Disable _Float16 for non ARM/SPIR Targets
As Discussed here: http://lists.llvm.org/pipermail/llvm-dev/2019-January/129543.html There are problems exposing the _Float16 type on architectures that haven't defined the ABI/ISel for the type yet, so we're temporarily disabling the type and making it opt-in. Differential Revision: https://reviews.llvm.org/D57188 Change-Id: I5db7366dedf1deb9485adb8948b1deb7e612a736 llvm-svn: 352221
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@ -474,44 +474,58 @@ Half-Precision Floating Point
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=============================
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Clang supports two half-precision (16-bit) floating point types: ``__fp16`` and
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``_Float16``. ``__fp16`` is defined in the ARM C Language Extensions (`ACLE
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<http://infocenter.arm.com/help/topic/com.arm.doc.ihi0053d/IHI0053D_acle_2_1.pdf>`_)
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and ``_Float16`` in ISO/IEC TS 18661-3:2015.
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``_Float16``. These types are supported in all language modes.
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``__fp16`` is a storage and interchange format only. This means that values of
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``__fp16`` promote to (at least) float when used in arithmetic operations.
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There are two ``__fp16`` formats. Clang supports the IEEE 754-2008 format and
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not the ARM alternative format.
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``__fp16`` is supported on every target, as it is purely a storage format; see below.
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``_Float16`` is currently only supported on the following targets, with further
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targets pending ABI standardization:
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- 32-bit ARM
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- 64-bit ARM (AArch64)
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- SPIR
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``_Float16`` will be supported on more targets as they define ABIs for it.
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ISO/IEC TS 18661-3:2015 defines C support for additional floating point types.
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``_FloatN`` is defined as a binary floating type, where the N suffix denotes
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the number of bits and is 16, 32, 64, or greater and equal to 128 and a
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multiple of 32. Clang supports ``_Float16``. The difference from ``__fp16`` is
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that arithmetic on ``_Float16`` is performed in half-precision, thus it is not
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a storage-only format. ``_Float16`` is available as a source language type in
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both C and C++ mode.
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``__fp16`` is a storage and interchange format only. This means that values of
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``__fp16`` are immediately promoted to (at least) ``float`` when used in arithmetic
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operations, so that e.g. the result of adding two ``__fp16`` values has type ``float``.
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The behavior of ``__fp16`` is specified by the ARM C Language Extensions (`ACLE <http://infocenter.arm.com/help/topic/com.arm.doc.ihi0053d/IHI0053D_acle_2_1.pdf>`_).
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Clang uses the ``binary16`` format from IEEE 754-2008 for ``__fp16``, not the ARM
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alternative format.
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It is recommended that portable code use the ``_Float16`` type because
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``__fp16`` is an ARM C-Language Extension (ACLE), whereas ``_Float16`` is
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defined by the C standards committee, so using ``_Float16`` will not prevent
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code from being ported to architectures other than Arm. Also, ``_Float16``
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arithmetic and operations will directly map on half-precision instructions when
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they are available (e.g. Armv8.2-A), avoiding conversions to/from
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single-precision, and thus will result in more performant code. If
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half-precision instructions are unavailable, values will be promoted to
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single-precision, similar to the semantics of ``__fp16`` except that the
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results will be stored in single-precision.
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``_Float16`` is an extended floating-point type. This means that, just like arithmetic on
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``float`` or ``double``, arithmetic on ``_Float16`` operands is formally performed in the
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``_Float16`` type, so that e.g. the result of adding two ``_Float16`` values has type
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``_Float16``. The behavior of ``_Float16`` is specified by ISO/IEC TS 18661-3:2015
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("Floating-point extensions for C"). As with ``__fp16``, Clang uses the ``binary16``
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format from IEEE 754-2008 for ``_Float16``.
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In an arithmetic operation where one operand is of ``__fp16`` type and the
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other is of ``_Float16`` type, the ``_Float16`` type is first converted to
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``__fp16`` type and then the operation is completed as if both operands were of
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``__fp16`` type.
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``_Float16`` arithmetic will be performed using native half-precision support
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when available on the target (e.g. on ARMv8.2a); otherwise it will be performed
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at a higher precision (currently always ``float``) and then truncated down to
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``_Float16``. Note that C and C++ allow intermediate floating-point operands
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of an expression to be computed with greater precision than is expressible in
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their type, so Clang may avoid intermediate truncations in certain cases; this may
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lead to results that are inconsistent with native arithmetic.
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To define a ``_Float16`` literal, suffix ``f16`` can be appended to the compile-time
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constant declaration. There is no default argument promotion for ``_Float16``; this
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applies to the standard floating types only. As a consequence, for example, an
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explicit cast is required for printing a ``_Float16`` value (there is no string
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format specifier for ``_Float16``).
