Commit Graph

56579 Commits

Author SHA1 Message Date
Nico Weber 3de7cc9fc0 Revert "[RISCV] Support mutilib in baremetal environment"
This reverts commit b6d7bbfa00.
Driver/riscv64-toolchain.c fails on Windows.
2019-11-19 08:16:55 -05:00
Zakk Chen b6d7bbfa00 [RISCV] Support mutilib in baremetal environment
Currently only support the set of multilibs same to riscv-gnu-toolchain.

Reviewers: espindola, asb, kito-cheng, lenary

Reviewed By: lenary

Differential Revision: https://reviews.llvm.org/D67508
2019-11-19 02:10:39 -08:00
Puyan Lotfi d044dcc5e4 Revert "[clang][IFS] Driver pipeline: generate interface stubs after standard pipeline."
This reverts commit 58ea00b51f.

Test for .o + .ifs sidecar files is brittle and failing on bots.
Reverting to unblock.
2019-11-19 02:08:22 -05:00
Puyan Lotfi 58ea00b51f [clang][IFS] Driver pipeline: generate interface stubs after standard pipeline.
Up until now, clang interface stubs has replaced the standard
PP -> C -> BE -> ASM -> LNK pipeline. With this change, it will happen in
conjunction with it. So what when you build your code you will get an
a.out or lib.so as well as an interface stub file.

Example:

clang -shared -o libfoo.so -emit-interface-stubs ...

will generate both a libfoo.so and a libfoo.ifso. The .so file will
contain the code from the standard compilation pipeline and the .ifso
file will contain the ELF stub library.

Differential Revision: https://reviews.llvm.org/D70274
2019-11-19 01:18:02 -05:00
Vedant Kumar ea1db31d20 [CodeGen] Assign locations to calls to special struct helpers
Assign artificial locations to calls to special struct-related helper
functions.

Such calls may not inherit a location if emitted within FinishFunction,
at which point the lexical scope stack may be empty, causing CGDebugInfo
to report the current DebugLoc as empty.

Fixes an IR verifier complaint about a call to '__destructor_8_s0' not
having a !dbg location attached.

rdar://57293361
2019-11-18 15:07:59 -08:00
Erich Keane 0213adde21 [NFC] Fix 'target' condition in checkTargetFeatures
checkTargetFeatures was incorrectly checking for cpu_specific instead of
just 'target'. While this function was never called in that situation,
it seemed correct to fix the condition.  Additionally, multiversion
functions can never be always_inline, but if any function accidentially
ended up here we shouldn't diagnose.

Note that the adding of target-features to the list is unnecessary since
the getFunctionFeatureMap actually considers attribute target,
however adding it results in significantly better error messages by
putting the 'target' features first (and thus first to fail).
Otherwise, the error message would be the first feature 'implied' by the
target attribute, and not necessarily the feature listed in the
attribute itself.
2019-11-18 13:43:52 -08:00
Dimitry Andric ee31adb7fa Populate CUDA flags on FreeBSD too, as many other toolchains do.
Summary:
This allows `clang` to be used to compile CUDA programs. Compiled
simple helloworld.cu with this.

Reviewers: dim, emaste, tra, yaxunl, ABataev

Reviewed By: tra

Subscribers: dim, emaste, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D69990
2019-11-18 21:54:25 +01:00
Erik Pilkington 8bfb353bb3 [Sema] Fix a -Wobjc-signed-char-bool false-positive
Unsigned bit-field flags can only have boolean values, so handle that case in
Expr::isKnownToHaveBooleanValue.

rdar://56256999
2019-11-18 12:15:20 -08:00
Pierre Habouzit d4e1ba3fa9 Implement __attribute__((objc_direct)), __attribute__((objc_direct_members))
__attribute__((objc_direct)) is an attribute on methods declaration, and
__attribute__((objc_direct_members)) on implementation, categories or
extensions.

