831b509d5f
When compiling the builtins with the undefined behavior sanitizer and running testcases you end up with the following warning: UBSan: fp_fixint_impl.inc:39:42: left shift of 8388608 by 40 places cannot be represented in type 'fixint_t' (aka 'long long') UBSan: fp_fixint_impl.inc:39:17: signed integer overflow: -1 * -9223372036854775808 cannot be represented in type 'fixint_t' (aka 'long long') This can be avoided by doing the shift and the multiplication in a matching unsigned variant of the type. The added test only trigger the intended signed overflow case when the builtins are built with -D__SOFTFP__. This was found in an out of tree target. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D159069
41 lines
1.5 KiB
C
41 lines
1.5 KiB
C
//===-- lib/fixdfsi.c - Double-precision -> integer conversion ----*- C -*-===//
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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 float to integer conversion for the
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// compiler-rt library.
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//
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//===----------------------------------------------------------------------===//
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#include "fp_lib.h"
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static __inline fixint_t __fixint(fp_t a) {
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const fixint_t fixint_max = (fixint_t)((~(fixuint_t)0) / 2);
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const fixint_t fixint_min = -fixint_max - 1;
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// Break a into sign, exponent, significand parts.
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const rep_t aRep = toRep(a);
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const rep_t aAbs = aRep & absMask;
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const fixint_t sign = aRep & signBit ? -1 : 1;
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const int exponent = (aAbs >> significandBits) - exponentBias;
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const rep_t significand = (aAbs & significandMask) | implicitBit;
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// If exponent is negative, the result is zero.
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if (exponent < 0)
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return 0;
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// If the value is too large for the integer type, saturate.
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if ((unsigned)exponent >= sizeof(fixint_t) * CHAR_BIT)
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return sign == 1 ? fixint_max : fixint_min;
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// If 0 <= exponent < significandBits, right shift to get the result.
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// Otherwise, shift left.
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if (exponent < significandBits)
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return sign * (significand >> (significandBits - exponent));
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else
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return sign * ((fixuint_t)significand << (exponent - significandBits));
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}
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