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It is recommended that portable code use ``_Float16`` instead of ``__fp16``,
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as it has been defined by the C standards committee and has behavior that is
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more familiar to most programmers.
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Because ``__fp16`` operands are always immediately promoted to ``float``, the
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common real type of ``__fp16`` and ``_Float16`` for the purposes of the usual
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arithmetic conversions is ``float``.
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A literal can be given ``_Float16`` type using the suffix ``f16``; for example:
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```
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3.14f16
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```
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Because default argument promotion only applies to the standard floating-point
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types, ``_Float16`` values are not promoted to ``double`` when passed as variadic
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or untyped arguments. As a consequence, some caution must be taken when using
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certain library facilities with ``_Float16``; for example, there is no ``printf`` format
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specifier for ``_Float16``, and (unlike ``float``) it will not be implicitly promoted to
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``double`` when passed to ``printf``, so the programmer must explicitly cast it to
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``double`` before using it with an ``%f`` or similar specifier.
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Messages on ``deprecated`` and ``unavailable`` Attributes
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=========================================================
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@ -63,6 +63,7 @@ protected:
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bool HasLegalHalfType; // True if the backend supports operations on the half
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// LLVM IR type.
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bool HasFloat128;
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bool HasFloat16;
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unsigned char PointerWidth, PointerAlign;
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unsigned char BoolWidth, BoolAlign;
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unsigned char IntWidth, IntAlign;
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@ -516,6 +517,9 @@ public:
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/// Determine whether the __float128 type is supported on this target.
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virtual bool hasFloat128Type() const { return HasFloat128; }
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/// Determine whether the _Float16 type is supported on this target.
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virtual bool hasFloat16Type() const { return HasFloat16; }
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/// Return the alignment that is suitable for storing any
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/// object with a fundamental alignment requirement.
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unsigned getSuitableAlign() const { return SuitableAlign; }
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@ -34,6 +34,7 @@ TargetInfo::TargetInfo(const llvm::Triple &T) : TargetOpts(), Triple(T) {
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NoAsmVariants = false;
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HasLegalHalfType = false;
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HasFloat128 = false;
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HasFloat16 = false;
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PointerWidth = PointerAlign = 32;
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BoolWidth = BoolAlign = 8;
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IntWidth = IntAlign = 32;
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@ -49,6 +49,7 @@ AArch64TargetInfo::AArch64TargetInfo(const llvm::Triple &Triple,
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// All AArch64 implementations support ARMv8 FP, which makes half a legal type.
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HasLegalHalfType = true;
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HasFloat16 = true;
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LongWidth = LongAlign = PointerWidth = PointerAlign = 64;
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MaxVectorAlign = 128;
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@ -396,6 +396,7 @@ bool ARMTargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
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SoftFloat = SoftFloatABI = false;
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HWDiv = 0;
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DotProd = 0;
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HasFloat16 = true;
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// This does not diagnose illegal cases like having both
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// "+vfpv2" and "+vfpv3" or having "+neon" and "+fp-only-sp".
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@ -47,6 +47,7 @@ public:
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AddrSpaceMap = &SPIRAddrSpaceMap;
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UseAddrSpaceMapMangling = true;
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HasLegalHalfType = true;
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HasFloat16 = true;
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// Define available target features
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// These must be defined in sorted order!
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NoAsmVariants = true;
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@ -1441,7 +1441,12 @@ static QualType ConvertDeclSpecToType(TypeProcessingState &state) {
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else
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Result = Context.Int128Ty;
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break;
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case DeclSpec::TST_float16: Result = Context.Float16Ty; break;
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case DeclSpec::TST_float16:
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if (!S.Context.getTargetInfo().hasFloat16Type())
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S.Diag(DS.getTypeSpecTypeLoc(), diag::err_type_unsupported)
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<< "_Float16";
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Result = Context.Float16Ty;
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break;
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case DeclSpec::TST_half: Result = Context.HalfTy; break;
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case DeclSpec::TST_float: Result = Context.FloatTy; break;