A `direct` property specifier is added (@property(direct) type name)

These attributes / specifiers cause the method to have no associated
Objective-C metadata (for the property or the method itself), and the
calling convention to be a direct C function call.

The symbol for the method has enforced hidden visibility and such direct
calls are hence unreachable cross image. An explicit C function must be
made if so desired to wrap them.

The implicit `self` and `_cmd` arguments are preserved, however to
maintain compatibility with the usual `objc_msgSend` semantics,
3 fundamental precautions are taken:

1) for instance methods, `self` is nil-checked. On arm64 backends this
   typically adds a single instruction (cbz x0, <closest-ret>) to the
   codegen, for the vast majority of the cases when the return type is a
   scalar.

2) for class methods, because the class may not be realized/initialized
   yet, a call to `[self self]` is emitted. When the proper deployment
   target is used, this is optimized to `objc_opt_self(self)`.

   However, long term we might want to emit something better that the
   optimizer can reason about. When inlining kicks in, these calls
   aren't optimized away as the optimizer has no idea that a single call
   is really necessary.

3) the calling convention for the `_cmd` argument is changed: the caller
   leaves the second argument to the call undefined, and the selector is
   loaded inside the body when it's referenced only.

As far as error reporting goes, the compiler refuses:
- making any overloads direct,
- making an overload of a direct method,
- implementations marked as direct when the declaration in the
  interface isn't (the other way around is allowed, as the direct
  attribute is inherited from the declaration),
- marking methods required for protocol conformance as direct,
- messaging an unqualified `id` with a direct method,
- forming any @selector() expression with only direct selectors.

As warnings:
- any inconsistency of direct-related calling convention when
  @selector() or messaging is used,
- forming any @selector() expression with a possibly direct selector.

Lastly an `objc_direct_members` attribute is added that can decorate
`@implementation` blocks and causes methods only declared there (and in
no `@interface`) to be automatically direct. When decorating an
`@interface` then all methods and properties declared in this block are
marked direct.

Radar-ID: rdar://problem/2684889
Differential Revision: https://reviews.llvm.org/D69991
Reviewed-By: John McCall
2019-11-18 11:48:40 -08:00
Francis Visoiu Mistrih e15b26fbbd Reland: [Remarks][Driver] Use different remark files when targeting multiple architectures
When the driver is targeting multiple architectures at once, for things
like Universal Mach-Os, we need to emit different remark files for each
cc1 invocation to avoid overwriting the files from a different
invocation.

For example:

$ clang -c -o foo.o -fsave-optimization-record -arch x86_64 -arch x86_64h

will create two remark files:

* foo-x86_64.opt.yaml
* foo-x86_64h.opt.yaml
2019-11-18 11:17:38 -08:00
Reid Kleckner 1ff5f0ced3 Revert "[Remarks][Driver] Use different remark files when targeting multiple architectures"
This reverts commit b4e2b112b5.

Test doesn't appear to pass on Windows, maybe all non-Mac.
2019-11-18 10:52:41 -08:00
Eric Christopher 30e7ee3c4b Temporarily Revert "Add support for options -frounding-math, ftrapping-math, -ffp-model=, and -ffp-exception-behavior="
and a follow-up NFC rearrangement as it's causing a crash on valid. Testcase is on the original review thread.

This reverts commits af57dbf12e and e6584b2b7b
2019-11-18 10:46:48 -08:00
Reid Kleckner a77b66a056 Allocate builtins table earlier to fix bug found by ubsan
Follow up to 979da9a4c3
2019-11-18 10:41:30 -08:00
Francis Visoiu Mistrih b4e2b112b5 [Remarks][Driver] Use different remark files when targeting multiple architectures
When the driver is targeting multiple architectures at once, for things
like Universal Mach-Os, we need to emit different remark files for each
cc1 invocation to avoid overwriting the files from a different
invocation.

