[APFloat] Fix truncation of certain subnormal numbers

Certain subnormals would be incorrectly rounded away from zero.

Fixes #55838

Differential Revision: https://reviews.llvm.org/D127140

[APFloat] Set size of PPCDoubleDouble to 128

566690b0 uses size information in float semantics, but PPCDoubleDouble
left them empty.

As follow-up, we can consider remove PPCDoubleDoubleLegacy and f

[APFloat] Set size of PPCDoubleDouble to 128

566690b0 uses size information in float semantics, but PPCDoubleDouble
left them empty.

As follow-up, we can consider remove PPCDoubleDoubleLegacy and fill
other fields in the future.

Reviewed By: foad

Differential Revision: https://reviews.llvm.org/D111398

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[APFloat] Common up some assertions. NFC.

[APFloat] Remove BitWidth argument from getAllOnesValue

There's no need to pass this in explicitly because it is
trivially available from the semantics.

[APInt] Normalize naming on keep constructors / predicate methods.

This renames the primary methods for creating a zero value to `getZero`
instead of `getNullValue` and renames predicates like `isAl

[APInt] Normalize naming on keep constructors / predicate methods.

This renames the primary methods for creating a zero value to `getZero`
instead of `getNullValue` and renames predicates like `isAllOnesValue`
to simply `isAllOnes`. This achieves two things:

1) This starts standardizing predicates across the LLVM codebase,
following (in this case) ConstantInt. The word "Value" doesn't
convey anything of merit, and is missing in some of the other things.

2) Calling an integer "null" doesn't make any sense. The original sin
here is mine and I've regretted it for years. This moves us to calling
it "zero" instead, which is correct!

APInt is widely used and I don't think anyone is keen to take massive source
breakage on anything so core, at least not all in one go. As such, this
doesn't actually delete any entrypoints, it "soft deprecates" them with a
comment.

Included in this patch are changes to a bunch of the codebase, but there are
more. We should normalize SelectionDAG and other APIs as well, which would
make the API change more mechanical.

Differential Revision: https://reviews.llvm.org/D109483

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[APInt.h] Reduce the APInt header file interface a bit. NFC

This moves one mid-size function out of line, inlines the
trivial tcAnd/tcOr/tcXor/tcComplement methods into their only
caller, and moves

[APInt.h] Reduce the APInt header file interface a bit. NFC

This moves one mid-size function out of line, inlines the
trivial tcAnd/tcOr/tcXor/tcComplement methods into their only
caller, and moves the magic/umagic functions into SelectionDAG
since they are implementation details of its algorithm. This
also removes the unit tests for magic, but these are already
tested in the divide lowering logic for various targets.

This also upgrades some C style comments to C++.

Differential Revision: https://reviews.llvm.org/D109476

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[APFloat] convertToDouble/Float can work on shorter types

Previously APFloat::convertToDouble may be called only for APFloats that
were built using double semantics. Other semantics like single prec

[APFloat] convertToDouble/Float can work on shorter types

Previously APFloat::convertToDouble may be called only for APFloats that
were built using double semantics. Other semantics like single precision
were not allowed although corresponding numbers could be converted to
double without loss of precision. The similar restriction applied to
APFloat::convertToFloat.

With this change any APFloat that can be precisely represented by double
can be handled with convertToDouble. Behavior of convertToFloat was
updated similarly. It make the conversion operations more convenient and
adds support for formats like half and bfloat.

Differential Revision: https://reviews.llvm.org/D102671

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Revert rGce587529ad8b5 - "[APFloat] multiplySignificand - pass IEEEFloat as const reference. NFCI."

Breaks on some buildbots

[APFloat] multiplySignificand - pass IEEEFloat as const reference. NFCI.

Avoids unnecessary IEEEFloat copies.

[APFloat] scalbn - pass DoubleAPFloat arg as const-ref. NFCI.

Avoid unnecessary copy and fix clang-tidy warning.

[Support] Add some missing namespace closure comments. NFCI.

Fixes some clang-tidy warnings.

Cleanup namespace comment to fix clang-tidy warning. NFCI.

