Before this change, it was always the first element of a vector that got splatted since the lower 6 bits of vshf.d $wd were always zero for little endian.
Additionally, masking has been performed for vshf via which splat.d is created.
Vshf has a property where if its first operand's elements have either bit 6 or 7 set, destination element is set to zero.
Initially masked with 63 to avoid this property, which would result in generation of and.v + vshf.d in all cases.
Masking with one results in generating a single splati.d instruction when possible.
Differential Revision: https://reviews.llvm.org/D32216
llvm-svn: 306090
This patch adds one more condition in selection DINS/INS
instruction, which fixes MultiSource/Applications/JM/ldecod/
for mips32r2 (and mips64r2 n32 abi).
Differential Revision: https://reviews.llvm.org/D33725
llvm-svn: 305888
Re-apply r276044/r279124/r305516. Fixed a problem where we would refuse
to place spills as the very first instruciton of a basic block and thus
artifically increase pressure (test in
test/CodeGen/PowerPC/scavenging.mir:spill_at_begin)
This is a variant of scavengeRegister() that works for
enterBasicBlockEnd()/backward(). The benefit of the backward mode is
that it is not affected by incomplete kill flags.
This patch also changes
PrologEpilogInserter::doScavengeFrameVirtualRegs() to use the register
scavenger in backwards mode.
Differential Revision: http://reviews.llvm.org/D21885
llvm-svn: 305625
Revert because of reports of some PPC input starting to spill when it
was predicted that it wouldn't and no spillslot was reserved.
This reverts commit r305516.
llvm-svn: 305566
This reverts commit r305455. This commit was reported as breaking one of
the sanitizer buildbots. Reverting until lab.llvm.org comes back online.
llvm-svn: 305557
Re-apply r276044/r279124. Trying to reproduce or disprove the ppc64
problems reported in the stage2 build last time, which I cannot
reproduce right now.
This is a variant of scavengeRegister() that works for
enterBasicBlockEnd()/backward(). The benefit of the backward mode is
that it is not affected by incomplete kill flags.
This patch also changes
PrologEpilogInserter::doScavengeFrameVirtualRegs() to use the register
scavenger in backwards mode.
Differential Revision: http://reviews.llvm.org/D21885
llvm-svn: 305516
Author: milena.vujosevic.janicic
Reviewers: sdardis
The patch extends size reduction pass for MicroMIPS.
The following instructions are examined and transformed, if possible:
ADDIU instruction is transformed into 16-bit instruction ADDIUSP
ADDIU instruction is transformed into 16-bit instruction ADDIUR1SP
Differential Revision: https://reviews.llvm.org/D33887
llvm-svn: 305455
For multiprecision arithmetic on MIPS, rather than using ISD::ADDE / ISD::ADDC,
get SelectionDAG to break down the operation into ISD::ADDs and ISD::SETCCs.
For MIPS, only the DSP ASE has a carry flag, so in the general case it is not
useful to directly support ISD::{ADDE, ADDC, SUBE, SUBC} nodes.
Also improve the generation code in such cases for targets with
TargetLoweringBase::ZeroOrOneBooleanContent by directly using the result of the
comparison node rather than using it in selects. Similarly for ISD::SUBE /
ISD::SUBC.
Address optimization breakage by moving the generation of MIPS specific integer
multiply-accumulate nodes to before legalization.
This revolves PR32713 and PR33424.
Thanks to Simonas Kazlauskas and Pirama Arumuga Nainar for reporting the issue!
Reviewers: slthakur
Differential Revision: https://reviews.llvm.org/D33494
llvm-svn: 305389
This patch fixes two systemic machine verifier errors in the long
branch pass. The first is the incorrect basic block successors
and the second was the incorrect construction of several jump
instructions.
This partially resolves PR27458 and the associated PR32146.
Reviewers: slthakur
Differential Revision: https://reviews.llvm.org/D33378
llvm-svn: 305382
While simplifying branches in the MachineInstr representation, the
routine BuildCondBr must preserve flags on register MachineOperands. In
particular, it must preserve the <undef> flag.
This fixes a bug that is unlikely to occur in any real scenario, but
which bugpoint is likely to introduce.
Patch By Nick Johnson!
Reviewers: ahatanak, sdardis
Differential Revision: https://reviews.llvm.org/D34041
llvm-svn: 305290
By target hookifying getRegisterType, getNumRegisters, getVectorBreakdown,
backends can request that LLVM to scalarize vector types for calls
and returns.
