This changes the interface of how targets describe how to legalize, see
the below description.
1. Interface for targets to describe how to legalize.
In GlobalISel, the API in the LegalizerInfo class is the main interface
for targets to specify which types are legal for which operations, and
what to do to turn illegal type/operation combinations into legal ones.
For each operation the type sizes that can be legalized without having
to change the size of the type are specified with a call to setAction.
This isn't different to how GlobalISel worked before. For example, for a
target that supports 32 and 64 bit adds natively:
for (auto Ty : {s32, s64})
setAction({G_ADD, 0, s32}, Legal);
or for a target that needs a library call for a 32 bit division:
setAction({G_SDIV, s32}, Libcall);
The main conceptual change to the LegalizerInfo API, is in specifying
how to legalize the type sizes for which a change of size is needed. For
example, in the above example, how to specify how all types from i1 to
i8388607 (apart from s32 and s64 which are legal) need to be legalized
and expressed in terms of operations on the available legal sizes
(again, i32 and i64 in this case). Before, the implementation only
allowed specifying power-of-2-sized types (e.g. setAction({G_ADD, 0,
s128}, NarrowScalar). A worse limitation was that if you'd wanted to
specify how to legalize all the sized types as allowed by the LLVM-IR
LangRef, i1 to i8388607, you'd have to call setAction 8388607-3 times
and probably would need a lot of memory to store all of these
specifications.
Instead, the legalization actions that need to change the size of the
type are specified now using a "SizeChangeStrategy". For example:
setLegalizeScalarToDifferentSizeStrategy(
G_ADD, 0, widenToLargerAndNarrowToLargest);
This example indicates that for type sizes for which there is a larger
size that can be legalized towards, do it by Widening the size.
For example, G_ADD on s17 will be legalized by first doing WidenScalar
to make it s32, after which it's legal.
The "NarrowToLargest" indicates what to do if there is no larger size
that can be legalized towards. E.g. G_ADD on s92 will be legalized by
doing NarrowScalar to s64.
Another example, taken from the ARM backend is:
for (unsigned Op : {G_SDIV, G_UDIV}) {
setLegalizeScalarToDifferentSizeStrategy(Op, 0,
widenToLargerTypesUnsupportedOtherwise);
if (ST.hasDivideInARMMode())
setAction({Op, s32}, Legal);
else
setAction({Op, s32}, Libcall);
}
For this example, G_SDIV on s8, on a target without a divide
instruction, would be legalized by first doing action (WidenScalar,
s32), followed by (Libcall, s32).
The same principle is also followed for when the number of vector lanes
on vector data types need to be changed, e.g.:
setAction({G_ADD, LLT::vector(8, 8)}, LegalizerInfo::Legal);
setAction({G_ADD, LLT::vector(16, 8)}, LegalizerInfo::Legal);
setAction({G_ADD, LLT::vector(4, 16)}, LegalizerInfo::Legal);
setAction({G_ADD, LLT::vector(8, 16)}, LegalizerInfo::Legal);
setAction({G_ADD, LLT::vector(2, 32)}, LegalizerInfo::Legal);
setAction({G_ADD, LLT::vector(4, 32)}, LegalizerInfo::Legal);
setLegalizeVectorElementToDifferentSizeStrategy(
G_ADD, 0, widenToLargerTypesUnsupportedOtherwise);
As currently implemented here, vector types are legalized by first
making the vector element size legal, followed by then making the number
of lanes legal. The strategy to follow in the first step is set by a
call to setLegalizeVectorElementToDifferentSizeStrategy, see example
above. The strategy followed in the second step
"moreToWiderTypesAndLessToWidest" (see code for its definition),
indicating that vectors are widened to more elements so they map to
natively supported vector widths, or when there isn't a legal wider
vector, split the vector to map it to the widest vector supported.
