Implement atan2pi builtin

This implementation was ported from the AMD builtin library
and has been tested with piglit, OpenCV, and the ocl conformance tests.

git-svn-id: https://llvm.org/svn/llvm-project/libclc/trunk@237138 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 270 insertions, 0 deletions

diff --git a/generic/include/clc/clc.h b/generic/include/clc/clc.h
index 9f1f75a..cab751d 100644
--- a/generic/include/clc/clc.h
+++ b/generic/include/clc/clc.h
@@ -40,6 +40,7 @@
 #include <clc/math/asinpi.h>
 #include <clc/math/atan.h>
 #include <clc/math/atan2.h>
+#include <clc/math/atan2pi.h>
 #include <clc/math/atanh.h>
 #include <clc/math/atanpi.h>
 #include <clc/math/copysign.h>
diff --git a/generic/include/clc/math/atan2pi.h b/generic/include/clc/math/atan2pi.h
new file mode 100644
index 0000000..2cf4c53
--- /dev/null
+++ b/generic/include/clc/math/atan2pi.h
@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2014, 2015 Advanced Micro Devices, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#define __CLC_BODY <clc/math/atan2pi.inc>
+#include <clc/math/gentype.inc>
diff --git a/generic/include/clc/math/atan2pi.inc b/generic/include/clc/math/atan2pi.inc
new file mode 100644
index 0000000..47a9d44
--- /dev/null
+++ b/generic/include/clc/math/atan2pi.inc
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2014, 2015 Advanced Micro Devices, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+_CLC_OVERLOAD _CLC_DECL __CLC_GENTYPE atan2pi(__CLC_GENTYPE x, __CLC_GENTYPE y);
diff --git a/generic/lib/SOURCES b/generic/lib/SOURCES
index a05ccea..6398d65 100644
--- a/generic/lib/SOURCES
+++ b/generic/lib/SOURCES
@@ -70,6 +70,7 @@ math/asinh.cl
 math/asinpi.cl
 math/atan.cl
 math/atan2.cl
+math/atan2pi.cl
 math/atanh.cl
 math/atanpi.cl
 math/copysign.cl
diff --git a/generic/lib/math/atan2pi.cl b/generic/lib/math/atan2pi.cl
new file mode 100644
index 0000000..a15b14f
--- /dev/null
+++ b/generic/lib/math/atan2pi.cl
@@ -0,0 +1,221 @@
+/*
+ * Copyright (c) 2014,2015 Advanced Micro Devices, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <clc/clc.h>
+
+#include "math.h"
+#include "tables.h"
+#include "../clcmacro.h"
+
+_CLC_OVERLOAD _CLC_DEF  float atan2pi(float y, float x) {
+    const float pi = 0x1.921fb6p+1f;
+
+    float ax = fabs(x);
+    float ay = fabs(y);
+    float v = min(ax, ay);
+    float u = max(ax, ay);
+
+    // Scale since u could be large, as in "regular" divide
+    float s = u > 0x1.0p+96f ? 0x1.0p-32f : 1.0f;
+    float vbyu = s * MATH_DIVIDE(v, s*u);
+
+    float vbyu2 = vbyu * vbyu;
+
+    float p = mad(vbyu2, mad(vbyu2, -0x1.7e1f78p-9f, -0x1.7d1b98p-3f), -0x1.5554d0p-2f) * vbyu2 * vbyu;
+    float q = mad(vbyu2, mad(vbyu2, 0x1.1a714cp-2f, 0x1.287c56p+0f), 1.0f);
+
+    // Octant 0 result
+    float a = MATH_DIVIDE(mad(p, MATH_RECIP(q), vbyu), pi);
+
+    // Fix up 3 other octants
+    float at = 0.5f - a;
+    a = ay > ax ? at : a;
+    at = 1.0f - a;
+    a = x < 0.0F ? at : a;
+
+    // y == 0 => 0 for x >= 0, pi for x < 0
+    at = as_int(x) < 0 ? 1.0f : 0.0f;
+    a = y == 0.0f ? at : a;
+
+    // if (!FINITE_ONLY()) {
+        // x and y are +- Inf
+        at = x > 0.0f ? 0.25f : 0.75f;
+        a = ax == INFINITY & ay == INFINITY ? at : a;
+
+	// x or y is NaN
+	a = isnan(x) | isnan(y) ? as_float(QNANBITPATT_SP32) : a;
+    // }
+
+    // Fixup sign and return
+    return copysign(a, y);
+}
+
+_CLC_BINARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, float, atan2pi, float, float)
+
+#ifdef cl_khr_fp64
+#pragma OPENCL EXTENSION cl_khr_fp64 : enable
+
+_CLC_OVERLOAD _CLC_DEF double atan2pi(double y, double x) {
+    const double pi = 3.1415926535897932e+00;          /* 0x400921fb54442d18 */
+    const double pi_head = 3.1415926218032836e+00;     /* 0x400921fb50000000 */
+    const double pi_tail = 3.1786509547056392e-08;     /* 0x3e6110b4611a6263 */
+    const double piby2_head = 1.5707963267948965e+00;  /* 0x3ff921fb54442d18 */
+    const double piby2_tail = 6.1232339957367660e-17;  /* 0x3c91a62633145c07 */
+
+    double x2 = x;
+    int xneg = as_int2(x).hi < 0;
+    int xexp = (as_int2(x).hi >> 20) & 0x7ff;
+
+    double y2 = y;
+    int yneg = as_int2(y).hi < 0;
