[libc-commits] [libc] 38cadd9 - [libc] Implement expf function that is correctly rounded for all rounding modes.
Tue Ly via libc-commits
libc-commits at lists.llvm.org
Fri Mar 11 04:17:05 PST 2022
Author: Tue Ly
Date: 2022-03-11T07:16:47-05:00
New Revision: 38cadd90b711699e25092260dca0ee05697f1b17
URL: https://github.com/llvm/llvm-project/commit/38cadd90b711699e25092260dca0ee05697f1b17
DIFF: https://github.com/llvm/llvm-project/commit/38cadd90b711699e25092260dca0ee05697f1b17.diff
LOG: [libc] Implement expf function that is correctly rounded for all rounding modes.
Implement expf function that is correctly rounded for all rounding modes.
Reviewed By: sivachandra, zimmermann6
Differential Revision: https://reviews.llvm.org/D121440
Added:
libc/test/src/math/exhaustive/expf_test.cpp
Modified:
libc/src/math/generic/CMakeLists.txt
libc/src/math/generic/expf.cpp
libc/test/src/math/exhaustive/CMakeLists.txt
libc/test/src/math/expf_test.cpp
Removed:
################################################################################
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
index cba0879be4802..e7449bdf1753d 100644
--- a/libc/src/math/generic/CMakeLists.txt
+++ b/libc/src/math/generic/CMakeLists.txt
@@ -476,9 +476,10 @@ add_entrypoint_object(
HDRS
../expf.h
DEPENDS
- .exp_utils
- .math_utils
+ libc.src.__support.FPUtil.fputil
libc.include.math
+ COMPILE_OPTIONS
+ -O3
)
add_entrypoint_object(
diff --git a/libc/src/math/generic/expf.cpp b/libc/src/math/generic/expf.cpp
index 451f12ab2f60a..9b4948751d2c6 100644
--- a/libc/src/math/generic/expf.cpp
+++ b/libc/src/math/generic/expf.cpp
@@ -7,64 +7,218 @@
//===----------------------------------------------------------------------===//
#include "src/math/expf.h"
-#include "exp_utils.h"
-#include "math_utils.h"
-
+#include "src/__support/FPUtil/BasicOperations.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FMA.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/PolyEval.h"
#include "src/__support/common.h"
-#include <math.h>
-
-#include <stdint.h>
-#define InvLn2N exp2f_data.invln2_scaled
-#define T exp2f_data.tab
-#define C exp2f_data.poly_scaled
-#define SHIFT exp2f_data.shift
+#include <errno.h>
namespace __llvm_libc {
+// Lookup table for exp(m) with m = -104, ..., 89.
+// -104 = floor(log(single precision's min denormal))
+// 89 = ceil(log(single precision's max normal))
+// Table is generated with Sollya as follow:
+// > display = hexadecimal;
+// > for i from -104 to 89 do { D(exp(i)); };
+static constexpr double EXP_M1[195] = {
+ 0x1.f1e6b68529e33p-151, 0x1.525be4e4e601dp-149, 0x1.cbe0a45f75eb1p-148,
+ 0x1.3884e838aea68p-146, 0x1.a8c1f14e2af5dp-145, 0x1.20a717e64a9bdp-143,
+ 0x1.8851d84118908p-142, 0x1.0a9bdfb02d240p-140, 0x1.6a5bea046b42ep-139,
+ 0x1.ec7f3b269efa8p-138, 0x1.4eafb87eab0f2p-136, 0x1.c6e2d05bbc000p-135,
+ 0x1.35208867c2683p-133, 0x1.a425b317eeacdp-132, 0x1.1d8508fa8246ap-130,
+ 0x1.840fbc08fdc8ap-129, 0x1.07b7112bc1ffep-127, 0x1.666d0dad2961dp-126,
+ 0x1.e726c3f64d0fep-125, 0x1.4b0dc07cabf98p-123, 0x1.c1f2daf3b6a46p-122,
+ 0x1.31c5957a47de2p-120, 0x1.9f96445648b9fp-119, 0x1.1a6baeadb4fd1p-117,
+ 0x1.7fd974d372e45p-116, 0x1.04da4d1452919p-114, 0x1.62891f06b3450p-113,
+ 0x1.e1dd273aa8a4ap-112, 0x1.4775e0840bfddp-110, 0x1.bd109d9d94bdap-109,
+ 0x1.2e73f53fba844p-107, 0x1.9b138170d6bfep-106, 0x1.175af0cf60ec5p-104,
+ 0x1.7baee1bffa80bp-103, 0x1.02057d1245cebp-101, 0x1.5eafffb34ba31p-100,
+ 0x1.dca23bae16424p-99, 0x1.43e7fc88b8056p-97, 0x1.b83bf23a9a9ebp-96,
+ 0x1.2b2b8dd05b318p-94, 0x1.969d47321e4ccp-93, 0x1.1452b7723aed2p-91,
+ 0x1.778fe2497184cp-90, 0x1.fe7116182e9ccp-89, 0x1.5ae191a99585ap-87,
+ 0x1.d775d87da854dp-86, 0x1.4063f8cc8bb98p-84, 0x1.b374b315f87c1p-83,
+ 0x1.27ec458c65e3cp-81, 0x1.923372c67a074p-80, 0x1.1152eaeb73c08p-78,
+ 0x1.737c5645114b5p-77, 0x1.f8e6c24b5592ep-76, 0x1.571db733a9d61p-74,
+ 0x1.d257d547e083fp-73, 0x1.3ce9b9de78f85p-71, 0x1.aebabae3a41b5p-70,
+ 0x1.24b6031b49bdap-68, 0x1.8dd5e1bb09d7ep-67, 0x1.0e5b73d1ff53dp-65,
+ 0x1.6f741de1748ecp-64, 0x1.f36bd37f42f3ep-63, 0x1.536452ee2f75cp-61,
+ 0x1.cd480a1b74820p-60, 0x1.39792499b1a24p-58, 0x1.aa0de4bf35b38p-57,
+ 0x1.2188ad6ae3303p-55, 0x1.898471fca6055p-54, 0x1.0b6c3afdde064p-52,
+ 0x1.6b7719a59f0e0p-51, 0x1.ee001eed62aa0p-50, 0x1.4fb547c775da8p-48,
+ 0x1.c8464f7616468p-47, 0x1.36121e24d3bbap-45, 0x1.a56e0c2ac7f75p-44,
+ 0x1.1e642baeb84a0p-42, 0x1.853f01d6d53bap-41, 0x1.0885298767e9ap-39,
+ 0x1.67852a7007e42p-38, 0x1.e8a37a45fc32ep-37, 0x1.4c1078fe9228ap-35,
+ 0x1.c3527e433fab1p-34, 0x1.32b48bf117da2p-32, 0x1.a0db0d0ddb3ecp-31,
+ 0x1.1b48655f37267p-29, 0x1.81056ff2c5772p-28, 0x1.05a628c699fa1p-26,
+ 0x1.639e3175a689dp-25, 0x1.e355bbaee85cbp-24, 0x1.4875ca227ec38p-22,
+ 0x1.be6c6fdb01612p-21, 0x1.2f6053b981d98p-19, 0x1.9c54c3b43bc8bp-18,
+ 0x1.18354238f6764p-16, 0x1.7cd79b5647c9bp-15, 0x1.02cf22526545ap-13,