The MIPS vector ABI requires that vector arguments and returns are passed in
integer registers. With SelectionDAG's new hooks, the MIPS backend can now
handle LLVM-IR with vector types in calls and returns. E.g.
'call @foo(<4 x i32> %4)'.
Previously these cases would be scalarized for the MIPS O32/N32/N64 ABI for
calls and returns if vector types were not legal. If vector types were legal,
a single 128bit vector argument would be assigned to a single 32 bit / 64 bit
integer register.
By teaching the MIPS backend to inspect the original types, it can now
implement the MIPS vector ABI which requires a particular method of
scalarizing vectors.
Previously, the MIPS backend relied on clang to scalarize types such as "call
@foo(<4 x float> %a) into "call @foo(i32 inreg %1, i32 inreg %2, i32 inreg %3,
i32 inreg %4)".
This patch enables the MIPS backend to take either form for vector types.
The previous version of this patch had a "conditional move or jump depends on
uninitialized value".
Reviewers: zoran.jovanovic, jaydeep, vkalintiris, slthakur
Differential Revision: https://reviews.llvm.org/D27845
llvm-svn: 305083
(0) RegAllocPBQP: Since getRawAllocationOrder() may return a collection that includes reserved physical registers, iterate to find an un-reserved physical register.
(1) VirtRegMap: Enforce the invariant: "no reserved physical registers" in assignVirt2Phys(). Previously, this was checked only after the fact in VirtRegRewriter::rewrite.
(2) MachineVerifier: updated the test per MatzeB's review.
(3) +testcase
Patch by Nick Johnson<Nicholas.Paul.Johnson@deshawresearch.com>!
Differential Revision: https://reviews.llvm.org/D33947
llvm-svn: 305016
Changed immediate type for repl.ph from uimm10 to simm10 as per the specs.
Repl.qb still accepts uimm8. Both instructions now mimic the behaviour of
GNU as.
Patch by Stefan Maksimovic.
Differential Revision: https://reviews.llvm.org/D33594
llvm-svn: 304918
The clang compiler by default uses FastISel when invoked with -O0, which
is also the default. In that case, passing of -mxgot does not get honored,
i.e. the code path that is to deal with large got is not taken.
Clang produces same output regardless of -mxgot being present or not.
This change checks whether -mxgot is passed as an option, and turns off
FastISel if it is.
Patch by Stefan Maksimovic.
Differential Revision: https://reviews.llvm.org/D33593
llvm-svn: 304906
Addition of a feature and a predicate used to control generation of madd.fmt
and similar instructions.
Patch by Stefan Maksimovic.
Differential Revision: https://reviews.llvm.org/D33400
llvm-svn: 304801
Author: milena.vujosevic.janicic
Reviewers: sdardis
The patch extends size reduction pass for MicroMIPS.
The following instructions are examined and transformed, if possible:
LBU instruction is transformed into 16-bit instruction LBU16
LHU instruction is transformed into 16-bit instruction LHU16
SB instruction is transformed into 16-bit instruction SB16
SH instruction is transformed into 16-bit instruction SH16
Differential Revision: https://reviews.llvm.org/D33091
llvm-svn: 304550
This patch adds handling of the `micromips` and `nomicromips` attributes
passed by front-end. The patch depends on D33363.
Differential revision: https://reviews.llvm.org/D33364
llvm-svn: 303545
Summary:
In SelectionDAG, when a store is immediately chained to another store
to the same address, elide the first store as it has no observable
effects. This is causes small improvements dealing with intrinsics
lowered to stores.
Test notes:
* Many testcases overwrite store addresses multiple times and needed
minor changes, mainly making stores volatile to prevent the
optimization from optimizing the test away.
* Many X86 test cases optimized out instructions associated with
associated with va_start.
* Note that test_splat in CodeGen/AArch64/misched-stp.ll no longer has
dependencies to check and can probably be removed and potentially
replaced with another test.
Reviewers: rnk, john.brawn
Subscribers: aemerson, rengolin, qcolombet, jyknight, nemanjai, nhaehnle, javed.absar, llvm-commits
Differential Revision: https://reviews.llvm.org/D33206
llvm-svn: 303198
Author: milena.vujosevic.janicic
Reviewers: sdardis
The code implements size reduction pass for MicroMIPS.