For example:

$ clang -c -o foo.o -fsave-optimization-record -arch x86_64 -arch x86_64h

will create two remark files:

* foo-x86_64.opt.yaml
* foo-x86_64h.opt.yaml
2019-11-18 10:38:10 -08:00
Joel E. Denny c85fa79d36 [Attr] Fix `-ast-print` for `asm` attribute
Without this fix, the tests introduced here produce the following
assert fail:

```
clang: /home/jdenny/llvm/clang/include/clang/Basic/AttributeCommonInfo.h:163: unsigned int clang::AttributeCommonInfo::getAttributeSpellingListIndex() const: Assertion `(isAttributeSpellingListCalculated() || AttrName) && "Spelling cannot be found"' failed.
```

The bug was introduced by D67368, which caused `AsmLabelAttr`'s
spelling index to be set to `SpellingNotCalculated`.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D70349
2019-11-18 11:55:25 -05:00
Alexey Bataev c3eded068c [OPENMP50]Fix PR44024: runtime assert in distribute construct.
If the code is emitted for distribute construct, the nonmonotonic
modifier should not be added.
2019-11-18 11:14:27 -05:00
Sam McCall d27a16eb39 Revert "[DWARF5]Addition of alignment atrribute in typedef DIE."
This reverts commit 423f541c1a, which
breaks llvm-c ABI.
2019-11-18 15:53:22 +01:00
Simon Pilgrim 1e3cc06d98 Fix "not all control paths return a value" warning. NFCI. 2019-11-18 11:42:14 +00:00
Simon Cook c00e5cf29d [RISCV] Set triple based on -march flag
For RISC-V the value provided to -march should determine whether to
compile for 32- or 64-bit RISC-V irrespective of the target provided to
the Clang driver. This adds a test for this flag for RISC-V and sets the
Target architecture correctly in these cases.

Differential Revision: https://reviews.llvm.org/D54214
2019-11-18 10:44:24 +00:00
Simon Tatham 4a4dd85e5a [ARM,MVE] Add intrinsics for vector comparisons.
This adds the `vcmp` family of ACLE MVE intrinsics: vector/vector,
vector/scalar, and the predicated forms of both. All are represented
using standard existing IR: vector/scalar comparisons are represented
by making a vector out of the scalar first, and predicated forms are
represented by taking the bitwise AND of the input predicate and the
output of the comparison. Existing LLVM-side tests demonstrate that
ISel will pattern-match all of that back down to single MVE VCMPs.

The idiom of handling a vector/scalar operation by generating IR to
expand the scalar into a second vector is going to be needed for a lot
of MVE intrinsics, so to make that easy, I've provided a helper
function that automatically works out the element count.

The comparison intrinsics are the first ones that have to //return// a
predicate, in the user-facing `mve_pred16_t` format. This means we
have to use the `arm_mve_pred_v2i` low-level intrinsic to convert it
back from the logical `<n x i1>` form used in IR. I've done that
explicitly in the code gen specification for the builtins, because it
happens much more rarely in the ACLE API than passing a Predicate as
input, so it didn't seem worth automating in MveEmitter.

Reviewers: ostannard, MarkMurrayARM, dmgreen

Reviewed By: dmgreen

Subscribers: kristof.beyls, hiraditya, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D70297
2019-11-18 10:39:30 +00:00
Sam McCall a433e7141f [AST] Attach comment in `/** doc */ typedef struct A {} B` to B as well as A.
Summary:
Semantically they're the same thing, and it's important when the underlying
struct is anonymous.

There doesn't seem to be a problem attaching the same comment to multiple things
as it already happens with `/** doc */ int a, b;`

This affects an Index test but the results look better (name present, USR points
to the typedef).

Fixes https://github.com/clangd/clangd/issues/189

Reviewers: kadircet, lh123

Subscribers: ilya-biryukov, jkorous, arphaman, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70203
2019-11-18 11:09:23 +01:00
Anna Welker 2d739f98d8 [ARM] Allocatable Global Register Variables for ARM
Provides support for using r6-r11 as globally scoped
      register variables. This requires a -ffixed-rN flag
      in order to reserve rN against general allocation.

