This patch implements the semantics for the 'arm_sve_vector_bits' type
attribute, defined by the Arm C Language Extensions (ACLE) for SVE [1].
The purpose of this attribute is to define vector-length-specific (VLS)
versions of existing vector-length-agnostic (VLA) types.
The semantics were already implemented by D83551, although the
implementation approach has since changed to represent VLSTs as
VectorType in the AST and fixed-length vectors in the IR everywhere
except in function args/returns. This is described in the prototype
patch D85128 demonstrating the new approach.
The semantic changes added in D83551 are changed since the
AttributedType is replaced by VectorType in the AST. Minimal changes
were necessary in the previous patch as the canonical type for both VLA
and VLS was the same (i.e. sizeless), except in constructs such as
globals and structs where sizeless types are unsupported. This patch
reverts the changes that permitted VLS types that were represented as
sizeless types in such circumstances, and adds support for implicit
casting between VLA <-> VLS types as described in section 3.7.3.2 of the
ACLE.
Since the SVE builtin types for bool and uint8 are both represented as
BuiltinType::UChar in VLSTs, two new vector kinds are implemented to
distinguish predicate and data vectors.
[1] https://developer.arm.com/documentation/100987/latest
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D85736
This patch moves FixedPointSemantics and APFixedPoint
from Clang to LLVM ADT.
This will make it easier to use the fixed-point
classes in LLVM for constructing an IR builder for
fixed-point and for reusing the APFixedPoint class
for constant evaluation purposes.
RFC: http://lists.llvm.org/pipermail/llvm-dev/2020-August/144025.html
Reviewed By: leonardchan, rjmccall
Differential Revision: https://reviews.llvm.org/D85312
This function returns a struct `BuiltinVectorTypeInfo` that contains
the builtin vector's element type, element count and number of vectors
(used for vector tuples).
Reviewed By: c-rhodes
Differential Revision: https://reviews.llvm.org/D86100
We can use this to remove some calls to initFeatureMap from Sema
and CodeGen when a function doesn't have a target attribute.
This reduces compile time of the linux kernel where this map
is needed to diagnose some inline assembly constraints based
on whether sse, avx, or avx512 is enabled.
Differential Revision: https://reviews.llvm.org/D85807
ASTContext::removeAddrSpaceQualType does not properly deal
with sugar. QualTypes derive their ASes from the AS on the
canonical type, not the type itself. However,
removeAddrSpaceQualType only strips the outermost qualifiers,
which means that it can fail to remove addrspace qualifiers
if there is sugar in the way.
Change the function to desugar types until the address space
really no longer exists on the corresponding QualType. This
should guarantee the removal of the address space.
This fixes the erroneous behavior in D62574.
Reviewed By: rjmccall, svenvh
Differential Revision: https://reviews.llvm.org/D83325
nvcc supports accessing file-scope static device variables in host code by host APIs
like cudaMemcpyToSymbol etc.
CUDA/HIP let users access device variables in host code by shadow variables. In host compilation,
clang emits a shadow variable for each device variable, and calls __*RegisterVariable to
register it in init function. The address of the shadow variable and the device side mangled
name of the device variable is passed to __*RegisterVariable. Runtime looks up the symbol
by name in the device binary to find the address of the device variable.
The problem with static device variables is that they have internal linkage, therefore their
name may be changed by the linker if there are multiple symbols with the same name. Also
they end up as local symbols in the elf file, whereas the runtime only looks up the global symbols.
Another reason for making the static device variables external linkage is that they may be
initialized externally by host code and their final value may be accessed by host code
after kernel execution, therefore they actually have external linkage. Giving them internal
linkage will cause incorrect optimizations on them.
To support accessing static device var in host code for -fno-gpu-rdc mode, change the intnernal
linkage to external linkage. The name does not need change since there is only one TU for
-fno-gpu-rdc mode. Also the externalization is done only if the device static var is referenced
by host code.