Therefore, for the above specification, some example legalizations are:
* getAction({G_ADD, LLT::vector(3, 3)})
returns {WidenScalar, LLT::vector(3, 8)}
* getAction({G_ADD, LLT::vector(3, 8)})
then returns {MoreElements, LLT::vector(8, 8)}
* getAction({G_ADD, LLT::vector(20, 8)})
returns {FewerElements, LLT::vector(16, 8)}
2. Key implementation aspects.
How to legalize a specific (operation, type index, size) tuple is
represented by mapping intervals of integers representing a range of
size types to an action to take, e.g.:
setScalarAction({G_ADD, LLT:scalar(1)},
{{1, WidenScalar}, // bit sizes [ 1, 31[
{32, Legal}, // bit sizes [32, 33[
{33, WidenScalar}, // bit sizes [33, 64[
{64, Legal}, // bit sizes [64, 65[
{65, NarrowScalar} // bit sizes [65, +inf[
});
Please note that most of the code to do the actual lowering of
non-power-of-2 sized types is currently missing, this is just trying to
make it possible for targets to specify what is legal, and how non-legal
types should be legalized. Probably quite a bit of further work is
needed in the actual legalizing and the other passes in GlobalISel to
support non-power-of-2 sized types.
I hope the documentation in LegalizerInfo.h and the examples provided in the
various {Target}LegalizerInfo.cpp and LegalizerInfoTest.cpp explains well
enough how this is meant to be used.
This drops the need for LLT::{half,double}...Size().
Differential Revision: https://reviews.llvm.org/D30529
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@317560 91177308-0d34-0410-b5e6-96231b3b80d8
The GlobalISel TableGen backend didn't check for predicates on the
source children. This caused it to generate code for ARM patterns such
as SMLABB or similar, but without properly checking for the sext_16_node
part of the operands. This in turn meant that we would select SMLABB
instead of MLA for simple sequences such as s32 + s32 * s32, which is
wrong (we want a MLA on the full operands, not just their bottom 16
bits).
This patch forces TableGen to skip patterns with predicates on the src
children, so it doesn't generate code for SMLABB and other similar ARM
instructions at all anymore. AArch64 and X86 are not affected.
Differential Revision: https://reviews.llvm.org/D39554
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@317313 91177308-0d34-0410-b5e6-96231b3b80d8
The generic dag combiner will fold:
(shl (add x, c1), c2) -> (add (shl x, c2), c1 << c2)
(shl (or x, c1), c2) -> (or (shl x, c2), c1 << c2)
This can create constants which are too large to use as an immediate.
Many ALU operations are also able of performing the shl, so we can
unfold the transformation to prevent a mov imm instruction from being
generated.
Other patterns, such as b + ((a << 1) | 510), can also be simplified
in the same manner.
Differential Revision: https://reviews.llvm.org/D38084
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@317197 91177308-0d34-0410-b5e6-96231b3b80d8
Remove the G_FADD testcases from arm-legalizer.mir, they are covered by
arm-legalizer-fp.mir (I probably forgot to delete them when I created
that test).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316573 91177308-0d34-0410-b5e6-96231b3b80d8
No need to check register classes in the register block anymore, since
we can now much more conveniently check them at their def.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316572 91177308-0d34-0410-b5e6-96231b3b80d8
We were generating BLX for all the calls, which was incorrect in most
cases. Update ARMCallLowering to generate BL for direct calls, and BLX,
BX_CALL or BMOVPCRX_CALL for indirect calls.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316570 91177308-0d34-0410-b5e6-96231b3b80d8
Separate the test cases that deal with calls from the rest of the IR
Translator tests.
