Commit Graph

1542 Commits

Author SHA1 Message Date
Tyker
b0561b3346 [NFC] Refactor representation of materialized temporaries
Summary:
this patch refactor representation of materialized temporaries to prevent an issue raised by rsmith in https://reviews.llvm.org/D63640#inline-612718

Reviewers: rsmith, martong, shafik

Reviewed By: rsmith

Subscribers: thakis, sammccall, ilya-biryukov, rnkovacs, arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D69360
2019-11-19 18:20:45 +01:00
Nico Weber
c9276fbfdf Revert "[NFC] Refactor representation of materialized temporaries"
This reverts commit 08ea1ee2db.
It broke ./ClangdTests/FindExplicitReferencesTest.All
on the bots, see comments on https://reviews.llvm.org/D69360
2019-11-17 02:09:25 -05:00
Tyker
08ea1ee2db [NFC] Refactor representation of materialized temporaries
Summary:
this patch refactor representation of materialized temporaries to prevent an issue raised by rsmith in https://reviews.llvm.org/D63640#inline-612718

Reviewers: rsmith, martong, shafik

Reviewed By: rsmith

Subscribers: rnkovacs, arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D69360
2019-11-16 17:56:09 +01:00
Akira Hatanaka
4516dc1c20 Don't add optnone or noinline if the function is already marked as
always_inline.

The assertion in SetLLVMFunctionAttributesForDefinition used to fail
when there was attribute OptimizeNone on the AST function and attribute
always_inline on the IR function. This happens because base destructors
are annotated with always_inline when the code is compiled with
-fapple-kext (see r124757).

rdar://problem/57169694
2019-11-15 15:44:04 -08:00
Reid Kleckner
4c1a1d3cf9 Add missing includes needed to prune LLVMContext.h include, NFC
These are a pre-requisite to removing #include "llvm/Support/Options.h"
from LLVMContext.h: https://reviews.llvm.org/D70280
2019-11-14 15:23:15 -08:00
Adrian Prantl
2073dd2da7 Redeclare Objective-C property accessors inside the ObjCImplDecl in which they are synthesized.
This patch is motivated by (and factored out from)
https://reviews.llvm.org/D66121 which is a debug info bugfix. Starting
with DWARF 5 all Objective-C methods are nested inside their
containing type, and that patch implements this for synthesized
Objective-C properties.

1. SemaObjCProperty populates a list of synthesized accessors that may
   need to inserted into an ObjCImplDecl.

2. SemaDeclObjC::ActOnEnd inserts forward-declarations for all
   accessors for which no override was provided into their
   ObjCImplDecl. This patch does *not* synthesize AST function
   *bodies*. Moving that code from the static analyzer into Sema may
   be a good idea though.

3. Places that expect all methods to have bodies have been updated.

I did not update the static analyzer's inliner for synthesized
properties to point back to the property declaration (see
test/Analysis/Inputs/expected-plists/nullability-notes.m.plist), which
I believed to be more bug than a feature.

Differential Revision: https://reviews.llvm.org/D68108

rdar://problem/53782400
2019-11-08 08:23:22 -08:00
Michael Liao
0a220de9e9 [HIP] Fix visibility for 'extern' device variables.
Summary:
- Fix a bug which misses the change for a variable to be set with
  target-specific attributes.

Reviewers: yaxunl

Subscribers: jvesely, nhaehnle, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D63020
2019-11-05 14:19:32 -05:00
Yaxun (Sam) Liu
bb1616ba47 [CodeGen] Fix invalid llvm.linker.options about pragma detect_mismatch
When a target does not support pragma detect_mismatch, an llvm.linker.options
metadata with an empty entry is created, which causes diagnostic in backend
since backend expects name/value pair in llvm.linker.options entries.

This patch fixes that.

