aaron.ballman added inline comments.
================
Comment at: clang-tidy/readability/MagicNumbersCheck.cpp:76-86
+ IgnoredFloatingPointValues.reserve(IgnoredFloatingPointValuesInput.size());
+ IgnoredDoublePointValues.reserve(IgnoredFloatingPointValuesInput.size());
+ for (const auto &InputValue : IgnoredFloatingPointValuesInput) {
+ llvm::APFloat FloatValue(llvm::APFloat::IEEEsingle());
+ FloatValue.convertFromString(InputValue, DefaultRoundingMode);
+ IgnoredFloatingPointValues.push_back(FloatValue.convertToFloat());
+
----------------
0x8000-0000 wrote:
> 0x8000-0000 wrote:
> > 0x8000-0000 wrote:
> > > 0x8000-0000 wrote:
> > > > 0x8000-0000 wrote:
> > > > > aaron.ballman wrote:
> > > > > > 0x8000-0000 wrote:
> > > > > > > aaron.ballman wrote:
> > > > > > > > 0x8000-0000 wrote:
> > > > > > > > > aaron.ballman wrote:
> > > > > > > > > > This is where I would construct an `APFloat` object from
> > > > > > > > > > the string given. As for the semantics to be used, I would
> > > > > > > > > > recommend getting it from `TargetInfo::getDoubleFormat()`
> > > > > > > > > > on the belief that we aren't going to care about precision
> > > > > > > > > > (explained in the documentation).
> > > > > > > > > Here is the problem I tried to explain last night but perhaps
> > > > > > > > > I wasn't clear enough.
> > > > > > > > >
> > > > > > > > > When we parse the input list from strings, we have to commit
> > > > > > > > > to one floating point value "semantic" - in our case single
> > > > > > > > > or double precision.
> > > > > > > > >
> > > > > > > > > When we encounter the value in the source code and it is
> > > > > > > > > captured by a matcher, it comes as either one of those values.
> > > > > > > > >
> > > > > > > > > Floats with different semantics can't be directly compared -
> > > > > > > > > so we have to maintain two distinct arrays.
> > > > > > > > >
> > > > > > > > > If we do that, rather than store APFloats and sort/compare
> > > > > > > > > them with awkward lambdas, we might as well just use the
> > > > > > > > > native float/double and be done with it more cleanly.
> > > > > > > > >When we encounter the value in the source code and it is
> > > > > > > > >captured by a matcher, it comes as either one of those values.
> > > > > > > >
> > > > > > > > It may also come in as long double or __float128, for instance,
> > > > > > > > because there are type suffixes for that.
> > > > > > > >
> > > > > > > > > Floats with different semantics can't be directly compared -
> > > > > > > > > so we have to maintain two distinct arrays.
> > > > > > > >
> > > > > > > > Yes, floats with different semantics cannot be directly
> > > > > > > > compared. That's why I said below that we should coerce the
> > > > > > > > literal values.
> > > > > > > >
> > > > > > > > > If we do that, rather than store APFloats and sort/compare
> > > > > > > > > them with awkward lambdas, we might as well just use the
> > > > > > > > > native float/double and be done with it more cleanly.
> > > > > > > >
> > > > > > > > There are too many different floating-point semantics for this
> > > > > > > > to be viable, hence why coercion is a reasonable behavior.
> > > > > > > Let me see if I understood it - your proposal is: store only
> > > > > > > doubles, and when a floating-point literal is encountered in
> > > > > > > code, do not use the FloatingLiteral instance, but parse it again
> > > > > > > into a double and compare exactly. If the comparison matches -
> > > > > > > ignore it.
> > > > > > >
> > > > > > > In that case what is the value of storing APFloats with double
> > > > > > > semantics in the IgnoredValues array, instead of doubles?
> > > > > > > Let me see if I understood it - your proposal is: store only
> > > > > > > doubles, and when a floating-point literal is encountered in
> > > > > > > code, do not use the FloatingLiteral instance, but parse it again
> > > > > > > into a double and compare exactly. If the comparison matches -
> > > > > > > ignore it.
