Commit Graph

59450 Commits

Author SHA1 Message Date
Bruno Ricci 00b89f66f9
[clang][NFC] Remove spurious +x flag on DeclTemplate.cpp and DeclTemplate.h 2020-08-05 13:54:30 +01:00
Yaxun (Sam) Liu 45f2a56856 [CUDA][HIP] Support accessing static device variable in host code for -fno-gpu-rdc
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
2020-08-05 07:57:38 -04:00
Yonghong Song 00602ee7ef BPF: simplify IR generation for __builtin_btf_type_id()
This patch simplified IR generation for __builtin_btf_type_id().
For __builtin_btf_type_id(obj, flag), previously IR builtin
looks like
   if (obj is a lvalue)
     llvm.bpf.btf.type.id(obj.ptr, 1, flag)  !type
   else
     llvm.bpf.btf.type.id(obj, 0, flag)  !type
The purpose of the 2nd argument is to differentiate
   __builtin_btf_type_id(obj, flag) where obj is a lvalue
vs.
   __builtin_btf_type_id(obj.ptr, flag)

Note that obj or obj.ptr is never used by the backend
and the `obj` argument is only used to derive the type.
This code sequence is subject to potential llvm CSE when
  - obj is the same .e.g., nullptr
  - flag is the same
  - metadata type is different, e.g., typedef of struct "s"
    and strust "s".
In the above, we don't want CSE since their metadata is different.

This patch change IR builtin to
   llvm.bpf.btf.type.id(seq_num, flag)  !type
and seq_num is always increasing. This will prevent potential
llvm CSE.

Also report an error if the type name is empty for
remote relocation since remote relocation needs non-empty
type name to do relocation against vmlinux.

Differential Revision: https://reviews.llvm.org/D85174
2020-08-04 16:29:42 -07:00
Dan Gohman 47f7174ffa [WebAssembly] Use "signed char" instead of "char" in SIMD intrinsics.
This allows people to use `int8_t` instead of `char`, -funsigned-char,
and generally decouples SIMD from the specialness of `char`.

And it makes intrinsics like `__builtin_wasm_add_saturate_s_i8x16`
and `__builtin_wasm_add_saturate_u_i8x16` use signed and unsigned
element types, respectively.

Differential Revision: https://reviews.llvm.org/D85074
2020-08-04 12:48:40 -07:00
Thorsten Schuett e18c6ef6b4 [clang] improve diagnostics for misaligned and large atomics
"Listing the alignment and access size (== expected alignment) in the warning
seems like a good idea."

solves PR 46947

  struct Foo {
    struct Bar {
      void * a;
      void * b;
    };
    Bar bar;
  };

  struct ThirtyTwo {
    struct Large {
      void * a;
      void * b;
      void * c;
      void * d;
    };
    Large bar;
  };

  void braz(Foo *foo, ThirtyTwo *braz) {
    Foo::Bar bar;
    __atomic_load(&foo->bar, &bar, __ATOMIC_RELAXED);

    ThirtyTwo::Large foobar;
    __atomic_load(&braz->bar, &foobar, __ATOMIC_RELAXED);
  }

repro.cpp:21:3: warning: misaligned atomic operation may incur significant performance penalty; the expected (16 bytes) exceeds the actual alignment (8 bytes) [-Watomic-alignment]
  __atomic_load(&foo->bar, &bar, __ATOMIC_RELAXED);
  ^
repro.cpp:24:3: warning: misaligned atomic operation may incur significant performance penalty; the expected (32 bytes) exceeds the actual alignment (8 bytes) [-Watomic-alignment]
  __atomic_load(&braz->bar, &foobar, __ATOMIC_RELAXED);
  ^
repro.cpp:24:3: warning: large atomic operation may incur significant performance penalty; the access size (32 bytes) exceeds the max lock-free size (16  bytes) [-Watomic-alignment]
3 warnings generated.