We split into 2 different files, one for testing parameter and result
lowering, and one for testing the various different kinds of calls that
can occur (BL, BLX, BX_CALL etc).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316569 91177308-0d34-0410-b5e6-96231b3b80d8
This updates the MIRPrinter to include the regclass when printing
virtual register defs, which is already valid syntax for the
parser. That is, given 64 bit %0 and %1 in a "gpr" regbank,
%1(s64) = COPY %0(s64)
would now be written as
%1:gpr(s64) = COPY %0(s64)
While this change alone introduces a bit of redundancy with the
registers block, it allows us to update the tests to be more concise
and understandable and brings us closer to being able to remove the
registers block completely.
Note: We generally only print the class in defs, but there is one
exception. If there are uses without any defs whatsoever, we'll print
the class on all uses. I'm not completely convinced this comes up in
meaningful machine IR, but for now the MIRParser and MachineVerifier
both accept that kind of stuff, so we don't want to have a situation
where we can print something we can't parse.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316479 91177308-0d34-0410-b5e6-96231b3b80d8
This is in preparation for a verifier check that makes sure
copies are of the same size (when generic virtual registers are involved).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316388 91177308-0d34-0410-b5e6-96231b3b80d8
This patch implements dynamic stack (re-)alignment for 16-bit Thumb. When
targeting processors, which support only the 16-bit Thumb instruction set
the compiler ignores the alignment attributes of automatic variables and may
silently generate incorrect code.
Differential revision: https://reviews.llvm.org/D38143
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316289 91177308-0d34-0410-b5e6-96231b3b80d8
These test cases don't really add anything that isn't covered by other
tests as well, so we can safely remove them.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316154 91177308-0d34-0410-b5e6-96231b3b80d8
This converts a large and somewhat arbitrary set of tests to use
update_mir_test_checks. I ran the script on all of the tests I expect
to need to modify for an upcoming mir syntax change and kept the ones
that obviously didn't change the tests in ways that might make it
harder to understand.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316137 91177308-0d34-0410-b5e6-96231b3b80d8
These are intended as integration tests, so they shouldn't be too
specific about what they're checking.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315083 91177308-0d34-0410-b5e6-96231b3b80d8
Unfortunately TableGen doesn't handle this yet:
Unable to deduce gMIR opcode to handle Src (which is a leaf).
Just add some temporary hand-written code to generate the proper MOVsr.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315071 91177308-0d34-0410-b5e6-96231b3b80d8
The new legalize combiner introduces shifts all over the place, so we
should support them sooner rather than later.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315064 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r314729.
Another bug has been encountered in an out-of-tree target reported by Quentin.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314814 91177308-0d34-0410-b5e6-96231b3b80d8
Issues addressed since original review:
- Avoid bug in regalloc greedy/machine verifier when forwarding to use
in an instruction that re-defines the same virtual register.
- Fixed bug when forwarding to use in EarlyClobber instruction slot.
- Fixed incorrect forwarding to register definitions that showed up in
explicit_uses() iterator (e.g. in INLINEASM).
- Moved removal of dead instructions found by
LiveIntervals::shrinkToUses() outside of loop iterating over
instructions to avoid instructions being deleted while pointed to by
iterator.
- Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907.
- The pass no longer forwards COPYs to physical register uses, since
doing so can break code that implicitly relies on the physical
register number of the use.
- The pass no longer forwards COPYs to undef uses, since doing so
can break the machine verifier by creating LiveRanges that don't
end on a use (since the undef operand is not considered a use).
[MachineCopyPropagation] Extend pass to do COPY source forwarding
This change extends MachineCopyPropagation to do COPY source forwarding.
This change also extends the MachineCopyPropagation pass to be able to
be run during register allocation, after physical registers have been
assigned, but before the virtual registers have been re-written, which
allows it to remove virtual register COPY LiveIntervals that become dead
through the forwarding of all of their uses.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314729 91177308-0d34-0410-b5e6-96231b3b80d8
LR is an untypical callee saved register in that it is restored into a
different register (PC) and thus does not live-out of the return block.
This case requires the `Restored` flag in CalleeSavedInfo to be cleared.