> > > > > >
> > > > > > My proposal is to use `APFloat` as the storage and comparison
> > > > > > medium. Read in strings from the configuration and convert them to
> > > > > > an `APFloat` that has double semantics. Read in literals and call
> > > > > > `FloatLiteral::getValue()` to get the `APFloat` from it, convert it
> > > > > > to one that has double semantics as needed, then perform the
> > > > > > comparison between those two `APFloat` objects.
> > > > > >
> > > > > > > In that case what is the value of storing APFloats with double
> > > > > > > semantics in the IgnoredValues array, instead of doubles?
> > > > > >
> > > > > > Mostly that it allows us to modify or extend the check for more
> > > > > > complicated semantics in the future. Also, it's good practice to
> > > > > > use something with consistent semantic behavior across hosts and
> > > > > > targets (comparisons between numbers that cannot be precisely
> > > > > > represented will at least be consistently compared across hosts
> > > > > > when compiling for the same target).
> > > > > >
> > > > > ok - coming right up!
> > > > > My proposal is to use APFloat as the storage and comparison medium.
> > > > > Read in strings from the configuration and convert them to an APFloat
> > > > > that has double semantics.
> > > >
> > > > This is easy.
> > > >
> > > > > Read in literals and call FloatLiteral::getValue() to get the APFloat
> > > > > from it,
> > > >
> > > > this is easy as well,
> > > >
> > > > > convert it to one that has double semantics as needed, then perform
> > > > > the comparison between those two APFloat objects.
> > > >
> > > > The conversion methods in `APFloat` only produce plain-old-data-types:
> > > > ```
> > > > double convertToDouble() const;
> > > >
> > > >
> > > > float convertToFloat() const;
> > > > ```
> > > >
> > > > There is no
> > > > ```
> > > > APFloat convertToOtherSemantics(const fltSemantics &) const;
> > > > ```
> > > > method.
> > > >
> > > > What I can do is
> > > > 1. convert the APFloat to float or double, depending on what the
> > > > semantics is; cast to double then load into an APFloat with double
> > > > semantics and then search into the set
> > > > 2. parse the textual representation of the FloatingLiteral directly
> > > > into an APFloat with double semantics.
> > > `TargetInfo::getDoubleFormat()` is not accessible directly from
> > > `ClangTidyContext` or from `MatchFinder`
> > 2. doesn't quite work; `APFloat.convertFromString` chokes on `3.14f` ;(
> Option 1 doesn't work, either:
> ```
> llvm::APFloat DoubleFloatValue(llvm::APFloat::IEEEdouble());
>
>
> if (&FloatValue.getSemantics() == &llvm::APFloat::IEEEdouble())
>
>
> DoubleFloatValue = FloatValue;
>
>
> else if (&FloatValue.getSemantics() == &llvm::APFloat::IEEEsingle()) {
>
>
> const float Value = FloatValue.convertToFloat();
>
>
> DoubleFloatValue = llvm::APFloat(static_cast<double>(Value));
>
>
> }
>
>
>
>
>
> return std::binary_search(IgnoredFloatingPointValues.begin(),
>
>
> IgnoredFloatingPointValues.end(),
>
>
> DoubleFloatValue, compareAPFloats);
> ```
> has problems with floating point values that are not integers.
>
> Unless somebody knows how to convert APFloats with any semantics into
> APFloats with double semantics, I'm stuck ;(
> There is no
> `APFloat convertToOtherSemantics(const fltSemantics &) const;`
> method.
```
opStatus convert(const fltSemantics &ToSemantics, roundingMode RM,
bool *losesInfo);
```
This function does exactly that?