Differential Revision: https://reviews.llvm.org/D69678
2019-10-31 22:27:35 -04:00
Andrew Paverd
d157a9bc8b Add Windows Control Flow Guard checks (/guard:cf).
Summary:
A new function pass (Transforms/CFGuard/CFGuard.cpp) inserts CFGuard checks on
indirect function calls, using either the check mechanism (X86, ARM, AArch64) or
or the dispatch mechanism (X86-64). The check mechanism requires a new calling
convention for the supported targets. The dispatch mechanism adds the target as
an operand bundle, which is processed by SelectionDAG. Another pass
(CodeGen/CFGuardLongjmp.cpp) identifies and emits valid longjmp targets, as
required by /guard:cf. This feature is enabled using the `cfguard` CC1 option.

Reviewers: thakis, rnk, theraven, pcc

Subscribers: ychen, hans, metalcanine, dmajor, tomrittervg, alex, mehdi_amini, mgorny, javed.absar, kristof.beyls, hiraditya, steven_wu, dexonsmith, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D65761
2019-10-28 15:19:39 +00:00
Matt Arsenault
40ab8ae9fb OpenMP: Add helper function for convergent runtime calls
Most of the functions emitted here should probably be convergent, but
only barriers are currently marked. Introduce this helper before
adding convergent to more functions.
2019-10-27 21:26:55 -07:00
Yaxun Liu
e6125fc0ec [AMDGPU] Fix assertion due to initializer list
Sometimes a global var is replaced by a different llvm value. clang use GetAddrOfGlobalVar to get the original llvm global variable.
For most targets, GetAddrOfGlobalVar returns either the llvm global variable or a bitcast of the llvm global variable.
However, for AMDGPU target, GetAddrOfGlobalVar returns the addrspace cast or addrspace cast plus bitcast of the llvm global variable.
To get the llvm global variable, these casts need to be stripped, otherwise there is assertion.

This patch fixes that.

Differential Revision: https://reviews.llvm.org/D69129

llvm-svn: 375362
2019-10-20 15:02:22 +00:00
Dmitry Mikulin
15984457a6 Revert Tag CFI-generated data structures with "#pragma clang section" attributes.
This reverts r375022 (git commit e2692b3bc0)

llvm-svn: 375069
2019-10-17 00:55:38 +00:00
Dmitry Mikulin
e2692b3bc0 Tag CFI-generated data structures with "#pragma clang section" attributes.
Differential Revision: https://reviews.llvm.org/D68808

llvm-svn: 375022
2019-10-16 17:51:40 +00:00
Sergey Dmitriev
5836c356fa [Clang][OpenMP Offload] Move offload registration code to the wrapper
The final list of OpenMP offload targets becomes known only at the link time and since offload registration code depends on the targets list it makes sense to delay offload registration code generation to the link time instead of adding it to the host part of every fat object. This patch moves offload registration code generation from clang to the offload wrapper tool.

This is the last part of the OpenMP linker script elimination patch https://reviews.llvm.org/D64943

Differential Revision: https://reviews.llvm.org/D68746

llvm-svn: 374937
2019-10-15 18:42:47 +00:00
Dmitry Mikulin
f14642f2f1 Added support for "#pragma clang section relro=<name>"
Differential Revision: https://reviews.llvm.org/D68806

llvm-svn: 374934
2019-10-15 18:31:10 +00:00
Alexey Bataev
c2cd2d40aa [OPENMP50]Support for declare variant directive for NVPTX target.
NVPTX does not support global aliases. Instead, we have to copy the full
body of the variant function for the original function.

llvm-svn: 374387
2019-10-10 17:28:10 +00:00
Richard Smith
48632af25c Fix crash or wrong code bug if a lifetime-extended temporary contains a
"non-constant" value.

If the constant evaluator evaluates part of a variable initializer,
including the initializer for some lifetime-extended temporary, but
fails to fully evaluate the initializer, it can leave behind wrong
values for temporaries encountered in that initialization. Don't try to
emit those from CodeGen! Instead, look at the values that constant
evaluation produced if (and only if) it actually succeeds and we're
emitting the lifetime-extending declaration's initializer as a constant.

llvm-svn: 374119
2019-10-08 21:26:03 +00:00
Richard Smith
772e266fbf Properly handle instantiation-dependent array bounds.
We previously failed to treat an array with an instantiation-dependent
but not value-dependent bound as being an instantiation-dependent type.
We now track the array bound expression as part of a constant array type
if it's an instantiation-dependent expression.

