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After this patch, the softfp implementations of floatdidf and floatundidf use a common implementation (int_to_fp.h and int_to_fp_impl.inc). This roughly follows the pattern used for a wide range of other builtins, e.g. fp_trunc_impl.inc. Currently there is substantial copy and paste for the various int to fp conversion functions, with just a few constants being changed. This is a barrier to maintainability, and it's also not attractive to copy this approach as we introduce additional int to fp conversion functions for bf16 and half (which we currently lack, but need - see <https://reviews.llvm.org/D157509>). I've opted to conservatively start by replacing just two functions, leaving a follow-up patch to replace others that follow the same pattern. Also, for better or worse I've left the logic in float[un]didf largely unchanged other than using a similar approach to fp_trunc_impl.inc to remove the constants that are tied to a specific output floating point format.
72 lines
2.1 KiB
C
72 lines
2.1 KiB
C
//===-- floatundidf.c - Implement __floatundidf ---------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements __floatundidf for the compiler_rt library.
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//
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//===----------------------------------------------------------------------===//
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// Returns: convert a to a double, rounding toward even.
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// Assumption: double is a IEEE 64 bit floating point type
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// du_int is a 64 bit integral type
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// seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm
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// mmmm
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#include "int_lib.h"
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#ifndef __SOFTFP__
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// Support for systems that have hardware floating-point; we'll set the inexact
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// flag as a side-effect of this computation.
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COMPILER_RT_ABI double __floatundidf(du_int a) {
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static const double twop52 = 4503599627370496.0; // 0x1.0p52
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static const double twop84 = 19342813113834066795298816.0; // 0x1.0p84
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static const double twop84_plus_twop52 =
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19342813118337666422669312.0; // 0x1.00000001p84
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union {
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uint64_t x;
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double d;
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} high = {.d = twop84};
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union {
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uint64_t x;
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double d;
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} low = {.d = twop52};
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high.x |= a >> 32;
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low.x |= a & UINT64_C(0x00000000ffffffff);
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const double result = (high.d - twop84_plus_twop52) + low.d;
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return result;
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}
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#else
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// Support for systems that don't have hardware floating-point; there are no
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// flags to set, and we don't want to code-gen to an unknown soft-float
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// implementation.
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#define SRC_U64
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#define DST_DOUBLE
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#include "int_to_fp_impl.inc"
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COMPILER_RT_ABI double __floatundidf(du_int a) { return __floatXiYf__(a); }
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#endif
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#if defined(__ARM_EABI__)
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#if defined(COMPILER_RT_ARMHF_TARGET)
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AEABI_RTABI double __aeabi_ul2d(du_int a) { return __floatundidf(a); }
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#else
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COMPILER_RT_ALIAS(__floatundidf, __aeabi_ul2d)
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#endif
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#endif
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#if defined(__MINGW32__) && defined(__arm__)
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COMPILER_RT_ALIAS(__floatundidf, __u64tod)
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#endif
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