================
Comment at: clang-tidy/readability/MagicNumbersCheck.cpp:76-86
+ IgnoredFloatingPointValues.reserve(IgnoredFloatingPointValuesInput.size());
+ IgnoredDoublePointValues.reserve(IgnoredFloatingPointValuesInput.size());
+ for (const auto &InputValue : IgnoredFloatingPointValuesInput) {
+ llvm::APFloat FloatValue(llvm::APFloat::IEEEsingle());
+ FloatValue.convertFromString(InputValue, DefaultRoundingMode);
+ IgnoredFloatingPointValues.push_back(FloatValue.convertToFloat());
+
----------------
aaron.ballman wrote:
> 0x8000-0000 wrote:
> > 0x8000-0000 wrote:
> > > 0x8000-0000 wrote:
> > > > 0x8000-0000 wrote:
> > > > > 0x8000-0000 wrote:
> > > > > > aaron.ballman wrote:
> > > > > > > 0x8000-0000 wrote:
> > > > > > > > aaron.ballman wrote:
> > > > > > > > > 0x8000-0000 wrote:
> > > > > > > > > > aaron.ballman wrote:
> > > > > > > > > > > This is where I would construct an `APFloat` object from
> > > > > > > > > > > the string given. As for the semantics to be used, I
> > > > > > > > > > > would recommend getting it from
> > > > > > > > > > > `TargetInfo::getDoubleFormat()` on the belief that we
> > > > > > > > > > > aren't going to care about precision (explained in the
> > > > > > > > > > > documentation).
> > > > > > > > > > Here is the problem I tried to explain last night but
> > > > > > > > > > perhaps I wasn't clear enough.
> > > > > > > > > >
> > > > > > > > > > When we parse the input list from strings, we have to
> > > > > > > > > > commit to one floating point value "semantic" - in our case
> > > > > > > > > > single or double precision.
> > > > > > > > > >
> > > > > > > > > > When we encounter the value in the source code and it is
> > > > > > > > > > captured by a matcher, it comes as either one of those
> > > > > > > > > > values.
> > > > > > > > > >
> > > > > > > > > > Floats with different semantics can't be directly compared
> > > > > > > > > > - so we have to maintain two distinct arrays.
> > > > > > > > > >
> > > > > > > > > > If we do that, rather than store APFloats and sort/compare
> > > > > > > > > > them with awkward lambdas, we might as well just use the
> > > > > > > > > > native float/double and be done with it more cleanly.
> > > > > > > > > >When we encounter the value in the source code and it is
> > > > > > > > > >captured by a matcher, it comes as either one of those
> > > > > > > > > >values.
> > > > > > > > >
> > > > > > > > > It may also come in as long double or __float128, for
> > > > > > > > > instance, because there are type suffixes for that.
> > > > > > > > >
> > > > > > > > > > Floats with different semantics can't be directly compared
> > > > > > > > > > - so we have to maintain two distinct arrays.
> > > > > > > > >
> > > > > > > > > Yes, floats with different semantics cannot be directly
> > > > > > > > > compared. That's why I said below that we should coerce the
> > > > > > > > > literal values.
> > > > > > > > >
> > > > > > > > > > If we do that, rather than store APFloats and sort/compare
> > > > > > > > > > them with awkward lambdas, we might as well just use the
> > > > > > > > > > native float/double and be done with it more cleanly.
> > > > > > > > >
> > > > > > > > > There are too many different floating-point semantics for
> > > > > > > > > this to be viable, hence why coercion is a reasonable
> > > > > > > > > behavior.
> > > > > > > > Let me see if I understood it - your proposal is: store only
> > > > > > > > doubles, and when a floating-point literal is encountered in
> > > > > > > > code, do not use the FloatingLiteral instance, but parse it
> > > > > > > > again into a double and compare exactly. If the comparison
> > > > > > > > matches - ignore it.
> > > > > > > >
> > > > > > > > In that case what is the value of storing APFloats with double
> > > > > > > > semantics in the IgnoredValues array, instead of doubles?
> > > > > > > > Let me see if I understood it - your proposal is: store only
> > > > > > > > doubles, and when a floating-point literal is encountered in
> > > > > > > > code, do not use the FloatingLiteral instance, but parse it
> > > > > > > > again into a double and compare exactly. If the comparison
> > > > > > > > matches - ignore it.