+ 0x1.5fc21041027adp-12, 0x1.de16b9c24a98fp-11, 0x1.44e51f113d4d6p-9,
+ 0x1.b993fe00d5376p-8, 0x1.2c155b8213cf4p-6, 0x1.97db0ccceb0afp-5,
+ 0x1.152aaa3bf81ccp-3, 0x1.78b56362cef38p-2, 0x1.0000000000000p+0,
+ 0x1.5bf0a8b145769p+1, 0x1.d8e64b8d4ddaep+2, 0x1.415e5bf6fb106p+4,
+ 0x1.b4c902e273a58p+5, 0x1.28d389970338fp+7, 0x1.936dc5690c08fp+8,
+ 0x1.122885aaeddaap+10, 0x1.749ea7d470c6ep+11, 0x1.fa7157c470f82p+12,
+ 0x1.5829dcf950560p+14, 0x1.d3c4488ee4f7fp+15, 0x1.3de1654d37c9ap+17,
+ 0x1.b00b5916ac955p+18, 0x1.259ac48bf05d7p+20, 0x1.8f0ccafad2a87p+21,
+ 0x1.0f2ebd0a80020p+23, 0x1.709348c0ea4f9p+24, 0x1.f4f22091940bdp+25,
+ 0x1.546d8f9ed26e1p+27, 0x1.ceb088b68e804p+28, 0x1.3a6e1fd9eecfdp+30,
+ 0x1.ab5adb9c43600p+31, 0x1.226af33b1fdc1p+33, 0x1.8ab7fb5475fb7p+34,
+ 0x1.0c3d3920962c9p+36, 0x1.6c932696a6b5dp+37, 0x1.ef822f7f6731dp+38,
+ 0x1.50bba3796379ap+40, 0x1.c9aae4631c056p+41, 0x1.370470aec28edp+43,
+ 0x1.a6b765d8cdf6dp+44, 0x1.1f43fcc4b662cp+46, 0x1.866f34a725782p+47,
+ 0x1.0953e2f3a1ef7p+49, 0x1.689e221bc8d5bp+50, 0x1.ea215a1d20d76p+51,
+ 0x1.4d13fbb1a001ap+53, 0x1.c4b334617cc67p+54, 0x1.33a43d282a519p+56,
+ 0x1.a220d397972ebp+57, 0x1.1c25c88df6862p+59, 0x1.8232558201159p+60,
+ 0x1.0672a3c9eb871p+62, 0x1.64b41c6d37832p+63, 0x1.e4cf766fe49bep+64,
+ 0x1.49767bc0483e3p+66, 0x1.bfc951eb8bb76p+67, 0x1.304d6aeca254bp+69,
+ 0x1.9d97010884251p+70, 0x1.19103e4080b45p+72, 0x1.7e013cd114461p+73,
+ 0x1.03996528e074cp+75, 0x1.60d4f6fdac731p+76, 0x1.df8c5af17ba3bp+77,
+ 0x1.45e3076d61699p+79, 0x1.baed16a6e0da7p+80, 0x1.2cffdfebde1a1p+82,
+ 0x1.9919cabefcb69p+83, 0x1.160345c9953e3p+85, 0x1.79dbc9dc53c66p+86,
+ 0x1.00c810d464097p+88, 0x1.5d009394c5c27p+89, 0x1.da57de8f107a8p+90,
+ 0x1.425982cf597cdp+92, 0x1.b61e5ca3a5e31p+93, 0x1.29bb825dfcf87p+95,
+ 0x1.94a90db0d6fe2p+96, 0x1.12fec759586fdp+98, 0x1.75c1dc469e3afp+99,
+ 0x1.fbfd219c43b04p+100, 0x1.5936d44e1a146p+102, 0x1.d531d8a7ee79cp+103,
+ 0x1.3ed9d24a2d51bp+105, 0x1.b15cfe5b6e17bp+106, 0x1.268038c2c0e00p+108,
+ 0x1.9044a73545d48p+109, 0x1.1002ab6218b38p+111, 0x1.71b3540cbf921p+112,
+ 0x1.f6799ea9c414ap+113, 0x1.55779b984f3ebp+115, 0x1.d01a210c44aa4p+116,
+ 0x1.3b63da8e91210p+118, 0x1.aca8d6b0116b8p+119, 0x1.234de9e0c74e9p+121,
+ 0x1.8bec7503ca477p+122, 0x1.0d0eda9796b90p+124, 0x1.6db0118477245p+125,
+ 0x1.f1056dc7bf22dp+126, 0x1.51c2cc3433801p+128, 0x1.cb108ffbec164p+129,
+};
+
+// Lookup table for exp(m * 2^(-7)) with m = 0, ..., 127.