Differential Revision: https://reviews.llvm.org/D80858
This patch introduces 2 new address spaces in OpenCL: global_device and global_host
which are a subset of a global address space, so the address space scheme will be
looking like:
```
generic->global->host
->device
->private
->local
constant
```
Justification: USM allocations may be associated with both host and device memory. We
want to give users a way to tell the compiler the allocation type of a USM pointer for
optimization purposes. (Link to the Unified Shared Memory extension:
https://github.com/intel/llvm/blob/sycl/sycl/doc/extensions/USM/cl_intel_unified_shared_memory.asciidoc)
Before this patch USM pointer could be only in opencl_global
address space, hence a device backend can't tell if a particular pointer
points to host or device memory. On FPGAs at least we can generate more
efficient hardware code if the user tells us where the pointer can point -
being able to distinguish between these types of pointers at compile time
allows us to instantiate simpler load-store units to perform memory
transactions.
Patch by Dmitry Sidorov.
Reviewed By: Anastasia
Differential Revision: https://reviews.llvm.org/D82174
types.
We previously did not treat a function type as dependent if it had a
parameter pack with a non-dependent type -- such a function type depends
on the arity of the pack so is dependent even though none of the
parameter types is dependent. In order to properly handle this, we now
treat pack expansion types as always being dependent types (depending on
at least the pack arity), and always canonically being pack expansion
types, even in the unusual case when the pattern is not a dependent
type. This does mean that we can have canonical types that are pack
expansions that contain no unexpanded packs, which is unfortunate but
not inaccurate.
We also previously did not treat a typedef type as
instantiation-dependent if its canonical type was not
instantiation-dependent. That's wrong because instantiation-dependence
is a property of the type sugar, not of the type; an
instantiation-dependent type can have a non-instantiation-dependent
canonical type.
Implement AIX default `power` alignment rule by adding `PreferredAlignment` and
`PreferredNVAlignment` in ASTRecordLayout class.
The patchh aims at returning correct value for `__alignof(x)` and `alignof(x)`
under `power` alignment rules.
Differential Revision: https://reviews.llvm.org/D79719
I was trying to pick this up a bit when reviewing D48426 (& perhaps D69778) - in any case, looks like D48426 added a module level flag that might not be needed.
The D48426 implementation worked by setting a module level flag, then code generating contents from the PCH a special case in ASTContext::DeclMustBeEmitted would be used to delay emitting the definition of these functions if they came from a Module with this flag.
This strategy is similar to the one initially implemented for modular codegen that was removed in D29901 in favor of the modular decls list and a bit on each decl to specify whether it's homed to a module.
One major difference between PCH object support and modular code generation, other than the specific list of decls that are homed, is the compilation model: MSVC PCH modules are built into the object file for some other source file (when compiling that source file /Yc is specified to say "this compilation is where the PCH is homed"), whereas modular code generation invokes a separate compilation for the PCH alone. So the current modular code generation test of to decide if a decl should be emitted "is the module where this decl is serialized the current main file" has to be extended (as Lubos did in D69778) to also test the command line flag -building-pch-with-obj.
Otherwise the whole thing is basically streamlined down to the modular code generation path.
This even offers one extra material improvement compared to the existing divergent implementation: Homed functions are not emitted into object files that use the pch. Instead at -O0 they are not emitted into the IR at all, and at -O1 they are emitted using available_externally (existing functionality implemented for modular code generation). The pch-codegen test has been updated to reflect this new behavior.
[If possible: I'd love it if we could not have the extra MSVC-style way of accessing dllexport-pch-homing, and just do it the modular codegen way, but I understand that it might be a limitation of existing build systems. @hans / @thakis: Do either of you know if it'd be practical to move to something more similar to .pcm handling, where the pch itself is passed to the compilation, rather than homed as a side effect of compiling some other source file?]
Reviewers: llunak, hans
Differential Revision: https://reviews.llvm.org/D83652
Summary:
This patch implements semantics for the 'arm_sve_vector_bits' type
attribute, defined by the Arm C Language Extensions (ACLE) for SVE [1].
The purpose of this attribute is to define fixed-length (VLST) versions
of existing sizeless types (VLAT).
Implemented in this patch is the the behaviour described in section 3.7.3.2
and minimal parts of sections 3.7.3.3 and 3.7.3.4, this includes:
* Defining VLST globals, structs, unions, and local variables
* Implicit casting between VLAT <=> VLST.
* Diagnosis of ill-formed conditional expressions of the form:
C ? E1 : E2
where E1 is a VLAT type and E2 is a VLST, or vice-versa. This
avoids any ambiguity about the nature of the result type (i.e is
it sized or sizeless).
