math: Add ilogb ported from amd-builtins

The scalar float/double function bodies are a direct copy/paste
with usage of the CLC wrappers to vectorize them.

This commit also adds in the FP_ILOGB0 and FP_ILOGBNAN macros which are
equal to the results of ilogb(0.0f) and ilogb(float nan) respectively.

v2: Add FP_ILOGB0 and FP_ILOGBNAN definitions

Signed-off-by: Aaron Watry <awatry@gmail.com>
Reviewed-by: Jan Vesely <jan.vesely@rutgers.edu>
v1 Reviewed-by: Tom Stellard <thomas.stellard@amd.com>

llvm-svn: 261639

libclc/generic/include/clc/clc.h

@@ -62,6 +62,7 @@
 #include <clc/math/half_rsqrt.h>
 #include <clc/math/half_sqrt.h>
 #include <clc/math/hypot.h>
+#include <clc/math/ilogb.h>
 #include <clc/math/ldexp.h>
 #include <clc/math/log.h>
 #include <clc/math/log10.h>

libclc/generic/include/clc/float/definitions.h

@@ -14,6 +14,9 @@
 #define FLT_MIN         0x1.0p-126f
 #define FLT_EPSILON     0x1.0p-23f
 
+#define FP_ILOGB0 (-2147483647 - 1)
+#define FP_ILOGBNAN (-2147483647 - 1)
+
 #define M_E_F           0x1.5bf0a8p+1f
 #define M_LOG2E_F       0x1.715476p+0f
 #define M_LOG10E_F      0x1.bcb7b2p-2f

libclc/generic/include/clc/math/ilogb.h

@@ -0,0 +1,5 @@
+#define __CLC_BODY <clc/math/ilogb.inc>
+
+#include <clc/math/gentype.inc>
+
+#undef __CLC_BODY

libclc/generic/include/clc/math/ilogb.inc

@@ -0,0 +1 @@
+_CLC_OVERLOAD _CLC_DECL __CLC_INTN ilogb(__CLC_GENTYPE x);

libclc/generic/lib/SOURCES

@@ -90,6 +90,7 @@ math/frexp.cl
 math/half_rsqrt.cl
 math/half_sqrt.cl
 math/hypot.cl
+math/ilogb.cl
 math/clc_ldexp.cl
 math/ldexp.cl
 math/log.cl

libclc/generic/lib/math/ilogb.cl

@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2015 Advanced Micro Devices, Inc.
+ * Copyright (c) 2016 Aaron Watry
+ *
+ * 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 "../clcmacro.h"
+#include "math.h"
+
+_CLC_OVERLOAD _CLC_DEF int ilogb(float x) {
+    uint ux = as_uint(x);
+    uint ax = ux & EXSIGNBIT_SP32;
+    int rs = -118 - (int) clz(ux & MANTBITS_SP32);
+    int r = (int) (ax >> EXPSHIFTBITS_SP32) - EXPBIAS_SP32;
+    r = ax < 0x00800000U ? rs : r;
+    r = ax > EXPBITS_SP32 | ax == 0 ? 0x80000000 : r;
+    r = ax == EXPBITS_SP32 ? 0x7fffffff : r;
+    return r;
+}
+
+_CLC_UNARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, int, ilogb, float);
+
+#ifdef cl_khr_fp64
+#pragma OPENCL EXTENSION cl_khr_fp64 : enable
+
+_CLC_OVERLOAD _CLC_DEF ilogb(double x) {
+    ulong ux = as_ulong(x);
+    ulong ax = ux & ~SIGNBIT_DP64;
+    int r = (int) (ax >> EXPSHIFTBITS_DP64) - EXPBIAS_DP64;
+    int rs = -1011 - (int) clz(ax & MANTBITS_DP64);
+    r = ax < 0x0010000000000000UL ? rs : r;
+    r = ax > 0x7ff0000000000000UL | ax == 0UL ? 0x80000000 : r;
+    r = ax == 0x7ff0000000000000UL ? 0x7fffffff : r;
+    return r;
+}
+
+_CLC_UNARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, int, ilogb, double);
+
+#endif // cl_khr_fp64