+// Table is generated with Sollya as follow:
+// > display = hexadecimal;
+// > for i from 0 to 127 do { D(exp(i / 128)); };
+static constexpr double EXP_M2[128] = {
+ 0x1.0000000000000p0, 0x1.0202015600446p0, 0x1.04080ab55de39p0,
+ 0x1.06122436410ddp0, 0x1.08205601127edp0, 0x1.0a32a84e9c1f6p0,
+ 0x1.0c49236829e8cp0, 0x1.0e63cfa7ab09dp0, 0x1.1082b577d34edp0,
+ 0x1.12a5dd543ccc5p0, 0x1.14cd4fc989cd6p0, 0x1.16f9157587069p0,
+ 0x1.192937074e0cdp0, 0x1.1b5dbd3f68122p0, 0x1.1d96b0eff0e79p0,
+ 0x1.1fd41afcba45ep0, 0x1.2216045b6f5cdp0, 0x1.245c7613b8a9bp0,
+ 0x1.26a7793f60164p0, 0x1.28f7170a755fdp0, 0x1.2b4b58b372c79p0,
+ 0x1.2da4478b620c7p0, 0x1.3001ecf601af7p0, 0x1.32645269ea829p0,
+ 0x1.34cb8170b5835p0, 0x1.373783a722012p0, 0x1.39a862bd3c106p0,
+ 0x1.3c1e2876834aap0, 0x1.3e98deaa11dccp0, 0x1.41188f42c3e32p0,
+ 0x1.439d443f5f159p0, 0x1.462707b2bac21p0, 0x1.48b5e3c3e8186p0,
+ 0x1.4b49e2ae5ac67p0, 0x1.4de30ec211e60p0, 0x1.50817263c13cdp0,
+ 0x1.5325180cfacf7p0, 0x1.55ce0a4c58c7cp0, 0x1.587c53c5a7af0p0,
+ 0x1.5b2fff3210fd9p0, 0x1.5de9176045ff5p0, 0x1.60a7a734ab0e8p0,
+ 0x1.636bb9a983258p0, 0x1.663559cf1bc7cp0, 0x1.690492cbf9433p0,
+ 0x1.6bd96fdd034a2p0, 0x1.6eb3fc55b1e76p0, 0x1.719443a03acb9p0,
+ 0x1.747a513dbef6ap0, 0x1.776630c678bc1p0, 0x1.7a57ede9ea23ep0,
+ 0x1.7d4f946f0ba8dp0, 0x1.804d30347b546p0, 0x1.8350cd30ac390p0,
+ 0x1.865a7772164c5p0, 0x1.896a3b1f66a0ep0, 0x1.8c802477b0010p0,
+ 0x1.8f9c3fd29beafp0, 0x1.92be99a09bf00p0, 0x1.95e73e6b1b75ep0,
+ 0x1.99163ad4b1dccp0, 0x1.9c4b9b995509bp0, 0x1.9f876d8e8c566p0,
+ 0x1.a2c9bda3a3e78p0, 0x1.a61298e1e069cp0, 0x1.a9620c6cb3374p0,
+ 0x1.acb82581eee54p0, 0x1.b014f179fc3b8p0, 0x1.b3787dc80f95fp0,
+ 0x1.b6e2d7fa5eb18p0, 0x1.ba540dba56e56p0, 0x1.bdcc2cccd3c85p0,
+ 0x1.c14b431256446p0, 0x1.c4d15e873c193p0, 0x1.c85e8d43f7cd0p0,
+ 0x1.cbf2dd7d490f2p0, 0x1.cf8e5d84758a9p0, 0x1.d3311bc7822b4p0,
+ 0x1.d6db26d16cd67p0, 0x1.da8c8d4a66969p0, 0x1.de455df80e3c0p0,
+ 0x1.e205a7bdab73ep0, 0x1.e5cd799c6a54ep0, 0x1.e99ce2b397649p0,
+ 0x1.ed73f240dc142p0, 0x1.f152b7a07bb76p0, 0x1.f539424d90f5ep0,
+ 0x1.f927a1e24bb76p0, 0x1.fd1de6182f8c9p0, 0x1.008e0f64294abp1,
+ 0x1.02912df5ce72ap1, 0x1.049856cd84339p1, 0x1.06a39207f0a09p1,
+ 0x1.08b2e7d2035cfp1, 0x1.0ac6606916501p1, 0x1.0cde041b0e9aep1,