Differential Revision: https://reviews.llvm.org/D85102
2020-08-04 11:10:29 -07:00
Yonghong Song 6d67506964 [clang][BPF] support type exist/size and enum exist/value relocations
This patch added the following additional compile-once
run-everywhere (CO-RE) relocations:
  - existence/size of typedef, struct/union or enum type
  - enum value and enum value existence

These additional relocations will make CO-RE bpf programs more
adaptive for potential kernel internal data structure changes.

For existence/size relocations, the following two code patterns
are supported:
  1. uint32_t __builtin_preserve_type_info(*(<type> *)0, flag);
  2. <type> var;
     uint32_t __builtin_preserve_field_info(var, flag);
flag = 0 for existence relocation and flag = 1 for size relocation.

For enum value existence and enum value relocations, the following code
pattern is supported:
  uint64_t __builtin_preserve_enum_value(*(<enum_type> *)<enum_value>,
                                         flag);
flag = 0 means existence relocation and flag = 1 for enum value.
relocation. In the above <enum_type> can be an enum type or
a typedef to enum type. The <enum_value> needs to be an enumerator
value from the same enum type. The return type is uint64_t to
permit potential 64bit enumerator values.

Differential Revision: https://reviews.llvm.org/D83242
2020-08-04 08:39:53 -07:00
Erich Keane 0a8ac91a08 Permit nowthrow and nonnull with multiversioning.
Some shipped versions of stdlib.h use nonnull and nothrow with function
multiversioning.  Support these, as they are generally harmless.
2020-08-04 07:40:27 -07:00
Erich Keane 961da69d7e Improve diagnostics for disallowed attributes used with multiversioning
Since we permit using SOME attributes (at the moment, just 1) with
multiversioning, we should improve the message as it still implies that
no attributes should be combined with multiversioning.
2020-08-04 07:40:27 -07:00
Eduardo Caldas 8ce15f7eeb [SyntaxTree] Fix crash on pointer to member function
Differential Revision: https://reviews.llvm.org/D85146
2020-08-04 14:31:12 +00:00
Eduardo Caldas 860cbbdd6b [SyntaxTree] Add support for `LiteralExpression`
We use inheritance to model the grammar's disjunction rule:
literal:
  integer-literal
  character-literal
  floating-point-literal
  string-literal
  boolean-literal
  pointer-literal
  user-defined-literal

Differential Revision: https://reviews.llvm.org/D85186
2020-08-04 14:05:09 +00:00
Haojian Wu 1c0a0dfa02 [Concepts] Include the found concept decl when dumping the ConceptSpecializationExpr
Differential Revision: https://reviews.llvm.org/D85124
2020-08-04 15:58:12 +02:00
Endre Fülöp 141cb8a1ee [analyzer] Model iterator random incrementation symmetrically
Summary:
In case a pointer iterator is incremented in a binary plus expression
(operator+), where the iterator is on the RHS, IteratorModeling should
now detect, and track the resulting value.

Reviewers: Szelethus, baloghadamsoftware

Reviewed By: baloghadamsoftware

Subscribers: rnkovacs, whisperity, xazax.hun, baloghadamsoftware, szepet, a.sidorin, mikhail.ramalho, Szelethus, donat.nagy, dkrupp, Charusso, steakhal, martong, ASDenysPetrov, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D83190
2020-08-04 11:04:12 +02:00
Daniel Sanders 1beb00db1f Fix use-after-scope in 7209f83112 caught by the sanitizer bots 2020-08-03 16:55:00 -07:00
Kazushi (Jam) Marukawa 045e79e77c [VE] Extend integer arguments and return values smaller than 64 bits
In order to follow NEC Aurora SX VE ABI correctly, change to sign/zero
extend integer arguments and return values smaller than 64 bits in clang.
Also update regression test.

Reviewed By: simoll

Differential Revision: https://reviews.llvm.org/D85071
2020-08-04 08:07:05 +09:00
Fangrui Song 7cf4603fae Reland D61689 Change -gz and -Wa,--compress-debug-sections to use gABI compression (SHF_COMPRESSED) with integrated assembler
This fixes an inconsistency: clang -c -gz -fno-integrated-as means SHF_COMPRESSED
while clang -c -gz -fintegrated-as means zlib-gnu.