* For vectors:
* sizeof(VLST) == N/8
* alignof(VLST) == 16
* For predicates:
* sizeof(VLST) == N/64
* alignof(VLST) == 2
VLSTs have the same representation as VLATs in the AST but are wrapped
with a TypeAttribute. Scalable types are currently emitted in the IR for
uses such as globals and structs which don't support these types, this
is addressed in the next patch with codegen, where VLSTs are lowered to
sized arrays for globals, structs / unions and arrays.
Not implemented in this patch is the behaviour guarded by the feature
macros:
* __ARM_FEATURE_SVE_VECTOR_OPERATORS
* __ARM_FEATURE_SVE_PREDICATE_OPERATORS
As such, the GNU __attribute__((vector_size)) extension is not available
and operators such as binary '+' are not supported for VLSTs. Support
for this is intended to be addressed by later patches.
[1] https://developer.arm.com/documentation/100987/latest
This is patch 2/4 of a patch series.
Reviewers: sdesmalen, rsandifo-arm, efriedma, cameron.mcinally, ctetreau, rengolin, aaron.ballman
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D83551
Reapply 49e5f603d4
which had been reverted in c94332919b.
Originally reverted because I hadn't updated it in quite a while when I
got around to committing it, so there were a bunch of missing changes to
new code since I'd written the patch.
Reviewers: aaron.ballman
Differential Revision: https://reviews.llvm.org/D76646
There is a version that just tests (also called
isIntegerConstantExpression) & whereas this version is specifically used
when the value is of interest (a few call sites were actually refactored
to calling the test-only version) so let's make the API look more like
it.
Reviewers: aaron.ballman
Differential Revision: https://reviews.llvm.org/D76646
not be a pack expansion type.
Using a pack expansion type for a pack declaration makes sense, but
general expressions should never have pack expansion types. If we have a
pack `T *...V`, then the type of `V` is the type `T *`, which contains
an unexpanded pack, and is a pointer type.
This allows us to better diagnose issues where a template is invalid due
to some non-dependent portion of a dependent type of a non-type template
parameter pack.
Summary:
The new SVE builtin type __SVBFloat16_t` is used to represent scalable
vectors of bfloat elements.
Reviewers: sdesmalen, efriedma, stuij, ctetreau, shafik, rengolin
Subscribers: tschuett, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D81304
The AAPCS specifies that the tuple types such as `svint32x2_t`
should use their `arm_sve.h` names when mangled instead of their
builtin names.
This patch also renames the internal types for the tuples to
be prefixed with `__clang_`, so they are not misinterpreted as
specified internal types like the non-tuple types which *are* defined
in the AAPCS. Using a builtin type for the tuples is a purely
a choice of the Clang implementation.
Reviewers: rsandifo-arm, c-rhodes, efriedma, rengolin
Reviewed By: efriedma
Tags: #clang
Differential Revision: https://reviews.llvm.org/D81721
This patch contains all of the clang changes from D72959.
- Generalize the relative vtables ABI such that it can be used by other targets.
- Add an enum VTableComponentLayout which controls whether components in the
vtable should be pointers to other structs or relative offsets to those structs.
Other ABIs can change this enum to restructure how components in the vtable
are laid out/accessed.
- Add methods to ConstantInitBuilder for inserting relative offsets to a
specified position in the aggregate being constructed.
- Fix failing tests under new PM and ASan and MSan issues.
See D72959 for background info.
Differential Revision: https://reviews.llvm.org/D77592
This reverts commit 2e009dbcb3.
Reverting since there were some test failures on buildbots that used the
new pass manager. ASan and MSan are also finding some bugs in this that
I'll need to address.
This patch contains all of the clang changes from D72959.
- Generalize the relative vtables ABI such that it can be used by other targets.
- Add an enum VTableComponentLayout which controls whether components in the
vtable should be pointers to other structs or relative offsets to those structs.
Other ABIs can change this enum to restructure how components in the vtable
are laid out/accessed.
- Add methods to ConstantInitBuilder for inserting relative offsets to a
specified position in the aggregate being constructed.
See D72959 for background info.
Differential Revision: https://reviews.llvm.org/D77592
Summary:
This patch upstreams support for a new storage only bfloat16 C type.