llvm-svn: 373685
2019-10-04 01:25:59 +00:00
Simon Pilgrim
1fae74480b Fix MSVC "result of 32-bit shift implicitly converted to 64 bits" warning. NFCI.
llvm-svn: 373613
2019-10-03 15:10:47 +00:00
Guillaume Chatelet
c79099e0f4 [Alignment][Clang][NFC] Add CharUnits::getAsAlign
Summary:
This is a prerequisite to removing `llvm::GlobalObject::setAlignment(unsigned)`.
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

Reviewers: courbet

Subscribers: jholewinski, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D68274

llvm-svn: 373592
2019-10-03 13:00:29 +00:00
Alexey Bataev
2df5f12ea1 [OPENMP50]Initial codegen for declare variant implementation vendor.
Initial implementation of global aliases emission for the declare
variant pragma with implementation vendor context selector set.

llvm-svn: 373387
2019-10-01 20:18:32 +00:00
Richard Smith
2b4fa5348e For P0784R7: compute whether a variable has constant destruction if it
has a constexpr destructor.

For constexpr variables, reject if the variable does not have constant
destruction. In all cases, do not emit runtime calls to the destructor
for variables with constant destruction.

llvm-svn: 373159
2019-09-29 05:08:46 +00:00
Adrian Prantl
350de4f05d Support for DWARF-5 C++ language tags.
This patch provides support for DW_LANG_C_plus_plus_11,
DW_LANG_C_plus_plus_14 tags in the Clang C++ frontend.

Patch by Sourabh Singh Tomar!
Differential Revision: https://reviews.llvm.org/D67613

Reapplies r372663 after adapting a failing test in the LLDB testsuite.

llvm-svn: 372681
2019-09-24 00:38:49 +00:00
Jonas Devlieghere
5c49c26714 Revert "Support for DWARF-5 C++ language tags."
This reverts commit bf9c8ffb54.

llvm-svn: 372672
2019-09-23 23:49:36 +00:00
Adrian Prantl
bf9c8ffb54 Support for DWARF-5 C++ language tags.
This patch provides support for DW_LANG_C_plus_plus_11,
DW_LANG_C_plus_plus_14 tags in the Clang C++ frontend.

Patch by Sourabh Singh Tomar!
Differential Revision: https://reviews.llvm.org/D67613

llvm-svn: 372663
2019-09-23 22:01:49 +00:00
Fangrui Song
9ca1b94a6d [CodeGen] Add alias for cpu_dispatch function with IFunc & Fix resolver linkage type
Multi-versioned functions defined by cpu_dispatch and implemented with IFunc
can not be called outside the translation units where they are defined due to
lack of symbols. This patch add function aliases for these functions and thus
make them visible outside.

Differential Revision: https://reviews.llvm.org/D67058
Patch by Senran Zhang

llvm-svn: 371586
2019-09-11 01:54:48 +00:00
Alexey Bataev
729e242a79 [OPENMP5.0]Add support for device_type clause in declare target
construct.

OpenMP 5.0 introduced new clause for declare target directive, device_type clause, which may accept values host, nohost, and any. Host means
that the function must be emitted only for the host, nohost - only for
the device, and any - for both, device and the host.

llvm-svn: 369775
2019-08-23 16:11:14 +00:00
Nick Desaulniers
f21bca02f7 [Clang][CodeGen] set alias linkage on QualType
Summary:
It seems that CodeGen was always using ExternalLinkage when emitting a
GlobalDecl with __attribute__((alias)). This leads to symbol
redefinitions (ODR) that cause failures at link time for static aliases.
This is readily attempting to link an ARM (32b) allyesconfig Linux
kernel built with Clang.