[APFloat] convert SNaN to QNaN in convert() and raise Invalid signal

This is an alternate fix (see D87835) for a bug where a NaN constant
gets wrongly transformed into Infinity via truncation.
In th

[APFloat] convert SNaN to QNaN in convert() and raise Invalid signal

This is an alternate fix (see D87835) for a bug where a NaN constant
gets wrongly transformed into Infinity via truncation.
In this patch, we uniformly convert any SNaN to QNaN while raising
'invalid op'.
But we don't have a way to directly specify a 32-bit SNaN value in LLVM IR,
so those are always encoded/decoded by calling convert from/to 64-bit hex.

See D88664 for a clang fix needed to allow this change.

Differential Revision: https://reviews.llvm.org/D88238

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[APFloat] Improve asserts in isSignificandAllOnes and isSignificandAllZeros so they protect shift operations from undefined behavior.

For example, the assert in isSignificandAllZeros allowed NumHigh

[APFloat] Improve asserts in isSignificandAllOnes and isSignificandAllZeros so they protect shift operations from undefined behavior.

For example, the assert in isSignificandAllZeros allowed NumHighBits
to be integerPartWidth. But since it is used directly as a shift amount
it must be less than integerPartWidth.

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Patch IEEEFloat::isSignificandAllZeros and IEEEFloat::isSignificandAllOnes (bug 34579)

Patch IEEEFloat::isSignificandAllZeros and IEEEFloat::isSignificandAllOnes to behave correctly in the case that

Patch IEEEFloat::isSignificandAllZeros and IEEEFloat::isSignificandAllOnes (bug 34579)

Patch IEEEFloat::isSignificandAllZeros and IEEEFloat::isSignificandAllOnes to behave correctly in the case that the size of the significand is a multiple of the width of the integerParts making up the significand.

The patch to IEEEFloat::isSignificandAllOnes fixes bug 34579, and the patch to IEEE:Float:isSignificandAllZeros fixes the unit test "APFloatTest.x87Next" I added here. I have included both in this diff since the changes are very similar.

Patch by Andrew Briand

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[APFloat] prevent NaN morphing into Inf on conversion (PR43907)

We shift the significand right on a truncation, but that needs to be made NaN-safe:
always set at least 1 bit in the significand.
http

[APFloat] prevent NaN morphing into Inf on conversion (PR43907)

We shift the significand right on a truncation, but that needs to be made NaN-safe:
always set at least 1 bit in the significand.
https://llvm.org/PR43907

See D88238 for the likely follow-up (but needs some plumbing fixes before it can proceed).

Differential Revision: https://reviews.llvm.org/D87835

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Revert rGf835779160ec303 "[APFloat] multiplySignificand - always pass IEEEFloat as const reference. NFCI."

This reverts commit f835779160ec30340676918915526615a07e826e while I investigate some build

Revert rGf835779160ec303 "[APFloat] multiplySignificand - always pass IEEEFloat as const reference. NFCI."

This reverts commit f835779160ec30340676918915526615a07e826e while I investigate some buildbot failures

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[APFloat] multiplySignificand - always pass IEEEFloat as const reference. NFCI.

We do this in all other cases.

[APFloat] Fix uninitialized variable in IEEEFloat constructors

Some constructors of IEEEFloat do not initialize member variable exponent.
Fix it by initializing exponent with the following values:

[APFloat] Fix uninitialized variable in IEEEFloat constructors

Some constructors of IEEEFloat do not initialize member variable exponent.
Fix it by initializing exponent with the following values:

For NaNs, the `exponent` is `maxExponent+1`.
For Infinities, the `exponent` is `maxExponent+1`.
For Zeroes, the `exponent` is `maxExponent-1`.

Patch by: @nullptr.cpp (Yang Fan)

Differential Revision: https://reviews.llvm.org/D86997

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Fix convertBFloatAPFloatToAPInt for NaN/Inf values

Bfloat type has an 8-bit exponent so the exponent of NaN/Inf numbers
must be 0xff instead of 0x1f. This is probably a copy-paste mistake
from the h

Fix convertBFloatAPFloatToAPInt for NaN/Inf values

Bfloat type has an 8-bit exponent so the exponent of NaN/Inf numbers
must be 0xff instead of 0x1f. This is probably a copy-paste mistake
from the half float type.

