03 14:23   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 15/28] softfloat: Convert floatx80_div " Richard Henderson
2021-06-03 14:23   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 16/28] softfloat: Convert floatx80_sqrt " Richard Henderson
2021-06-03 14:24   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 17/28] softfloat: Convert floatx80_round " Richard Henderson
2021-06-03 14:25   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 18/28] softfloat: Convert floatx80_round_to_int " Richard Henderson
2021-06-03 14:26   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 19/28] softfloat: Convert integer to floatx80 " Richard Henderson
2021-06-03 14:26   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 20/28] softfloat: Convert floatx80 float conversions " Richard Henderson
2021-06-03 14:26   ` Alex Bennée
2021-05-25 15:06 ` [PATCH v2 21/28] softfloat: Convert floatx80 to integer " Richard Henderson
2021-06-03 14:27   ` Alex Bennée
2021-05-25 15:07 ` [PATCH v2 22/28] softfloat: Convert floatx80_scalbn " Richard Henderson
2021-06-03 14:34   ` Alex Bennée
2021-05-25 15:07 ` [PATCH v2 23/28] softfloat: Convert floatx80 compare " Richard Henderson
2021-06-03 14:34   ` Alex Bennée
2021-05-25 15:07 ` Richard Henderson [this message]
2021-06-03 14:44   ` [PATCH v2 24/28] softfloat: Convert float32_exp2 " Alex Bennée
2021-05-25 15:07 ` [PATCH v2 25/28] softfloat: Move floatN_log2 to softfloat-parts.c.inc Richard Henderson
2021-06-02 15:28   ` Alex Bennée
2021-05-25 15:07 ` [PATCH v2 26/28] softfloat: Convert modrem operations to FloatParts Richard Henderson
2021-06-03 14:48   ` Alex Bennée
2021-05-25 15:07 ` [PATCH v2 27/28] tests/fp: Enable more tests Richard Henderson
2021-05-25 15:07 ` [PATCH v2 28/28] softfloat: Use hard-float for {u}int64_to_float{32, 64} Richard Henderson
2021-06-03 14:57   ` [PATCH v2 28/28] softfloat: Use hard-float for {u}int64_to_float{32,64} Alex Bennée
2021-05-25 16:51 ` [PATCH v2 00/28] Convert floatx80 and float128 to FloatParts no-reply

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