      If for a given GRV declaration the corresponding flag
      is not found, or the the register in question is the
      target's FP, we fail with a diagnostic.

      Differential Revision: https://reviews.llvm.org/D68862
2019-11-18 10:07:37 +00:00
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
Sourabh Singh Tomar 423f541c1a [DWARF5]Addition of alignment atrribute in typedef DIE.
This patch, adds support for DW_AT_alignment[DWARF5] attribute, to be emitted with typdef DIE.
When explicit alignment is specified.

Patch by Awanish Pandey <Awanish.Pandey@amd.com>

Reviewers: aprantl, dblaikie, jini.susan.george, SouraVX, alok,
deadalinx

Differential Revision: https://reviews.llvm.org/D70111
2019-11-16 21:56:53 +05:30
mydeveloperday 5987cc1bb5 [clang-format] fix regression in middle pointer alignment
Summary:
a75f8d98d7 introduced a regression with Middle pointer alignment,
which this patch fixes.

Reviewers: MyDeveloperDay, klimek, sammccall

Reviewed By: MyDeveloperDay, sammccall

Subscribers: cfe-commits, merge_guards_bot

Patch by: Typz

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70305
2019-11-16 14:37:47 +00:00
Sylvestre Ledru 9b40a7f3bf Remove +x permission on some files 2019-11-16 14:47:20 +01:00
Sylvestre Ledru d4819fe0ec Remove +x permission on clang/lib/Format/Format.cpp 2019-11-16 14:44:35 +01:00
mydeveloperday a4a7c1259e [clang-format] Add SpaceBeforeBrackets
Summary: Adds a new option SpaceBeforeBrackets to add spaces before brackets (i.e. int a[23]; -> int a [23];)  This is present as an option in the Visual Studio C++ code formatting settings, but there was no matching setting in clang-format.

Reviewers: djasper, MyDeveloperDay, mitchell-stellar

Reviewed By: MyDeveloperDay

Subscribers: llvm-commits, cfe-commits, klimek

Patch by: Anteru

Tags: #clang, #clang-format, #llvm

Differential Revision: https://reviews.llvm.org/D6920
2019-11-16 11:54:21 +00:00
Sylvestre Ledru 42effc1069 Add support of the next Ubuntu (Ubuntu 20.04 - Focal Fossa) 2019-11-16 12:21:54 +01:00
Reid Kleckner 979da9a4c3 Avoid including Builtins.h in Preprocessor.h
Builtins are rarely if ever accessed via the Preprocessor. They are
typically found on the ASTContext, so there should be no performance
penalty to using a pointer indirection to store the builtin context.
2019-11-15 16:45:16 -08:00
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
Alexandre Ganea caf3166d40 Revert "re-land [DebugInfo] Add debug location to stubs generated by CGDeclCXX and mark them as artificial"
This reverts commit 9c1baa2352.
2019-11-15 16:21:17 -05:00
Alexandre Ganea 9c1baa2352 re-land [DebugInfo] Add debug location to stubs generated by CGDeclCXX and mark them as artificial
Differential Revision: https://reviews.llvm.org/D66328
2019-11-15 16:01:39 -05:00
cchen e06f3e064a [OpenMP 5.0] - Extend defaultmap, by Chi Chun Chen.
Summary:
For the extended defaultmap, most of the work is inside sema.
The only difference for codegen is to set different initial
maptype for different implicit-behavior.