+ 0x1.0ef9db467dcf8p1, 0x1.1119ee5ac36b6p1, 0x1.133e45d82e952p1,
+ 0x1.1566ea50201d7p1, 0x1.1793e4652cc50p1, 0x1.19c53ccb3fc6bp1,
+ 0x1.1bfafc47bda73p1, 0x1.1e352bb1a74adp1, 0x1.2073d3f1bd518p1,
+ 0x1.22b6fe02a3b9cp1, 0x1.24feb2f105cb8p1, 0x1.274afbdbba4a6p1,
+ 0x1.299be1f3e7f1cp1, 0x1.2bf16e7d2a38cp1, 0x1.2e4baacdb6614p1,
+ 0x1.30aaa04e80d05p1, 0x1.330e587b62b28p1, 0x1.3576dce33feadp1,
+ 0x1.37e437282d4eep1, 0x1.3a5670ff972edp1, 0x1.3ccd9432682b4p1,
+ 0x1.3f49aa9d30590p1, 0x1.41cabe304cb34p1, 0x1.4450d8f00edd4p1,
+ 0x1.46dc04f4e5338p1, 0x1.496c4c6b832dap1, 0x1.4c01b9950a111p1,
+ 0x1.4e9c56c731f5dp1, 0x1.513c2e6c731d7p1, 0x1.53e14b042f9cap1,
+ 0x1.568bb722dd593p1, 0x1.593b7d72305bbp1,
+};
+
+INLINE_FMA
LLVM_LIBC_FUNCTION(float, expf, (float x)) {
- uint32_t abstop;
- uint64_t ki, t;
- // double_t for better performance on targets with FLT_EVAL_METHOD == 2.
- double_t kd, xd, z, r, r2, y, s;
+ using FPBits = typename fputil::FPBits<float>;
+ FPBits xbits(x);
- xd = static_cast<double_t>(x);
- abstop = top12_bits(x) & 0x7ff;
- if (unlikely(abstop >= top12_bits(88.0f))) {
- // |x| >= 88 or x is nan.
- if (as_uint32_bits(x) == as_uint32_bits(-INFINITY))
+ // When x < log(2^-150) or nan
+ if (unlikely(xbits.uintval() >= 0xc2cf'f1b5U)) {
+ // exp(-Inf) = 0
+ if (xbits.is_inf())
return 0.0f;
- if (abstop >= top12_bits(INFINITY))
- return x + x;
- if (x > as_float(0x42b17217)) // x > log(0x1p128) ~= 88.72
- return overflow<float>(0);
- if (x < as_float(0xc2cff1b4)) // x < log(0x1p-150) ~= -103.97
- return underflow<float>(0);
- if (x < as_float(0xc2ce8ecf)) // x < log(0x1p-149) ~= -103.28
- return may_underflow<float>(0);
+ // exp(nan) = nan
+ if (xbits.is_nan())
+ return x;
+ if (fputil::get_round() == FE_UPWARD)
+ return static_cast<float>(FPBits(FPBits::MIN_SUBNORMAL));
+ if (x != 0.0f)
+ errno = ERANGE;
+ return 0.0f;
}
+ // x >= 89 or nan
+ if (unlikely(!xbits.get_sign() && (xbits.uintval() >= 0x42b2'0000))) {
+ if (xbits.uintval() < 0x7f80'0000U) {
+ int rounding = fputil::get_round();
+ if (rounding == FE_DOWNWARD || rounding == FE_TOWARDZERO)
+ return static_cast<float>(FPBits(FPBits::MAX_NORMAL));
- // x*N/Ln2 = k + r with r in [-1/2, 1/2] and int k.