Load and store instructions are examined and transformed, if possible.
lw32 instruction is transformed into 16-bit instruction lwsp
sw32 instruction is transformed into 16-bit instruction swsp
Arithmetic instrcutions are examined and transformed, if possible.
addu32 instruction is transformed into 16-bit instruction addu16
subu32 instruction is transformed into 16-bit instruction subu16
Differential Revision: https://reviews.llvm.org/D15144
llvm-svn: 301540
Removed micro mips register classes for gp initialization because gp initialization uses pure mips64 instruction. Even when compiling for micro mips, gp initialization can be done with pure mips64 instructions.
Reviewed by Simon Dardis
Differential: D32286
llvm-svn: 301394
Masked vectors which hold shift amounts when creating the following nodes:
ISD::SHL, ISD::SRL or ISD::SRA.
Instructions that use said nodes, which have had their arguments altered are
sll, srl, sra, bneg, bclr and bset.
For said instructions, the shift amount or the bit position that is
specified in the corresponding vector elements will be interpreted as the
shift amount/bit position modulo the size of the element in bits.
The problem lies in compiling with -O2 enabled, where the instructions for
formats .w and .d are not generated, but are instead optimized away.
In this case, having shift amounts that are either negative or greater than
the element bit size results in generation of incorrect results when
constant folding.
We remedy this by masking the operands for the nodes mentioned above before
actually creating them, so that the final result is correct before placed
into the constant pool.
Patch by Stefan Maksimovic.
Differential Revision: https://reviews.llvm.org/D31331
llvm-svn: 300839
This reverts commit r299766. This change appears to have broken the MIPS
buildbots. Reverting while I investigate.
Revert "[mips] Remove usage of debug only variable (NFC)"
This reverts commit r299769. Follow up commit.
llvm-svn: 299788
We have two cases here, the first one being the following instruction
selection from the builtin function:
bm(n)zi builtin -> vselect node -> bins[lr]i machine instruction
In case of bm(n)zi having an immediate which has either its high or low bits
set, a bins[lr] instruction can be selected through the selectVSplatMask[LR]
function. The function counts the number of bits set, and that value is
being passed to the bins[lr]i instruction as its immediate, which in turn
copies immediate modulo the size of the element in bits plus 1 as per specs,
where we get the off-by-one-error.
The other case is:
bins[lr]i -> vselect node -> bsel.v
In this case, a bsel.v instruction gets selected with a mask having one bit
less set than required.
Patch by Stefan Maksimovic.
Differential Revision: https://reviews.llvm.org/D30579
llvm-svn: 299768
By target hookifying getRegisterType, getNumRegisters, getVectorBreakdown,
backends can request that LLVM to scalarize vector types for calls
and returns.
The MIPS vector ABI requires that vector arguments and returns are passed in
integer registers. With SelectionDAG's new hooks, the MIPS backend can now
handle LLVM-IR with vector types in calls and returns. E.g.
'call @foo(<4 x i32> %4)'.
Previously these cases would be scalarized for the MIPS O32/N32/N64 ABI for
calls and returns if vector types were not legal. If vector types were legal,
a single 128bit vector argument would be assigned to a single 32 bit / 64 bit
integer register.
By teaching the MIPS backend to inspect the original types, it can now
implement the MIPS vector ABI which requires a particular method of
scalarizing vectors.
Previously, the MIPS backend relied on clang to scalarize types such as "call
@foo(<4 x float> %a) into "call @foo(i32 inreg %1, i32 inreg %2, i32 inreg %3,
i32 inreg %4)".
This patch enables the MIPS backend to take either form for vector types.
Reviewers: zoran.jovanovic, jaydeep, vkalintiris, slthakur
Differential Revision: https://reviews.llvm.org/D27845
llvm-svn: 299766
This patch teaches the hazard scheduler how to handle empty blocks
when search for the next real instruction when dealing with forbidden
slots.
Reviewers: slthakur
Differential Revision: https://reviews.llvm.org/D31293
llvm-svn: 299427
Implementation of TargetInstrInfo::findCommutedOpIndices for MIPS target,
restricting commutativity to second and third operand only for
dpaadd_[su].df instructions therein.
Prior to this change, there were cases where the vector that is to be added
to the dot product of the other two could take a position other than the
first one in the instruction, generating false output in the destination
vector.