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case DeclSpec::TST_double:
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@ -1,5 +1,5 @@
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// RUN: %clang_cc1 -std=c++11 -ast-dump %s | FileCheck %s --strict-whitespace
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// RUN: %clang_cc1 -std=c++11 -ast-dump -fnative-half-type %s | FileCheck %s --check-prefix=CHECK-NATIVE --strict-whitespace
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// RUN: %clang_cc1 -std=c++11 -ast-dump -triple aarch64-linux-gnu %s | FileCheck %s --strict-whitespace
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// RUN: %clang_cc1 -std=c++11 -ast-dump -triple aarch64-linux-gnu -fnative-half-type %s | FileCheck %s --check-prefix=CHECK-NATIVE --strict-whitespace
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/* Various contexts where type _Float16 can appear. */
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@ -1,5 +1,4 @@
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// RUN: %clang -std=c++11 --target=aarch64-arm--eabi -S -emit-llvm %s -o - | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-AARCH64
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// RUN: %clang -std=c++11 --target=x86_64 -S -emit-llvm %s -o - | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-X86
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/* Various contexts where type _Float16 can appear. */
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@ -15,7 +14,6 @@ namespace {
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_Float16 arr1n[10];
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// CHECK-AARCH64-DAG: @_ZN12_GLOBAL__N_15arr1nE = internal global [10 x half] zeroinitializer, align 2
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// CHECK-X86-DAG: @_ZN12_GLOBAL__N_15arr1nE = internal global [10 x half] zeroinitializer, align 16
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_Float16 arr2n[] = { 1.2, 3.0, 3.e4 };
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// CHECK-DAG: @_ZN12_GLOBAL__N_15arr2nE = internal global [3 x half] [half 0xH3CCD, half 0xH4200, half 0xH7753], align 2
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_Float16 f1f;
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// CHECK-AARCH64-DAG: @f1f = dso_local global half 0xH0000, align 2
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// CHECK-X86-DAG: @f1f = dso_local global half 0xH0000, align 2
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_Float16 f2f = 32.4;
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// CHECK-DAG: @f2f = dso_local global half 0xH500D, align 2
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_Float16 arr1f[10];
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// CHECK-AARCH64-DAG: @arr1f = dso_local global [10 x half] zeroinitializer, align 2
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// CHECK-X86-DAG: @arr1f = dso_local global [10 x half] zeroinitializer, align 16
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_Float16 arr2f[] = { -1.2, -3.0, -3.e4 };
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// CHECK-DAG: @arr2f = dso_local global [3 x half] [half 0xHBCCD, half 0xHC200, half 0xHF753], align 2
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long double cvtld = f2n;
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//CHECK-AARCh64-DAG: [[H2LD:%[a-z0-9]+]] = fpext half {{%[0-9]+}} to fp128
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//CHECK-AARCh64-DAG: store fp128 [[H2LD]], fp128* %{{.*}}, align 16
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//CHECK-X86-DAG: [[H2LD:%[a-z0-9]+]] = fpext half {{%[0-9]+}} to x86_fp80
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//CHECK-X86-DAG: store x86_fp80 [[H2LD]], x86_fp80* %{{.*}}, align 16
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_Float16 f2h = 42.0f;
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//CHECK-DAG: store half 0xH5140, half* %{{.*}}, align 2
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@ -1,5 +1,6 @@
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// RUN: %clang_cc1 -fblocks -emit-llvm %s -o - -triple=i386-pc-win32 -std=c++98 | FileCheck %s
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// RUN: %clang_cc1 -fblocks -emit-llvm %s -o - -triple=x86_64-pc-win32 -std=c++98| FileCheck -check-prefix X64 %s
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// RUN: %clang_cc1 -fblocks -emit-llvm %s -o - -triple=aarch64-pc-win32 -std=c++98 -DARM | FileCheck -check-prefixes=X64,ARM %s
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int a;
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// CHECK-DAG: @"?a@@3HA"
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// CHECK-DAG: define dso_local void @"?f@Complex@@YAXU?$_Complex@H@__clang@@@Z"(
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void f(_Complex int) {}
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}
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#ifdef ARM
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namespace Float16 {
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// CHECK-DAG: define dso_local void @"?f@Float16@@YAXU_Float16@__clang@@@Z"(
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// ARM-DAG: define dso_local void @"?f@Float16@@YAXU_Float16@__clang@@@Z"(
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void f(_Float16) {}
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}
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#endif // ARM
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namespace PR26029 {
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template <class>
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@ -1,4 +1,4 @@
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// RUN: %clang_cc1 -fsyntax-only -verify -pedantic %s
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// RUN: %clang_cc1 -fsyntax-only -verify -pedantic -triple aarch64-linux-gnu %s
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float a = 1.0h; // expected-error{{no matching literal operator for call to 'operator""h' with argument of type 'long double' or 'const char *', and no matching literal operator template}}
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float b = 1.0H; // expected-error{{invalid suffix 'H' on floating constant}}
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@ -0,0 +1,11 @@
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// RUN: %clang_cc1 -fsyntax-only -verify -triple x86_64-linux-pc %s
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// RUN: %clang_cc1 -fsyntax-only -verify -triple spir-unknown-unknown %s -DHAVE
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// RUN: %clang_cc1 -fsyntax-only -verify -triple armv7a-linux-gnu %s -DHAVE
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// RUN: %clang_cc1 -fsyntax-only -verify -triple aarch64-linux-gnu %s -DHAVE
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#ifdef HAVE
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// expected-no-diagnostics
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#else
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// expected-error@+2{{_Float16 is not supported on this target}}
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#endif // HAVE
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_Float16 f;
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