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//===-- ctfloat.cpp -------------------------------------------------------===//
//
// LDC – the LLVM D compiler
//
// This file is distributed under the BSD-style LDC license. See the LICENSE
// file for details.
//
//===----------------------------------------------------------------------===//
#include "dmd/root/ctfloat.h"
#include "gen/llvm.h"
#include "llvm/Support/Error.h"
using llvm::APFloat;
namespace {
const llvm::fltSemantics *apSemantics = nullptr;
constexpr unsigned numUint64Parts = (sizeof(real_t) + 7) / 8;
union CTFloatUnion {
real_t fp;
uint64_t bits[numUint64Parts];
};
APFloat parseLiteral(const llvm::fltSemantics &semantics, const char *literal,
bool *isOutOfRange = nullptr) {
APFloat ap(semantics, APFloat::uninitialized);
auto r =
#if LDC_LLVM_VER >= 1000
llvm::cantFail
#endif
(ap.convertFromString(literal, APFloat::rmNearestTiesToEven));
if (isOutOfRange) {
*isOutOfRange = (r & (APFloat::opOverflow | APFloat::opUnderflow)) != 0;
}
return ap;
}
} // anonymous namespace
////////////////////////////////////////////////////////////////////////////////
void CTFloat::initialize() {
if (apSemantics)
return;
#ifdef _MSC_VER
// MSVC hosts use dmd.root.longdouble (80-bit x87)
apSemantics = &APFloat::x87DoubleExtended();
#else
static_assert(std::numeric_limits<real_t>::is_specialized,
"real_t is not an arithmetic type");
constexpr int digits = std::numeric_limits<real_t>::digits;
if (digits == 53) {
apSemantics = &APFloat::IEEEdouble();
} else if (digits == 64) {
apSemantics = &APFloat::x87DoubleExtended();
} else if (digits == 113) {
apSemantics = &APFloat::IEEEquad();
} else if (digits == 106) {
apSemantics = &APFloat::PPCDoubleDouble();
} else {
llvm_unreachable("Unknown host real_t type for compile-time reals");
}
#endif
zero = 0;
one = 1;
minusone = -1;
half = 0.5;
nan = fromAPFloat(APFloat::getQNaN(*apSemantics));
infinity = fromAPFloat(APFloat::getInf(*apSemantics));
}
////////////////////////////////////////////////////////////////////////////////
void CTFloat::toAPFloat(const real_t src, APFloat &dst) {
if (sizeof(real_t) == 8) {
dst = APFloat(static_cast<double>(src));
return;
}
CTFloatUnion u;
u.fp = src;
const unsigned sizeInBits = APFloat::getSizeInBits(*apSemantics);
const APInt bits = APInt(sizeInBits, numUint64Parts, u.bits);
dst = APFloat(*apSemantics, bits);
}
////////////////////////////////////////////////////////////////////////////////
real_t CTFloat::fromAPFloat(const APFloat &src_) {
APFloat src = src_;
if (&src.getSemantics() != apSemantics) {
bool ignored;
src.convert(*apSemantics, APFloat::rmNearestTiesToEven, &ignored);
}
const APInt bits = src.bitcastToAPInt();
CTFloatUnion u;
memcpy(u.bits, bits.getRawData(), bits.getBitWidth() / 8);
return u.fp;
}
////////////////////////////////////////////////////////////////////////////////
real_t CTFloat::parse(const char *literal, bool *isOutOfRange) {
const APFloat ap = parseLiteral(*apSemantics, literal, isOutOfRange);
return fromAPFloat(ap);
}
bool CTFloat::isFloat32LiteralOutOfRange(const char *literal) {
bool isOutOfRange;
parseLiteral(APFloat::IEEEsingle(), literal, &isOutOfRange);
return isOutOfRange;
}
bool CTFloat::isFloat64LiteralOutOfRange(const char *literal) {
bool isOutOfRange;
parseLiteral(APFloat::IEEEdouble(), literal, &isOutOfRange);
return isOutOfRange;
}
////////////////////////////////////////////////////////////////////////////////
int CTFloat::sprint(char *str, char fmt, real_t x) {
assert(fmt == 'g' || fmt == 'a' || fmt == 'A');
const bool uppercase = fmt == 'A';
// We try to keep close to C printf and handle a few divergences of the LLVM
// to-string utility functions.
if (isNaN(x)) {
int length = 0;
if (copysign(one, x) != one) {
str[0] = '-';
++length;
}
memcpy(str + length, uppercase ? "NAN" : "nan", 3);
length += 3;
str[length] = 0;
return length;
}
if (isInfinity(x)) { // incl. -inf
int length = 0;
if (x < 0) {
str[0] = '-';
++length;
}
memcpy(str + length, uppercase ? "INF" : "inf", 3);
length += 3;
str[length] = 0;
return length;
}
// Use LLVM for printing hex strings.
if (fmt == 'a' || fmt == 'A') {
APFloat ap(0.0);
toAPFloat(x, ap);
int length =
ap.convertToHexString(str, 0, uppercase, APFloat::rmNearestTiesToEven);
// insert a '+' prefix for non-negative exponents (incl. 0) as visual aid
const char p = uppercase ? 'P' : 'p';
for (int i = length - 2; i >= 0; --i) {
if (str[i] == p) {
if (str[i + 1] != '-' && str[i + 1] != '+') {
for (int j = length - 1; j > i; --j)
str[j + 1] = str[j];
str[i + 1] = '+';
++length;
}
break;
}
}
str[length] = 0;
return length;
}
assert(fmt == 'g');
// Use the host C runtime for printing decimal strings;
// llvm::APFloat::toString() seems not to round correctly, e.g., with LLVM 10:
// * powl(2.5L, 2.5L) = 9.882117688... => `9.88211` (not 9.88212)
// * 1e-300L => `9.99999e-301`
#ifdef _MSC_VER
int length = sprintf(str, "%g", static_cast<double>(x));
#else
int length = sprintf(str, "%Lg", x);
#endif
// 1 => 1.0 to distinguish from integers
bool needsFPSuffix = true;
for (int i = 0; i < length; ++i) {
if (str[i] != '-' && !isdigit(str[i])) {
needsFPSuffix = false;
break;
}
}
if (needsFPSuffix) {
memcpy(str + length, ".0", 2);
length += 2;
}
str[length] = 0;
return length;
}
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