- z = InvLn2N * xd;
+ errno = ERANGE;
+ }
+ return x + static_cast<float>(FPBits::inf());
+ }
+ // |x| < 2^-25
+ if (unlikely(xbits.get_unbiased_exponent() <= 101)) {
+ return 1.0f + x;
+ }
- // Round and convert z to int, the result is in [-150*N, 128*N] and
- // ideally nearest int is used, otherwise the magnitude of r can be
- // bigger which gives larger approximation error.
- kd = static_cast<double>(z + SHIFT);
- ki = as_uint64_bits(kd);
- kd -= SHIFT;
- r = z - kd;
+ // For -104 < x < 89, to compute exp(x), we perform the following range
+ // reduction: find hi, mid, lo such that:
+ // x = hi + mid + lo, in which
+ // hi is an integer,
+ // mid * 2^7 is an integer
+ // -2^(-8) <= lo < 2^-8.
+ // In particular,
+ // hi + mid = round(x * 2^7) * 2^(-7).
+ // Then,
+ // exp(x) = exp(hi + mid + lo) = exp(hi) * exp(mid) * exp(lo).
+ // We store exp(hi) and exp(mid) in the lookup tables EXP_M1 and EXP_M2
+ // respectively. exp(lo) is computed using a degree-7 minimax polynomial
+ // generated by Sollya.
- // exp(x) = 2^(k/N) * 2^(r/N) ~= s *(C0*r^3 + C1*r^2 + C2*r + 1)
- t = T[ki % N];
- t += ki << (52 - EXP2F_TABLE_BITS);
- s = as_double(t);
- z = C[0] * r + C[1];
- r2 = r * r;
- y = C[2] * r + 1;
- y = z * r2 + y;
- y = y * s;
- return static_cast<float>(y);
+ // x_hi = hi + mid.
+ int x_hi = static_cast<int>(x * 0x1.0p7f);
+ // Subtract (hi + mid) from x to get lo.
+ x -= static_cast<float>(x_hi) * 0x1.0p-7f;
+ double xd = static_cast<double>(x);
+ // Make sure that -2^(-8) <= lo < 2^-8.
