GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libcompiler_rt/fp_mul_impl.inc Lines: 0 38 0.0 %
Date: 2017-11-13 Branches: 0 40 0.0 %

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//===---- lib/fp_mul_impl.inc - floating point multiplication -----*- C -*-===//
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//
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//                     The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements soft-float multiplication with the IEEE-754 default
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// rounding (to nearest, ties to even).
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//
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//===----------------------------------------------------------------------===//
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#include "fp_lib.h"
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static __inline fp_t __mulXf3__(fp_t a, fp_t b) {
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    const unsigned int aExponent = toRep(a) >> significandBits & maxExponent;
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    const unsigned int bExponent = toRep(b) >> significandBits & maxExponent;
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    const rep_t productSign = (toRep(a) ^ toRep(b)) & signBit;
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    rep_t aSignificand = toRep(a) & significandMask;
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    rep_t bSignificand = toRep(b) & significandMask;
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    int scale = 0;
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    // Detect if a or b is zero, denormal, infinity, or NaN.
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    if (aExponent-1U >= maxExponent-1U || bExponent-1U >= maxExponent-1U) {
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        const rep_t aAbs = toRep(a) & absMask;
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        const rep_t bAbs = toRep(b) & absMask;
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        // NaN * anything = qNaN
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        if (aAbs > infRep) return fromRep(toRep(a) | quietBit);
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        // anything * NaN = qNaN
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        if (bAbs > infRep) return fromRep(toRep(b) | quietBit);
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        if (aAbs == infRep) {
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            // infinity * non-zero = +/- infinity
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            if (bAbs) return fromRep(aAbs | productSign);
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            // infinity * zero = NaN
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            else return fromRep(qnanRep);
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        }
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        if (bAbs == infRep) {
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            //? non-zero * infinity = +/- infinity
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            if (aAbs) return fromRep(bAbs | productSign);
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            // zero * infinity = NaN
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            else return fromRep(qnanRep);
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        }
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        // zero * anything = +/- zero
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        if (!aAbs) return fromRep(productSign);
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        // anything * zero = +/- zero
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        if (!bAbs) return fromRep(productSign);
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        // one or both of a or b is denormal, the other (if applicable) is a
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        // normal number.  Renormalize one or both of a and b, and set scale to
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        // include the necessary exponent adjustment.
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        if (aAbs < implicitBit) scale += normalize(&aSignificand);
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        if (bAbs < implicitBit) scale += normalize(&bSignificand);
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    }
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    // Or in the implicit significand bit.  (If we fell through from the
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    // denormal path it was already set by normalize( ), but setting it twice
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    // won't hurt anything.)
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    aSignificand |= implicitBit;
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    bSignificand |= implicitBit;
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    // Get the significand of a*b.  Before multiplying the significands, shift
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    // one of them left to left-align it in the field.  Thus, the product will
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    // have (exponentBits + 2) integral digits, all but two of which must be
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    // zero.  Normalizing this result is just a conditional left-shift by one
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    // and bumping the exponent accordingly.
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    rep_t productHi, productLo;
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    wideMultiply(aSignificand, bSignificand << exponentBits,
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                 &productHi, &productLo);
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    int productExponent = aExponent + bExponent - exponentBias + scale;
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    // Normalize the significand, adjust exponent if needed.
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    if (productHi & implicitBit) productExponent++;
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    else wideLeftShift(&productHi, &productLo, 1);
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    // If we have overflowed the type, return +/- infinity.
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    if (productExponent >= maxExponent) return fromRep(infRep | productSign);
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    if (productExponent <= 0) {
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        // Result is denormal before rounding
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        //
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        // If the result is so small that it just underflows to zero, return
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        // a zero of the appropriate sign.  Mathematically there is no need to
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        // handle this case separately, but we make it a special case to
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        // simplify the shift logic.
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        const unsigned int shift = REP_C(1) - (unsigned int)productExponent;
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        if (shift >= typeWidth) return fromRep(productSign);
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        // Otherwise, shift the significand of the result so that the round
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        // bit is the high bit of productLo.
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        wideRightShiftWithSticky(&productHi, &productLo, shift);
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    }
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    else {
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        // Result is normal before rounding; insert the exponent.
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        productHi &= significandMask;
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        productHi |= (rep_t)productExponent << significandBits;
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    }
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    // Insert the sign of the result:
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    productHi |= productSign;
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    // Final rounding.  The final result may overflow to infinity, or underflow
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    // to zero, but those are the correct results in those cases.  We use the
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    // default IEEE-754 round-to-nearest, ties-to-even rounding mode.
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    if (productLo > signBit) productHi++;
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    if (productLo == signBit) productHi += productHi & 1;
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    return fromRep(productHi);
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}