includes extracting ints for copying elsewhere and inserting ints when
copying into the alloca. This should fix the CanSROA assertion coming
out of Clang's regression test suite.
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and generally clean up the memset handling. It had rotted a bit as the
other rewriting logic got polished more.
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cases where we have partial integer loads and stores to an otherwise
promotable alloca to widen[1] those loads and stores to cover the entire
alloca and bitcast them into the appropriate type such that promotion
can proceed.
These partial loads and stores stem from an annoying confluence of ARM's
calling convention and ABI lowering and the FCA pre-splitting which
takes place in SROA. Clang lowers a { double, double } in-register
function argument as a [4 x i32] function argument to ensure it is
placed into integer 32-bit registers (a really unnerving implicit
contract between Clang and the ARM backend I would add). This results in
a FCA load of [4 x i32]* from the { double, double } alloca, and SROA
decomposes this into a sequence of i32 loads and stores. Inlining
proceeds, code gets folded, but at the end of the day, we still have i32
stores to the low and high halves of a double alloca. Widening these to
be i64 operations, and bitcasting them to double prior to loading or
storing allows promotion to proceed for these allocas.
I looked quite a bit changing the IR which Clang produces for this case
to be more friendly, but small changes seem unlikely to help. I think
the best representation we could use currently would be to pass 4 i32
arguments thereby avoiding any FCAs, but that would still require this
fix. It seems like it might eventually be nice to somehow encode the ABI
register selection choices outside of the parameter type system so that
the parameter can be a { double, double }, but the CC register
annotations indicate that this should be passed via 4 integer registers.
This patch does not address the second problem in PR14059, which is the
reverse: when a struct alloca is loaded as a *larger* single integer.
This patch also does not address some of the code quality issues with
the FCA-splitting. Those don't actually impede any optimizations really,
but they're on my list to clean up.
[1]: Pedantic footnote: for those concerned about memory model issues
here, this is safe. For the alloca to be promotable, it cannot escape or
have any use of its address that could allow these loads or stores to be
racing. Thus, widening is always safe.
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This patch migrates the strcmp and strncmp optimizations from the
simplify-libcalls pass into the instcombine library call simplifier.
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The new coalescer can merge a dead def into an unused lane of an
otherwise live vector register.
Clear the <dead> flag when that happens since the flag refers to the
full virtual register which is still live after the partial dead def.
This fixes PR14079.
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This patch migrates the strchr and strrchr optimizations from the
simplify-libcalls pass into the instcombine library call simplifier.
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This patch migrates the strcat and strncat optimizations from the
simplify-libcalls pass into the instcombine library call simplifier.
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It is possible that the live range of the value being pruned loops back
into the kill MBB where the search started. When that happens, make sure
that the beginning of KillMBB is also pruned.
Instead of starting a DFS at KillMBB and skipping the root of the
search, start a DFS at each KillMBB successor, and allow the search to
loop back to KillMBB.
This fixes PR14078.
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type coercion code, especially when targetting ARM. Things like [1
x i32] instead of i32 are very common there.
The goal of this logic is to ensure that when we are picking an alloca
type, we look through such wrapper aggregates and across any zero-length
aggregate elements to find the simplest type possible to form a type
partition.
This logic should (generally speaking) rarely fire. It only ends up
kicking in when an alloca is accessed using two different types (for
instance, i32 and float), and the underlying alloca type has wrapper
aggregates around it. I noticed a significant amount of this occurring
looking at stepanov_abstraction generated code for arm, and suspect it
happens elsewhere as well.
Note that this doesn't yet address truly heinous IR productions such as
PR14059 is concerning. Those result in mismatched *sizes* of types in
addition to mismatched access and alloca types.
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X86 doesn't have i8 cmovs so isel would emit a branch. Emitting branches at this
level is often not a good idea because it's too late for many optimizations to
kick in. This solution doesn't add any extensions (truncs are free) and tries
to avoid introducing partial register stalls by filtering direct copyfromregs.
I'm seeing a ~10% speedup on reading a random .png file with libpng15 via
graphicsmagick on x86_64/westmere, but YMMV depending on the microarchitecture.
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local frame causes problem.
For example:
void f(StructToPass s) {
g(&s, sizeof(s));
}
will cause problem with tail-call since part of s is passed via registers and
saved in f's local frame. When g tries to access s, part of s may be corrupted
since f's local frame is popped out before the tail-call.
