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+.file "atan.s"
+
+
+// Copyright (c) 2000 - 2003, Intel Corporation
+// All rights reserved.
+//
+// Contributed 2000 by the Intel Numerics Group, Intel Corporation
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//
+// * Redistributions in binary form must reproduce the above copyright
+// notice, this list of conditions and the following disclaimer in the
+// documentation and/or other materials provided with the distribution.
+//
+// * The name of Intel Corporation may not be used to endorse or promote
+// products derived from this software without specific prior written
+// permission.
+
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTEL OR ITS
+// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY OR TORT (INCLUDING
+// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// Intel Corporation is the author of this code, and requests that all
+// problem reports or change requests be submitted to it directly at
+// http://www.intel.com/software/products/opensource/libraries/num.htm.
+//
+// History
+//==============================================================
+// 02/02/00  Initial version
+// 04/13/00  Improved speed
+// 04/19/00  Removed the qualifying predicate from the fmerge.s that
+//           takes the absolute value.
+// 06/16/00  Reassigned FP registers to eliminate stalls on loads
+// 08/30/00  Saved 5 cycles in main path by rearranging large argument logic
+//           and delaying use of result of fcmp in load by 1 group
+// 05/20/02  Cleaned up namespace and sf0 syntax
+// 08/20/02  Use atan2 algorithm with x=1 for better accuracy
+// 02/06/03  Reordered header: .section, .global, .proc, .align
+//
+// API
+//==============================================================
+// double atan(double Y)
+//
+// Overview of operation
+//==============================================================
+//
+// The atan function returns values in the interval [-pi/2,+pi/2].
+//
+// The algorithm used is the atan2(Y,X) algorithm where we fix X=1.0.
+//
+// There are two basic paths: swap true and swap false.
+// atan2(Y,X) ==> atan2(V/U) where U >= V. If Y > X, we must swap.
+//
+// p6  swap True    |Y| > |X|
+// p7  swap False   |Y| <= |X|
+//
+//
+// Simple trigonometric identities show
+//   Region 1
+//         |Y|<=1.0, V=Y, U=1.0     atan2(Y,X) = sgnY * (0 + atan(V/U))
+//
+//   Region 2
+//         |Y|>1.0, V=1.0, U=Y      atan2(Y,X) = sgnY * (pi/2 - atan(V/U))
+//
+//
+// We compute atan(V/U) from the identity
+//      atan(z) + atan([(V/U)-z] / [1+(V/U)z])
+//      where z is a limited precision approximation (16 bits) to V/U
+//
+// z is calculated with the assistance of the frcpa instruction.
+//
+// atan(z) is calculated by a polynomial z + z^3 * p(w),  w=z^2
+// where p(w) = P0+P1*w+...+P22*w^22
+//
+// Let d = [(V/U)-z] / [1+(V/U)z]) = (V-U*z)/(U+V*z)
+//
+// Approximate atan(d) by d + P0*d^3
+// Let F = 1/(U+V*z) * (1-a), where |a|< 2^-8.8.
+// Compute q(a) = 1 + a + ... + a^5.
+// Then F*q(a) approximates the reciprocal to more than 50 bits.
