Simplify the spill weight calculation a bit by bypassing
getApproximateInstructionCount() and using LiveInterval::getSize() directly.
This changes the computed spill weights, but only by a constant factor in each
function. It should not affect how spill weights compare against each other, and
so it shouldn't affect code generation.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125530 91177308-0d34-0410-b5e6-96231b3b80d8
This is a lot easier than trying to get kill flags right during live range
splitting and rematerialization.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125113 91177308-0d34-0410-b5e6-96231b3b80d8
After uses of a live range are removed, recompute the live range to only cover
the remaining uses. This is necessary after rematerializing the value before
some (but not all) uses.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125058 91177308-0d34-0410-b5e6-96231b3b80d8
A live range cannot be split everywhere in a basic block. A split must go before
the first terminator, and if the variable is live into a landing pad, the split
must happen before the call that can throw.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124894 91177308-0d34-0410-b5e6-96231b3b80d8
These functions not longer assert when passed 0, but simply return false instead.
No functional change intended.
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Print virtual registers numbered from 0 instead of the arbitrary
FirstVirtualRegister. The first virtual register is printed as %vreg0.
TRI::NoRegister is printed as %noreg.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123107 91177308-0d34-0410-b5e6-96231b3b80d8
Always spill the full representative register at any point where any subregister
is live.
This fixes PR8620 which caused the old logic to get confused and not spill
anything at all.
The fundamental problem here is that the coalescer is too aggressive about
physical register coalescing. It sometimes makes it impossible to allocate
registers without these emergency spills.
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The live range of a register defined by an early clobber starts at the use slot,
not the def slot.
Except when it is an early clobber tied to a use operand. Then it starts at the
def slot like a standard def.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119305 91177308-0d34-0410-b5e6-96231b3b80d8
benchmarks hitting an assertion.
Adds LiveIntervalUnion::collectInterferingVRegs.
Fixes "late spilling" by checking for any unspillable live vregs among
all physReg aliases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118701 91177308-0d34-0410-b5e6-96231b3b80d8
perform initialization without static constructors AND without explicit initialization
by the client. For the moment, passes are required to initialize both their
(potential) dependencies and any passes they preserve. I hope to be able to relax
the latter requirement in the future.
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When the normalizeSpillWeights function was introduced, I forgot to remove this
normalization.
This change could affect register allocation. Hopefully for the better.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110119 91177308-0d34-0410-b5e6-96231b3b80d8
inserted in a MBB, and return an already inserted MI.
This target API change is necessary to allow foldMemoryOperand to call
storeToStackSlot and loadFromStackSlot when folding a COPY to a stack slot
reference in a target independent way.
The foldMemoryOperandImpl hook is going to change in the same way, but I'll wait
until COPY folding is actually implemented. Most targets only fold copies and
won't need to specialize this hook at all.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107991 91177308-0d34-0410-b5e6-96231b3b80d8
EXTRACT_SUBREG no longer appears as a machine instruction. Use COPY instead.
Add isCopy() checks in many places using isMoveInstr() and isExtractSubreg().
The isMoveInstr hook will be removed later.
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INSERT_SUBREG will now only appear in SSA machine instructions.
Fix the handling of partial redefs in ProcessImplicitDefs. This is now relevant
since partial redef COPY instructions appear.
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This code is transitional, it will soon be possible to eliminate
isExtractSubreg, isInsertSubreg, and isMoveInstr in most places.
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The VNInfo.kills vector was almost unused except for all the code keeping it
updated. The few places using it were easily rewritten to check for interval
ends instead.
The two new methods LiveInterval::killedAt and killedInRange are replacements.
This brings us down to 3 independent data structures tracking kills.
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This method was always a bit too simplistic for the real world. It didn't really
deal with subregisters and such.
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This code path has never really been used, and we are going to be handling
spilling through the Spiller interface in the future.
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CoalescerPair can determine if a copy can be coalesced, and which register gets
merged away. The old logic in SimpleRegisterCoalescing had evolved into
something a bit too convoluted.
This second attempt fixes some crashes that only occurred Linux.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106769 91177308-0d34-0410-b5e6-96231b3b80d8
In this case it is essential that the kill is real because the spiller will
decide to omit a spill if it thinks there is a later kill.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106751 91177308-0d34-0410-b5e6-96231b3b80d8
CoalescerPair can determine if a copy can be coalesced, and which register gets
merged away. The old logic in SimpleRegisterCoalescing had evolved into
something a bit too convoluted.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106701 91177308-0d34-0410-b5e6-96231b3b80d8
instructions, but it doesn't really understand live ranges, so the first
INSERT_SUBREG uses an implicitly defined register.
