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When compiling compiler-rt with -fsanitize=undefined and running testcases you end up with the following warning: UBSan: floatsidf.c:32:9: negation of -2147483648 cannot be represented in type 'si_int' (aka 'long'); cast to an unsigned type to negate this value to itself The same kind of pattern exists in floatsisf.c This was found in an out of tree target. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D146123
67 lines
1.9 KiB
C
67 lines
1.9 KiB
C
//===-- lib/floatsisf.c - integer -> single-precision 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 integer to single-precision conversion for the
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// compiler-rt library in the IEEE-754 default round-to-nearest, ties-to-even
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// mode.
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//
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//===----------------------------------------------------------------------===//
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#define SINGLE_PRECISION
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#include "fp_lib.h"
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#include "int_lib.h"
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COMPILER_RT_ABI fp_t __floatsisf(si_int a) {
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const int aWidth = sizeof a * CHAR_BIT;
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// Handle zero as a special case to protect clz
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if (a == 0)
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return fromRep(0);
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// All other cases begin by extracting the sign and absolute value of a
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rep_t sign = 0;
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su_int aAbs = (su_int)a;
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if (a < 0) {
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sign = signBit;
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aAbs = -aAbs;
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}
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// Exponent of (fp_t)a is the width of abs(a).
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const int exponent = (aWidth - 1) - clzsi(aAbs);
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rep_t result;
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// Shift a into the significand field, rounding if it is a right-shift
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if (exponent <= significandBits) {
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const int shift = significandBits - exponent;
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result = (rep_t)aAbs << shift ^ implicitBit;
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} else {
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const int shift = exponent - significandBits;
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result = (rep_t)aAbs >> shift ^ implicitBit;
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rep_t round = (rep_t)aAbs << (typeWidth - shift);
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if (round > signBit)
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result++;
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if (round == signBit)
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result += result & 1;
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}
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// Insert the exponent
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result += (rep_t)(exponent + exponentBias) << significandBits;
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// Insert the sign bit and return
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return fromRep(result | sign);
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}
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#if defined(__ARM_EABI__)
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#if defined(COMPILER_RT_ARMHF_TARGET)
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AEABI_RTABI fp_t __aeabi_i2f(int a) { return __floatsisf(a); }
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#else
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COMPILER_RT_ALIAS(__floatsisf, __aeabi_i2f)
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#endif
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#endif
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