Reviewers: jdoerfert, ABataev

Reviewed By: ABataev

Subscribers: dreachem, sandoval, cfe-commits

Tags: #clang, #openmp

Differential Revision: https://reviews.llvm.org/D69204
2019-11-15 13:53:32 -05:00
Sam McCall 575e09d9f8 [AST] Let DeclarationNameInfo printing use PrintingPolicy, and fix const-correctness 2019-11-15 19:19:41 +01:00
Cameron Desrochers 358eaa3dce [clang-format] Flexible line endings
Line ending detection is now set with the `DeriveLineEnding` option.
CRLF can now be used as the default line ending by setting `UseCRLF`.
When line ending detection is disabled, all line endings are converted
according to the `UseCRLF` option.

Differential Revision: https://reviews.llvm.org/D19031
2019-11-15 11:50:22 -05:00
Momchil Velikov aa6d48fa70 Implement target(branch-protection) attribute for AArch64
This patch implements `__attribute__((target("branch-protection=...")))`
in a manner, compatible with the analogous GCC feature:

https://gcc.gnu.org/onlinedocs/gcc-9.2.0/gcc/AArch64-Function-Attributes.html#AArch64-Function-Attributes

Differential Revision: https://reviews.llvm.org/D68711
2019-11-15 15:40:46 +00:00
Ed Maste cb1761465a clang: enable unwind tables on FreeBSD !amd64
There doesn't seem to be much sense in defaulting "on" unwind tables on
amd64 and not on other arches. It causes surprising differences between
platforms, such as the PR below[1].

Prior to this change, FreeBSD inherited the default implementation of the
method from the Gnu.h Generic_Elf => Generic_GCC parent class, which
returned true only for amd64 targets.  Override that and opt on always,
similar to, e.g., NetBSD's driver.

[1] https://bugs.freebsd.org/241562

Patch by cem (Conrad Meyer).

Reviewed By: dim

Differential Revision: https://reviews.llvm.org/D70110
2019-11-15 10:37:45 -05:00
Sam Elliott e3d5ff5a0b [RISCV] Match GCC `-march`/`-mabi` driver defaults
Summary:
Clang/LLVM is a cross-compiler, and so we don't have to make a choice
about `-march`/`-mabi` at build-time, but we may have to compute a
default `-march`/`-mabi` when compiling a program. Until now, each
place that has needed a default `-march` has calculated one itself.

This patch adds a single place where a default `-march` is calculated,
in order to avoid calculating different defaults in different places.

This patch adds a new function `riscv::getRISCVArch` which encapsulates
this logic based on GCC's for computing a default `-march` value
when none is provided. This patch also updates the logic in
`riscv::getRISCVABI` to match the logic in GCC's build system for
computing a default `-mabi`.

This patch also updates anywhere that `-march` is used to now use the
new function which can compute a default. In particular, we now
explicitly pass a `-march` value down to the gnu assembler.

GCC has convoluted logic in its build system to choose a default
`-march`/`-mabi` based on build options, which would be good to match.
This patch is based on the logic in GCC 9.2.0. This commit's logic is
different to GCC's only for baremetal targets, where we default
to rv32imac/ilp32 or rv64imac/lp64 depending on the target triple.

Tests have been updated to match the new logic.

Reviewers: asb, luismarques, rogfer01, kito-cheng, khchen

Reviewed By: asb, luismarques

Subscribers: sameer.abuasal, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, shiva0217, jrtc27, MaskRay, zzheng, edward-jones, MartinMosbeck, brucehoult, the_o, rkruppe, PkmX, jocewei, psnobl, benna, Jim, s.egerton, pzheng, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D69383
2019-11-15 15:10:42 +00:00
Sam McCall fa3b87fbeb [CodeComplete] Constructor overload candidates report as vector(int) instead of vector<string>(int)
Summary:
This is shorter, shouldn't be confusing (is consistent with how they're declared),
and avoids messy cases that are printed as myclass<type-param-0-0>(int) in the
case of partial specialization.

Fixes part of https://github.com/clangd/clangd/issues/76

Reviewers: hokein, lh123

Subscribers: ilya-biryukov, kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70307
2019-11-15 15:42:18 +01:00
Balázs Kéri c2f6efc732 [Clang][ASTImporter] Added visibility check for ClassTemplateDecl.
Summary:
ASTImporter makes now difference between class templates with same
name in different translation units if these are not visible outside.

