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[NFC][LLVM][AsmWriter] Extract logic to write out ConstantFP from Wri…
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…teConstantInternal.

This makes is easier to extend the code to support vector types.
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@paulwalker-arm
paulwalker-arm committed Feb 13, 2024
1 parent 485ebbf commit 4f13f35
Showing 1 changed file with 94 additions and 88 deletions.
182 changes: 94 additions & 88 deletions llvm/lib/IR/AsmWriter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1406,6 +1406,99 @@ static void WriteOptimizationInfo(raw_ostream &Out, const User *U) {
}
}

static void WriteAPFloatInternal(raw_ostream &Out, const APFloat &APF) {
if (&APF.getSemantics() == &APFloat::IEEEsingle() ||
&APF.getSemantics() == &APFloat::IEEEdouble()) {
// We would like to output the FP constant value in exponential notation,
// but we cannot do this if doing so will lose precision. Check here to
// make sure that we only output it in exponential format if we can parse
// the value back and get the same value.
//
bool ignored;
bool isDouble = &APF.getSemantics() == &APFloat::IEEEdouble();
bool isInf = APF.isInfinity();
bool isNaN = APF.isNaN();

if (!isInf && !isNaN) {
double Val = APF.convertToDouble();
SmallString<128> StrVal;
APF.toString(StrVal, 6, 0, false);
// Check to make sure that the stringized number is not some string like
// "Inf" or NaN, that atof will accept, but the lexer will not. Check
// that the string matches the "[-+]?[0-9]" regex.
//
assert((isDigit(StrVal[0]) ||
((StrVal[0] == '-' || StrVal[0] == '+') && isDigit(StrVal[1]))) &&
"[-+]?[0-9] regex does not match!");
// Reparse stringized version!
if (APFloat(APFloat::IEEEdouble(), StrVal).convertToDouble() == Val) {
Out << StrVal;
return;
}
}

// Otherwise we could not reparse it to exactly the same value, so we must
// output the string in hexadecimal format! Note that loading and storing
// floating point types changes the bits of NaNs on some hosts, notably
// x86, so we must not use these types.
static_assert(sizeof(double) == sizeof(uint64_t),
"assuming that double is 64 bits!");
APFloat apf = APF;

// Floats are represented in ASCII IR as double, convert.
// FIXME: We should allow 32-bit hex float and remove this.
if (!isDouble) {
// A signaling NaN is quieted on conversion, so we need to recreate the
// expected value after convert (quiet bit of the payload is clear).
bool IsSNAN = apf.isSignaling();
apf.convert(APFloat::IEEEdouble(), APFloat::rmNearestTiesToEven,
&ignored);
if (IsSNAN) {
APInt Payload = apf.bitcastToAPInt();
apf =
APFloat::getSNaN(APFloat::IEEEdouble(), apf.isNegative(), &Payload);
}
}

Out << format_hex(apf.bitcastToAPInt().getZExtValue(), 0, /*Upper=*/true);
return;
}

// Either half, bfloat or some form of long double.
// These appear as a magic letter identifying the type, then a
// fixed number of hex digits.
Out << "0x";
APInt API = APF.bitcastToAPInt();
if (&APF.getSemantics() == &APFloat::x87DoubleExtended()) {
Out << 'K';
Out << format_hex_no_prefix(API.getHiBits(16).getZExtValue(), 4,
/*Upper=*/true);
Out << format_hex_no_prefix(API.getLoBits(64).getZExtValue(), 16,
/*Upper=*/true);
} else if (&APF.getSemantics() == &APFloat::IEEEquad()) {
Out << 'L';
Out << format_hex_no_prefix(API.getLoBits(64).getZExtValue(), 16,
/*Upper=*/true);
Out << format_hex_no_prefix(API.getHiBits(64).getZExtValue(), 16,
/*Upper=*/true);
} else if (&APF.getSemantics() == &APFloat::PPCDoubleDouble()) {
Out << 'M';
Out << format_hex_no_prefix(API.getLoBits(64).getZExtValue(), 16,
/*Upper=*/true);
Out << format_hex_no_prefix(API.getHiBits(64).getZExtValue(), 16,
/*Upper=*/true);
} else if (&APF.getSemantics() == &APFloat::IEEEhalf()) {
Out << 'H';
Out << format_hex_no_prefix(API.getZExtValue(), 4,
/*Upper=*/true);
} else if (&APF.getSemantics() == &APFloat::BFloat()) {
Out << 'R';
Out << format_hex_no_prefix(API.getZExtValue(), 4,
/*Upper=*/true);
} else
llvm_unreachable("Unsupported floating point type");
}