This fixes a number of cases where this wasn't handled correctly yet.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314471 91177308-0d34-0410-b5e6-96231b3b80d8
In setupEntryBlockAndCallSites in CodeGen/SjLjEHPrepare.cpp,
we fetch and store the actual frame pointer, but on return via
the longjmp intrinsic, it always was restored into the r7 variable.
On windows, the frame pointer should be restored into r11 instead of r7.
On Darwin (where sjlj exception handling is used by default), the frame
pointer is always r7, both in arm and thumb mode, and likewise, on
windows, the frame pointer always is r11.
On linux however, if sjlj exception handling is enabled (which it isn't
by default), libcxxabi and the user code can be built in differing modes
using different registers as frame pointer. Therefore, when restoring
registers on a platform where we don't always use the same register
depending on code mode, restore both r7 and r11.
Differential Revision: https://reviews.llvm.org/D38253
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314451 91177308-0d34-0410-b5e6-96231b3b80d8
It leads to some improvements, but also a regression for the simple
case, so it's not clearly a good idea.
test/CodeGen/ARM/vcvt.ll now has test coverage to show the difference.
Ultimately, the right solution is probably to custom-lower fp-to-int
conversions, to something like ARMISD::VCVT_F32_S32 plus a bitcast.
It's hard to do the right thing when the implicit bitcast isn't visible
to DAG transforms.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314169 91177308-0d34-0410-b5e6-96231b3b80d8
This is what I meant to do in r314161; I didn't realize I'd messed up
because the generated assembly is currently identical.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314163 91177308-0d34-0410-b5e6-96231b3b80d8
This teach simplifyDemandedBits to handle constant splat vector shifts.
This required changing some uses of getZExtValue to getLimitedValue since we can't rely on legalization using getShiftAmountTy for the shift amount.
I believe there may have been a bug in the ((X << C1) >>u ShAmt) handling where we didn't check if the inner shift was too large. I've fixed that here.
I had to add new patterns to ARM because the zext/sext the patterns were trying to look for got turned into an any_extend with this patch. Happy to split that out too, but not sure how to test without this change.
Differential Revision: https://reviews.llvm.org/D37665
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314139 91177308-0d34-0410-b5e6-96231b3b80d8
For the following function:
double fn1(double d0, double d1, double d2) {
double a = -d0 - d1 * d2;
return a;
}
on ARM, LLVM generates code along the lines of
vneg.f64 d0, d0
vmls.f64 d0, d1, d2
i.e., a negate and a multiply-subtract.
The attached patch adds instruction selection patterns to allow it to generate the single instruction
vnmla.f64 d0, d1, d2
(multiply-add with negation) instead, like GCC does.
Committed on behalf of @gergo- (Gergö Barany)
Differential Revision: https://reviews.llvm.org/D35911
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313972 91177308-0d34-0410-b5e6-96231b3b80d8
This is a preparatory step for D34515.
This change:
- makes nodes ISD::ADDCARRY and ISD::SUBCARRY legal for i32
- lowering is done by first converting the boolean value into the carry flag
using (_, C) ← (ARMISD::ADDC R, -1) and converted back to an integer value
using (R, _) ← (ARMISD::ADDE 0, 0, C). An ARMISD::ADDE between the two
operations does the actual addition.
- for subtraction, given that ISD::SUBCARRY second result is actually a
borrow, we need to invert the value of the second operand and result before
and after using ARMISD::SUBE. We need to invert the carry result of
ARMISD::SUBE to preserve the semantics.
- given that the generic combiner may lower ISD::ADDCARRY and
ISD::SUBCARRYinto ISD::UADDO and ISD::USUBO we need to update their lowering
as well otherwise i64 operations now would require branches. This implies
updating the corresponding test for unsigned.