---

Since July 15, 2015 (binutils-gdb commit
19a7fe52ae3d0971e67a134bcb1648899e21ae1c, included in 2.26), gas
--compress-debug-sections=zlib (gcc -gz) means zlib-gabi:
SHF_COMPRESSED. Before that GCC/binutils used zlib-gnu (.zdebug).

clang's -gz was introduced in rC306115 (Jun 2017) to indicate zlib-gnu. It
is 2020 now and it is not unreasonable to assume users of the new
feature to have new linkers (ld.bfd/gold >= 2.26, lld >= rLLD273661).

Change clang's default accordingly to improve standard conformance.
zlib-gnu becomes out of fashion and gets poorer toolchain support.
Its mangled names confuse tools and are more likely to cause problems.

Reviewed By: compnerd

Differential Revision: https://reviews.llvm.org/D61689
2020-08-03 15:12:01 -07:00
Thomas Lively cb32792210 [WebAssembly] Implement prototype v128.load{32,64}_zero instructions
Specified in https://github.com/WebAssembly/simd/pull/237, these
instructions load the first vector lane from memory and zero the other
lanes. Since these instructions are not officially part of the SIMD
proposal, they are only available on an opt-in basis via LLVM
intrinsics and clang builtin functions. If these instructions are
merged to the proposal, this implementation will change so that the
instructions will be generated from normal IR. At that point the
intrinsics and builtin functions would be removed.

This PR also changes the opcodes for the experimental f32x4.qfm{a,s}
instructions because their opcodes conflicted with those of the
v128.load{32,64}_zero instructions. The new opcodes were chosen to
match those used in V8.

Differential Revision: https://reviews.llvm.org/D84820
2020-08-03 13:54:00 -07:00
Akira Hatanaka 41b1e97b12 [CodeGen][ObjC] Mark calls to objc_unsafeClaimAutoreleasedReturnValue as
notail on x86-64

This is needed because the epilogue code inserted before tail calls on
x86-64 breaks the handshake between the caller and callee.

Calls to objc_retainAutoreleasedReturnValue used to have the same
problem, which was fixed in https://reviews.llvm.org/D59656.

rdar://problem/66029552

Differential Revision: https://reviews.llvm.org/D84540
2020-08-03 13:25:25 -07:00
Daniel Sanders 7209f83112 Allow .dSYM's to be directly placed in an alternate directory
Once available in the relevant toolchains this will allow us to implement
LLVM_EXTERNALIZE_DEBUGINFO_OUTPUT_DIR after D84127 by directly placing the dSYM
in the desired location instead of emitting next to the output file and moving
it.

Reviewed By: JDevlieghere

Differential Revision: https://reviews.llvm.org/D84572
2020-08-03 13:18:52 -07:00
Denys Petrov 86e1b73507 [analyzer] Simplify function SVal::getAsSymbolicExpression and similar ones
Summary: Simplify functions SVal::getAsSymbolicExpression SVal::getAsSymExpr and SVal::getAsSymbol. After revision I concluded that `getAsSymbolicExpression` and `getAsSymExpr` repeat functionality of `getAsSymbol`, thus them can be removed.

Fix: Remove functions SVal::getAsSymbolicExpression and SVal::getAsSymExpr.

Differential Revision: https://reviews.llvm.org/D85034
2020-08-03 15:03:35 +03:00
Kadir Cetinkaya 76c3ec814d
[clang][Tooling] Optimize addTargetAndMode in case of invalid modes
This skips searching for `target` related flags in the existing args if
we don't have a valid target to insert.

Depends on D85076

Differential Revision: https://reviews.llvm.org/D85077
2020-08-03 13:58:27 +02:00
Kadir Cetinkaya 87de54dbb6
[clang][Tooling] Fix addTargetAndModeForProgramName to use correct flag names
The logic was using incorrect flag versions. For example:
- `-target=` can't be a prefix, it must be `--target=`.
- `--driver-mode` can't appear on its own, value must be attached to it.

While fixing those, also changes the append logic to make use of new
`--target=X` format instead of the legacy `-target X` version.