This type is used to implement primitive support for bfloat16 data, in
line with the Bfloat16 extension of the Armv8.6-a architecture, as
detailed here:
https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/arm-architecture-developments-armv8-6-a
The bfloat type, and its properties are specified in the Arm Architecture
Reference Manual:
https://developer.arm.com/docs/ddi0487/latest/arm-architecture-reference-manual-armv8-for-armv8-a-architecture-profile
In detail this patch:
- introduces an opaque, storage-only C-type __bf16, which introduces a new bfloat IR type.
This is part of a patch series, starting with command-line and Bfloat16
assembly support. The subsequent patches will upstream intrinsics
support for BFloat16, followed by Matrix Multiplication and the
remaining Virtualization features of the armv8.6-a architecture.
The following people contributed to this patch:
- Luke Cheeseman
- Momchil Velikov
- Alexandros Lamprineas
- Luke Geeson
- Simon Tatham
- Ties Stuij
Reviewers: SjoerdMeijer, rjmccall, rsmith, liutianle, RKSimon, craig.topper, jfb, LukeGeeson, fpetrogalli
Reviewed By: SjoerdMeijer
Subscribers: labrinea, majnemer, asmith, dexonsmith, kristof.beyls, arphaman, danielkiss, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D76077
This patch implements matrix index expressions
(matrix[RowIdx][ColumnIdx]).
It does so by introducing a new MatrixSubscriptExpr(Base, RowIdx, ColumnIdx).
MatrixSubscriptExprs are built in 2 steps in ActOnMatrixSubscriptExpr. First,
if the base of a subscript is of matrix type, we create a incomplete
MatrixSubscriptExpr(base, idx, nullptr). Second, if the base is an incomplete
MatrixSubscriptExpr, we create a complete
MatrixSubscriptExpr(base->getBase(), base->getRowIdx(), idx)
Similar to vector elements, it is not possible to take the address of
a MatrixSubscriptExpr.
For CodeGen, a new MatrixElt type is added to LValue, which is very
similar to VectorElt. The only difference is that we may need to cast
the type of the base from an array to a vector type when accessing it.
Reviewers: rjmccall, anemet, Bigcheese, rsmith, martong
Reviewed By: rjmccall
Differential Revision: https://reviews.llvm.org/D76791
The headers provided with recent GNU toolchains for PPC have code that includes
typedefs such as:
typedef _Complex float __cfloat128 __attribute__ ((__mode__ (__KC__)))
This patch allows clang to compile programs that contain
#include <math.h>
with -mfloat128 which it currently fails to compile.
Fixes: https://bugs.llvm.org/show_bug.cgi?id=46068
Differential revision: https://reviews.llvm.org/D80374
Commit 73152a2ec2 fixed type checking for
blocks with qualified id parameters. But there are existing APIs in
Apple SDKs relying on the old type checking behavior. Specifically,
these are APIs using NSItemProviderCompletionHandler in
Foundation/NSItemProvider.h. To keep existing code working and to allow
developers to use affected APIs introduce a compatibility mode that
enables the previous and the fixed type checking. This mode is enabled
only on Darwin platforms.
Reviewed By: jyknight, ahatanak
Differential Revision: https://reviews.llvm.org/D79511
This patch adds a matrix type to Clang as described in the draft
specification in clang/docs/MatrixSupport.rst. It introduces a new option
-fenable-matrix, which can be used to enable the matrix support.
The patch adds new MatrixType and DependentSizedMatrixType types along
with the plumbing required. Loads of and stores to pointers to matrix
values are lowered to memory operations on 1-D IR arrays. After loading,
the loaded values are cast to a vector. This ensures matrix values use
the alignment of the element type, instead of LLVM's large vector
alignment.
The operators and builtins described in the draft spec will will be added in
follow-up patches.
Reviewers: martong, rsmith, Bigcheese, anemet, dexonsmith, rjmccall, aaron.ballman
Reviewed By: rjmccall
Differential Revision: https://reviews.llvm.org/D72281
Summary:
Conflicting types for the same section name defined in clang section
pragmas and GNU-style section attributes were not properly captured by
Clang's Sema. The lack of diagnostics was caused by the fact the section
specification coming from attributes was handled by Sema as implicit,
even though explicitly defined by the user.
This patch enables the diagnostics for section type conflicts between
those specifications by making sure sections defined in section
attributes are correctly handled as explicit.