Reported-by: nathanchance
Suggested-by: ihalip
Link: https://bugs.llvm.org/show_bug.cgi?id=42377
Link: https://github.com/ClangBuiltLinux/linux/issues/631

Reviewers: rsmith, aaron.ballman, erichkeane

Reviewed By: aaron.ballman

Subscribers: javed.absar, kristof.beyls, cfe-commits, srhines, ihalip, nathanchance

Tags: #clang

Differential Revision: https://reviews.llvm.org/D66492

llvm-svn: 369705
2019-08-22 20:47:12 +00:00
Jonas Devlieghere
2b3d49b610 [Clang] Migrate llvm::make_unique to std::make_unique
Now that we've moved to C++14, we no longer need the llvm::make_unique
implementation from STLExtras.h. This patch is a mechanical replacement
of (hopefully) all the llvm::make_unique instances across the monorepo.

Differential revision: https://reviews.llvm.org/D66259

llvm-svn: 368942
2019-08-14 23:04:18 +00:00
Peter Collingbourne
0e497d1554 cfi-icall: Allow the jump table to be optionally made non-canonical.
The default behavior of Clang's indirect function call checker will replace
the address of each CFI-checked function in the output file's symbol table
with the address of a jump table entry which will pass CFI checks. We refer
to this as making the jump table `canonical`. This property allows code that
was not compiled with ``-fsanitize=cfi-icall`` to take a CFI-valid address
of a function, but it comes with a couple of caveats that are especially
relevant for users of cross-DSO CFI:

- There is a performance and code size overhead associated with each
  exported function, because each such function must have an associated
  jump table entry, which must be emitted even in the common case where the
  function is never address-taken anywhere in the program, and must be used
  even for direct calls between DSOs, in addition to the PLT overhead.

- There is no good way to take a CFI-valid address of a function written in
  assembly or a language not supported by Clang. The reason is that the code
  generator would need to insert a jump table in order to form a CFI-valid
  address for assembly functions, but there is no way in general for the
  code generator to determine the language of the function. This may be
  possible with LTO in the intra-DSO case, but in the cross-DSO case the only
  information available is the function declaration. One possible solution
  is to add a C wrapper for each assembly function, but these wrappers can
  present a significant maintenance burden for heavy users of assembly in
  addition to adding runtime overhead.

For these reasons, we provide the option of making the jump table non-canonical
with the flag ``-fno-sanitize-cfi-canonical-jump-tables``. When the jump
table is made non-canonical, symbol table entries point directly to the
function body. Any instances of a function's address being taken in C will
be replaced with a jump table address.

This scheme does have its own caveats, however. It does end up breaking
function address equality more aggressively than the default behavior,
especially in cross-DSO mode which normally preserves function address
equality entirely.

Furthermore, it is occasionally necessary for code not compiled with
``-fsanitize=cfi-icall`` to take a function address that is valid
for CFI. For example, this is necessary when a function's address
is taken by assembly code and then called by CFI-checking C code. The
``__attribute__((cfi_jump_table_canonical))`` attribute may be used to make
the jump table entry of a specific function canonical so that the external
code will end up taking a address for the function that will pass CFI checks.

Fixes PR41972.

Differential Revision: https://reviews.llvm.org/D65629

llvm-svn: 368495
2019-08-09 22:31:59 +00:00
Saleem Abdulrasool
a5af238343 CodeGen: ensure 8-byte aligned String Swift CF ABI
CFStrings should be 8-byte aligned when built for the Swift CF runtime
ABI as the atomic CF info field must be properly aligned.  This is a
problem on 32-bit platforms which would give the structure 4-byte
alignment rather than 8-byte alignment.

llvm-svn: 368471
2019-08-09 19:29:05 +00:00
Rui Ueyama
49a3ad21d6 Fix parameter name comments using clang-tidy. NFC.
This patch applies clang-tidy's bugprone-argument-comment tool
to LLVM, clang and lld source trees. Here is how I created this
patch:

$ git clone https://github.com/llvm/llvm-project.git
$ cd llvm-project
$ mkdir build
$ cd build
$ cmake -GNinja -DCMAKE_BUILD_TYPE=Debug \
    -DLLVM_ENABLE_PROJECTS='clang;lld;clang-tools-extra' \
    -DCMAKE_EXPORT_COMPILE_COMMANDS=On -DLLVM_ENABLE_LLD=On \
    -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ ../llvm
$ ninja
$ parallel clang-tidy -checks='-*,bugprone-argument-comment' \
    -config='{CheckOptions: [{key: StrictMode, value: 1}]}' -fix \
    ::: ../llvm/lib/**/*.{cpp,h} ../clang/lib/**/*.{cpp,h} ../lld/**/*.{cpp,h}

llvm-svn: 366177
2019-07-16 04:46:31 +00:00
Evgeniy Stepanov
c5e7f56249 ARM MTE stack sanitizer.
Add "memtag" sanitizer that detects and mitigates stack memory issues
using armv8.5 Memory Tagging Extension.

