The callee-saved registers cannot be live across an invoke call because the
control flow may continue along the exceptional edge. When this happens, all of
the callee-saved registers are no longer valid.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142018 91177308-0d34-0410-b5e6-96231b3b80d8
successor. Remove the old landing pad from their successor list, because it's
now the successor of the dispatch block. Now that the landing pad blocks are no
longer the destination of invokes, we can mark them as normal basic blocks
instead of landing pads.
This more closely resembles what the CFG is actually doing.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141436 91177308-0d34-0410-b5e6-96231b3b80d8
others. They take the call site value. Determine if it's a proper value. And
then jumps to the correct call site via a jump table.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141341 91177308-0d34-0410-b5e6-96231b3b80d8
to an infinite loop because of the def-use chains.
Also use a frame load instead of store for the LD instruction.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141263 91177308-0d34-0410-b5e6-96231b3b80d8
This is a first pass at generating the jump table for the sjlj dispatch. It
currently generates something plausible, but hasn't been tested thoroughly.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141140 91177308-0d34-0410-b5e6-96231b3b80d8
This code will replace the version in ARMAsmPrinter.cpp. It creates a new
machine basic block, which is the dispatch for the return from a longjmp
call. It then shoves the address of that machine basic block into the correct
place in the function context so that the EH runtime will jump to it directly
instead of having to go through a compare-and-jump-to-the-dispatch bit. This
should be more efficient in the common case.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141031 91177308-0d34-0410-b5e6-96231b3b80d8
Encode the immediate into its 8-bit form as part of isel rather than later,
which simplifies things for mapping the encoding bits, allows the removal
of the custom disassembler decoding hook, makes the operand printer trivial,
and prepares things more cleanly for handling these in the asm parser.
rdar://10211428
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140834 91177308-0d34-0410-b5e6-96231b3b80d8
This is still a hack until we can teach tblgen to generate the
optional CPSR operand rather than an implicit CPSR def. But the
strangeness is now limited to the selection DAG. ADD/SUB MI's no
longer have implicit CPSR defs, nor do we allow flag setting variants
of these opcodes in machine code. There are several corner cases to
consider, and getting one wrong would previously lead to nasty
miscompilation. It's not the first time I've debugged one, so this
time I added enough verification to ensure it won't happen again.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140228 91177308-0d34-0410-b5e6-96231b3b80d8
Modified ARMISelLowering::AdjustInstrPostInstrSelection to handle the
full gamut of CPSR defs/uses including instructins whose "optional"
cc_out operand is not really optional. This allowed removal of the
hasPostISelHook to simplify the .td files and make the implementation
more robust.
Fixes rdar://10137436: sqlite3 miscompile
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140134 91177308-0d34-0410-b5e6-96231b3b80d8
with a vector condition); such selects become VSELECT codegen nodes.
This patch also removes VSETCC codegen nodes, unifying them with SETCC
nodes (codegen was actually often using SETCC for vector SETCC already).
This ensures that various DAG combiner optimizations kick in for vector
comparisons. Passes dragonegg bootstrap with no testsuite regressions
(nightly testsuite as well as "make check-all"). Patch mostly by
Nadav Rotem.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139159 91177308-0d34-0410-b5e6-96231b3b80d8
Now the 'S' instructions, e.g. ADDS, treat S bit as optional operand as well.
Also fix isel hook to correctly set the optional operand.
rdar://10073745
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139157 91177308-0d34-0410-b5e6-96231b3b80d8
Add a instruction flag: hasPostISelHook which tells the pre-RA scheduler to
call a target hook to adjust the instruction. For ARM, this is used to
adjust instructions which may be setting the 's' flag. ADC, SBC, RSB, and RSC
instructions have implicit def of CPSR (required since it now uses CPSR physical
register dependency rather than "glue"). If the carry flag is used, then the
target hook will *fill in* the optional operand with CPSR. Otherwise, the hook
will remove the CPSR implicit def from the MachineInstr.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@138810 91177308-0d34-0410-b5e6-96231b3b80d8
register dependency (rather than glue them together). This is general
goodness as it gives scheduler more freedom. However it is motivated by
a nasty bug in isel.