Fix it in LiveVariableAnalysis by adding the <undef> flag.
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LiveVariableAnalysis was a bit picky about a register only being redefined once,
but that really isn't necessary.
Here is an example of chained INSERT_SUBREGs that we can handle now:
68 %reg1040<def> = INSERT_SUBREG %reg1040, %reg1028<kill>, 14
register: %reg1040 +[70,134:0)
76 %reg1040<def> = INSERT_SUBREG %reg1040, %reg1029<kill>, 13
register: %reg1040 replace range with [70,78:1) RESULT: %reg1040,0.000000e+00 = [70,78:1)[78,134:0) 0@78-(134) 1@70-(78)
84 %reg1040<def> = INSERT_SUBREG %reg1040, %reg1030<kill>, 12
register: %reg1040 replace range with [78,86:2) RESULT: %reg1040,0.000000e+00 = [70,78:1)[78,86:2)[86,134:0) 0@86-(134) 1@70-(78) 2@78-(86)
92 %reg1040<def> = INSERT_SUBREG %reg1040, %reg1031<kill>, 11
register: %reg1040 replace range with [86,94:3) RESULT: %reg1040,0.000000e+00 = [70,78:1)[78,86:2)[86,94:3)[94,134:0) 0@94-(134) 1@70-(78) 2@78-(86) 3@86-(94)
rdar://problem/8096390
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106152 91177308-0d34-0410-b5e6-96231b3b80d8
spills and reloads.
This means that a partial define of a register causes a reload so the other
parts of the register are preserved.
The reload can be prevented by adding an <imp-def> operand for the full
register. This is already done by the coalescer and live interval analysis where
relevant.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105369 91177308-0d34-0410-b5e6-96231b3b80d8
that are aliases of the specified register.
- Rename modifiesRegister to definesRegister since it's looking a def of the
specific register or one of its super-registers. It's not looking for def of a
sub-register or alias that could change the specified register.
- Added modifiesRegister to look for defs of aliases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104377 91177308-0d34-0410-b5e6-96231b3b80d8
<imp-def> operand for the full register. This ensures that the full physical
register is marked live after register allocation.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104320 91177308-0d34-0410-b5e6-96231b3b80d8
debug output is showing machine instructions, the IR-level basic block names
aren't very meaningful, and because multiple machine basic blocks may be
derived from one IR-level BB, they're also not unique.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102960 91177308-0d34-0410-b5e6-96231b3b80d8
- Also, update dbg_value is the value is being re-matted from a frame slot, e.g. fixed slots for arguments.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102565 91177308-0d34-0410-b5e6-96231b3b80d8
MachineBasicBlock::livein_iterator a const_iterator, because
clients shouldn't ever be using the iterator interface to
mutate the livein set.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101147 91177308-0d34-0410-b5e6-96231b3b80d8
on all objects it has allocated, if they are all of the same size and alignment.
Use this to destruct all VNInfos allocated in LiveIntervalAnalysis (PR6653).
valnos is not reliable for this purpose, as seen in r99400
(which still leaked, and sometimes caused double frees).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@99881 91177308-0d34-0410-b5e6-96231b3b80d8
--- Reverse-merging r99400 into '.':
D test/CodeGen/Generic/2010-03-24-liveintervalleak.ll
U lib/CodeGen/LiveIntervalAnalysis.cpp
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@99419 91177308-0d34-0410-b5e6-96231b3b80d8
otherwise the SmallVector it contains doesn't free its memory.
In most cases LiveIntervalAnalysis could get away by not calling the destructor,
because VNInfos are bumpptr-allocated, and smallvectors usually don't grow.
However when the SmallVector does grow it always leaks.