Reviewers: hans, rnk, javed.absar
Reviewed By: rnk
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D78573
Looks like this was just a copy & paste mistake from
getDependentSizedExtVectorType. rdar://60092165
Differential revision: https://reviews.llvm.org/D79012
When a category/extension doesn't repeat a type bound, corresponding
type parameter is substituted with `id` when used as a type argument. As
a result, in the added test case it was causing errors like
> type argument 'T' (aka 'id') does not satisfy the bound ('id<NSCopying>') of type parameter 'T'
We are already checking that type parameters should be consistent
everywhere (see `checkTypeParamListConsistency`) and update
`ObjCTypeParamDecl` to have correct underlying type. And when we use the
type parameter as a method return type or a method parameter type, it is
substituted to the bounded type. But when we use the type parameter as a
type argument, we check `ObjCTypeParamType` that wasn't updated and
remains `id`.
Fix by updating not only `ObjCTypeParamDecl` UnderlyingType but also
TypeForDecl as we use the underlying type to create a canonical type for
`ObjCTypeParamType` (see `ASTContext::getObjCTypeParamType`).
This is a different approach to fixing the issue. The previous one was
02c2ab3d88 which was reverted in
4c539e8da1. The problem with the previous
approach was that `ObjCTypeParamType::desugar` was returning underlying
type for `ObjCTypeParamDecl` without applying any protocols stored in
`ObjCTypeParamType`. It caused inconsistencies in comparing types before
and after desugaring.
Re-applying after fixing intermittent test failures.
rdar://problem/54329242
Reviewed By: erik.pilkington
Differential Revision: https://reviews.llvm.org/D72872
This is a code clean up of the PropertyAttributeKind and
ObjCPropertyAttributeKind enums in ObjCPropertyDecl and ObjCDeclSpec that are
exactly identical. This non-functional change consolidates these enums
into one. The changes are to many files across clang (and comments in LLVM) so
that everything refers to the new consolidated enum in DeclObjCCommon.h.
2nd Landing Attempt...
Differential Revision: https://reviews.llvm.org/D77233
This is a code clean up of the PropertyAttributeKind and
ObjCPropertyAttributeKind enums in ObjCPropertyDecl and ObjCDeclSpec that are
exactly identical. This non-functional change consolidates these enums
into one. The changes are to many files across clang (and comments in LLVM) so
that everything refers to the new consolidated enum in DeclObjCCommon.h.
Differential Revision: https://reviews.llvm.org/D77233
This reverts commit 61ba1481e2.
I'm reverting this because it breaks the lldb build with
incomplete switch coverage warnings. I would fix it forward,
but am not familiar enough with lldb to determine the correct
fix.
lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp:3958:11: error: enumeration values 'DependentExtInt' and 'ExtInt' not handled in switch [-Werror,-Wswitch]
switch (qual_type->getTypeClass()) {
^
lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp:4633:11: error: enumeration values 'DependentExtInt' and 'ExtInt' not handled in switch [-Werror,-Wswitch]
switch (qual_type->getTypeClass()) {
^
lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp:4889:11: error: enumeration values 'DependentExtInt' and 'ExtInt' not handled in switch [-Werror,-Wswitch]
switch (qual_type->getTypeClass()) {
Introduction/Motivation:
LLVM-IR supports integers of non-power-of-2 bitwidth, in the iN syntax.
Integers of non-power-of-two aren't particularly interesting or useful
on most hardware, so much so that no language in Clang has been
motivated to expose it before.
However, in the case of FPGA hardware normal integer types where the
full bitwidth isn't used, is extremely wasteful and has severe
performance/space concerns. Because of this, Intel has introduced this
functionality in the High Level Synthesis compiler[0]
under the name "Arbitrary Precision Integer" (ap_int for short). This
has been extremely useful and effective for our users, permitting them
to optimize their storage and operation space on an architecture where
both can be extremely expensive.
We are proposing upstreaming a more palatable version of this to the
community, in the form of this proposal and accompanying patch. We are
proposing the syntax _ExtInt(N). We intend to propose this to the WG14
committee[1], and the underscore-capital seems like the active direction
for a WG14 paper's acceptance. An alternative that Richard Smith
suggested on the initial review was __int(N), however we believe that
is much less acceptable by WG14. We considered _Int, however _Int is
used as an identifier in libstdc++ and there is no good way to fall
back to an identifier (since _Int(5) is indistinguishable from an
unnamed initializer of a template type named _Int).