+
+// Special values
+//==============================================================
+// atan(QNAN)  = QNAN
+// atan(SNAN)  = quieted SNAN
+// atan(+-inf) = +- pi/2
+// atan(+-0)   = +-0
+
+// Registers used
+//==============================================================
+
+// predicate registers used:
+// p6 -> p15
+
+// floating-point registers used:
+// f8, input
+// f32 -> f116
+
+// general registers used
+// r14 -> r16
+
+// Assembly macros
+//==============================================================
+
+EXP_AD_P1                    = r14
+EXP_AD_P2                    = r15
+rsig_near_one                = r16
+
+atan2_Y                      = f8
+atan2_X                      = f1
+
+atan2_u1_X                   = f32
+atan2_u1_Y                   = f33
+atan2_z2_X                   = f34
+
+atan2_two                    = f36
+atan2_B1sq_Y                 = f37
+atan2_z1_X                   = f38
+atan2_B1X                    = f40
+
+atan2_B1Y                    = f41
+atan2_wp_X                   = f42
+atan2_B1sq_X                 = f43
+atan2_z                      = f44
+atan2_w                      = f45
+
+atan2_P0                     = f46
+atan2_P1                     = f47
+atan2_P2                     = f48
+atan2_P3                     = f49
+atan2_P4                     = f50
+
+atan2_P5                     = f51
+atan2_P6                     = f52
+atan2_P7                     = f53
+atan2_P8                     = f54
+atan2_P9                     = f55
+
+atan2_P10                    = f56
+atan2_P11                    = f57
+atan2_P12                    = f58
+atan2_P13                    = f59
+atan2_P14                    = f60
+
+atan2_P15                    = f61
+atan2_P16                    = f62
+atan2_P17                    = f63
+atan2_P18                    = f64
+atan2_P19                    = f65
+
+atan2_P20                    = f66
+atan2_P21                    = f67
+atan2_P22                    = f68
+atan2_pi_by_2                = f69
+atan2_sgn_pi_by_2            = f69
+atan2_V13                    = f70
+
+atan2_W11                    = f71
+atan2_E                      = f72
+atan2_wp_Y                   = f73
+atan2_V11                    = f74
+atan2_V12                    = f75
+
+atan2_V7                     = f76
+atan2_V8                     = f77
+atan2_W7                     = f78
+atan2_W8                     = f79
+atan2_W3                     = f80
+
+atan2_W4                     = f81
+atan2_V3                     = f82
+atan2_V4                     = f83
+atan2_F                      = f84
+atan2_gV                     = f85
+
+atan2_V10                    = f86
+atan2_zcub                   = f87
+atan2_V6                     = f88
+atan2_V9                     = f89
+atan2_W10                    = f90
+
+atan2_W6                     = f91
+atan2_W2                     = f92
+atan2_V2                     = f93
+atan2_alpha                  = f94
+atan2_alpha_1                = f95
+
+atan2_gVF                    = f96
+atan2_V5                     = f97
+atan2_W12                    = f98
+atan2_W5                     = f99
+atan2_alpha_sq               = f100
+
+atan2_Cp                     = f101
+atan2_V1                     = f102
+atan2_ysq                    = f103
+atan2_W1                     = f104
+atan2_alpha_cub              = f105
+
+atan2_C                      = f106
+atan2_d                      = f108
+atan2_A_hi                   = f109
+atan2_dsq                    = f110
+
+atan2_pd                     = f111
+atan2_A_lo                   = f112
+atan2_A                      = f113
+atan2_Pp                     = f114
+atan2_sgnY                   = f115
+
+atan2_sig_near_one           = f116
+atan2_near_one               = f116
+
+/////////////////////////////////////////////////////////////
+
+