When a i64 sub is expanded to subc + sube.
libcall #1
\
\ subc
\ / \
\ / \
\ / libcall #2
sube
If the libcalls are not serialized (i.e. both have chains which are dag
entry), legalizer can serialize them in arbitrary orders. If it's
unlucky, it can force libcall #2 before libcall #1 in the above case.
subc
|
libcall #2
|
libcall #1
|
sube
However since subc and sube are "glued" together, this ends up being a
cycle when the scheduler combine subc and sube as a single scheduling
unit.
The right solution is to fix LegalizeType too chains the libcalls together.
However, LegalizeType is not processing nodes in order so that's harder than
it should be. For now, the move to physical register dependency will do.
rdar://10019576
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@138791 91177308-0d34-0410-b5e6-96231b3b80d8
I don't really like the patterns, but I'm having trouble coming up with a
better way to handle them.
I plan on making other targets use the same legalization
ARM-without-memory-barriers is using... it's not especially efficient, but
if anyone cares, it's not that hard to fix for a given target if there's
some better lowering.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@138621 91177308-0d34-0410-b5e6-96231b3b80d8
Refactor STR[B] pre and post indexed instructions to use addressing modes for
memory operands, which is necessary for assembly parsing and is more consistent
with the rest of the memory instruction definitions. Make some incremental
progress on refactoring away the mega-operand addrmode2 along the way, which
is nice.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136978 91177308-0d34-0410-b5e6-96231b3b80d8
Refactor the SXTB, SXTH, SXTB16, UXTB, UXTH, and UXTB16 instructions to not
have an 'r' and an 'r_rot' version, but just a single version with a rotate
that can be zero. Use plain Pat<>'s for the ISel of the non-rotated version.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136225 91177308-0d34-0410-b5e6-96231b3b80d8
if (x != 0) x = 1
if (x == 1) x = 1
Previous codegen looks like this:
mov r1, r0
cmp r1, #1
mov r0, #0
moveq r0, #1
The naive lowering select between two different values. It should recognize the
test is equality test so it's more a conditional move rather than a select:
cmp r0, #1
movne r0, #0
rdar://9758317
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135017 91177308-0d34-0410-b5e6-96231b3b80d8
The DSP instructions in the Thumb2 instruction set are an optional extension
in the Cortex-M* archtitecture. When present, the implementation is considered
an "ARMv7E-M implementation," and when not, an "ARMv7-M implementation."
Add a subtarget feature hook for the v7e-m instructions and hook it up. The
cortex-m3 cpu is an example of a v7m implementation, while the cortex-m4 is
a v7e-m implementation.
rdar://9572992
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134261 91177308-0d34-0410-b5e6-96231b3b80d8
sink them into MC layer.
- Added MCInstrInfo, which captures the tablegen generated static data. Chang
TargetInstrInfo so it's based off MCInstrInfo.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134021 91177308-0d34-0410-b5e6-96231b3b80d8
instructions can be used to match combinations of multiply/divide and VCVT
(between floating-point and integer, Advanced SIMD). Basically the VCVT
immediate operand that specifies the number of fraction bits corresponds to a
floating-point multiply or divide by the corresponding power of 2.
For example, VCVT (floating-point to fixed-point, Advanced SIMD) can replace a
combination of VMUL and VCVT (floating-point to integer) as follows:
Example (assume d17 = <float 8.000000e+00, float 8.000000e+00>):
vmul.f32 d16, d17, d16
vcvt.s32.f32 d16, d16
becomes:
vcvt.s32.f32 d16, d16, #3
Similarly, VCVT (fixed-point to floating-point, Advanced SIMD) can replace a
combinations of VCVT (integer to floating-point) and VDIV as follows:
Example (assume d17 = <float 8.000000e+00, float 8.000000e+00>):
vcvt.f32.s32 d16, d16
vdiv.f32 d16, d17, d16
becomes:
vcvt.f32.s32 d16, d16, #3
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133813 91177308-0d34-0410-b5e6-96231b3b80d8
accumulator forwarding. Specifically (from SVN log entry):
Distribute (A + B) * C to (A * C) + (B * C) to make use of NEON multiplier
accumulator forwarding:
vadd d3, d0, d1
vmul d3, d3, d2
=>
vmul d3, d0, d2
vmla d3, d1, d2
Make sure it catches cases where operand 1 is add/fadd/sub/fsub, which was
intended in the original revision.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133127 91177308-0d34-0410-b5e6-96231b3b80d8
the bits being cleared by the AND are not demanded by the BFI.