In addition to that makes use of the OPTTable instead of hardcoded strings to
make sure helper also gets updated if clang's options are modified.

Differential Revision: https://reviews.llvm.org/D85076
2020-08-03 11:46:58 +02:00
Saiyedul Islam 160ff83765 [OpenMP][AMDGCN] Support OpenMP offloading for AMDGCN architecture - Part 3
Provides AMDGCN and NVPTX specific specialization of getGPUWarpSize,
getGPUThreadID, and getGPUNumThreads methods. Adds tests for AMDGCN
codegen for these methods in generic and simd modes. Also changes the
precondition in InitTempAlloca to be slightly more permissive. Useful for
AMDGCN OpenMP codegen where allocas are created with a cast to an
address space.

Reviewed By: ABataev

Differential Revision: https://reviews.llvm.org/D84260
2020-08-03 05:38:39 +00:00
Simon Pilgrim 90dab1aece Remove unused param tag to fix Wdocumentation warning. NFC. 2020-08-02 15:12:01 +01:00
Richard Smith 234f51a65a Don't crash if we deserialize a pack expansion type whose pattern
contains no packs.

Fixes a regression from 740a164dec.
2020-07-31 17:19:44 -07:00
Hsiangkai Wang 721d93fc5a Support experimental v extension v0.9.
Differential revision: https://reviews.llvm.org/D81213
2020-08-01 07:42:06 +08:00
Jaydeep Chauhan 38d3e75332
[clang] Use the location of the void parameters when complaining that only a single void parameter should be present.
Fixes PR46417.

Differential Revision: https://reviews.llvm.org/D84678

Reviewed By: aaron.ballman
2020-07-31 20:36:58 +01:00
Amy Kwan c4e5743232 [PowerPC] Implement low-order Vector Modulus Builtins, and add Vector Multiply/Divide/Modulus Builtins Tests
Power10 introduces new instructions for vector multiply, divide and modulus.
These instructions can be exploited by the builtin functions: vec_mul, vec_div,
and vec_mod, respectively.

This patch aims adds the function prototype, vec_mod, as vec_mul and vec_div
been previously implemented in altivec.h.

This patch also adds the following front end tests:
vec_mul for v2i64
vec_div for v4i32 and v2i64
vec_mod for v4i32 and v2i64

Differential Revision: https://reviews.llvm.org/D82576
2020-07-31 10:58:07 -05:00
Erich Keane e704aa4f25 DR2303: Prefer 'nearer' base classes during template deduction.
DR2303 fixes the case where the derived-base match for template
deduction is ambiguous if a base-of-base ALSO matches. The canonical
example (as shown in the test) is just like the MSVC implementation of
std::tuple.

This fixes a fairly sizable issue, where if a user inherits from
std::tuple on Windows (with the MS STL), they cannot use that type to
call a function that takes std::tuple.

Differential Revision: https://reviews.llvm.org/D84048
2020-07-31 05:39:55 -07:00
Kadir Cetinkaya 1618828165
[clang][Syntax] syntax::Arena doesnt own TokenBuffer
Currently an Arena can only be built while consuming a TokenBuffer,
some users (like clangd) might want to share a TokenBuffer with multiple
compenents. This patch changes Arena's TokenBuffer member to be a reference so
that it can be created with read-only token buffers.

Differential Revision: https://reviews.llvm.org/D84973
2020-07-31 11:50:01 +02:00
Fangrui Song c06e22fe07 [Driver] Exclude options::LinkerInput for GCC linking
options::LinkerInput options may get duplicated after 6a75496836ea14bcfd2f4b59d35a1cad4ac58cee..
2020-07-31 00:04:09 -07:00
Eli Friedman 8dfb5d767e [clang codegen][AArch64] Use llvm.aarch64.neon.fcvtzs/u where it's necessary
fptosi/fptoui have similar, but not identical, semantics.  In
particular, the behavior on overflow is different.

Fixes https://bugs.llvm.org/show_bug.cgi?id=46844 for 64-bit.  (The
corresponding patch for 32-bit is more involved because the equivalent
intrinsics don't exist, as far as I can tell.)