+RODATA
+
+.align 16
+
+LOCAL_OBJECT_START(atan2_tb1)
+data8 0xA21922DC45605EA1 ,  0x00003FFA // P11
+data8 0xB199DD6D2675C40F ,  0x0000BFFA // P10
+data8 0xC2F01E5DDD100DBE ,  0x00003FFA // P9
+data8 0xD78F28FC2A592781 ,  0x0000BFFA // P8
+data8 0xF0F03ADB3FC930D3 ,  0x00003FFA // P7
+data8 0x88887EBB209E3543 ,  0x0000BFFB // P6
+data8 0x9D89D7D55C3287A5 ,  0x00003FFB // P5
+data8 0xBA2E8B9793955C77 ,  0x0000BFFB // P4
+data8 0xE38E38E320A8A098 ,  0x00003FFB // P3
+data8 0x9249249247E37913 ,  0x0000BFFC // P2
+data8 0xCCCCCCCCCCC906CD ,  0x00003FFC // P1
+data8 0xAAAAAAAAAAAAA8A9 ,  0x0000BFFD // P0
+data8 0x0000000000000000 ,  0x00000000 // pad to avoid bank conflict
+LOCAL_OBJECT_END(atan2_tb1)
+
+LOCAL_OBJECT_START(atan2_tb2)
+data8 0xCE585A259BD8374C ,  0x00003FF0 // P21
+data8 0x9F90FB984D8E39D0 ,  0x0000BFF3 // P20
+data8 0x9D3436AABE218776 ,  0x00003FF5 // P19
+data8 0xDEC343E068A6D2A8 ,  0x0000BFF6 // P18
+data8 0xF396268151CFB11C ,  0x00003FF7 // P17
+data8 0xD818B4BB43D84BF2 ,  0x0000BFF8 // P16
+data8 0xA2270D30A90AA220 ,  0x00003FF9 // P15
+data8 0xD5F4F2182E7A8725 ,  0x0000BFF9 // P14
+data8 0x80D601879218B53A ,  0x00003FFA // P13
+data8 0x9297B23CCFFB291F ,  0x0000BFFA // P12
+data8 0xFE7E52D2A89995B3 ,  0x0000BFEC // P22
+data8 0xC90FDAA22168C235 ,  0x00003FFF // pi/2
+LOCAL_OBJECT_END(atan2_tb2)
+
+
+
+
+.section .text
+GLOBAL_LIBM_ENTRY(atan)
+
+{ .mfi
+           nop.m 999
+           frcpa.s1     atan2_u1_Y,p7 = f1,atan2_Y
+           nop.i 999
+}
+{ .mfi
+           addl         EXP_AD_P1   = @ltoff(atan2_tb1), gp
+           fma.s1       atan2_two  = f1,f1,f1
+           nop.i 999
+;;
+}
+
+{ .mfi
+           ld8  EXP_AD_P1 = [EXP_AD_P1]
+           frcpa.s1     atan2_u1_X,p6 = f1,atan2_X
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_ysq  = atan2_Y,atan2_Y,f0
+           nop.i 999
+}
+;;
+
+{ .mfi
+           add  EXP_AD_P2 = 0xd0,EXP_AD_P1
+           fmerge.s     atan2_sgnY = atan2_Y,f1
+           nop.i 999
+}
+;;
+
+
+{ .mfi
+           ldfe         atan2_P11  = [EXP_AD_P1],16
+           fclass.m p10,p0 = atan2_Y, 0xc3     // Test for y=nan
+           nop.i 999
+}
+{ .mfi
+           ldfe         atan2_P21  = [EXP_AD_P2],16
+           nop.f 999
+           nop.i 999
+;;
+}
+
+
+{ .mfi
+           ldfe         atan2_P10  = [EXP_AD_P1],16
+           fnma.s1      atan2_B1Y  = atan2_u1_Y, atan2_Y, atan2_two
+           nop.i 999
+}
+{ .mfi
+           ldfe         atan2_P20  = [EXP_AD_P2],16
+           fma.s1       atan2_wp_Y   = atan2_u1_Y, atan2_u1_Y, f0
+           nop.i 999
+;;
+}
+
+{ .mfi
+           ldfe         atan2_P9   = [EXP_AD_P1],16
+           fma.s1       atan2_z1_X = atan2_u1_X, atan2_Y, f0
+           nop.i 999
+}
+{ .mfi
+           ldfe         atan2_P19  = [EXP_AD_P2],16
+           fnma.s1      atan2_B1X  = atan2_u1_X, atan2_X, atan2_two
+           nop.i 999
+}
+;;
+
+{ .mfi
+           ldfe         atan2_P8   = [EXP_AD_P1],16
+           fma.s1       atan2_z2_X = atan2_u1_X, atan2_ysq, f0
+           nop.i 999
+}
+{ .mfb
+           ldfe         atan2_P18  = [EXP_AD_P2],16
+(p10)      fma.d.s0 f8 = atan2_Y,atan2_X,f0   // If y=nan, result quietized y
+(p10)      br.ret.spnt b0        // Exit if y=nan
+}
+;;
+
+// p6 true if swap,    means |y| >  1.0    or ysq > 1.0
+// p7 true if no swap, means 1.0 >= |y|    or 1.0 >= ysq
+{ .mfi
+           ldfe         atan2_P7   = [EXP_AD_P1],16
+           fcmp.ge.s1 p7,p6    = f1, atan2_ysq
+           nop.i 999
+}
+{ .mmf
+           ldfe         atan2_P17  = [EXP_AD_P2],16
+           nop.m 999
+           nop.f 999
+}
+;;
+
+{ .mfi
+           ldfe         atan2_P6   = [EXP_AD_P1],16
+           fma.s1       atan2_E         = atan2_u1_Y, atan2_B1Y, atan2_Y
+           nop.i 999
+}
+{ .mfi
+           ldfe         atan2_P16  = [EXP_AD_P2],16
+           fma.s1       atan2_B1sq_Y = atan2_B1Y, atan2_B1Y, f0