Reviewers: martong, a.sidorin, shafik

Reviewed By: martong

Subscribers: rnkovacs, dkrupp, Szelethus, gamesh411, teemperor, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D67543
2019-11-15 15:05:26 +01:00
Serge Pavlov e6584b2b7b Move floating point related entities to namespace level
Enumerations that describe rounding mode and exception behavior were
defined inside ConstrainedFPIntrinsic. It makes sense to use the same
definitions to represent the same properties in other cases, not only
in constrained intrinsics. It was however inconvenient as required to
include constrained intrinsics definitions even if they were not needed.
Also using long scope prefix reduced readability.

This change moves these definitioins to the namespace llvm::fp.
No functional changes.

Differential Revision: https://reviews.llvm.org/D69552
2019-11-15 19:56:33 +07:00
Alex Richardson 3c3048c18b Include the mangled name in -ast-dump=json
I am planning to use this feature to make update_cc_test_checks.py less fragile
by obtaining the mangled names directly from -ast-dump=json. Currently,
it uses c-index-test which ignores the -triple=, etc. arguments that are
in the RUN: line and therefore does not generate checks for some targets.

The AST dump tests were updated using the following command:
`python $LLVM_BINDIR/gen_ast_dump_json_test.py --update --source $LLVM_SRC/clang/test/AST/*-json.*`

Reviewers: aaron.ballman

Reviewed By: aaron.ballman

Subscribers: rsmith, MaskRay, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D69564
2019-11-15 12:52:56 +00:00
Djordje Todorovic 41d6ad6efd Revert "[clang] Remove the DIFlagArgumentNotModified debug info flag"
This reverts commit rG1643734741d2 due to LLDB test failure.
2019-11-15 12:16:44 +01:00
Djordje Todorovic 1643734741 [clang] Remove the DIFlagArgumentNotModified debug info flag
It turns out that the ExprMutationAnalyzer can be very slow when AST
gets huge in some cases. The idea is to move this analysis to the LLVM
back-end level (more precisely, in the LiveDebugValues pass). The new
approach will remove the performance regression, simplify the
implementation and give us front-end independent implementation.

Differential Revision: https://reviews.llvm.org/D68206
2019-11-15 11:10:19 +01:00
Sam McCall 87054ec07b [AST] Use written names instead of `type-param-0-0` in more cases when printing types and decls.
Summary:
This doesn't cover decls in diagnostics, which use NamedDecl::getNameForDiagnostic().
(That should also be fixed later I think).

This covers some cases of https://github.com/clangd/clangd/issues/76
(hover, but not outline or sighelp)

Reviewers: hokein

Subscribers: ilya-biryukov, jkorous, arphaman, kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70236
2019-11-15 10:40:38 +01:00
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
Yonghong Song dd16b3fe25 [BPF] Restrict preserve_access_index attribute to C only
This patch is a follow-up for commit 4e2ce228ae
  [BPF] Add preserve_access_index attribute for record definition
to restrict attribute for C only. A new test case is added
to check for this restriction.

Additional code polishing is done based on
Aaron Ballman's suggestion in https://reviews.llvm.org/D69759/new/.

Differential Revision: https://reviews.llvm.org/D70257
2019-11-14 14:14:59 -08:00
Craig Topper 3cec2a17de [X86] Fix the implementation of __readcr3/__writecr3 to work in 64-bit mode
We need to use a 64-bit type in 64-bit mode so a 64-bit register
will get used in the generated assembly. I've also changed the
constraints to just use "r" intead of "q". "q" forces to a only
an a/b/c/d register in 32-bit mode, but I see no reason that
would matter here.

Fixes Nico's note in PR19301 over 4 years ago.

Differential Revision: https://reviews.llvm.org/D70101
2019-11-14 13:21:36 -08:00