The current fix is to disable tail-call if getVarArgsRegSaveSize is not 0 for
the caller. This is a conservative approach, if we can prove the address of
s or part of s is not taken and passed to g, it should be okay to perform
tail-call.
rdar://12442472
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Completely update one interval at a time instead of collecting live
range fragments to be updated. This avoids building data structures,
except for a single SmallPtrSet of updated intervals.
Also share code between handleMove() and handleMoveIntoBundle().
Add support for moving dead defs across other live values in the
interval. The MI scheduler can do that.
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PHIElimination inserts IMPLICIT_DEF instructions to guarantee that all
PHI predecessors have a live-out value. These IMPLICIT_DEF values are
not considered to be real interference when coalescing virtual
registers:
%vreg1 = IMPLICIT_DEF
%vreg2 = MOV32r0
When joining %vreg1 and %vreg2, the IMPLICIT_DEF instruction and its
value number should simply be erased since the %vreg2 value number now
provides a live-out value for the PHI predecesor block.
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On PowerPC, a bitcast of <16 x i8> to i128 may run through a code
path in ExpandRes_BITCAST that attempts to do an intermediate
bitcast to a <4 x i32> vector, and then construct the Hi and Lo parts
of the resulting i128 by pairing up two of those i32 vector elements
each. The code already recognizes that on a big-endian system, the
first two vector elements form the Hi part, and the final two vector
elements form the Lo part (vice-versa from the little-endian situation).
However, we also need to take endianness into account when forming each
of those separate pairs: on a big-endian system, vector element 0 is
the *high* part of the pair making up the Hi part of the result, and
vector element 1 is the low part of the pair. The code currently always
uses vector element 0 as the low part and vector element 1 as the high
part, as is appropriate for little-endian platforms only.
This patch fixes this by swapping the vector elements as they are
paired up as appropriate.
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not legal. However, it should use a div instruction + mul + sub if divide is
legal. The rem legalization code was missing a check and incorrectly uses a
divrem libcall even when div is legal.
rdar://12481395
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to the instruction position. The old encoding would give an absolute
ID which counts up within a function, and only resets at the next function.
I.e., Instead of having:
... = icmp eq i32 n-1, n-2
br i1 ..., label %bb1, label %bb2
it will now be roughly:
... = icmp eq i32 1, 2
br i1 1, label %bb1, label %bb2
This makes it so that ids remain relatively small and can be encoded
in fewer bits.
With this encoding, forward reference operands will be given
negative-valued IDs. Use signed VBRs for the most common case
of forward references, which is phi instructions.
To retain backward compatibility we bump the bitcode version
from 0 to 1 to distinguish between the different encodings.
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Not all instructions define a virtual register in their first operand.
Specifically, INLINEASM has a different format.
<rdar://problem/12472811>
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For function calls on the 64-bit PowerPC SVR4 target, each parameter
is mapped to as many doublewords in the parameter save area as
necessary to hold the parameter. The first 13 non-varargs
floating-point values are passed in registers; any additional
floating-point parameters are passed in the parameter save area. A
single-precision floating-point parameter (32 bits) must be mapped to
the second (rightmost, low-order) word of its assigned doubleword
slot.
Currently LLVM violates this ABI requirement by mapping such a
parameter to the first (leftmost, high-order) word of its assigned
doubleword slot. This is internally self-consistent but will not
interoperate correctly with libraries compiled with an ABI-compliant
compiler.
This patch corrects the problem by adjusting the parameter addressing
on both sides of the calling convention.
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Note: [D]M{T,F}CP2 is just a recommended encoding. Vendors often provide a
custom CP2 that interprets instructions differently and may wish to add their
own instructions that use this opcode. We should ensure that this is easy to
do. I will probably add a 'has custom CP{0-3}' subtarget flag to make this
easy: We want to avoid the GCC situation where every MIPS vendor makes a custom
fork that breaks every other MIPS CPU and so can't be merged upstream.
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Patch from Preston Briggs <preston.briggs@gmail.com>.
This is an updated version of the dependence-analysis patch, including an MIV
test based on Banerjee's inequalities.
It's a fairly complete implementation of the paper
Practical Dependence Testing
Gina Goff, Ken Kennedy, and Chau-Wen Tseng
PLDI 1991
It cannot yet propagate constraints between coupled RDIV subscripts (discussed
in Section 5.3.2 of the paper).
