[compiler-rt] r342917 - [compiler-rt] [builtins] Add logb/logbf/logbl methods to compiler-rt to avoid libm dependencies when possible.
Hans Wennborg via llvm-commits
llvm-commits at lists.llvm.org
Wed Sep 26 04:25:23 PDT 2018
The tests don't work on Windows, see e.g.
http://lab.llvm.org:8011/builders/clang-x64-ninja-win7/builds/13351
I've disabled them in r343095.
On Mon, Sep 24, 2018 at 10:39 PM, Jordan Rupprecht via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Author: rupprecht
> Date: Mon Sep 24 13:39:19 2018
> New Revision: 342917
>
> URL: http://llvm.org/viewvc/llvm-project?rev=342917&view=rev
> Log:
> [compiler-rt] [builtins] Add logb/logbf/logbl methods to compiler-rt to avoid libm dependencies when possible.
>
> Summary:
> The complex division builtins (div?c3) use logb methods from libm to scale numbers during division and avoid rounding issues. However, these come from libm, meaning anyone that uses --rtlib=compiler-rt also has to include -lm. Implement logb* methods for standard ieee 754 floats so we can avoid -lm on those platforms, falling back to the old behavior (using either logb() or `__builtin_logb()`) when not supported.
>
> These new methods are defined internally as `__compiler_rt_logb` so as not to conflict with the libm definitions in any way.
>
> This fixes just the libm methods mentioned in PR32279 and PR28652. libc is still required, although that seems to not be an issue.
>
> Note: this is proposed as an alternative to just adding -lm: D49330.
>
> Reviewers: efriedma, compnerd, scanon, echristo
>
> Reviewed By: echristo
>
> Subscribers: jsji, echristo, nemanjai, dberris, mgorny, kbarton, delcypher, llvm-commits, #sanitizers
>
> Differential Revision: https://reviews.llvm.org/D49514
>
> Added:
> compiler-rt/trunk/test/builtins/Unit/compiler_rt_logb_test.c
> compiler-rt/trunk/test/builtins/Unit/compiler_rt_logbf_test.c
> compiler-rt/trunk/test/builtins/Unit/compiler_rt_logbl_test.c
> Modified:
> compiler-rt/trunk/lib/builtins/divdc3.c
> compiler-rt/trunk/lib/builtins/divsc3.c
> compiler-rt/trunk/lib/builtins/divtc3.c
> compiler-rt/trunk/lib/builtins/fp_lib.h
> compiler-rt/trunk/lib/builtins/int_math.h
> compiler-rt/trunk/lib/builtins/ppc/divtc3.c
>
> Modified: compiler-rt/trunk/lib/builtins/divdc3.c
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/builtins/divdc3.c?rev=342917&r1=342916&r2=342917&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/builtins/divdc3.c (original)
> +++ compiler-rt/trunk/lib/builtins/divdc3.c Mon Sep 24 13:39:19 2018
> @@ -12,6 +12,8 @@
> * ===----------------------------------------------------------------------===
> */
>
> +#define DOUBLE_PRECISION
> +#include "fp_lib.h"
> #include "int_lib.h"
> #include "int_math.h"
>
> @@ -21,7 +23,7 @@ COMPILER_RT_ABI Dcomplex
> __divdc3(double __a, double __b, double __c, double __d)
> {
> int __ilogbw = 0;
> - double __logbw = crt_logb(crt_fmax(crt_fabs(__c), crt_fabs(__d)));
> + double __logbw = __compiler_rt_logb(crt_fmax(crt_fabs(__c), crt_fabs(__d)));
> if (crt_isfinite(__logbw))
> {
> __ilogbw = (int)__logbw;
>
> Modified: compiler-rt/trunk/lib/builtins/divsc3.c
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/builtins/divsc3.c?rev=342917&r1=342916&r2=342917&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/builtins/divsc3.c (original)
> +++ compiler-rt/trunk/lib/builtins/divsc3.c Mon Sep 24 13:39:19 2018
> @@ -12,6 +12,8 @@
> *===----------------------------------------------------------------------===
> */
>
> +#define SINGLE_PRECISION
> +#include "fp_lib.h"
> #include "int_lib.h"