The previous BFI dag combine rule was actually incorrect (or used to be
correct until BFI representation changed).
rdar://9609030
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133034 91177308-0d34-0410-b5e6-96231b3b80d8
causing an assertion failure downstream. This fixes <rdar://problem/9562908>.
This really seems like it should always be set at CCState creation time, so mistakes like
this can never happen. I'll take a look at doing that.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132811 91177308-0d34-0410-b5e6-96231b3b80d8
addressing mode problem mentioned in r132559.
Backend part of rdar://9037836 and part of rdar://9119939
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132561 91177308-0d34-0410-b5e6-96231b3b80d8
This is important for the correct lowering of unwind instructions
(which doesn't matter at all) and llvm.eh.resume calls (which does).
Take 2, now with more basic competence.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132295 91177308-0d34-0410-b5e6-96231b3b80d8
This is important for the correct lowering of unwind instructions
(which doesn't matter at all) and llvm.eh.resume calls (which does).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132291 91177308-0d34-0410-b5e6-96231b3b80d8
to load/store i64 values. Since there's no current support to explicitly
declare such restrictions, implement it by using specific hardcoded register
pairs during isel.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132248 91177308-0d34-0410-b5e6-96231b3b80d8
intrinsic call. This prevents it from being reordered so that it appears
*before* the setjmp intrinsic (thus making it completely useless).
<rdar://problem/9409683>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131174 91177308-0d34-0410-b5e6-96231b3b80d8
model constants which can be added to base registers via add-immediate
instructions which don't require an additional register to materialize
the immediate.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130743 91177308-0d34-0410-b5e6-96231b3b80d8
Fixes Thumb2 ADCS and SBCS lowering: <rdar://problem/9275821>.
t2ADCS/t2SBCS are now pseudo instructions, consistent with ARM, so the
assembly printer correctly prints the 's' suffix.
Fixes Thumb2 adde -> SBC matching to check for live/dead carry flags.
Fixes the internal ARM machine opcode mnemonic for ADCS/SBCS.
Fixes ARM SBC lowering to check for live carry (potential bug).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130048 91177308-0d34-0410-b5e6-96231b3b80d8
It needed to be moved closer to the setjmp statement, because the code directly
after the setjmp needs to know about values that are on the stack. Also, the
'bitcast' of the function context was causing a dead load. This wouldn't be too
horrible, except that at -O0 it wasn't optimized out, and because it wasn't
using the correct base pointer (if there is a VLA), it would try to access a
value from a garbage address.
<rdar://problem/9130540>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128873 91177308-0d34-0410-b5e6-96231b3b80d8
registers that arise from argument shuffling with the soft float ABI. These
instructions are particularly slow on Cortex A8. This fixes one half of
<rdar://problem/8674845>.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128759 91177308-0d34-0410-b5e6-96231b3b80d8
was lowering them to sext / uxt + mul instructions. Unfortunately the
optimization passes may hoist the extensions out of the loop and separate them.
When that happens, the long multiplication instructions can be broken into
several scalar instructions, causing significant performance issue.
Note the vmla and vmls intrinsics are not added back. Frontend will codegen them
as intrinsics vmull* + add / sub. Also note the isel optimizations for catching
mul + sext / zext are not changed either.
First part of rdar://8832507, rdar://9203134
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128502 91177308-0d34-0410-b5e6-96231b3b80d8
isel lowering to fold the zero-extend's and take advantage of no-stall
back to back vmul + vmla:
vmull q0, d4, d6
vmlal q0, d5, d6
is faster than
vaddl q0, d4, d5
vmovl q1, d6
vmul q0, q0, q1
This allows us to vmull + vmlal for:
f = vmull_u8( vget_high_u8(s), c);
f = vmlal_u8(f, vget_low_u8(s), c);
rdar://9197392
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128444 91177308-0d34-0410-b5e6-96231b3b80d8
masks to match inversely for the code as is to work. For the example given
we actually want:
bfi r0, r2, #1, #1
not #0, however, given the way the pattern is written it's not possible
at the moment.
Fixes rdar://9177502
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128320 91177308-0d34-0410-b5e6-96231b3b80d8
to have single return block (at least getting there) for optimizations. This
is general goodness but it would prevent some tailcall optimizations.