static void WriteConstantInternal(raw_ostream &Out, const Constant *CV,
AsmWriterContext &WriterCtx) {
if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
Expand All @@ -1418,94 +1511,7 @@ static void WriteConstantInternal(raw_ostream &Out, const Constant *CV,
}

if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV)) {
const APFloat &APF = CFP->getValueAPF();
if (&APF.getSemantics() == &APFloat::IEEEsingle() ||
&APF.getSemantics() == &APFloat::IEEEdouble()) {
// We would like to output the FP constant value in exponential notation,
// but we cannot do this if doing so will lose precision. Check here to
// make sure that we only output it in exponential format if we can parse
// the value back and get the same value.
//
bool ignored;
bool isDouble = &APF.getSemantics() == &APFloat::IEEEdouble();
bool isInf = APF.isInfinity();
bool isNaN = APF.isNaN();
if (!isInf && !isNaN) {
double Val = APF.convertToDouble();
SmallString<128> StrVal;
APF.toString(StrVal, 6, 0, false);
// Check to make sure that the stringized number is not some string like
// "Inf" or NaN, that atof will accept, but the lexer will not. Check
// that the string matches the "[-+]?[0-9]" regex.
//
assert((isDigit(StrVal[0]) || ((StrVal[0] == '-' || StrVal[0] == '+') &&
isDigit(StrVal[1]))) &&
"[-+]?[0-9] regex does not match!");
// Reparse stringized version!
if (APFloat(APFloat::IEEEdouble(), StrVal).convertToDouble() == Val) {
Out << StrVal;
return;
}
}
// Otherwise we could not reparse it to exactly the same value, so we must
// output the string in hexadecimal format! Note that loading and storing
// floating point types changes the bits of NaNs on some hosts, notably
// x86, so we must not use these types.
static_assert(sizeof(double) == sizeof(uint64_t),
"assuming that double is 64 bits!");
APFloat apf = APF;
// Floats are represented in ASCII IR as double, convert.
// FIXME: We should allow 32-bit hex float and remove this.
if (!isDouble) {
// A signaling NaN is quieted on conversion, so we need to recreate the
// expected value after convert (quiet bit of the payload is clear).
bool IsSNAN = apf.isSignaling();
apf.convert(APFloat::IEEEdouble(), APFloat::rmNearestTiesToEven,
&ignored);
if (IsSNAN) {
APInt Payload = apf.bitcastToAPInt();
apf = APFloat::getSNaN(APFloat::IEEEdouble(), apf.isNegative(),
&Payload);
}
}
Out << format_hex(apf.bitcastToAPInt().getZExtValue(), 0, /*Upper=*/true);
return;
}

// Either half, bfloat or some form of long double.
// These appear as a magic letter identifying the type, then a
// fixed number of hex digits.
Out << "0x";
APInt API = APF.bitcastToAPInt();
if (&APF.getSemantics() == &APFloat::x87DoubleExtended()) {
Out << 'K';
Out << format_hex_no_prefix(API.getHiBits(16).getZExtValue(), 4,
/*Upper=*/true);
Out << format_hex_no_prefix(API.getLoBits(64).getZExtValue(), 16,
/*Upper=*/true);
return;
} else if (&APF.getSemantics() == &APFloat::IEEEquad()) {
Out << 'L';
Out << format_hex_no_prefix(API.getLoBits(64).getZExtValue(), 16,
/*Upper=*/true);
Out << format_hex_no_prefix(API.getHiBits(64).getZExtValue(), 16,
/*Upper=*/true);
} else if (&APF.getSemantics() == &APFloat::PPCDoubleDouble()) {
Out << 'M';
Out << format_hex_no_prefix(API.getLoBits(64).getZExtValue(), 16,
/*Upper=*/true);
Out << format_hex_no_prefix(API.getHiBits(64).getZExtValue(), 16,
/*Upper=*/true);
} else if (&APF.getSemantics() == &APFloat::IEEEhalf()) {
Out << 'H';
Out << format_hex_no_prefix(API.getZExtValue(), 4,
/*Upper=*/true);
} else if (&APF.getSemantics() == &APFloat::BFloat()) {
Out << 'R';
Out << format_hex_no_prefix(API.getZExtValue(), 4,
/*Upper=*/true);
} else
llvm_unreachable("Unsupported floating point type");
WriteAPFloatInternal(Out, CFP->getValueAPF());
return;
}

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