From 37c00bd42f4999aeedb2ef3f523e75daaca46ed6 Mon Sep 17 00:00:00 2001 From: Reuben Dunnington Date: Tue, 19 Sep 2023 20:51:13 -0700 Subject: [PATCH] fix compile errors with pow/powf --- src/libc-shim/include/math.h | 1 + src/libc-shim/src/__math_oflowf.c | 6 + src/libc-shim/src/__math_uflowf.c | 6 + src/libc-shim/src/exp2f_data.c | 35 ++++++ src/libc-shim/src/exp2f_data.h | 23 ++++ src/libc-shim/src/libm.h | 8 ++ src/libc-shim/src/powf.c | 187 ++++++++++++++++++++++++++++++ src/libc-shim/src/powf_data.c | 34 ++++++ src/libc-shim/src/powf_data.h | 26 +++++ 9 files changed, 326 insertions(+) create mode 100644 src/libc-shim/src/__math_oflowf.c create mode 100644 src/libc-shim/src/__math_uflowf.c create mode 100644 src/libc-shim/src/exp2f_data.c create mode 100644 src/libc-shim/src/exp2f_data.h create mode 100644 src/libc-shim/src/powf.c create mode 100644 src/libc-shim/src/powf_data.c create mode 100644 src/libc-shim/src/powf_data.h diff --git a/src/libc-shim/include/math.h b/src/libc-shim/include/math.h index 787e99e..7e186ee 100644 --- a/src/libc-shim/include/math.h +++ b/src/libc-shim/include/math.h @@ -82,6 +82,7 @@ double log2(double); float log2f(float); double pow(double, double); +float powf(float, float); double scalbn(double, int); diff --git a/src/libc-shim/src/__math_oflowf.c b/src/libc-shim/src/__math_oflowf.c new file mode 100644 index 0000000..fa7d062 --- /dev/null +++ b/src/libc-shim/src/__math_oflowf.c @@ -0,0 +1,6 @@ +#include "libm.h" + +float __math_oflowf(uint32_t sign) +{ + return __math_xflowf(sign, 0x1p97f); +} diff --git a/src/libc-shim/src/__math_uflowf.c b/src/libc-shim/src/__math_uflowf.c new file mode 100644 index 0000000..94d50f2 --- /dev/null +++ b/src/libc-shim/src/__math_uflowf.c @@ -0,0 +1,6 @@ +#include "libm.h" + +float __math_uflowf(uint32_t sign) +{ + return __math_xflowf(sign, 0x1p-95f); +} diff --git a/src/libc-shim/src/exp2f_data.c b/src/libc-shim/src/exp2f_data.c new file mode 100644 index 0000000..be32472 --- /dev/null +++ b/src/libc-shim/src/exp2f_data.c @@ -0,0 +1,35 @@ +/* + * Shared data between expf, exp2f and powf. + * + * Copyright (c) 2017-2018, Arm Limited. + * SPDX-License-Identifier: MIT + */ + +#include "exp2f_data.h" + +#define N (1 << EXP2F_TABLE_BITS) + +const struct exp2f_data __exp2f_data = { + /* tab[i] = uint(2^(i/N)) - (i << 52-BITS) + used for computing 2^(k/N) for an int |k| < 150 N as + double(tab[k%N] + (k << 52-BITS)) */ + .tab = { +0x3ff0000000000000, 0x3fefd9b0d3158574, 0x3fefb5586cf9890f, 0x3fef9301d0125b51, +0x3fef72b83c7d517b, 0x3fef54873168b9aa, 0x3fef387a6e756238, 0x3fef1e9df51fdee1, +0x3fef06fe0a31b715, 0x3feef1a7373aa9cb, 0x3feedea64c123422, 0x3feece086061892d, +0x3feebfdad5362a27, 0x3feeb42b569d4f82, 0x3feeab07dd485429, 0x3feea47eb03a5585, +0x3feea09e667f3bcd, 0x3fee9f75e8ec5f74, 0x3feea11473eb0187, 0x3feea589994cce13, +0x3feeace5422aa0db, 0x3feeb737b0cdc5e5, 0x3feec49182a3f090, 0x3feed503b23e255d, +0x3feee89f995ad3ad, 0x3feeff76f2fb5e47, 0x3fef199bdd85529c, 0x3fef3720dcef9069, +0x3fef5818dcfba487, 0x3fef7c97337b9b5f, 0x3fefa4afa2a490da, 