> #include "int_math.h"
>
> @@ -21,7 +23,8 @@ COMPILER_RT_ABI Fcomplex
> __divsc3(float __a, float __b, float __c, float __d)
> {
> int __ilogbw = 0;
> - float __logbw = crt_logbf(crt_fmaxf(crt_fabsf(__c), crt_fabsf(__d)));
> + float __logbw =
> + __compiler_rt_logbf(crt_fmaxf(crt_fabsf(__c), crt_fabsf(__d)));
> if (crt_isfinite(__logbw))
> {
> __ilogbw = (int)__logbw;
>
> Modified: compiler-rt/trunk/lib/builtins/divtc3.c
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/builtins/divtc3.c?rev=342917&r1=342916&r2=342917&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/builtins/divtc3.c (original)
> +++ compiler-rt/trunk/lib/builtins/divtc3.c Mon Sep 24 13:39:19 2018
> @@ -12,6 +12,8 @@
> *===----------------------------------------------------------------------===
> */
>
> +#define QUAD_PRECISION
> +#include "fp_lib.h"
> #include "int_lib.h"
> #include "int_math.h"
>
> @@ -21,7 +23,8 @@ COMPILER_RT_ABI Lcomplex
> __divtc3(long double __a, long double __b, long double __c, long double __d)
> {
> int __ilogbw = 0;
> - long double __logbw = crt_logbl(crt_fmaxl(crt_fabsl(__c), crt_fabsl(__d)));
> + long double __logbw =
> + __compiler_rt_logbl(crt_fmaxl(crt_fabsl(__c), crt_fabsl(__d)));
> if (crt_isfinite(__logbw))
> {
> __ilogbw = (int)__logbw;
>
> Modified: compiler-rt/trunk/lib/builtins/fp_lib.h
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/builtins/fp_lib.h?rev=342917&r1=342916&r2=342917&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/builtins/fp_lib.h (original)
> +++ compiler-rt/trunk/lib/builtins/fp_lib.h Mon Sep 24 13:39:19 2018
> @@ -25,6 +25,7 @@
> #include <stdbool.h>
> #include <limits.h>
> #include "int_lib.h"
> +#include "int_math.h"
>
> // x86_64 FreeBSD prior v9.3 define fixed-width types incorrectly in
> // 32-bit mode.
> @@ -265,6 +266,62 @@ static __inline void wideRightShiftWithS
> *hi = 0;
> }
> }
> +
> +// Implements logb methods (logb, logbf, logbl) for IEEE-754. This avoids
> +// pulling in a libm dependency from compiler-rt, but is not meant to replace
> +// it (i.e. code calling logb() should get the one from libm, not this), hence
> +// the __compiler_rt prefix.
> +static __inline fp_t __compiler_rt_logbX(fp_t x) {
> + rep_t rep = toRep(x);
> + int exp = (rep & exponentMask) >> significandBits;
> +
> + // Abnormal cases:
> + // 1) +/- inf returns +inf; NaN returns NaN
> + // 2) 0.0 returns -inf
> + if (exp == maxExponent) {
> + if (((rep & signBit) == 0) || (x != x)) {
> + return x; // NaN or +inf: return x
> + } else {
> + return -x; // -inf: return -x
> + }
> + } else if (x == 0.0) {
> + // 0.0: return -inf
> + return fromRep(infRep | signBit);
> + }
> +
> + if (exp != 0) {
> + // Normal number
> + return exp - exponentBias; // Unbias exponent
> + } else {
> + // Subnormal number; normalize and repeat
> + rep &= absMask;
> + const int shift = 1 - normalize(&rep);
> + exp = (rep & exponentMask) >> significandBits;
> + return exp - exponentBias - shift; // Unbias exponent
> + }
> +}
> +#endif
> +
> +#if defined(SINGLE_PRECISION)
> +static __inline fp_t __compiler_rt_logbf(fp_t x) {
> + return __compiler_rt_logbX(x);
> +}
> +#elif defined(DOUBLE_PRECISION)
> +static __inline fp_t __compiler_rt_logb(fp_t x) {
> + return __compiler_rt_logbX(x);
> +}
> +#elif defined(QUAD_PRECISION)
> + #if defined(CRT_LDBL_128BIT)
> +static __inline fp_t __compiler_rt_logbl(fp_t x) {
> + return __compiler_rt_logbX(x);
> +}
> + #else
> +// The generic implementation only works for ieee754 floating point. For other
> +// floating point types, continue to rely on the libm implementation for now.