It is similar in principle to HWASan, which is a software implementation
of the same idea, but there are enough differencies to warrant a new
sanitizer type IMHO. It is also expected to have very different
performance properties.

The new sanitizer does not have a runtime library (it may grow one
later, along with a "debugging" mode). Similar to SafeStack and
StackProtector, the instrumentation pass (in a follow up change) will be
inserted in all cases, but will only affect functions marked with the
new sanitize_memtag attribute.

Reviewers: pcc, hctim, vitalybuka, ostannard

Subscribers: srhines, mehdi_amini, javed.absar, kristof.beyls, hiraditya, cryptoad, steven_wu, dexonsmith, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D64169

llvm-svn: 366123
2019-07-15 20:02:23 +00:00
Anastasia Stulova
960ff0810d [OpenCL][PR41727] Prevent ICE on global dtors
Pass NULL to pointer arg of __cxa_atexit if addr space
is not matching with its param. This doesn't align yet
with how dtors are generated that should be changed too.

Differential Revision: https://reviews.llvm.org/D62413

llvm-svn: 366059
2019-07-15 11:58:10 +00:00
Saar Raz
d7aae33a95 [Concepts] Concept definitions (D40381)
First in a series of patches to land C++2a Concepts support.
This patch adds AST and parsing support for concept-declarations.

llvm-svn: 365699
2019-07-10 21:25:49 +00:00
Yaxun Liu
c3dfe9082b [HIP] Support attribute hip_pinned_shadow
This patch introduces support of hip_pinned_shadow variable for HIP.

A hip_pinned_shadow variable is a global variable with attribute hip_pinned_shadow.
It has external linkage on device side and has no initializer. It has internal
linkage on host side and has initializer or static constructor. It can be accessed
in both device code and host code.

This allows HIP runtime to implement support of HIP texture reference.

Differential Revision: https://reviews.llvm.org/D62738

llvm-svn: 364381
2019-06-26 03:47:37 +00:00
Konstantin Pyzhov
15e678e843 [CUDA][HIP] Don't set comdat attribute for CUDA device stub functions.\nDifferential Revision: https://reviews.llvm.org/D63277
llvm-svn: 364183
2019-06-24 14:40:20 +00:00
Gheorghe-Teodor Bercea
0034e84aa5 [OpenMP] Add support for handling declare target to clause when unified memory is required
Summary:
This patch adds support for the handling of the variables under the declare target to clause.

The variables in this case are handled like link variables are. A pointer is created on the host and then mapped to the device. The runtime will then copy the address of the host variable in the device pointer.

Reviewers: ABataev, AlexEichenberger, caomhin

Reviewed By: ABataev

Subscribers: guansong, jdoerfert, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D63108

llvm-svn: 363959
2019-06-20 18:04:47 +00:00
Michael Liao
e40f879eb2 [HIP] Add the interface deriving the stub name of device kernels.
Summary:
- Revise the interface to derive the stub name and simplify the
  assertion of it.