Differential Revision: https://reviews.llvm.org/D84703
2020-07-30 15:41:54 -07:00
Richard Smith 1e7f026c3b PR46908: Emit undef destroying_delete_t as an aggregate RValue.
We previously used a non-aggregate RValue to represent the passed value,
which violated the assumptions of call arg lowering in some cases, in
particular on 32-bit Windows, where we'd end up producing an FCA store
with TBAA metadata, that the IR verifier would reject.
2020-07-30 14:50:01 -07:00
Johannes Doerfert ebad64dfe1 [OpenMP][FIX] Consistently use OpenMPIRBuilder if requested
When we use the OpenMPIRBuilder for the parallel region we need to also
use it to get the thread ID (among other things) in the body. This is
because CGOpenMPRuntime::getThreadID() and
CGOpenMPRuntime::emitUpdateLocation implicitly assumes that if they are
called from within a parallel region there is a certain structure to the
code and certain members of the OMPRegionInfo are initialized. It might
make sense to initialize them even if we use the OpenMPIRBuilder but we
would preferably get rid of such state instead.

Bug reported by Anchu Rajendran Sudhakumari.

Depends on D82470.

Reviewed By: anchu-rajendran

Differential Revision: https://reviews.llvm.org/D82822
2020-07-30 10:19:40 -05:00
Johannes Doerfert 19756ef53a [OpenMP][IRBuilder] Support allocas in nested parallel regions
We need to keep track of the alloca insertion point (which we already
communicate via the callback to the user) as we place allocas as well.

Reviewed By: fghanim, SouraVX

Differential Revision: https://reviews.llvm.org/D82470
2020-07-30 10:19:39 -05:00
Alexey Bataev 622e46156d [OPENMP]Fix PR46824: Global declare target pointer cannot be accessed in target region.
Need to map the base pointer for all directives, not only target
data-based ones.
The base pointer is mapped for array sections, array subscript, array
shaping and other array-like constructs with the base pointer. Also,
codegen for use_device_ptr clause was modified to correctly handle
mapping combination of array like constructs + use_device_ptr clause.
The data for use_device_ptr clause is emitted as the last records in the
data mapping array.

Reviewed By: ye-luo

Differential Revision: https://reviews.llvm.org/D84767
2020-07-30 11:18:33 -04:00
Alexey Bataev b69357c2f4 Revert "[OPENMP]Fix PR46824: Global declare target pointer cannot be accessed in target region."
This reverts commit 142d0d3ed8 to
investigate undefined behavior revealed by buildbots.
2020-07-30 10:57:56 -04:00
Alexey Bataev 142d0d3ed8 [OPENMP]Fix PR46824: Global declare target pointer cannot be accessed in target region.
Need to map the base pointer for all directives, not only target
data-based ones.
The base pointer is mapped for array sections, array subscript, array
shaping and other array-like constructs with the base pointer. Also,
codegen for use_device_ptr clause was modified to correctly handle
mapping combination of array like constructs + use_device_ptr clause.
The data for use_device_ptr clause is emitted as the last records in the
data mapping array.
It applies only for global pointers.

Differential Revision: https://reviews.llvm.org/D84767
2020-07-30 09:40:05 -04:00
Balázs Kéri 1745ba41b1 [Analyzer] Remove inclusion of uniqueing decl from diagnostic profile.
The uniqueing decl in PathDiagnostic is the declaration with the
uniqueing loc, as stated by documentation comments.
It is enough to include the uniqueing loc in the profile. It is possible
to have objects with different uniqueing decl but same location, at
least with templates. These belong to the same class and should have
same profile.

Reviewed By: vsavchenko, NoQ

Differential Revision: https://reviews.llvm.org/D84843
2020-07-30 09:52:28 +02:00
Haojian Wu 73c12bd8ff [Concepts] Fix a deserialization crash.
`TemplateTypeParmDecl::hasTypeConstraint` is not a safe guard for
checking `TemplateTypeParmDecl::getTypeConstraint()` result is null.

in somecases (e.g. implicit deduction guide templates synthesized from the
constructor, immediately-declared constraint is not formed because of an error),
hasTypeConstraint returns false, and getTypeConstraint returns a nullptr.