> +static __inline long double __compiler_rt_logbl(long double x) {
> + return crt_logbl(x);
> +}
> + #endif
> #endif
>
> #endif // FP_LIB_HEADER
>
> Modified: compiler-rt/trunk/lib/builtins/int_math.h
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/builtins/int_math.h?rev=342917&r1=342916&r2=342917&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/builtins/int_math.h (original)
> +++ compiler-rt/trunk/lib/builtins/int_math.h Mon Sep 24 13:39:19 2018
> @@ -92,12 +92,8 @@
> #endif
>
> #if defined(_MSC_VER) && !defined(__clang__)
> -#define crt_logb(x) logb((x))
> -#define crt_logbf(x) logbf((x))
> #define crt_logbl(x) logbl((x))
> #else
> -#define crt_logb(x) __builtin_logb((x))
> -#define crt_logbf(x) __builtin_logbf((x))
> #define crt_logbl(x) __builtin_logbl((x))
> #endif
>
>
> Modified: compiler-rt/trunk/lib/builtins/ppc/divtc3.c
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/builtins/ppc/divtc3.c?rev=342917&r1=342916&r2=342917&view=diff
> ==============================================================================
> --- compiler-rt/trunk/lib/builtins/ppc/divtc3.c (original)
> +++ compiler-rt/trunk/lib/builtins/ppc/divtc3.c Mon Sep 24 13:39:19 2018
> @@ -4,6 +4,11 @@
>
> #include "DD.h"
> #include "../int_math.h"
> +// Use DOUBLE_PRECISION because the soft-fp method we use is logb (on the upper
> +// half of the long doubles), even though this file defines complex division for
> +// 128-bit floats.
> +#define DOUBLE_PRECISION
> +#include "../fp_lib.h"
>
> #if !defined(CRT_INFINITY) && defined(HUGE_VAL)
> #define CRT_INFINITY HUGE_VAL
> @@ -21,9 +26,10 @@ __divtc3(long double a, long double b, l
> DD dDD = { .ld = d };
>
> int ilogbw = 0;
> - const double logbw = crt_logb(crt_fmax(crt_fabs(cDD.s.hi), crt_fabs(dDD.s.hi) ));
> -
> - if (crt_isfinite(logbw))
> + const double logbw = __compiler_rt_logb(
> + crt_fmax(crt_fabs(cDD.s.hi), crt_fabs(dDD.s.hi)));
> +
> + if (crt_isfinite(logbw))
> {
> ilogbw = (int)logbw;
>
>
> Added: compiler-rt/trunk/test/builtins/Unit/compiler_rt_logb_test.c
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/builtins/Unit/compiler_rt_logb_test.c?rev=342917&view=auto
> ==============================================================================
> --- compiler-rt/trunk/test/builtins/Unit/compiler_rt_logb_test.c (added)
> +++ compiler-rt/trunk/test/builtins/Unit/compiler_rt_logb_test.c Mon Sep 24 13:39:19 2018
> @@ -0,0 +1,63 @@
> +// RUN: %clang_builtins %s %librt -lm -o %t && %run %t
> +//===-- compiler_rt_logb_test.c - Test __compiler_rt_logb -----------------===//
> +//
> +// The LLVM Compiler Infrastructure
> +//
> +// This file is dual licensed under the MIT and the University of Illinois Open
> +// Source Licenses. See LICENSE.TXT for details.
> +//
> +//===----------------------------------------------------------------------===//
> +//
> +// This file checks __compiler_rt_logb from the compiler_rt library for
> +// conformance against libm.