Such behavior has been noticed in the two functions generating v2i64 output
values so far. Other ones may exhibit such behavior as well, just not for
the vector operands which are present in the test at the moment.
Tests altered so that the function's first operand is a constant splat so
that it can be loaded with a ldi instruction, since that is the case in
which the erroneous instruction operand placement has occurred. We check
that the register which is present in the ldi instruction is placed as the
first operand in the corresponding dpadd instruction.
Patch by Stefan Maksimovic.
Differential Revision: https://reviews.llvm.org/D30827
llvm-svn: 299223
In the long-term, we want to replace statistics with something
finer-grained that lets us gather per-function data.
Remarks are that replacement.
Create an ORE instance in SelectionDAGISel, and pass it to
SelectionDAG.
SelectionDAG was used so that we can emit remarks from all
SelectionDAG-related code, including TargetLowering and DAGCombiner.
This isn't used in the current patch but Adam tells me he's interested
for the fp-contract combines.
Use the ORE instance to emit FastISel failures as remarks (instead of
the mix of dbgs() dumps and statistics that we currently have).
Eventually, we want to have an API that tells us whether remarks are
enabled (http://llvm.org/PR32352) so that we don't emit expensive
remarks (in this case, dumping IR) when it's not needed. For now, use
'isEnabled' as a crude replacement.
This does mean that the replacement for '-fast-isel-verbose' is now
'-pass-remarks-missed=isel'. Additionally, clang users also need to
enable remark diagnostics, using '-Rpass-missed=isel'.
This also removes '-fast-isel-verbose2': there are no static statistics
that we want to only enable in asserts builds, so we can always use
the remarks regardless of the build type.
Differential Revision: https://reviews.llvm.org/D31405
llvm-svn: 299093
This produces a 1% speedup on an important internal Google benchmark
(protocol buffers), with no other regressions in google or in the llvm
test-suite. Only 5 targets in the entire llvm test-suite are affected,
and on those 5 targets the size increase is 0.027%
llvm-svn: 297925
This patch adds support for recognizing more patterns to match to DEXT and
CINS instructions.
It finds cases where multiple instructions could be replaced with a single
DEXT or CINS instruction.
For example, for the following:
define i64 @dext_and32(i64 zeroext %a) {
entry:
%and = and i64 %a, 4294967295
ret i64 %and
}
instead of generating:
0000000000000088 <dext_and32>:
88: 64010001 daddiu at,zero,1
8c: 0001083c dsll32 at,at,0x0
90: 6421ffff daddiu at,at,-1
94: 03e00008 jr ra
98: 00811024 and v0,a0,at
9c: 00000000 nop
the following gets generated:
0000000000000068 <dext_and32>:
68: 03e00008 jr ra
6c: 7c82f803 dext v0,a0,0x0,0x20
Cases that are covered:
DEXT:
1. and $src, mask where mask > 0xffff
2. zext $src zero extend from i32 to i64
CINS:
1. and (shl $src, pos), mask
2. shl (and $src, mask), pos
3. zext (shl $src, pos) zero extend from i32 to i64
Patch by Violeta Vukobrat.
Differential Revision: https://reviews.llvm.org/D30464
llvm-svn: 297832
Recommiting with compiler time improvements
Recommitting after fixup of 32-bit aliasing sign offset bug in DAGCombiner.
* Simplify Consecutive Merge Store Candidate Search
Now that address aliasing is much less conservative, push through
simplified store merging search and chain alias analysis which only
checks for parallel stores through the chain subgraph. This is cleaner
as the separation of non-interfering loads/stores from the
store-merging logic.
When merging stores search up the chain through a single load, and
finds all possible stores by looking down from through a load and a
TokenFactor to all stores visited.
This improves the quality of the output SelectionDAG and the output
Codegen (save perhaps for some ARM cases where we correctly constructs
wider loads, but then promotes them to float operations which appear
but requires more expensive constant generation).
Some minor peephole optimizations to deal with improved SubDAG shapes (listed below)
Additional Minor Changes:
1. Finishes removing unused AliasLoad code
2. Unifies the chain aggregation in the merged stores across code
paths
3. Re-add the Store node to the worklist after calling
SimplifyDemandedBits.
4. Increase GatherAllAliasesMaxDepth from 6 to 18. That number is
arbitrary, but seems sufficient to not cause regressions in
tests.