[0]https://www.intel.com/content/www/us/en/software/programmable/quartus-prime/hls-compiler.html)
[1]http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2472.pdf
Differential Revision: https://reviews.llvm.org/D73967
Summary:
Previously, we treated CXXUuidofExpr as quite a special case: it was the
only kind of expression that could be a canonical template argument, it
could be a constant lvalue base object, and so on. In addition, we
represented the UUID value as a string, whose source form we did not
preserve faithfully, and that we partially parsed in multiple different
places.
With this patch, we create an MSGuidDecl object to represent the
implicit object of type 'struct _GUID' created by a UuidAttr. Each
UuidAttr holds a pointer to its 'struct _GUID' and its original
(as-written) UUID string. A non-value-dependent CXXUuidofExpr behaves
like a DeclRefExpr denoting that MSGuidDecl object. We cache an APValue
representation of the GUID on the MSGuidDecl and use it from constant
evaluation where needed.
This allows removing a lot of the special-case logic to handle these
expressions. Unfortunately, many parts of Clang assume there are only
a couple of interesting kinds of ValueDecl, so the total amount of
special-case logic is not really reduced very much.
This fixes a few bugs and issues:
* PR38490: we now support reading from GUID objects returned from
__uuidof during constant evaluation.
* Our Itanium mangling for a non-instantiation-dependent template
argument involving __uuidof no longer depends on which CXXUuidofExpr
template argument we happened to see first.
* We now predeclare ::_GUID, and permit use of __uuidof without
any header inclusion, better matching MSVC's behavior. We do not
predefine ::__s_GUID, though; that seems like a step too far.
* Our IR representation for GUID constants now uses the correct IR type
wherever possible. We will still fall back to using the
{i32, i16, i16, [8 x i8]}
layout if a definition of struct _GUID is not available. This is not
ideal: in principle the two layouts could have different padding.
Reviewers: rnk, jdoerfert
Subscribers: arphaman, cfe-commits, aeubanks
Tags: #clang
Differential Revision: https://reviews.llvm.org/D78171
In particular, this affects Clang's vectors. Users encounter this issue
when a struct contains an __m128 type.
Fixes PR45420
Reviewed By: rjmccall
Differential Revision: https://reviews.llvm.org/D77754
If we have a function definition in `omp begin/end declare variant` it
is a specialization of a base function with the same name and
"compatible" type. Before, we just created a declaration for the base.
With this patch we try to find an existing declaration first and only
create a new one if we did not find any with a compatible type. This is
preferable as we can tolerate slight mismatches, especially if the
specialized version is "more constrained", e.g., constexpr.
Reviewed By: mikerice
Differential Revision: https://reviews.llvm.org/D77252
When a category/extension doesn't repeat a type bound, corresponding
type parameter is substituted with `id` when used as a type argument. As
a result, in the added test case it was causing errors like
> type argument 'T' (aka 'id') does not satisfy the bound ('id<NSCopying>') of type parameter 'T'
We are already checking that type parameters should be consistent
everywhere (see `checkTypeParamListConsistency`) and update
`ObjCTypeParamDecl` to have correct underlying type. And when we use the
type parameter as a method return type or a method parameter type, it is
substituted to the bounded type. But when we use the type parameter as a
type argument, we check `ObjCTypeParamType` that wasn't updated and
remains `id`.
Fix by updating not only `ObjCTypeParamDecl` UnderlyingType but also
TypeForDecl as we use the underlying type to create a canonical type for
`ObjCTypeParamType` (see `ASTContext::getObjCTypeParamType`).
This is a different approach to fixing the issue. The previous one was
02c2ab3d88 which was reverted in
4c539e8da1. The problem with the previous
approach was that `ObjCTypeParamType::desugar` was returning underlying
type for `ObjCTypeParamDecl` without applying any protocols stored in
`ObjCTypeParamType`. It caused inconsistencies in comparing types before
and after desugaring.
rdar://problem/54329242
Reviewed By: erik.pilkington
Differential Revision: https://reviews.llvm.org/D72872
Cullen Rhodes