It's organized as a FunctionPass with a single entry point that supports testing
for dependence between two instructions in a function. If there's no dependence,
it returns null. If there's a dependence, it returns a pointer to a Dependence
which can be queried about details (what kind of dependence, is it loop
independent, direction and distance vector entries, etc). I haven't included
every imaginable feature, but there's a good selection that should be adequate
for supporting many loop transformations. Of course, it can be extended as
necessary.
Included in the patch file are many test cases, commented with C code showing
the loops and array references.
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value but later turns out to be a function.
Unfortunately, we can't fold tests into a single file because we only get one
error out of llvm-as.
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Original message:
The attached is the fix to radar://11663049. The optimization can be outlined by following rules:
(select (x != c), e, c) -> select (x != c), e, x),
(select (x == c), c, e) -> select (x == c), x, e)
where the <c> is an integer constant.
The reason for this change is that : on x86, conditional-move-from-constant needs two instructions;
however, conditional-move-from-register need only one instruction.
While the LowerSELECT() sounds to be the most convenient place for this optimization, it turns out to be a bad place. The reason is that by replacing the constant <c> with a symbolic value, it obscure some instruction-combining opportunities which would otherwise be very easy to spot. For that reason, I have to postpone the change to last instruction-combining phase.
The change passes the test of "make check-all -C <build-root/test" and "make -C project/test-suite/SingleSource".
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the compiler makes use of GPR0. However, there are two flavors of
GPR0 defined by the target: the 32-bit GPR0 (R0) and the 64-bit GPR0
(X0). The spill/reload code makes use of R0 regardless of whether we
are generating 32- or 64-bit code.
This patch corrects the problem in the obvious manner, using X0 and
ADDI8 for 64-bit and R0 and ADDI for 32-bit.
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the Altivec extensions were introduced. Its use is optional, and
allows the compiler to communicate to the operating system which
vector registers should be saved and restored during a context switch.
In practice, this information is ignored by the various operating
systems using the SVR4 ABI; the kernel saves and restores the entire
register state. Setting the VRSAVE register is no longer performed by
the AIX XL compilers, the IBM i compilers, or by GCC on Power Linux
systems. It seems best to avoid this logic within LLVM as well.
This patch avoids generating code to update and restore VRSAVE for the
PowerPC SVR4 ABIs (32- and 64-bit). The code remains in place for the
Darwin ABI.
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- Due to the current matching vector elements constraints in
ISD::FP_ROUND, rounding from v2f64 to v4f32 (after legalization from
v2f32) is scalarized. Add a customized v2f32 widening to convert it
into a target-specific X86ISD::VFPROUND to work around this
constraints.
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SDNode for LDRB_POST_IMM is invalid: number of registers added to SDNode fewer
that described in .td.
7 ops is needed, but SDNode with only 6 is created.
In more details:
In ARMInstrInfo.td, in multiclass AI2_ldridx, in definition _POST_IMM, offset
operand is defined as am2offset_imm. am2offset_imm is complex parameter type,
and actually it consists from dummy register and imm itself. As I understood
trick with dummy reg was made for AsmParser. In ARMISelLowering.cpp, this dummy
register was not added to SDNode, and it cause crash in Peephole Optimizer pass.
The problem fixed by setting up additional dummy reg when emitting
LDRB_POST_IMM instruction.
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SchedulerDAGInstrs::buildSchedGraph ignores dependencies between FixedStack
objects and byval parameters. So loading byval parameters from stack may be
inserted *before* it will be stored, since these operations are treated as
independent.
Fix:
Currently ARMTargetLowering::LowerFormalArguments saves byval registers with
FixedStack MachinePointerInfo. To fix the problem we need to store byval
registers with MachinePointerInfo referenced to first the "byval" parameter.
Also commit adds two new fields to the InputArg structure: Function's argument
index and InputArg's part offset in bytes relative to the start position of
Function's argument. E.g.: If function's argument is 128 bit width and it was
splitted onto 32 bit regs, then we got 4 InputArg structs with same arg index,
but different offset values.