- add new combiner to remove the redundant conversions from/to carry flags
to/from boolean values (ARMISD::ADDC (ARMISD::ADDE 0, 0, C), -1) → C
- fixes PR34045
- fixes PR34564
Differential Revision: https://reviews.llvm.org/D35192
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313618 91177308-0d34-0410-b5e6-96231b3b80d8
This was causing PR34045 to fire again.
> This is a preparatory step for D34515 and also is being recommitted as its
> first version caused PR34045.
>
> This change:
> - makes nodes ISD::ADDCARRY and ISD::SUBCARRY legal for i32
> - lowering is done by first converting the boolean value into the carry flag
> using (_, C) ← (ARMISD::ADDC R, -1) and converted back to an integer value
> using (R, _) ← (ARMISD::ADDE 0, 0, C). An ARMISD::ADDE between the two
> operations does the actual addition.
> - for subtraction, given that ISD::SUBCARRY second result is actually a
> borrow, we need to invert the value of the second operand and result before
> and after using ARMISD::SUBE. We need to invert the carry result of
> ARMISD::SUBE to preserve the semantics.
> - given that the generic combiner may lower ISD::ADDCARRY and
> ISD::SUBCARRYinto ISD::UADDO and ISD::USUBO we need to update their lowering
> as well otherwise i64 operations now would require branches. This implies
> updating the corresponding test for unsigned.
> - add new combiner to remove the redundant conversions from/to carry flags
> to/from boolean values (ARMISD::ADDC (ARMISD::ADDE 0, 0, C), -1) → C
> - fixes PR34045
>
> Differential Revision: https://reviews.llvm.org/D35192
Also revert follow-up r313010:
> [ARM] Fix typo when creating ISD::SUB nodes
>
> In D35192, I accidentally introduced a typo when creating ISD::SUB nodes,
> giving them two values instead of one.
>
> This fails when the merge_values combiner finds one of these nodes.
>
> This change fixes PR34564.
>
> Differential Revision: https://reviews.llvm.org/D37690
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313044 91177308-0d34-0410-b5e6-96231b3b80d8
This is a preparatory step for D34515 and also is being recommitted as its
first version caused PR34045.
This change:
- makes nodes ISD::ADDCARRY and ISD::SUBCARRY legal for i32
- lowering is done by first converting the boolean value into the carry flag
using (_, C) ← (ARMISD::ADDC R, -1) and converted back to an integer value
using (R, _) ← (ARMISD::ADDE 0, 0, C). An ARMISD::ADDE between the two
operations does the actual addition.
- for subtraction, given that ISD::SUBCARRY second result is actually a
borrow, we need to invert the value of the second operand and result before
and after using ARMISD::SUBE. We need to invert the carry result of
ARMISD::SUBE to preserve the semantics.
- given that the generic combiner may lower ISD::ADDCARRY and
ISD::SUBCARRYinto ISD::UADDO and ISD::USUBO we need to update their lowering
as well otherwise i64 operations now would require branches. This implies
updating the corresponding test for unsigned.
- add new combiner to remove the redundant conversions from/to carry flags
to/from boolean values (ARMISD::ADDC (ARMISD::ADDE 0, 0, C), -1) → C
- fixes PR34045
Differential Revision: https://reviews.llvm.org/D35192
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313009 91177308-0d34-0410-b5e6-96231b3b80d8
It caused PR34564.
> This is a preparatory step for D34515 and also is being recommitted as its
> first version caused PR34045.
>
> This change:
> - makes nodes ISD::ADDCARRY and ISD::SUBCARRY legal for i32
> - lowering is done by first converting the boolean value into the carry flag
> using (_, C) ← (ARMISD::ADDC R, -1) and converted back to an integer value
> using (R, _) ← (ARMISD::ADDE 0, 0, C). An ARMISD::ADDE between the two
> operations does the actual addition.
> - for subtraction, given that ISD::SUBCARRY second result is actually a
> borrow, we need to invert the value of the second operand and result before
> and after using ARMISD::SUBE. We need to invert the carry result of
> ARMISD::SUBE to preserve the semantics.