+           nop.i 999
+;;
+}
+
+{ .mfi
+           ldfe         atan2_P5   = [EXP_AD_P1],16
+(p7)       fma.s1       atan2_wp_X   = atan2_z1_X, atan2_z1_X, f0
+           nop.i 999
+}
+{ .mfi
+           ldfe         atan2_P15       = [EXP_AD_P2],16
+(p7)       fma.s1       atan2_B1sq_X = atan2_B1X, atan2_B1X, f0
+           nop.i 999
+;;
+}
+
+{ .mfi
+           ldfe         atan2_P4   = [EXP_AD_P1],16
+(p6)       fma.s1       atan2_z         = atan2_u1_Y, atan2_B1Y, f0
+           nop.i 999
+}
+{ .mfi
+           ldfe         atan2_P14  = [EXP_AD_P2],16
+(p7)       fma.s1       atan2_E         = atan2_z2_X, atan2_B1X, atan2_X
+           nop.i 999
+;;
+}
+
+
+{ .mfi
+           ldfe         atan2_P3        = [EXP_AD_P1],16
+           fcmp.eq.s0  p14,p15=atan2_X,atan2_Y  // Dummy for denorm and invalid
+           nop.i 999
+}
+{ .mmf
+           ldfe         atan2_P13  = [EXP_AD_P2],16
+           nop.m 999
+(p7)       fma.s1       atan2_z         = atan2_z1_X, atan2_B1X, f0
+;;
+}
+
+{ .mfi
+           ldfe         atan2_P2        = [EXP_AD_P1],16
+(p6)       fma.s1       atan2_w         = atan2_wp_Y, atan2_B1sq_Y,f0
+           nop.i 999
+}
+{ .mlx
+           ldfe         atan2_P12  = [EXP_AD_P2],16
+           movl         rsig_near_one = 0x8000000000000001 // signif near 1.0
+;;
+}
+
+{ .mfi
+           ldfe         atan2_P1        = [EXP_AD_P1],16
+           fclass.m p9,p0 = atan2_Y, 0x23  // test if y inf
+           nop.i 999
+}
+{ .mfi
+           ldfe         atan2_P22       = [EXP_AD_P2],16
+(p7)       fma.s1       atan2_w         = atan2_wp_X, atan2_B1sq_X,f0
+           nop.i 999
+;;
+}
+
+{ .mfi
+           ldfe         atan2_P0        = [EXP_AD_P1],16
+           frcpa.s1     atan2_F,p0     = f1, atan2_E
+           nop.i 999
+}
+{ .mfi
+           ldfe         atan2_pi_by_2   = [EXP_AD_P2],16
+(p6)       fnma.s1       atan2_gV        = atan2_Y, atan2_z, atan2_X
+           nop.i 999
+;;
+}
+
+{ .mfi
+           setf.sig      atan2_sig_near_one = rsig_near_one
+(p7)       fnma.s1       atan2_gV        = atan2_X, atan2_z, atan2_Y
+           nop.i 999
+}
+{ .mfb
+           nop.m 999
+(p9)       fma.d.s0  f8 = atan2_sgnY, atan2_pi_by_2, f0  // +-pi/2 if y inf
+(p9)       br.ret.spnt b0      // exit if y inf, result is +-pi/2
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_V13       = atan2_w, atan2_P11, atan2_P10
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_W11       = atan2_w, atan2_P21, atan2_P20
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_V11       = atan2_w, atan2_P9, atan2_P8
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_V12       = atan2_w, atan2_w, f0
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_V8        = atan2_w, atan2_P7 , atan2_P6
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_W8        = atan2_w, atan2_P19, atan2_P18
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fnma.s1      atan2_alpha     = atan2_E, atan2_F, f1
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fnma.s1      atan2_alpha_1   = atan2_E, atan2_F, atan2_two
+           nop.i 999
+;;
+}
+
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_V7        = atan2_w, atan2_P5 , atan2_P4
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_W7        = atan2_w, atan2_P17, atan2_P16
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_V4        = atan2_w, atan2_P3 , atan2_P2
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_W4        = atan2_w, atan2_P15, atan2_P14
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_V3        = atan2_w, atan2_P1 , atan2_P0
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_W3        = atan2_w, atan2_P13, atan2_P12
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_V10       = atan2_V12, atan2_V13, atan2_V11
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_gVF       = atan2_gV, atan2_F, f0