One specific case is code like this:
int f1(void);
int f2(void);
int f3(void);
int f4(void);
int f5(void);
int f6(void);
int foo(int x) {
switch(x) {
case 1: return f1();
case 2: return f2();
case 3: return f3();
case 4: return f4();
case 5: return f5();
case 6: return f6();
}
}
=>
LBB0_2: ## %sw.bb
callq _f1
popq %rbp
ret
LBB0_3: ## %sw.bb1
callq _f2
popq %rbp
ret
LBB0_4: ## %sw.bb3
callq _f3
popq %rbp
ret
This patch teaches codegenprep to duplicate returns when the return value
is a phi and where the phi operands are produced by tail calls followed by
an unconditional branch:
sw.bb7: ; preds = %entry
%call8 = tail call i32 @f5() nounwind
br label %return
sw.bb9: ; preds = %entry
%call10 = tail call i32 @f6() nounwind
br label %return
return:
%retval.0 = phi i32 [ %call10, %sw.bb9 ], [ %call8, %sw.bb7 ], ... [ 0, %entry ]
ret i32 %retval.0
This allows codegen to generate better code like this:
LBB0_2: ## %sw.bb
jmp _f1 ## TAILCALL
LBB0_3: ## %sw.bb1
jmp _f2 ## TAILCALL
LBB0_4: ## %sw.bb3
jmp _f3 ## TAILCALL
rdar://9147433
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127953 91177308-0d34-0410-b5e6-96231b3b80d8
accept. If a value in the mask is out of range, it uses the value 0, for VTBL,
or leaves the value unchanged, for VTBX.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127700 91177308-0d34-0410-b5e6-96231b3b80d8
The previous codegen for the slow path (when values are in VFP / NEON
registers) was incorrect if the source is NaN.
The new codegen uses NEON vbsl instruction to copy the sign bit. e.g.
vmov.i32 d1, #0x80000000
vbsl d1, d2, d0
If NEON is not available, it uses integer instructions to copy the sign bit.
rdar://9034702
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126295 91177308-0d34-0410-b5e6-96231b3b80d8
In other words, do not keep track of argument's location. The debugger (gdb) is not prepared to see line table entries for arguments. For the debugger, "second" line table entry marks beginning of function body.
This requires some coordination with debugger to get this working.
- The debugger needs to be aware of prolog_end attribute attached with line table entries.
- The compiler needs to accurately mark prolog_end in line table entries (at -O0 and at -O1+)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126155 91177308-0d34-0410-b5e6-96231b3b80d8
This
define float @foo(float %x, float %y) nounwind readnone {
entry:
%0 = tail call float @copysignf(float %x, float %y) nounwind readnone
ret float %0
}
Was compiled to:
vmov s0, r1
bic r0, r0, #-2147483648
vmov s1, r0
vcmpe.f32 s0, #0
vmrs apsr_nzcv, fpscr
it lt
vneglt.f32 s1, s1
vmov r0, s1
bx lr
This fails to copy the sign of -0.0f because it's lost during the float to int
conversion. Also, it's sub-optimal when the inputs are in GPR registers.
Now it uses integer and + or operations when it's profitable. And it's correct!
lsrs r1, r1, #31
bfi r0, r1, #31, #1
bx lr
rdar://8984306
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125357 91177308-0d34-0410-b5e6-96231b3b80d8
The vld1-lane, vld1-dup and vst1-lane instructions do not yet support using
post-increment versions, but all the rest of the NEON load/store instructions
should be handled now.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125014 91177308-0d34-0410-b5e6-96231b3b80d8
the load, then it may be legal to transform the load and store to integer
load and store of the same width.
This is done if the target specified the transformation as profitable. e.g.
On arm, this can transform:
vldr.32 s0, []
vstr.32 s0, []
to
ldr r12, []
str r12, []
rdar://8944252
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124708 91177308-0d34-0410-b5e6-96231b3b80d8
1. Fixed ARM pc adjustment.
2. Fixed dynamic-no-pic codegen
3. CSE of pc-relative load of global addresses.
It's now enabled by default for Darwin.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123991 91177308-0d34-0410-b5e6-96231b3b80d8
TargetInstrInfo:
Change produceSameValue() to take MachineRegisterInfo as an optional argument.
When in SSA form, targets can use it to make more aggressive equality analysis.
Machine LICM:
1. Eliminate isLoadFromConstantMemory, use MI.isInvariantLoad instead.
2. Fix a bug which prevent CSE of instructions which are not re-materializable.
3. Use improved form of produceSameValue.
ARM:
1. Teach ARM produceSameValue to look pass some PIC labels.
2. Look for operands from different loads of different constant pool entries
which have same values.