+ if (x >= 0x1.0p-8f) {
+ ++x_hi;
+ xd -= 0x1.0p-7;
+ }
+ if (x < -0x1.0p-8f) {
+ --x_hi;
+ xd += 0x1.0p-7;
+ }
+ x_hi += 104 << 7;
+ // hi = x_hi >> 7
+ double exp_hi = EXP_M1[x_hi >> 7];
+ // lo = x_hi & 0x0000'007fU;
+ double exp_mid = EXP_M2[x_hi & 0x7f];
+ // Degree-7 minimax polynomial generated by Sollya with the following
+ // commands:
+ // > display = hexadecimal;
+ // > Q = fpminimax(expm1(x)/x, 6, [|D...|], [-2^-8, 2^-8]);
+ // > Q;
+ double exp_lo = fputil::polyeval(
+ xd, 0x1p0, 0x1p0, 0x1p-1, 0x1.5555555555555p-3, 0x1.55555555553ap-5,
+ 0x1.1111111204dfcp-7, 0x1.6c16cb2da593ap-10, 0x1.9ff1648996d2ep-13);
+ return static_cast<float>(exp_hi * exp_mid * exp_lo);
}
} // namespace __llvm_libc
diff --git a/libc/test/src/math/exhaustive/CMakeLists.txt b/libc/test/src/math/exhaustive/CMakeLists.txt
index 2507bdfe90a2f..01ffc79dde215 100644
--- a/libc/test/src/math/exhaustive/CMakeLists.txt
+++ b/libc/test/src/math/exhaustive/CMakeLists.txt
@@ -47,6 +47,23 @@ add_fp_unittest(
libc.src.__support.FPUtil.fputil
)
+add_fp_unittest(
+ expf_test
+ NO_RUN_POSTBUILD
+ NEED_MPFR
+ SUITE
+ libc_math_exhaustive_tests
+ SRCS
+ expf_test.cpp
+ DEPENDS
+ .exhaustive_test
+ libc.include.math
+ libc.src.math.expf
+ libc.src.__support.FPUtil.fputil
+ LINK_OPTIONS
+ -lpthread
+)
+
add_fp_unittest(
expm1f_test
NEED_MPFR
diff --git a/libc/test/src/math/exhaustive/expf_test.cpp b/libc/test/src/math/exhaustive/expf_test.cpp
new file mode 100644
index 0000000000000..a53d2aaf16b8b
--- /dev/null
+++ b/libc/test/src/math/exhaustive/expf_test.cpp
@@ -0,0 +1,79 @@
+//===-- Exhaustive test for expf ------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "exhaustive_test.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/math/expf.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+#include "utils/UnitTest/FPMatcher.h"
+
+using FPBits = __llvm_libc::fputil::FPBits<float>;
+
+namespace mpfr = __llvm_libc::testing::mpfr;
+
+struct LlvmLibcExpfExhaustiveTest : public LlvmLibcExhaustiveTest<uint32_t> {
+ void check(uint32_t start, uint32_t stop,
+ mpfr::RoundingMode rounding) override {
+ mpfr::ForceRoundingMode r(rounding);
+ uint32_t bits = start;
+ do {
+ FPBits xbits(bits);
+ float x = float(xbits);
+ EXPECT_MPFR_MATCH(mpfr::Operation::Exp, x, __llvm_libc::expf(x), 0.5,
+ rounding);
+ } while (bits++ < stop);
+ }
+};
+
+static constexpr int NUM_THREADS = 16;
+
+// Range: [0, 89];
+static constexpr uint32_t POS_START = 0x0000'0000U;
+static constexpr uint32_t POS_STOP = 0x42b2'0000U;
+
+TEST_F(LlvmLibcExpfExhaustiveTest, PostiveRangeRoundNearestTieToEven) {
+ test_full_range(POS_START, POS_STOP, NUM_THREADS,
+ mpfr::RoundingMode::Nearest);
+}
+
+TEST_F(LlvmLibcExpfExhaustiveTest, PostiveRangeRoundUp) {
+ test_full_range(POS_START, POS_STOP, NUM_THREADS, mpfr::RoundingMode::Upward);
+}
+
+TEST_F(LlvmLibcExpfExhaustiveTest, PostiveRangeRoundDown) {
+ test_full_range(POS_START, POS_STOP, NUM_THREADS,
+ mpfr::RoundingMode::Downward);