5. Remove Chain dependencies of Memory operations on CopyfromReg
nodes as these are captured by data dependence
6. Forward loads-store values through tokenfactors containing
{CopyToReg,CopyFromReg} Values.
7. Peephole to convert buildvector of extract_vector_elt to
extract_subvector if possible (see
CodeGen/AArch64/store-merge.ll)
8. Store merging for the ARM target is restricted to 32-bit as
some in some contexts invalid 64-bit operations are being
generated. This can be removed once appropriate checks are
added.
This finishes the change Matt Arsenault started in r246307 and
jyknight's original patch.
Many tests required some changes as memory operations are now
reorderable, improving load-store forwarding. One test in
particular is worth noting:
CodeGen/PowerPC/ppc64-align-long-double.ll - Improved load-store
forwarding converts a load-store pair into a parallel store and
a memory-realized bitcast of the same value. However, because we
lose the sharing of the explicit and implicit store values we
must create another local store. A similar transformation
happens before SelectionDAG as well.
Reviewers: arsenm, hfinkel, tstellarAMD, jyknight, nhaehnle
llvm-svn: 297695
This patches teaches the MIPS backend to accept more values for constant
splats. Previously, only 10 bit signed immediates or values that could be
loaded using an ldi.[bhwd] instruction would be acceptted. This patch relaxes
that constraint so that any constant value that be splatted is accepted.
As a result, the constant pool is used less for vector operations, and the
suite of bit manipulation instructions b(clr|set|neg)i can now be used with
the full range of their immediate operand.
Reviewers: slthakur
Differential Revision: https://reviews.llvm.org/D30640
llvm-svn: 297457
The fix introduces segfaults and clobbers the value to be stored when
the atomic sequence loops.
Revert "[Target/MIPS] Kill dead code, no functional change intended."
This reverts commit r296153.
Revert "Recommit "[mips] Fix atomic compare and swap at O0.""
This reverts commit r296134.
llvm-svn: 297380
Fix a machine verifier issue where a instruction was using a invalid
register. The return pseudo is expanded and has the return address
register added to it. The return register may have been spuriously
mark as killed earlier.
This partially resolves PR/27458
Thanks to Quentin Colombet for reporting the issue!
llvm-svn: 297372
This patch causes compile times for some patterns to explode. I have
a (large, unreduced) test case that slows down by more than 20x and
several test cases slow down by 2x. I'm sending some of the test cases
directly to Nirav and following up with more details in the review log,
but this should unblock anyone else hitting this.
llvm-svn: 296862
Summary:
Avoids tons of prologue boilerplate when arguments are passed in memory
and left in memory. This can happen in a debug build or in a release
build when an argument alloca is escaped. This will dramatically affect
the code size of x86 debug builds, because X86 fast isel doesn't handle
arguments passed in memory at all. It only handles the x86_64 case of up
to 6 basic register parameters.
This is implemented by analyzing the entry block before ISel to identify
copy elision candidates. A copy elision candidate is an argument that is
used to fully initialize an alloca before any other possibly escaping
uses of that alloca. If an argument is a copy elision candidate, we set
a flag on the InputArg. If the the target generates loads from a fixed
stack object that matches the size and alignment requirements of the
alloca, the SelectionDAG builder will delete the stack object created
for the alloca and replace it with the fixed stack object. The load is
left behind to satisfy any remaining uses of the argument value. The
store is now dead and is therefore elided. The fixed stack object is
also marked as mutable, as it may now be modified by the user, and it
would be invalid to rematerialize the initial load from it.
Supersedes D28388
Fixes PR26328
Reviewers: chandlerc, MatzeB, qcolombet, inglorion, hans
Subscribers: igorb, llvm-commits
Differential Revision: https://reviews.llvm.org/D29668
llvm-svn: 296683
Recommiting after fixup of 32-bit aliasing sign offset bug in DAGCombiner.
* Simplify Consecutive Merge Store Candidate Search
Now that address aliasing is much less conservative, push through
simplified store merging search and chain alias analysis which only
checks for parallel stores through the chain subgraph. This is cleaner
as the separation of non-interfering loads/stores from the
store-merging logic.
When merging stores search up the chain through a single load, and
finds all possible stores by looking down from through a load and a
TokenFactor to all stores visited.
This improves the quality of the output SelectionDAG and the output
Codegen (save perhaps for some ARM cases where we correctly constructs
wider loads, but then promotes them to float operations which appear
but requires more expensive constant generation).