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This patch provides initial implementation of load address
macro instruction for Mips. We have implemented two kinds
of expansions with their variations depending on the size
of immediate operand:
1) load address with immediate value directly:
* la d,j => addiu d,$zero,j (for -32768 <= j <= 65535)
* la d,j => lui d,hi16(j)
ori d,d,lo16(j) (for any other 32 bit value of j)
2) load load address with register offset value
* la d,j(s) => addiu d,s,j (for -32768 <= j <= 65535)
* la d,j(s) => lui d,hi16(j) (for any other 32 bit value of j)
ori d,d,lo16(j)
addu d,d,s
This patch does not cover the case when the address is loaded
from the value of the label or function.
Contributer: Vladimir Medic
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DeadArgumentElimination pass can replace one LLVM function with another,
invalidating a pointer stored in debug info metadata entry for this function.
To fix this, we collect debug info descriptors for functions before
running a DeadArgumentElimination pass and "patch" pointers in metadata nodes
if we replace a function.
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lit -jN works on cygwin in most cases, but still sometimes I can see stalls with iterative run on the buildbot.
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Thanks to Benjamin for the raw test case. This one took about 50 times
longer to reduce than to fix. =/
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When the CFG contains a loop with multiple entry blocks, the traces
computed by MachineTraceMetrics don't always have the same nice
properties. Loop back-edges are normally excluded from traces, but
MachineLoopInfo doesn't recognize loops with multiple entry blocks, so
those back-edges may be included.
Avoid asserting when that happens by adding an isEarlierInSameTrace()
function that accurately determines if a dominating block is part of the
same trace AND is above the currrent block in the trace.
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Vector compare using altivec 'vcmpxxx' instructions have as third argument
a vector register instead of CR one, different from integer and float-point
compares. This leads to a failure in code generation, where 'SelectSETCC'
expects a DAG with a CR register and gets vector register instead.
This patch changes the behavior by just returning a DAG with the
vector compare instruction based on the type. The patch also adds a testcase
for all vector types llvm defines.
It also included a fix on signed 5-bits predicates printing, where
signed values were not handled correctly as signed (char are unsigned by
default for PowerPC). This generates 'vspltisw' (vector splat)
instruction with SIM out of range.
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are in fact identity operations. We detect these and kill their
partitions so that even splitting is unaffected by them. This is
particularly important because Clang relies on emitting identity memcpy
operations for struct copies, and these fold away to constants very
often after inlining.
Fixes the last big performance FIXME I have on my plate.
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Make sure functions located in user specified text sections (via the
section attribute) are located together with the default text sections.
Otherwise, for large object files, the relocations for call instructions
are more likely to be out of range. This becomes even more likely in the
presence of LTO.
rdar://12402636
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a) frame setup instructions define the prologue
b) we shouldn't change our location mid-stream
Add a test to make sure that the stack adjustment stays within
the prologue.
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We conservatively only check the first use to avoid walking long use chains.
This catches the common case of having both a load and a store to a pointer
supplied by a PHI node.
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cpyDest can be mutated in some cases, which would then cause a crash later if
indeed the memory was underaligned. This brought down several buildbots, so
I guess the underaligned case is much more common than I thought!
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Currently, we re-visit allocas when something changes about the way they
might be *split* to allow better scalarization to take place. However,
we weren't handling the case when the *promotion* is what would change
the behavior of SROA. When an address derived from an alloca is stored
into another alloca, we consider the first to have escaped. If the
second is ever promoted to an SSA value, we will suddenly be able to run
the SROA pass on the first alloca.
This patch adds explicit support for this form if iteration. When we
detect a store of a pointer derived from an alloca, we flag the
underlying alloca for reprocessing after promotion. The logic works hard
to only do this when there is definitely going to be promotion and it
might remove impediments to the analysis of the alloca.
Thanks to Nick for the great test case and Benjamin for some sanity
check review.
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was less aligned than the old. In the testcase this results in an overaligned
memset: the memset alignment was correct for the original memory but is too much
for the new memory. Fix this by either increasing the alignment of the new
memory or bailing out if that isn't possible. Should fix the gcc-4.7 self-host
buildbot failure.
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Sorry for this being broken so long. =/
As part of this, switch all of the existing tests to be Little Endian,
which is the behavior I was asserting in them anyways! Add in a new
big-endian test that checks the interesting behavior there.