> - given that the generic combiner may lower ISD::ADDCARRY and
> ISD::SUBCARRYinto ISD::UADDO and ISD::USUBO we need to update their lowering
> as well otherwise i64 operations now would require branches. This implies
> updating the corresponding test for unsigned.
> - add new combiner to remove the redundant conversions from/to carry flags
> to/from boolean values (ARMISD::ADDC (ARMISD::ADDE 0, 0, C), -1) → C
> - fixes PR34045
>
> Differential Revision: https://reviews.llvm.org/D35192
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312980 91177308-0d34-0410-b5e6-96231b3b80d8
As discussed on llvm-dev in
http://lists.llvm.org/pipermail/llvm-dev/2017-September/117301.html
this changes the command line interface of llvm-dwarfdump to match the
one used by the dwarfdump utility shipping on macOS. In addition to
being shorter to type this format also has the advantage of allowing
more than one section to be specified at the same time.
In a nutshell, with this change
$ llvm-dwarfdump --debug-dump=info
$ llvm-dwarfdump --debug-dump=apple-objc
becomes
$ dwarfdump --debug-info --apple-objc
Differential Revision: https://reviews.llvm.org/D37714
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312970 91177308-0d34-0410-b5e6-96231b3b80d8
This is a preparatory step for D34515 and also is being recommitted as its
first version caused PR34045.
This change:
- makes nodes ISD::ADDCARRY and ISD::SUBCARRY legal for i32
- lowering is done by first converting the boolean value into the carry flag
using (_, C) ← (ARMISD::ADDC R, -1) and converted back to an integer value
using (R, _) ← (ARMISD::ADDE 0, 0, C). An ARMISD::ADDE between the two
operations does the actual addition.
- for subtraction, given that ISD::SUBCARRY second result is actually a
borrow, we need to invert the value of the second operand and result before
and after using ARMISD::SUBE. We need to invert the carry result of
ARMISD::SUBE to preserve the semantics.
- given that the generic combiner may lower ISD::ADDCARRY and
ISD::SUBCARRYinto ISD::UADDO and ISD::USUBO we need to update their lowering
as well otherwise i64 operations now would require branches. This implies
updating the corresponding test for unsigned.
- add new combiner to remove the redundant conversions from/to carry flags
to/from boolean values (ARMISD::ADDC (ARMISD::ADDE 0, 0, C), -1) → C
- fixes PR34045
Differential Revision: https://reviews.llvm.org/D35192
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312898 91177308-0d34-0410-b5e6-96231b3b80d8
rL312641 Allowed llvm.memcpy/memset/memmove to be tail calls when parent
function return the intrinsics's first argument. However on arm-none-eabi
platform, llvm.memcpy will be expanded to __aeabi_memcpy which doesn't
have return value. The fix is to check the libcall name after expansion
to match "memcpy/memset/memmove" before allowing those intrinsic to be
tail calls.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312799 91177308-0d34-0410-b5e6-96231b3b80d8
These don't add any value as they're just compositions of existing
patterns. However, they can confuse the cost logic in ISel, leading to
duplicated vcvt instructions like in PR33199.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312724 91177308-0d34-0410-b5e6-96231b3b80d8
Globals that are promoted to an ARM constant pool may alias with another
existing constant pool entry. We need to keep a reference to all globals
that were promoted to each constant pool value so that we can emit a
distinct label for each promoted global. These labels are necessary so
that debug info can refer to the promoted global without an undefined
reference during linking.
Patch by Stephen Crane!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312692 91177308-0d34-0410-b5e6-96231b3b80d8
Missing these could potentially screw up post-ra scheduling.
Issue found by inspection, so I don't have a real testcase. Included
test just verifies the expected operands after expansion.
Differential Revision: https://reviews.llvm.org/D35156
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312589 91177308-0d34-0410-b5e6-96231b3b80d8