Some minor peephole optimizations to deal with improved SubDAG shapes (listed below)
Additional Minor Changes:
1. Finishes removing unused AliasLoad code
2. Unifies the chain aggregation in the merged stores across code
paths
3. Re-add the Store node to the worklist after calling
SimplifyDemandedBits.
4. Increase GatherAllAliasesMaxDepth from 6 to 18. That number is
arbitrary, but seems sufficient to not cause regressions in
tests.
5. Remove Chain dependencies of Memory operations on CopyfromReg
nodes as these are captured by data dependence
6. Forward loads-store values through tokenfactors containing
{CopyToReg,CopyFromReg} Values.
7. Peephole to convert buildvector of extract_vector_elt to
extract_subvector if possible (see
CodeGen/AArch64/store-merge.ll)
8. Store merging for the ARM target is restricted to 32-bit as
some in some contexts invalid 64-bit operations are being
generated. This can be removed once appropriate checks are
added.
This finishes the change Matt Arsenault started in r246307 and
jyknight's original patch.
Many tests required some changes as memory operations are now
reorderable, improving load-store forwarding. One test in
particular is worth noting:
CodeGen/PowerPC/ppc64-align-long-double.ll - Improved load-store
forwarding converts a load-store pair into a parallel store and
a memory-realized bitcast of the same value. However, because we
lose the sharing of the explicit and implicit store values we
must create another local store. A similar transformation
happens before SelectionDAG as well.
Reviewers: arsenm, hfinkel, tstellarAMD, jyknight, nhaehnle
llvm-svn: 296476
Recommiting after fixup of 32-bit aliasing sign offset bug in DAGCombiner.
* Simplify Consecutive Merge Store Candidate Search
Now that address aliasing is much less conservative, push through
simplified store merging search and chain alias analysis which only
checks for parallel stores through the chain subgraph. This is cleaner
as the separation of non-interfering loads/stores from the
store-merging logic.
When merging stores search up the chain through a single load, and
finds all possible stores by looking down from through a load and a
TokenFactor to all stores visited.
This improves the quality of the output SelectionDAG and the output
Codegen (save perhaps for some ARM cases where we correctly constructs
wider loads, but then promotes them to float operations which appear
but requires more expensive constant generation).
Some minor peephole optimizations to deal with improved SubDAG shapes (listed below)
Additional Minor Changes:
1. Finishes removing unused AliasLoad code
2. Unifies the chain aggregation in the merged stores across code
paths
3. Re-add the Store node to the worklist after calling
SimplifyDemandedBits.
4. Increase GatherAllAliasesMaxDepth from 6 to 18. That number is
arbitrary, but seems sufficient to not cause regressions in
tests.
5. Remove Chain dependencies of Memory operations on CopyfromReg
nodes as these are captured by data dependence
6. Forward loads-store values through tokenfactors containing
{CopyToReg,CopyFromReg} Values.
7. Peephole to convert buildvector of extract_vector_elt to
extract_subvector if possible (see
CodeGen/AArch64/store-merge.ll)
8. Store merging for the ARM target is restricted to 32-bit as
some in some contexts invalid 64-bit operations are being
generated. This can be removed once appropriate checks are
added.
This finishes the change Matt Arsenault started in r246307 and
jyknight's original patch.
Many tests required some changes as memory operations are now
reorderable, improving load-store forwarding. One test in
particular is worth noting:
CodeGen/PowerPC/ppc64-align-long-double.ll - Improved load-store
forwarding converts a load-store pair into a parallel store and
a memory-realized bitcast of the same value. However, because we
lose the sharing of the explicit and implicit store values we
must create another local store. A similar transformation
happens before SelectionDAG as well.
Reviewers: arsenm, hfinkel, tstellarAMD, jyknight, nhaehnle
llvm-svn: 296252
This time with the missing files.
Similar to PR/25526, fast-regalloc introduces spills at the end of basic
blocks. When this occurs in between an ll and sc, the store can cause the
atomic sequence to fail.
This patch fixes the issue by introducing more pseudos to represent atomic
operations and moving their lowering to after the expansion of postRA
pseudos.
This resolves PR/32020.
Thanks to James Cowgill for reporting the issue!
Reviewers: slthakur
Differential Revision: https://reviews.llvm.org/D30257
llvm-svn: 296134
Simon Dardis