0x3fefd0765b6e4540, + }, + .shift_scaled = 0x1.8p+52 / N, + .poly = { + 0x1.c6af84b912394p-5, 0x1.ebfce50fac4f3p-3, 0x1.62e42ff0c52d6p-1, + }, + .shift = 0x1.8p+52, + .invln2_scaled = 0x1.71547652b82fep+0 * N, + .poly_scaled = { + 0x1.c6af84b912394p-5/N/N/N, 0x1.ebfce50fac4f3p-3/N/N, 0x1.62e42ff0c52d6p-1/N, + }, +}; diff --git a/src/libc-shim/src/exp2f_data.h b/src/libc-shim/src/exp2f_data.h new file mode 100644 index 0000000..af78348 --- /dev/null +++ b/src/libc-shim/src/exp2f_data.h @@ -0,0 +1,23 @@ +/* + * Copyright (c) 2017-2018, Arm Limited. + * SPDX-License-Identifier: MIT + */ +#ifndef _EXP2F_DATA_H +#define _EXP2F_DATA_H + +#include +#include + +/* Shared between expf, exp2f and powf. */ +#define EXP2F_TABLE_BITS 5 +#define EXP2F_POLY_ORDER 3 +extern const struct exp2f_data { + uint64_t tab[1 << EXP2F_TABLE_BITS]; + double shift_scaled; + double poly[EXP2F_POLY_ORDER]; + double shift; + double invln2_scaled; + double poly_scaled[EXP2F_POLY_ORDER]; +} __exp2f_data; + +#endif diff --git a/src/libc-shim/src/libm.h b/src/libc-shim/src/libm.h index ee69eb6..9edc438 100644 --- a/src/libc-shim/src/libm.h +++ b/src/libc-shim/src/libm.h @@ -1,3 +1,6 @@ +#ifndef _LIBM_H +#define _LIBM_H + #include #include #include @@ -144,8 +147,13 @@ int __rem_pio2f(float, double*); float __sindf(double); float __cosdf(double); +float __math_xflowf(uint32_t, float); +float __math_uflowf(uint32_t); +float __math_oflowf(uint32_t); float __math_invalidf(float); double __math_xflow(uint32_t, double); double __math_uflow(uint32_t); double __math_oflow(uint32_t); double __math_invalid(double); + +#endif // _LIBM_H diff --git a/src/libc-shim/src/powf.c b/src/libc-shim/src/powf.c new file mode 100644 index 0000000..2356811 --- /dev/null +++ b/src/libc-shim/src/powf.c @@ -0,0 +1,187 @@ +/* + * Copyright (c) 2017-2018, Arm Limited. + * SPDX-License-Identifier: MIT + */ + +#include +#include +#include "libm.h" +#include "exp2f_data.h" +#include "powf_data.h" + +/* +POWF_LOG2_POLY_ORDER = 5 +EXP2F_TABLE_BITS = 5 + +ULP error: 0.82 (~ 0.5 + relerr*2^24) +relerr: 1.27 * 2^-26 (Relative error ~= 128*Ln2*relerr_log2 + relerr_exp2) +relerr_log2: 1.83 * 2^-33 (Relative error of logx.) +relerr_exp2: 1.69 * 2^-34 (Relative error of exp2(ylogx).) +*/ + +#define N (1 << POWF_LOG2_TABLE_BITS) +#define T __powf_log2_data.tab +#define A __powf_log2_data.poly +#define OFF 0x3f330000 + +/* Subnormal input is normalized so ix has negative biased exponent. + Output is multiplied by N (POWF_SCALE) if TOINT_INTRINICS is set. */ +static inline double_t log2_inline(uint32_t ix) +{ + double_t z, r, r2, r4, p, q, y, y0, invc, logc; + uint32_t iz, top, tmp; + int k, i; + + /* x = 2^k z; where z is in range [OFF,2*OFF] and exact. + The range is split into N subintervals. + The ith subinterval contains z and c is near its center. */ + tmp = ix - OFF; + i = (tmp >> (23 - POWF_LOG2_TABLE_BITS)) % N; + top = tmp & 0xff800000; + iz = ix - top; + k = (int32_t)top >> (23 - POWF_SCALE_BITS); /* arithmetic shift */ + invc = T[i].invc; + logc = T[i].logc; + z = (double_t)asfloat(iz); + + /* log2(x) = log1p(z/c-1)/ln2 + log2(c) + k */ + r = z * invc - 1; + y0 = logc + (double_t)k; + + /* Pipelined polynomial evaluation to approximate log1p(r)/ln2. */ + r2 = r * r; + y = A[0] * r + A[1]; + p = A[2] * r + A[3]; + r4 = r2 * r2; + q = A[4] * r + y0; + q = p * r2 + q; + y = y * r4 + q; + return y; +} + +#undef N +#undef T +#define N (1 << EXP2F_TABLE_BITS) +#define T __exp2f_data.tab +#define SIGN_BIAS (1 << (EXP2F_TABLE_BITS + 11)) + +/* The output of log2 and thus the input of exp2 is either scaled by N + (in case of fast toint intrinsics) or not. The unscaled xd must be + in [-1021,1023], sign_bias sets the sign of the result. */ +static inline float exp2_inline(double_t xd, uint32_t sign_bias) +{ + uint64_t ki, ski, t; + double_t kd, z, r, r2, y, s; + +#if TOINT_INTRINSICS +#define C __exp2f_data.poly_scaled + /* N*x = k + r with r in [-1/2, 1/2] */ + kd = roundtoint(xd); /* k */ + ki = converttoint(xd); +#else +#define C __exp2f_data.poly +#define SHIFT __exp2f_data.shift_scaled + /* x = k/N + r with r in [-1/(2N), 1/(2N)] */ + kd = eval_as_double(xd + SHIFT); + ki = asuint64(kd); + kd -= SHIFT; /* k/N */ +#endif + r = xd - kd; + + /* exp2(x) = 2^(k/N) * 2^r ~= s * (C0*r^3 + C1*r^2 + C2*r + 1) */ + t = T[ki % N]; + ski = ki + sign_bias; + t += ski << (52 - EXP2F_TABLE_BITS); + s = asdouble(t); + z = C[0] * r + C[1]; + r2 = r * r; + y = C[2] * r + 1; + y = z * r2 + y; + y = y * s; + return eval_as_float(y); +} + +/* Returns 0 if not int, 1 if odd int, 2 if even int. The argument is + the bit representation of a non-zero finite floating-point value. */ +static inline int checkint(uint32_t iy) +{ + int e = iy >> 23 & 0xff; + if (e < 0x7f) + return 0; + if (e > 0x7f + 23) + return 2; + if (iy & ((1 << (0x7f + 23 - e)) - 1)) + return 0; + if (iy & (1 << (0x7f + 23 - e))) + return 1; + return 2; +} + +static inline int zeroinfnan(uint32_t ix) +{ + return 2 * ix - 1 >= 2u * 0x7f800000 - 1; +} + +float powf(float x, float y) +{ + uint32_t sign_bias = 0; + uint32_t ix, iy; + + ix = asuint(x); + iy = asuint(y); + if (predict_false(ix - 0x00800000 >= 0x7f800000 - 0x00800000 || + zeroinfnan(iy))) { + /* Either (x < 0x1p-126 or inf or nan) or (y is 0 or inf or nan). */ + if (predict_false(zeroinfnan(iy))) { + if (2 * iy == 0) + return issignalingf_inline(x) ? x + y : 1.0f; + if (ix == 0x3f800000) + return issignalingf_inline(y) ? x + y : 1.0f; + if (2 * ix > 2u * 0x7f800000 || + 2 * iy > 2u * 0x7f800000) + return x + y; + if (2 * ix == 2 * 0x3f800000) + return 1.0f; + if ((2 * ix < 2 * 0x3f800000) == !(iy & 0x80000000)) + return 0.0f; /* |x|<1 && y==inf or |x|>1 && y==-inf. */ + return y * y; + } + if (predict_false(zeroinfnan(ix))) { + float_t x2 = x * x; + if (ix & 0x80000000 && checkint(iy) == 1) + x2 = -x2; + /* Without the barrier some versions of clang hoist the 1/x2 and + thus division by zero exception can be signaled spuriously. */ + // NOTE(orca): no fp barriers + //return iy & 0x80000000 ? fp_barrierf(1 / x2) : x2; + return iy & 0x80000000 ? (1 / x2) : x2; + } + /* x and y are non-zero finite. */ + if (ix & 0x80000000) { + /* Finite