+}
+
+TEST_F(LlvmLibcExpfExhaustiveTest, PostiveRangeRoundTowardZero) {
+ test_full_range(POS_START, POS_STOP, NUM_THREADS,
+ mpfr::RoundingMode::TowardZero);
+}
+
+// Range: [-104, 0];
+static constexpr uint32_t NEG_START = 0x8000'0000U;
+static constexpr uint32_t NEG_STOP = 0xc2d0'0000U;
+
+TEST_F(LlvmLibcExpfExhaustiveTest, NegativeRangeRoundNearestTieToEven) {
+ test_full_range(NEG_START, NEG_STOP, NUM_THREADS,
+ mpfr::RoundingMode::Nearest);
+}
+
+TEST_F(LlvmLibcExpfExhaustiveTest, NegativeRangeRoundUp) {
+ test_full_range(NEG_START, NEG_STOP, NUM_THREADS, mpfr::RoundingMode::Upward);
+}
+
+TEST_F(LlvmLibcExpfExhaustiveTest, NegativeRangeRoundDown) {
+ test_full_range(NEG_START, NEG_STOP, NUM_THREADS,
+ mpfr::RoundingMode::Downward);
+}
+
+TEST_F(LlvmLibcExpfExhaustiveTest, NegativeRangeRoundTowardZero) {
+ test_full_range(NEG_START, NEG_STOP, NUM_THREADS,
+ mpfr::RoundingMode::TowardZero);
+}
diff --git a/libc/test/src/math/expf_test.cpp b/libc/test/src/math/expf_test.cpp
index 09c4cabe98e2d..3b8bbe2bb9fb5 100644
--- a/libc/test/src/math/expf_test.cpp
+++ b/libc/test/src/math/expf_test.cpp
@@ -57,11 +57,13 @@ TEST(LlvmLibcExpfTest, Underflow) {
EXPECT_MATH_ERRNO(ERANGE);
float x = float(FPBits(0xc2cffff8U));
- EXPECT_MPFR_MATCH(mpfr::Operation::Exp, x, __llvm_libc::expf(x), 1.0);
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp, x, __llvm_libc::expf(x),
+ 0.5);
EXPECT_MATH_ERRNO(ERANGE);
x = float(FPBits(0xc2d00008U));
- EXPECT_MPFR_MATCH(mpfr::Operation::Exp, x, __llvm_libc::expf(x), 1.0);
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp, x, __llvm_libc::expf(x),
+ 0.5);
EXPECT_MATH_ERRNO(ERANGE);
}
@@ -72,19 +74,23 @@ TEST(LlvmLibcExpfTest, Borderline) {
errno = 0;
x = float(FPBits(0x42affff8U));
- ASSERT_MPFR_MATCH(mpfr::Operation::Exp, x, __llvm_libc::expf(x), 1.0);
+ ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp, x, __llvm_libc::expf(x),
+ 0.5);
EXPECT_MATH_ERRNO(0);
x = float(FPBits(0x42b00008U));
- ASSERT_MPFR_MATCH(mpfr::Operation::Exp, x, __llvm_libc::expf(x), 1.0);
+ ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp, x, __llvm_libc::expf(x),
+ 0.5);
EXPECT_MATH_ERRNO(0);
x = float(FPBits(0xc2affff8U));
- ASSERT_MPFR_MATCH(mpfr::Operation::Exp, x, __llvm_libc::expf(x), 1.0);
+ ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp, x, __llvm_libc::expf(x),
+ 0.5);
EXPECT_MATH_ERRNO(0);
x = float(FPBits(0xc2b00008U));
- ASSERT_MPFR_MATCH(mpfr::Operation::Exp, x, __llvm_libc::expf(x), 1.0);
+ ASSERT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp, x, __llvm_libc::expf(x),
+ 0.5);
EXPECT_MATH_ERRNO(0);
}
@@ -104,6 +110,7 @@ TEST(LlvmLibcExpfTest, InFloatRange) {
// wider precision.
if (isnan(result) || isinf(result) || errno != 0)
continue;
- ASSERT_MPFR_MATCH(mpfr::Operation::Exp, x, __llvm_libc::expf(x), 1.0);
+ EXPECT_MPFR_MATCH_ALL_ROUNDING(mpfr::Operation::Exp, x,
+ __llvm_libc::expf(x), 0.5);
}
}
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