> +//
> +//===----------------------------------------------------------------------===//
> +
> +#define DOUBLE_PRECISION
> +#include <math.h>
> +#include <stdio.h>
> +#include "fp_lib.h"
> +
> +int test__compiler_rt_logb(fp_t x) {
> + fp_t crt_value = __compiler_rt_logb(x);
> + fp_t libm_value = logb(x);
> + // Compare actual rep, e.g. to avoid NaN != the same NaN
> + if (toRep(crt_value) != toRep(libm_value)) {
> + printf("error: in __compiler_rt_logb(%a [%lX]) = %a [%lX] != %a [%lX]\n",
> + x, toRep(x), crt_value, toRep(crt_value), libm_value,
> + toRep(libm_value));
> + return 1;
> + }
> + return 0;
> +}
> +
> +double cases[] = {
> + 1.e-6, -1.e-6, NAN, -NAN, INFINITY, -INFINITY, -1,
> + -0.0, 0.0, 1, -2, 2, -0.5, 0.5,
> +};
> +
> +int main() {
> + const unsigned N = sizeof(cases) / sizeof(cases[0]);
> + unsigned i;
> + for (i = 0; i < N; ++i) {
> + if (test__compiler_rt_logb(cases[i])) return 1;
> + }
> +
> + // Test a moving 1 bit, especially to handle denormal values.
> + // Test the negation as well.
> + rep_t x = signBit;
> + while (x) {
> + if (test__compiler_rt_logb(fromRep(x))) return 1;
> + if (test__compiler_rt_logb(fromRep(signBit ^ x))) return 1;
> + x >>= 1;
> + }
> + // Also try a couple moving ones
> + x = signBit | (signBit >> 1) | (signBit >> 2);
> + while (x) {
> + if (test__compiler_rt_logb(fromRep(x))) return 1;
> + if (test__compiler_rt_logb(fromRep(signBit ^ x))) return 1;
> + x >>= 1;
> + }
> +
> + return 0;
> +}
>
> Added: compiler-rt/trunk/test/builtins/Unit/compiler_rt_logbf_test.c
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/builtins/Unit/compiler_rt_logbf_test.c?rev=342917&view=auto
> ==============================================================================
> --- compiler-rt/trunk/test/builtins/Unit/compiler_rt_logbf_test.c (added)
> +++ compiler-rt/trunk/test/builtins/Unit/compiler_rt_logbf_test.c Mon Sep 24 13:39:19 2018
> @@ -0,0 +1,63 @@
> +// RUN: %clang_builtins %s %librt -lm -o %t && %run %t
> +//===-- compiler_rt_logbf_test.c - Test __compiler_rt_logbf ---------------===//
> +//
> +// The LLVM Compiler Infrastructure
> +//
> +// This file is dual licensed under the MIT and the University of Illinois Open
> +// Source Licenses. See LICENSE.TXT for details.
> +//
> +//===----------------------------------------------------------------------===//
> +//
> +// This file checks __compiler_rt_logbf from the compiler_rt library for
> +// conformance against libm.
> +//
> +//===----------------------------------------------------------------------===//
> +
> +#define SINGLE_PRECISION
> +#include <math.h>
> +#include <stdio.h>
> +#include "fp_lib.h"
> +
> +int test__compiler_rt_logbf(fp_t x) {
> + fp_t crt_value = __compiler_rt_logbf(x);
> + fp_t libm_value = logbf(x);
> + // Compare actual rep, e.g. to avoid NaN != the same NaN
> + if (toRep(crt_value) != toRep(libm_value)) {
> + printf("error: in __compiler_rt_logb(%a [%X]) = %a [%X] != %a [%X]\n", x,
> + toRep(x), crt_value, toRep(crt_value), libm_value,
> + toRep(libm_value));
> + return 1;
> + }
> + return 0;
> +}
> +
> +double cases[] = {
> + 1.e-6, -1.e-6, NAN, -NAN, INFINITY, -INFINITY, -1,
> + -0.0, 0.0, 1, -2, 2, -0.5, 0.5,
> +};
> +
> +int main() {
> + const unsigned N = sizeof(cases) / sizeof(cases[0]);
> + unsigned i;
> + for (i = 0; i < N; ++i) {
> + if (test__compiler_rt_logbf(cases[i])) return 1;
> + }
> +
> + // Test a moving 1 bit, especially to handle denormal values.
> + // Test the negation as well.