Reviewed By: lattner

Differential Revision: https://reviews.llvm.org/D81302

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[IR][BFloat] Add BFloat IR type

Summary:
The BFloat IR type is introduced to provide support for, initially, the BFloat16
datatype introduced with the Armv8.6 architecture (optional from Armv8.2
onw

[IR][BFloat] Add BFloat IR type

Summary:
The BFloat IR type is introduced to provide support for, initially, the BFloat16
datatype introduced with the Armv8.6 architecture (optional from Armv8.2
onwards). It has an 8-bit exponent and a 7-bit mantissa and behaves like an IEEE
754 floating point IR type.

This is part of a patch series upstreaming Armv8.6 features. Subsequent patches
will upstream intrinsics support and C-lang support for BFloat.

Reviewers: SjoerdMeijer, rjmccall, rsmith, liutianle, RKSimon, craig.topper, jfb, LukeGeeson, sdesmalen, deadalnix, ctetreau

Subscribers: hiraditya, llvm-commits, danielkiss, arphaman, kristof.beyls, dexonsmith

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D78190

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[FPEnv] Use single enum to represent rounding mode

Now compiler defines 5 sets of constants to represent rounding mode.
These are:

1. `llvm::APFloatBase::roundingMode`. It specifies all 5 rounding

[FPEnv] Use single enum to represent rounding mode

Now compiler defines 5 sets of constants to represent rounding mode.
These are:

1. `llvm::APFloatBase::roundingMode`. It specifies all 5 rounding modes
defined by IEEE-754 and is used in `APFloat` implementation.

2. `clang::LangOptions::FPRoundingModeKind`. It specifies 4 of 5 IEEE-754
rounding modes and a special value for dynamic rounding mode. It is used
in clang frontend.

3. `llvm::fp::RoundingMode`. Defines the same values as
`clang::LangOptions::FPRoundingModeKind` but in different order. It is
used to specify rounding mode in in IR and functions that operate IR.

4. Rounding mode representation used by `FLT_ROUNDS` (C11, 5.2.4.2.2p7).
Besides constants for rounding mode it also uses a special value to
indicate error. It is convenient to use in intrinsic functions, as it
represents platform-independent representation for rounding mode. In this
role it is used in some pending patches.

5. Values like `FE_DOWNWARD` and other, which specify rounding mode in
library calls `fesetround` and `fegetround`. Often they represent bits
of some control register, so they are target-dependent. The same names
(not values) and a special name `FE_DYNAMIC` are used in
`#pragma STDC FENV_ROUND`.

The first 4 sets of constants are target independent and could have the
same numerical representation. It would simplify conversion between the
representations. Also now `clang::LangOptions::FPRoundingModeKind` and
`llvm::fp::RoundingMode` do not contain the value for IEEE-754 rounding
direction `roundTiesToAway`, although it is supported natively on
some targets.

This change defines all the rounding mode type via one `llvm::RoundingMode`,
which also contains rounding mode for IEEE rounding direction `roundTiesToAway`.

Differential Revision: https://reviews.llvm.org/D77379

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Make IEEEFloat::roundToIntegral more standard conformant

Behavior of IEEEFloat::roundToIntegral is aligned with IEEE-754
operation roundToIntegralExact. In partucular this function now:
- returns op

Make IEEEFloat::roundToIntegral more standard conformant

Behavior of IEEEFloat::roundToIntegral is aligned with IEEE-754
operation roundToIntegralExact. In partucular this function now:
- returns opInvalid for signaling NaNs,
- returns opInexact if the result of rounding differs from argument.

Differential Revision: https://reviews.llvm.org/D75246

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[APFloat] Make use of new overloaded comparison operators. NFC.

Reviewers: ekatz, spatel, jfb, tlively, craig.topper, RKSimon, nikic, scanon

Subscribers: arsenm, jvesely, nhaehnle, hiraditya, dexon

[APFloat] Make use of new overloaded comparison operators. NFC.

Reviewers: ekatz, spatel, jfb, tlively, craig.topper, RKSimon, nikic, scanon

Subscribers: arsenm, jvesely, nhaehnle, hiraditya, dexonsmith, kerbowa, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75744

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[APFloat] Fix FP remainder operation

Reimplement IEEEFloat::remainder() function.

Fix PR3359.

Differential Revision: https://reviews.llvm.org/D69776