> > > > > > >
> > > > > > > My proposal is to use `APFloat` as the storage and comparison
> > > > > > > medium. Read in strings from the configuration and convert them
> > > > > > > to an `APFloat` that has double semantics. Read in literals and
> > > > > > > call `FloatLiteral::getValue()` to get the `APFloat` from it,
> > > > > > > convert it to one that has double semantics as needed, then
> > > > > > > perform the comparison between those two `APFloat` objects.
> > > > > > >
> > > > > > > > In that case what is the value of storing APFloats with double
> > > > > > > > semantics in the IgnoredValues array, instead of doubles?
> > > > > > >
> > > > > > > Mostly that it allows us to modify or extend the check for more
> > > > > > > complicated semantics in the future. Also, it's good practice to
> > > > > > > use something with consistent semantic behavior across hosts and
> > > > > > > targets (comparisons between numbers that cannot be precisely
> > > > > > > represented will at least be consistently compared across hosts
> > > > > > > when compiling for the same target).
> > > > > > >
> > > > > > ok - coming right up!
> > > > > > My proposal is to use APFloat as the storage and comparison medium.
> > > > > > Read in strings from the configuration and convert them to an
> > > > > > APFloat that has double semantics.
> > > > >
> > > > > This is easy.
> > > > >
> > > > > > Read in literals and call FloatLiteral::getValue() to get the
> > > > > > APFloat from it,
> > > > >
> > > > > this is easy as well,
> > > > >
> > > > > > convert it to one that has double semantics as needed, then perform
> > > > > > the comparison between those two APFloat objects.
> > > > >
> > > > > The conversion methods in `APFloat` only produce
> > > > > plain-old-data-types:
> > > > > ```
> > > > > double convertToDouble() const;
> > > > >
> > > > >
> > > > > float convertToFloat() const;
> > > > > ```
> > > > >
> > > > > There is no
> > > > > ```
> > > > > APFloat convertToOtherSemantics(const fltSemantics &) const;
> > > > > ```
> > > > > method.
> > > > >
> > > > > What I can do is
> > > > > 1. convert the APFloat to float or double, depending on what the
> > > > > semantics is; cast to double then load into an APFloat with double
> > > > > semantics and then search into the set
> > > > > 2. parse the textual representation of the FloatingLiteral directly
> > > > > into an APFloat with double semantics.
> > > > `TargetInfo::getDoubleFormat()` is not accessible directly from
> > > > `ClangTidyContext` or from `MatchFinder`
> > > 2. doesn't quite work; `APFloat.convertFromString` chokes on `3.14f` ;(
> > Option 1 doesn't work, either:
> > ```
> > llvm::APFloat DoubleFloatValue(llvm::APFloat::IEEEdouble());
> >
> >
> > if (&FloatValue.getSemantics() == &llvm::APFloat::IEEEdouble())
> >
> >
> > DoubleFloatValue = FloatValue;
> >
> >
> > else if (&FloatValue.getSemantics() == &llvm::APFloat::IEEEsingle()) {
> >
> >
> > const float Value = FloatValue.convertToFloat();
> >
> >
> > DoubleFloatValue = llvm::APFloat(static_cast<double>(Value));
> >
> >
> > }
> >
> >
> >
> >
> >
> > return std::binary_search(IgnoredFloatingPointValues.begin(),
> >
> >
> > IgnoredFloatingPointValues.end(),
> >
> >
> > DoubleFloatValue, compareAPFloats);
> > ```
> > has problems with floating point values that are not integers.
> >
> > Unless somebody knows how to convert APFloats with any semantics into
> > APFloats with double semantics, I'm stuck ;(
> > There is no
> > `APFloat convertToOtherSemantics(const fltSemantics &) const;`
> > method.
> ```
> opStatus convert(const fltSemantics &ToSemantics, roundingMode RM,
> bool *losesInfo);
> ```
> This function does exactly that?
> `TargetInfo::getDoubleFormat()` is not accessible directly from
> `ClangTidyContext` or from `MatchFinder`
`MatchFinder` has an `ASTContext` object on which you can call
`ASTContext::getTargetInfo()`, I believe.
Repository:
rCTE Clang Tools Extra
https://reviews.llvm.org/D49114
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