> + rep_t x = signBit;
> + while (x) {
> + if (test__compiler_rt_logbf(fromRep(x))) return 1;
> + if (test__compiler_rt_logbf(fromRep(signBit ^ x))) return 1;
> + x >>= 1;
> + }
> + // Also try a couple moving ones
> + x = signBit | (signBit >> 1) | (signBit >> 2);
> + while (x) {
> + if (test__compiler_rt_logbf(fromRep(x))) return 1;
> + if (test__compiler_rt_logbf(fromRep(signBit ^ x))) return 1;
> + x >>= 1;
> + }
> +
> + return 0;
> +}
>
> Added: compiler-rt/trunk/test/builtins/Unit/compiler_rt_logbl_test.c
> URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/test/builtins/Unit/compiler_rt_logbl_test.c?rev=342917&view=auto
> ==============================================================================
> --- compiler-rt/trunk/test/builtins/Unit/compiler_rt_logbl_test.c (added)
> +++ compiler-rt/trunk/test/builtins/Unit/compiler_rt_logbl_test.c Mon Sep 24 13:39:19 2018
> @@ -0,0 +1,79 @@
> +// RUN: %clang_builtins %s %librt -lm -o %t && %run %t
> +//===-- compiler_rt_logbl_test.c - Test __compiler_rt_logbl ---------------===//
> +//
> +// The LLVM Compiler Infrastructure
> +//
> +// This file is dual licensed under the MIT and the University of Illinois Open
> +// Source Licenses. See LICENSE.TXT for details.
> +//
> +//===----------------------------------------------------------------------===//
> +//
> +// This file checks __compiler_rt_logbl from the compiler_rt library for
> +// conformance against libm.
> +//
> +//===----------------------------------------------------------------------===//
> +
> +#define QUAD_PRECISION
> +#include <math.h>
> +#include <stdio.h>
> +#include "fp_lib.h"
> +#include "int_lib.h"
> +
> +#if defined(CRT_HAS_128BIT) && defined(CRT_LDBL_128BIT)
> +
> +int test__compiler_rt_logbl(fp_t x) {
> + fp_t crt_value = __compiler_rt_logbl(x);
> + fp_t libm_value = logbl(x);
> + // Compare actual rep, e.g. to avoid NaN != the same NaN
> + if (toRep(crt_value) != toRep(libm_value)) {
> + // Split expected values into two for printf
> + twords x_t, crt_value_t, libm_value_t;
> + x_t.all = toRep(x);
> + crt_value_t.all = toRep(crt_value);
> + libm_value_t.all = toRep(libm_value);
> + printf(
> + "error: in __compiler_rt_logb(%a [%llX %llX]) = %a [%llX %llX] != %a "
> + "[%llX %llX]\n",
> + x, x_t.s.high, x_t.s.low, crt_value, crt_value_t.s.high,
> + crt_value_t.s.low, libm_value, libm_value_t.s.high, libm_value_t.s.low);
> + return 1;
> + }
> + return 0;
> +}
> +
> +double cases[] = {
> + 1.e-6, -1.e-6, NAN, -NAN, INFINITY, -INFINITY, -1,
> + -0.0, 0.0, 1, -2, 2, -0.5, 0.5,
> +};
> +
> +#endif
> +
> +int main() {
> +#if defined(CRT_HAS_128BIT) && defined(CRT_LDBL_128BIT)
> + const unsigned N = sizeof(cases) / sizeof(cases[0]);
> + unsigned i;
> + for (i = 0; i < N; ++i) {
> + if (test__compiler_rt_logbl(cases[i])) return 1;
> + }
> +
> + // Test a moving 1 bit, especially to handle denormal values.
> + // Test the negation as well.
> + rep_t x = signBit;
> + while (x) {
> + if (test__compiler_rt_logbl(fromRep(x))) return 1;
> + if (test__compiler_rt_logbl(fromRep(signBit ^ x))) return 1;
> + x >>= 1;
> + }
> + // Also try a couple moving ones
> + x = signBit | (signBit >> 1) | (signBit >> 2);
> + while (x) {
> + if (test__compiler_rt_logbl(fromRep(x))) return 1;
> + if (test__compiler_rt_logbl(fromRep(signBit ^ x))) return 1;
> + x >>= 1;
> + }
> +#else
> + printf("skipped\n");
> +#endif
> +
> + return 0;
> +}
>
>
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