3. Re-implement PIC GA materialization using movw + movt. Combine the pair with
a "add pc" or "ldr [pc]" to form pseudo instructions. This makes it possible
to re-materialize the instruction, allow machine LICM to hoist the set of
instructions out of the loop and make it possible to CSE them. It's a bit
hacky, but it significantly improve code quality.
4. Some minor bug fixes as well.
With the fixes, using movw + movt to materialize GAs significantly outperform the
load from constantpool method. 186.crafty and 255.vortex improved > 20%, 254.gap
and 176.gcc ~10%.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123905 91177308-0d34-0410-b5e6-96231b3b80d8
of the floating point types less than 64-bits. It's somewhat of a temporary
hack but forces more accurate modeling of register pressure and results
in fewer spills.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123811 91177308-0d34-0410-b5e6-96231b3b80d8
movw r0, :lower16:(L_foo$non_lazy_ptr-(LPC0_0+4))
movt r0, :upper16:(L_foo$non_lazy_ptr-(LPC0_0+4))
LPC0_0:
add r0, pc, r0
It's not yet enabled by default as some tests are failing. I suspect bugs in
down stream tools.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123619 91177308-0d34-0410-b5e6-96231b3b80d8
These functions not longer assert when passed 0, but simply return false instead.
No functional change intended.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123155 91177308-0d34-0410-b5e6-96231b3b80d8
Also fix an off-by-one in SelectionDAGBuilder that was preventing shuffle
vectors from being translated to EXTRACT_SUBVECTOR.
Patch by Tim Northover.
The test changes are needed to keep those spill-q tests from testing aligned
spills and restores. If the only aligned stack objects are spill slots, we
no longer realign the stack frame. Prior to this patch, an EXTRACT_SUBVECTOR
was legalized by loading from the stack, which created an aligned frame index.
Now, however, there is nothing except the spill slot in the stack frame, so
I added an aligned alloca.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122995 91177308-0d34-0410-b5e6-96231b3b80d8
etc. takes an option OptSize. If OptSize is true, it would return
the inline limit for functions with attribute OptSize.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122952 91177308-0d34-0410-b5e6-96231b3b80d8
If the basic block containing the BCCi64 (or BCCZi64) instruction ends with
an unconditional branch, that branch needs to be deleted before appending
the expansion of the BCCi64 to the end of the block.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122521 91177308-0d34-0410-b5e6-96231b3b80d8
Type legalization splits up i64 values into pairs of i32 values, which leads
to poor quality code when inserting or extracting i64 vector elements.
If the vector element is loaded or stored, it can be treated as an f64 value
and loaded or stored directly from a VPR register. Use the pre-legalization
DAG combiner to cast those vector elements to f64 types so that the type
legalizer won't mess them up. Radar 8755338.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122319 91177308-0d34-0410-b5e6-96231b3b80d8
zextOrTrunc(), and APSInt methods extend(), extOrTrunc() and new method
trunc(), to be const and to return a new value instead of modifying the
object in place.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121120 91177308-0d34-0410-b5e6-96231b3b80d8
legalization time. Since at legalization time there is no mapping from
SDNode back to the corresponding LLVM instruction and the return
SDNode is target specific, this requires a target hook to check for
eligibility. Only x86 and ARM support this form of sibcall optimization
right now.
rdar://8707777
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120501 91177308-0d34-0410-b5e6-96231b3b80d8
We need to check if the individual vector elements are sign/zero-extended
values. For now this only handles constants values. Radar 8687140.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120034 91177308-0d34-0410-b5e6-96231b3b80d8
This function was being called from two different places for completely
unrelated reasons. During type legalization, it was called to expand 64-bit
shift operations. During operation legalization, it was called to handle
Neon vector shifts. The vector shift code was not written to check for
illegal types, since it was assumed to be only called after type legalization.
Fixed this by splitting off the 64-bit shift expansion into a separate
function. I don't have a particular testcase for this; I just noticed it
by inspection.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119738 91177308-0d34-0410-b5e6-96231b3b80d8
It is only supported for ARM code. Normally Thumb2 code would use DMB instead,
but depending on how the compiler is invoked (e.g., -mattr=-db) that might be
disabled. This prevents a "cannot select MEMBARRIER_MCR" error in that
situation. Radar 8644195
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118642 91177308-0d34-0410-b5e6-96231b3b80d8