x < 0. */ + int yint = checkint(iy); + if (yint == 0) + return __math_invalidf(x); + if (yint == 1) + sign_bias = SIGN_BIAS; + ix &= 0x7fffffff; + } + if (ix < 0x00800000) { + /* Normalize subnormal x so exponent becomes negative. */ + ix = asuint(x * 0x1p23f); + ix &= 0x7fffffff; + ix -= 23 << 23; + } + } + double_t logx = log2_inline(ix); + double_t ylogx = y * logx; /* cannot overflow, y is single prec. */ + if (predict_false((asuint64(ylogx) >> 47 & 0xffff) >= + asuint64(126.0 * POWF_SCALE) >> 47)) { + /* |y*log(x)| >= 126. */ + if (ylogx > 0x1.fffffffd1d571p+6 * POWF_SCALE) + return __math_oflowf(sign_bias); + if (ylogx <= -150.0 * POWF_SCALE) + return __math_uflowf(sign_bias); + } + return exp2_inline(ylogx, sign_bias); +} diff --git a/src/libc-shim/src/powf_data.c b/src/libc-shim/src/powf_data.c new file mode 100644 index 0000000..13e1d9a --- /dev/null +++ b/src/libc-shim/src/powf_data.c @@ -0,0 +1,34 @@ +/* + * Data definition for powf. + * + * Copyright (c) 2017-2018, Arm Limited. + * SPDX-License-Identifier: MIT + */ + +#include "powf_data.h" + +const struct powf_log2_data __powf_log2_data = { + .tab = { + { 0x1.661ec79f8f3bep+0, -0x1.efec65b963019p-2 * POWF_SCALE }, + { 0x1.571ed4aaf883dp+0, -0x1.b0b6832d4fca4p-2 * POWF_SCALE }, + { 0x1.49539f0f010bp+0, -0x1.7418b0a1fb77bp-2 * POWF_SCALE }, + { 0x1.3c995b0b80385p+0, -0x1.39de91a6dcf7bp-2 * POWF_SCALE }, + { 0x1.30d190c8864a5p+0, -0x1.01d9bf3f2b631p-2 * POWF_SCALE }, + { 0x1.25e227b0b8eap+0, -0x1.97c1d1b3b7afp-3 * POWF_SCALE }, + { 0x1.1bb4a4a1a343fp+0, -0x1.2f9e393af3c9fp-3 * POWF_SCALE }, + { 0x1.12358f08ae5bap+0, -0x1.960cbbf788d5cp-4 * POWF_SCALE }, + { 0x1.0953f419900a7p+0, -0x1.a6f9db6475fcep-5 * POWF_SCALE }, + { 0x1p+0, 0x0p+0 * POWF_SCALE }, + { 0x1.e608cfd9a47acp-1, 0x1.338ca9f24f53dp-4 * POWF_SCALE }, + { 0x1.ca4b31f026aap-1, 0x1.476a9543891bap-3 * POWF_SCALE }, + { 0x1.b2036576afce6p-1, 0x1.e840b4ac4e4d2p-3 * POWF_SCALE }, + { 0x1.9c2d163a1aa2dp-1, 0x1.40645f0c6651cp-2 * POWF_SCALE }, + { 0x1.886e6037841edp-1, 0x1.88e9c2c1b9ff8p-2 * POWF_SCALE }, + { 0x1.767dcf5534862p-1, 0x1.ce0a44eb17bccp-2 * POWF_SCALE }, + }, + .poly = { + 0x1.27616c9496e0bp-2 * POWF_SCALE, -0x1.71969a075c67ap-2 * POWF_SCALE, + 0x1.ec70a6ca7baddp-2 * POWF_SCALE, -0x1.7154748bef6c8p-1 * POWF_SCALE, + 0x1.71547652ab82bp0 * POWF_SCALE, + } +}; diff --git a/src/libc-shim/src/powf_data.h b/src/libc-shim/src/powf_data.h new file mode 100644 index 0000000..a7b997a --- /dev/null +++ b/src/libc-shim/src/powf_data.h @@ -0,0 +1,26 @@ +/* + * Copyright (c) 2017-2018, Arm Limited. + * SPDX-License-Identifier: MIT + */ +#ifndef _POWF_DATA_H +#define _POWF_DATA_H + +#include "libm.h" +#include "exp2f_data.h" + +#define POWF_LOG2_TABLE_BITS 4 +#define POWF_LOG2_POLY_ORDER 5 +#if TOINT_INTRINSICS +#define POWF_SCALE_BITS EXP2F_TABLE_BITS +#else +#define POWF_SCALE_BITS 0 +#endif +#define POWF_SCALE ((double)(1 << POWF_SCALE_BITS)) +extern const struct powf_log2_data { + struct { + double invc, logc; + } tab[1 << POWF_LOG2_TABLE_BITS]; + double poly[POWF_LOG2_POLY_ORDER]; +} __powf_log2_data; + +#endif