+    int yexp = (as_int2(y).hi >> 20) & 0x7ff;
+
+    int cond2 = (xexp < 1021) & (yexp < 1021);
+    int diffexp = yexp - xexp;
+
+    // Scale up both x and y if they are both below 1/4
+    double x1 = ldexp(x, 1024);
+    int xexp1 = (as_int2(x1).hi >> 20) & 0x7ff;
+    double y1 = ldexp(y, 1024);
+    int yexp1 = (as_int2(y1).hi >> 20) & 0x7ff;
+    int diffexp1 = yexp1 - xexp1;
+
+    diffexp = cond2 ? diffexp1 : diffexp;
+    x = cond2 ? x1 : x;
+    y = cond2 ? y1 : y;
+
+    // General case: take absolute values of arguments
+    double u = fabs(x);
+    double v = fabs(y);
+
+    // Swap u and v if necessary to obtain 0 < v < u. Compute v/u.
+    int swap_vu = u < v;
+    double uu = u;
+    u = swap_vu ? v : u;
+    v = swap_vu ? uu : v;
+
+    double vbyu = v / u;
+    double q1, q2;
+
+    // General values of v/u. Use a look-up table and series expansion.
+
+    {
+        double val = vbyu > 0.0625 ? vbyu : 0.063;
+        int index = convert_int(fma(256.0, val, 0.5));
+	double2 tv = USE_TABLE(atan_jby256_tbl, (index - 16));
+	q1 = tv.s0;
+	q2 = tv.s1;
+        double c = (double)index * 0x1.0p-8;
+
+        // We're going to scale u and v by 2^(-u_exponent) to bring them close to 1
+        // u_exponent could be EMAX so we have to do it in 2 steps
+        int m = -((int)(as_ulong(u) >> EXPSHIFTBITS_DP64) - EXPBIAS_DP64);
+	    double um = ldexp(u, m);
+	    double vm = ldexp(v, m);
+
+        // 26 leading bits of u
+        double u1 = as_double(as_ulong(um) & 0xfffffffff8000000UL);
+        double u2 = um - u1;
+
+        double r = MATH_DIVIDE(fma(-c, u2, fma(-c, u1, vm)), fma(c, vm, um));
+
+        // Polynomial approximation to atan(r)
+        double s = r * r;
+        q2 = q2 + fma((s * fma(-s, 0.19999918038989143496, 0.33333333333224095522)), -r, r);
+    }
+
+
+    double q3, q4;
+    {
+        q3 = 0.0;
+        q4 = vbyu;
+    }
+
+    double q5, q6;
+    {
+        double u1 = as_double(as_ulong(u) & 0xffffffff00000000UL);
+        double u2 = u - u1;
+        double vu1 = as_double(as_ulong(vbyu) & 0xffffffff00000000UL);
+        double vu2 = vbyu - vu1;
+
+        q5 = 0.0;
+        double s = vbyu * vbyu;
+        q6 = vbyu + fma(-vbyu * s,
+                        fma(-s,
+                            fma(-s,
+                                fma(-s,
+                                    fma(-s, 0.90029810285449784439E-01,
+                                        0.11110736283514525407),
+                                    0.14285713561807169030),
+                                0.19999999999393223405),
+                            0.33333333333333170500),
+			 MATH_DIVIDE(fma(-u, vu2, fma(-u2, vu1, fma(-u1, vu1, v))), u));
+    }
+
+
+    q3 = vbyu < 0x1.d12ed0af1a27fp-27 ? q3 : q5;
+    q4 = vbyu < 0x1.d12ed0af1a27fp-27 ? q4 : q6;
+
+    q1 = vbyu > 0.0625 ? q1 : q3;
+    q2 = vbyu > 0.0625 ? q2 : q4;
+
+    // Tidy-up according to which quadrant the arguments lie in
+    double res1, res2, res3, res4;
+    q1 = swap_vu ? piby2_head - q1 : q1;
+    q2 = swap_vu ? piby2_tail - q2 : q2;
+    q1 = xneg ? pi_head - q1 : q1;
+    q2 = xneg ? pi_tail - q2 : q2;
+    q1 = MATH_DIVIDE(q1 + q2, pi);
+    res4 = yneg ? -q1 : q1;
+
+    res1 = yneg ? -0.75 : 0.75;
+    res2 = yneg ? -0.25 : 0.25;
+    res3 = xneg ? res1 : res2;
+
+    res3 = isinf(y2) & isinf(x2) ? res3 : res4;
+    res1 = yneg ? -1.0 : 1.0;
+
+    // abs(x)/abs(y) > 2^56 and x < 0
+    res3 = (diffexp < -56 && xneg) ? res1 : res3;
+
+    res4 = MATH_DIVIDE(MATH_DIVIDE(y, x), pi);
+    // x positive and dominant over y by a factor of 2^28
+    res3 = diffexp < -28 & xneg == 0 ? res4 : res3;
+
+    // abs(y)/abs(x) > 2^56
+    res4 = yneg ? -0.5 : 0.5;        // atan(y/x) is insignificant compared to piby2
+    res3 = diffexp > 56 ? res4 : res3;
+
+    res3 = x2 == 0.0 ? res4 : res3;  // Zero x gives +- pi/2 depending on sign of y
+    res4 = xneg ? res1 : y2;
+
+    res3 = y2 == 0.0 ? res4 : res3;  // Zero y gives +-0 for positive x and +-pi for negative x
+    res3 = isnan(y2) ? y2 : res3;
+    res3 = isnan(x2) ? x2 : res3;
+
+    return res3;
+}
+
+
+_CLC_BINARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, double, atan2pi, double, double)
+
+#endif