Reviewers: yaxunl, tra

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D63335

llvm-svn: 363553
2019-06-17 12:51:36 +00:00
Akira Hatanaka
6cb2d9dbd2 [CodeGen][ObjC] Annotate retain-agnostic ObjC globals with attribute
'objc_arc_inert'

The attribute enables the ARC optimizer to delete ObjC ARC runtime calls
on the annotated globals (see https://reviews.llvm.org/D62433). We
currently only annotate global variables for string literals and global
blocks with the attribute.

rdar://problem/49839633

Differential Revision: https://reviews.llvm.org/D62831

llvm-svn: 363467
2019-06-14 22:06:28 +00:00
Peter Collingbourne
e08e68de21 Driver, IRGen: Set partitions on GlobalValues according to -fsymbol-partition flag.
Differential Revision: https://reviews.llvm.org/D62636

llvm-svn: 362829
2019-06-07 19:10:08 +00:00
Anastasia Stulova
f61b5481fd [OpenCL] Fix OpenCL/SPIR version metadata in C++ mode.
C++ is derived from OpenCL v2.0 therefore set the versions
identically.

Differential Revision: https://reviews.llvm.org/D62657

llvm-svn: 362102
2019-05-30 15:18:07 +00:00
Michael Liao
4b7a713acc [CUDA][HIP] Skip setting externally_initialized for static device variables.
Summary:
- By declaring device variables as `static`, we assume they won't be
  addressable from the host side. Thus, no `externally_initialized` is
  required.

Reviewers: yaxunl

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D62603

llvm-svn: 361994
2019-05-29 17:23:27 +00:00
Yaxun Liu
02afe4e077 [CUDA][HIP] Emit dependent libs for host only
Recently D60274 was introduced to allow lld to handle dependent libs. However current
usage of dependent libs (e.g. pragma comment(lib, *) in windows header files) are intended
for host only. Emitting the metadata in device IR causes link error in device path.

Until there is a way to different it dependent libs for device or host, metadata for dependent
libs should be emitted for host only. This patch enforces that.

Differential Revision: https://reviews.llvm.org/D62483

llvm-svn: 361880
2019-05-28 21:18:59 +00:00
Richard Smith
e637cbe4e4 Refactor: split Uninitialized state on APValue into an "Absent" state
representing no such object, and an "Indeterminate" state representing
an uninitialized object. The latter is not yet used, but soon will be.

llvm-svn: 361328
2019-05-21 23:15:18 +00:00
Gheorghe-Teodor Bercea
66cdbb47d2 [OpenMP] Add support for registering requires directives with the runtime
Summary:
This patch adds support for the registration of the requires directives with the runtime.

Each requires directive clause will enable a particular flag to be set.

The set of flags is passed to the runtime to be checked for compatibility with other such flags coming from other object files.

The registration function is called whenever OpenMP is present even if a requires directive is not present. This helps detect cases in which requires directives are used inconsistently.

Reviewers: ABataev, AlexEichenberger, caomhin

Reviewed By: ABataev, AlexEichenberger

Subscribers: jholewinski, guansong, jfb, jdoerfert, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D60568

llvm-svn: 361298
2019-05-21 19:42:01 +00:00
Alexey Bataev
6b21c4a4ee [OPENMP]Use the attributes for dso locality when building for device.
Currently, we ignore all dso locality attributes/info when building for
the device and thus all symblos are externally visible and can be
preemted at the runtime. It may lead to incorrect results. We need to
follow the same logic, compiler uses for static/pie builds.

llvm-svn: 361283
2019-05-21 18:20:08 +00:00
Ben Dunbobbin
1d16515fb4 [ELF] Implement Dependent Libraries Feature
This patch implements a limited form of autolinking primarily designed to allow
either the --dependent-library compiler option, or "comment lib" pragmas (
https://docs.microsoft.com/en-us/cpp/preprocessor/comment-c-cpp?view=vs-2017) in
C/C++ e.g. #pragma comment(lib, "foo"), to cause an ELF linker to automatically
add the specified library to the link when processing the input file generated
by the compiler.

Currently this extension is unique to LLVM and LLD. However, care has been taken
to design this feature so that it could be supported by other ELF linkers.

The design goals were to provide:

- A simple linking model for developers to reason about.
- The ability to to override autolinking from the linker command line.
- Source code compatibility, where possible, with "comment lib" pragmas in other
  environments (MSVC in particular).

Dependent library support is implemented differently for ELF platforms than on
the other platforms. Primarily this difference is that on ELF we pass the
dependent library specifiers directly to the linker without manipulating them.
This is in contrast to other platforms where they are mapped to a specific
linker option by the compiler. This difference is a result of the greater
variety of ELF linkers and the fact that ELF linkers tend to handle libraries in
a more complicated fashion than on other platforms. This forces us to defer
handling the specifiers to the linker.