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_alpha_sq  = atan2_alpha, atan2_alpha, f0
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_Cp        = atan2_alpha, atan2_alpha_1, f1
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_V9        = atan2_V12, atan2_V12, f0
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_W10       = atan2_V12, atan2_P22 , atan2_W11
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_V6        = atan2_V12, atan2_V8 , atan2_V7
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_W6        = atan2_V12, atan2_W8 , atan2_W7
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_V2        = atan2_V12, atan2_V4 , atan2_V3
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_W2        = atan2_V12, atan2_W4  , atan2_W3
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_alpha_cub = atan2_alpha, atan2_alpha_sq, f0
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_C         = atan2_gVF, atan2_Cp, f0
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_W12       = atan2_V9, atan2_V9, f0
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_V5        = atan2_V9, atan2_V10, atan2_V6
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_W5        = atan2_V9, atan2_W10, atan2_W6
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fclass.m p8,p0 = atan2_Y, 0x07  // Test for y=0
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_d         = atan2_alpha_cub, atan2_C, atan2_C
+           nop.i 999
+}
+;;
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_W12       = atan2_V9, atan2_W12, f0
+           nop.i 999
+}
+;;
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_V1        = atan2_V9, atan2_V5, atan2_V2
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_W1        = atan2_V9, atan2_W5, atan2_W2
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+(p8)       fmerge.s     f8              = atan2_sgnY, f0  // +-0 if y=0
+           nop.i 999
+}
+{ .mfb
+           nop.m 999
+           fma.s1       atan2_zcub      = atan2_z, atan2_w, f0
+(p8)       br.ret.spnt b0      // Exit if y=0
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_pd        = atan2_P0, atan2_d, f0
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_dsq       = atan2_d, atan2_d, f0
+           nop.i 999
+;;
+}
+
+
+{ .mfi
+           nop.m 999
+           fmerge.se    atan2_near_one = f1, atan2_sig_near_one // Const ~1.0
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_Pp        = atan2_W12, atan2_W1, atan2_V1
+           nop.i 999
+;;
+}
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_sgn_pi_by_2 = atan2_pi_by_2, atan2_sgnY, f0
+           nop.i 999
+}
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_A_lo      = atan2_pd, atan2_dsq, atan2_d
+           nop.i 999
+;;
+}
+
+
+{ .mfi
+           nop.m 999
+           fma.s1       atan2_A_hi      = atan2_zcub, atan2_Pp, atan2_z
+           nop.i 999
+;;
+}
+
+
+{ .mfi
+           nop.m 999
+(p6)       fma.s1       atan2_A         = atan2_A_hi, f1, atan2_A_lo
+           nop.i 999
+}
+// For |Y| <= |X| and X > 0, result is A_hi + A_lo
+{ .mfi
+           nop.m 999
+(p7)       fma.d.s0       f8         = atan2_A_hi, f1, atan2_A_lo
+           nop.i 999
+;;
+}
+
+// For |Y| > |X|, result is  +- pi/2 - (A_hi + A_lo)
+// We perturb A by multiplying by 1.0+1ulp as we produce the result
+// in order to get symmetrically rounded results in directed rounding modes.
+// If we don't do this, there are a few cases where the trailing 11 bits of
+// the significand of the result, before converting to double, are zero.  These
+// cases do not round symmetrically in round to +infinity or round to -infinity.
+{ .mfb
+           nop.m 999
+(p6)       fnma.d.s0      f8        = atan2_A, atan2_near_one, atan2_sgn_pi_by_2
+           br.ret.sptk  b0
+;;
+}
+
+GLOBAL_LIBM_END(atan)