[PATCH] Aarch32/64: Support __FLT_EVAL_METHOD__ values other than 0, 1, 2
Andrea Corallo <[email protected]>
| Newsgroups | gmane.comp.lib.newlib |
|---|---|
| Message-ID | <[email protected]> |
Hi all, when _Float16 in native precision is supported GCC defines __FLT_EVAL_METHOD__ to 16 as per ISO/IEC TS 18661-3. Ex: $ ./arm-none-eabi-gcc -mthumb -march=armv8.1-m.main+fp -mfloat-abi=softfp -xc /dev/null -E -dM | grep FLT_EVAL #define __FLT_EVAL_METHOD__ 16 #define __FLT_EVAL_METHOD_TS_18661_3__ 16 Unfortunately libc/include/math.h understands only values 0, 1 and 2 leading to have newlib non compilable for those configurations. I think in newlib we should either: 1- Handle __FLT_EVAL_METHOD__ == 16 2- Build in a C mode which does not enable _Float16 (ex -std=c11) 3- Build without the _FloatN extensions -fpermitted-flt-eval-methods=c11 I think 1 should be the favorite approach. ISO/IEC 9899:201x [1] suggests that for other values of FLT_EVAL_METHOD other than 0, 1, 2 the definition of float_t and double_t is implementation-defined. The suggested patch implements that for arm and Aarch64. Note, some previous discussion on this topic can be found here [2] as follow-up to a patch addressing the same issue (only for the case__FLT_EVAL_METHOD__ == 16 case). Best Regards Andrea [1] <http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1548.pdf> [2] <https://sourceware.org/legacy-ml/newlib/2019/msg00597.html>
0001-PATH-Aarch32-64-Support-__FLT_EVAL_METHOD__-values-o.patch
(text/plain, 1.9 KB)
From d4c38a902e7bd5a2686d4d758c5cd563069c5bb2 Mon Sep 17 00:00:00 2001 From: Andrea Corallo <[email protected]> Date: Wed, 30 Mar 2022 15:40:59 +0200 Subject: [PATCH] Aarch32/64: Support __FLT_EVAL_METHOD__ values other than 0, 1, 2 2022-03-30 Andrea Corallo <[email protected]> * libc/include/machine/ieeefp.h (__FLOAT_TYPE, __DOUBLE_TYPE): New macros. * libc/include/math.h: Uses __DOUBLE_TYPE __FLOAT_TYPE to define double_t float_t if possible. --- newlib/libc/include/machine/ieeefp.h | 4 ++++ newlib/libc/include/math.h | 9 +++++++++ 2 files changed, 13 insertions(+) diff --git a/newlib/libc/include/machine/ieeefp.h b/newlib/libc/include/machine/ieeefp.h index 4dc13828c..c65c67769 100644 --- a/newlib/libc/include/machine/ieeefp.h +++ b/newlib/libc/include/machine/ieeefp.h @@ -90,6 +90,8 @@ #ifndef __SOFTFP__ # define _SUPPORTS_ERREXCEPT #endif +#define __DOUBLE_TYPE double +#define __FLOAT_TYPE float #endif #if defined (__aarch64__) @@ -102,6 +104,8 @@ #ifdef __ARM_FP # define _SUPPORTS_ERREXCEPT #endif +#define __DOUBLE_TYPE double +#define __FLOAT_TYPE float #endif #ifdef __epiphany__ diff --git a/newlib/libc/include/math.h b/newlib/libc/include/math.h index ba1a8a17e..da056b5b6 100644 --- a/newlib/libc/include/math.h +++ b/newlib/libc/include/math.h @@ -158,6 +158,15 @@ extern int isnan (double); #else /* Implementation-defined. Assume float_t and double_t have been * defined previously for this configuration (e.g. config.h). */ + + /* If __DOUBLE_TYPE is defined (__FLOAT_TYPE is then supposed to be + defined as well) float_t and double_t definition is suggested by + an arch specific header. */ + #ifdef __DOUBLE_TYPE + typedef __DOUBLE_TYPE double_t + typedef __FLOAT_TYPE float_t + #endif + /* Assume config.h has provided these types. */ #endif #else /* Assume basic definitions. */ -- 2.25.1