In order to achieve a level of source code compatibility with other platforms
we have restricted this feature to work with libraries that meet the following
"reasonable" requirements:

1. There are no competing defined symbols in a given set of libraries, or
   if they exist, the program owner doesn't care which is linked to their
   program.
2. There may be circular dependencies between libraries.

The binary representation is a mergeable string section (SHF_MERGE,
SHF_STRINGS), called .deplibs, with custom type SHT_LLVM_DEPENDENT_LIBRARIES
(0x6fff4c04). The compiler forms this section by concatenating the arguments of
the "comment lib" pragmas and --dependent-library options in the order they are
encountered. Partial (-r, -Ur) links are handled by concatenating .deplibs
sections with the normal mergeable string section rules. As an example, #pragma
comment(lib, "foo") would result in:

.section ".deplibs","MS",@llvm_dependent_libraries,1
         .asciz "foo"

For LTO, equivalent information to the contents of a the .deplibs section can be
retrieved by the LLD for bitcode input files.

LLD processes the dependent library specifiers in the following way:

1. Dependent libraries which are found from the specifiers in .deplibs sections
   of relocatable object files are added when the linker decides to include that
   file (which could itself be in a library) in the link. Dependent libraries
   behave as if they were appended to the command line after all other options. As
   a consequence the set of dependent libraries are searched last to resolve
   symbols.
2. It is an error if a file cannot be found for a given specifier.
3. Any command line options in effect at the end of the command line parsing apply
   to the dependent libraries, e.g. --whole-archive.
4. The linker tries to add a library or relocatable object file from each of the
   strings in a .deplibs section by; first, handling the string as if it was
   specified on the command line; second, by looking for the string in each of the
   library search paths in turn; third, by looking for a lib<string>.a or
   lib<string>.so (depending on the current mode of the linker) in each of the
   library search paths.
5. A new command line option --no-dependent-libraries tells LLD to ignore the
   dependent libraries.

Rationale for the above points:

1. Adding the dependent libraries last makes the process simple to understand
   from a developers perspective. All linkers are able to implement this scheme.
2. Error-ing for libraries that are not found seems like better behavior than
   failing the link during symbol resolution.
3. It seems useful for the user to be able to apply command line options which
   will affect all of the dependent libraries. There is a potential problem of
   surprise for developers, who might not realize that these options would apply
   to these "invisible" input files; however, despite the potential for surprise,
   this is easy for developers to reason about and gives developers the control
   that they may require.
4. This algorithm takes into account all of the different ways that ELF linkers
   find input files. The different search methods are tried by the linker in most
   obvious to least obvious order.
5. I considered adding finer grained control over which dependent libraries were
   ignored (e.g. MSVC has /nodefaultlib:<library>); however, I concluded that this
   is not necessary: if finer control is required developers can fall back to using
   the command line directly.

RFC thread: http://lists.llvm.org/pipermail/llvm-dev/2019-March/131004.html.

Differential Revision: https://reviews.llvm.org/D60274

llvm-svn: 360984
2019-05-17 03:44:15 +00:00
Lubos Lunak
ab8cde446b make -ftime-trace also print template arguments
Without this, I get e.g. 'PerformPendingInstantiations' -> 'std::fill',
now I get 'std::fill<unsigned long *, int>'.

Differential Revision: https://reviews.llvm.org/D61822

llvm-svn: 360539
2019-05-12 10:39:21 +00:00
Anastasia Stulova
e6cf6c78f8 [OpenCL] Make global ctor init function a kernel
We need to be able to enqueue internal function that initializes
global constructors on the host side. Therefore it has to be
converted to a kernel.

This change factors out common logic for adding kernel metadata
and moves it from CodeGenFunction to CodeGenModule in order to
make it accessible for the extra use case.

Differential revision: https://reviews.llvm.org/D61488

llvm-svn: 360342
2019-05-09 13:55:44 +00:00