Another part of this is to tighten the rules abotu when we perform the
full-integer promotion. This logic now rejects cases where there fully
promoted integer is a non-multiple-of-8 bitwidth or cases where the
loads or stores touch bits which are in the allocated space of the
alloca but are not loaded or stored when accessing the integer. Sadly,
these aren't really observable today as the rest of the pass will
already ensure the invariants hold. However, the latter situation is
likely to become a potential concern in the future.
Thanks to Benjamin and Duncan for early review of this patch. I'm still
looking into whether there are further endianness issues, please let me
know if anyone sees BE failures persisting past this.
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macro instruction (li) in the assembler.
We have identified three possible expansions depending on
the size of immediate operand:
1) for 0 ≤ j ≤ 65535.
li d,j =>
ori d,$zero,j
2) for −32768 ≤ j < 0.
li d,j =>
addiu d,$zero,j
3) for any other value of j that is representable as a 32-bit integer.
li d,j =>
lui d,hi16(j)
ori d,d,lo16(j)
All of the above have been implemented in ths patch.
Contributer: Vladimir Medic
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.set option
The patch implements following options
at - lets the assembler use the $at register for macros,
but generates warnings if the source program uses $at
noat - let source programs use $at without issuingwarnings.
noreorder - prevents the assembler from reordering machine
language instructions.
nomacro - causes the assembler to print a warning whenever
an assembler operation generates more than one
machine language instruction.
macro - lets the assembler generate multiple machine instructions
from a single assembler instruction
reorder - lets the assembler reorder machine language
instructions to improve performance
The above variants are parsed and their boolean values set or unset.
The code to actually use them will come later.
Following options are not implemented yet:
nomips16
nomicromips
move
nomove
Contributer: Vladimir Medic
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in the Intel syntax.
The MC layer supports emitting in the Intel syntax, but this would require the
inline assembly MachineInstr to be lowered to an MCInst before emission. This
is potential future work, but for now emitting directly from the MachineInstr
suffices.
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multiple stores with a single load. We create the wide loads and stores (and their chains)
before we remove the scalar loads and stores and fix the DAG chain. We attempted to merge
loads with a different chain. When that happened, the assumption that it is safe to RAUW
broke and a cycle was introduced.
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is not profitable in many cases because modern processors perform multiple stores
in parallel and merging stores prior to merging requires extra work. We handle two main cases:
1. Store of multiple consecutive constants:
q->a = 3;
q->4 = 5;
In this case we store a single legal wide integer.
2. Store of multiple consecutive loads:
int a = p->a;
int b = p->b;
q->a = a;
q->b = b;
In this case we load/store either ilegal vector registers or legal wide integer registers.
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a memcpy to reflect that '0' has a different meaning when applied to
a load or store. Now we correctly use underaligned loads and stores for
the test case added.
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necessary during rewriting. As part of this, fix a real think-o here
where we might have left off an alignment specification when the address
is in fact underaligned. I haven't come up with any way to trigger this,
as there is always some other factor that reduces the alignment, but it
certainly might have been an observable bug in some way I can't think
of. This also slightly changes the strategy for placing explicit
alignments on loads and stores to only do so when the alignment does not
match that required by the ABI. This causes a few redundant alignments
to go away from test cases.
I've also added a couple of tests that really push on the alignment that
we end up with on loads and stores. More to come here as I try to fix an
underlying bug I have conjectured and produced test cases for, although
it's not clear if this bug is the one currently hitting dragonegg's
gcc47 bootstrap.
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Enable the pass by default for targets that request it, and change the
-enable-early-ifcvt to the opposite -disable-early-ifcvt.
There are still some x86 regressions when enabling early if-conversion
because of the missing machine models. Disable the pass for x86 until
machine models are added.
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X86DAGToDAGISel::PreprocessISelDAG(), isel is moving load inside
callseq_start / callseq_end so it can be folded into a call. This can
create a cycle in the DAG when the call is glued to a copytoreg. We
have been lucky this hasn't caused too many issues because the pre-ra
scheduler has special handling of call sequences. However, it has
caused a crash in a specific tailcall case.
rdar://12393897
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scheduled for processing on the worklist eventually gets deleted while
we are processing another alloca, fixing the original test case in
PR13990.
To facilitate this, add a remove_if helper to the SetVector abstraction.
It's not easy to use the standard abstractions for this because of the
specifics of SetVectors types and implementation.
Finally, a nice small test case is included. Thanks to Benjamin for the
fantastic reduced test case here! All I had to do was delete some empty
basic blocks!
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