Fix https://bugs.llvm.org/show_bug.cgi?id=46790

Differential Revision: https://reviews.llvm.org/D84455
2020-07-30 09:25:15 +02:00
Balázs Kéri b22b97b3d0 [Analyzer] Use of BugType in DereferenceChecker (NFC).
Use of BuiltinBug is replaced by BugType.
Class BuiltinBug seems to have no benefits and is confusing.

Reviewed By: Szelethus, martong, NoQ, vsavchenko

Differential Revision: https://reviews.llvm.org/D84494
2020-07-30 08:33:12 +02:00
Amy Huang f71deb43ab [DebugInfo] Fix to ctor homing to ignore classes with trivial ctors.
Previously ctor homing was omitting debug info for classes if they
have both trival and nontrivial constructors, but we should only omit debug
info if the class doesn't have any trivial constructors.

retained types list.

bug: https://bugs.llvm.org/show_bug.cgi?id=46537

Differential Revision: https://reviews.llvm.org/D84870
2020-07-29 19:55:20 -07:00
Richard Smith a648834313 PR46729: Reject explicit and partial specializations with C linkage. 2020-07-29 17:44:32 -07:00
Alex Lorenz dc22182d1f [darwin] build and link with a separate compiler-rt builtins library
for device simulators

This change separates out the iOS/tvOS/watchOS simulator slices from the "libclang_rt.<os>.a"
fat archive, by moving them out to their own "libclang_rt.<os>sim.a" static archive.
This allows us to build and to link with an arm64 device simulator slice for the simulators running
on Apple Silicons, and to distribute it in one archive alongside the Intel simulator slices.

Differential Revision: https://reviews.llvm.org/D84564
2020-07-29 15:32:30 -07:00
Richard Smith 1cbdf932b4 PR46231: Promote diagnostic for 'template<...>;' from ExtWarn to Error.
No other compiler accepts this as an extension, not even in permissive
mode. We're not doing anyone any favors by allowing this, and it's
unlikely to be at all common, even in Clang-only code, in the wild.
2020-07-29 12:35:18 -07:00
Richard Smith e69138dad5 PR46859: Fix crash if declaring a template in a DeclScope with no DeclContext.
This can happen during error recovery; it could also happen at block
scope if we ever parsed a template declaration at block scope.
2020-07-29 12:02:55 -07:00
Baptiste Saleil 7aaa85627b [PowerPC] Add options to control paired vector memops support
Adds frontend and backend options to enable and disable the
PowerPC paired vector memory operations added in ISA 3.1.
Instructions using these options will be added in subsequent patches.

Differential Revision: https://reviews.llvm.org/D83722
2020-07-29 14:00:53 -05:00
Arthur Eubanks 71d0a2b8a3 [DFSan][NewPM] Port DataFlowSanitizer to NewPM
Reviewed By: ychen, morehouse

Differential Revision: https://reviews.llvm.org/D84707
2020-07-29 10:19:15 -07:00
Joel E. Denny 9f2f3b9de6 [OpenMP] Implement TR8 `present` motion modifier in Clang (1/2)
This patch implements Clang front end support for the OpenMP TR8
`present` motion modifier for `omp target update` directives.  The
next patch in this series implements OpenMP runtime support.

Reviewed By: ABataev

Differential Revision: https://reviews.llvm.org/D84711
2020-07-29 12:18:45 -04:00
Johannes Doerfert ee05167cc4 [OpenMP] Allow traits for the OpenMP context selector `isa`
It was unclear what `isa` was supposed to mean so we did not provide any
traits for this context selector. With this patch we will allow *any*
string or identifier. We use the target attribute and target info to
determine if the trait matches. In other words, we will check if the
provided value is a target feature that is available (at the call site).

Fixes PR46338

Reviewed By: ABataev

Differential Revision: https://reviews.llvm.org/D83281
2020-07-29 10:22:27 -05:00
Alexey Bader 8d27be8dba [OpenCL] Add global_device and global_host address spaces
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
2020-07-29 17:24:53 +03:00