This is the valgrind shown leak from the original testcase:
==8206== 18,304 bytes in 151 blocks are definitely lost in loss record 164 of 164
==8206== at 0x4A079C7: operator new(unsigned long) (vg_replace_malloc.c:220)
==8206== by 0x4DB7A7E: llvm::SmallVectorBase::grow_pod(unsigned long, unsigned long) (in /home/edwin/clam/git/builds/defaul
t/libclamav/.libs/libclamav.so.6.1.0)
==8206== by 0x4F90382: llvm::VNInfo::addKill(llvm::SlotIndex) (in /home/edwin/clam/git/builds/default/libclamav/.libs/libcl
amav.so.6.1.0)
==8206== by 0x5126B5C: llvm::LiveIntervals::handleVirtualRegisterDef(llvm::MachineBasicBlock*, llvm::ilist_iterator<llvm::M
achineInstr>, llvm::SlotIndex, llvm::MachineOperand&, unsigned int, llvm::LiveInterval&) (in /home/edwin/clam/git/builds/defau
lt/libclamav/.libs/libclamav.so.6.1.0)
==8206== by 0x512725E: llvm::LiveIntervals::handleRegisterDef(llvm::MachineBasicBlock*, llvm::ilist_iterator<llvm::MachineI
nstr>, llvm::SlotIndex, llvm::MachineOperand&, unsigned int) (in /home/edwin/clam/git/builds/default/libclamav/.libs/libclamav
.so.6.1.0)
==8206== by 0x51278A8: llvm::LiveIntervals::computeIntervals() (in /home/edwin/clam/git/builds/default/libclamav/.libs/libc
lamav.so.6.1.0)
==8206== by 0x5127CB4: llvm::LiveIntervals::runOnMachineFunction(llvm::MachineFunction&) (in /home/edwin/clam/git/builds/de
fault/libclamav/.libs/libclamav.so.6.1.0)
==8206== by 0x4DAE935: llvm::FPPassManager::runOnFunction(llvm::Function&) (in /home/edwin/clam/git/builds/default/libclama
v/.libs/libclamav.so.6.1.0)
==8206== by 0x4DAEB10: llvm::FunctionPassManagerImpl::run(llvm::Function&) (in /home/edwin/clam/git/builds/default/libclama
v/.libs/libclamav.so.6.1.0)
==8206== by 0x4DAED3D: llvm::FunctionPassManager::run(llvm::Function&) (in /home/edwin/clam/git/builds/default/libclamav/.l
ibs/libclamav.so.6.1.0)
==8206== by 0x4D8BE8E: llvm::JIT::runJITOnFunctionUnlocked(llvm::Function*, llvm::MutexGuard const&) (in /home/edwin/clam/git/builds/default/libclamav/.libs/libclamav.so.6.1.0)
==8206== by 0x4D8CA72: llvm::JIT::getPointerToFunction(llvm::Function*) (in /home/edwin/clam/git/builds/default/libclamav/.libs/libclamav.so.6.1.0)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@99400 91177308-0d34-0410-b5e6-96231b3b80d8
cl = EXTRACT_SUBREG reg1024, 1, is overly conservative. It should check
for overlaps of vr's live interval with the super registers of the
physical register (ECX in this case) and let JoinIntervals() handle checking
the coalescing feasibility against the physical register (cl in this case).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98251 91177308-0d34-0410-b5e6-96231b3b80d8
Previously, LiveIntervalAnalysis would infer phi joins by looking for multiply
defined registers. That doesn't work if the phi join is implicitly defined in
all but one of the predecessors.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96994 91177308-0d34-0410-b5e6-96231b3b80d8
Moderate the weight given to very small intervals.
The spill weight given to new intervals created when spilling was not
normalized in the same way as the original spill weights calculated by
CalcSpillWeights. That meant that restored registers would tend to hang around
because they had a much higher spill weight that unspilled registers.
This improves the runtime of a few tests by up to 10%, and there are no
significant regressions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96613 91177308-0d34-0410-b5e6-96231b3b80d8
register coalescing. This fixes many crashes and
places where debug info affects codegen (when
dbg.value is lowered to machine instructions, which
it isn't yet in TOT).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95739 91177308-0d34-0410-b5e6-96231b3b80d8
into TargetOpcodes.h. #include the new TargetOpcodes.h
into MachineInstr. Add new inline accessors (like isPHI())
to MachineInstr, and start using them throughout the
codebase.
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only run for x86 with fastisel. I've found it being very effective in
eliminating some obvious dead code as result of formal parameter lowering
especially when tail call optimization eliminated the need for some of the loads
from fixed frame objects. It also shrinks a number of the tests. A couple of
tests no longer make sense and are now eliminated.
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This fixes an in-place update bug where code inserted at the end of basic blocks may not be covered by existing intervals which were live across the entire block. It is also consistent with the way ranges are specified for live intervals.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91859 91177308-0d34-0410-b5e6-96231b3b80d8
Tail duplication produces lots of identical phi nodes in different basic
blocks. Teach PHIElimination to reuse the join registers when lowering a phi
node that is identical to an already lowered node. This saves virtual
registers, and more importantly it avoids creating copies the the coalescer
doesn't know how to eliminate.
Teach LiveIntervalAnalysis about the phi joins with multiple uses.
This patch significantly reduces code size produced by -pre-regalloc-taildup.
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The coalescer is supposed to clean these up, but when setting up parameters
for a function call, there may be copies to physregs. If the defining
instruction has been LICM'ed far away, the coalescer won't touch it.
The register allocation hint does not always work - when the register
allocator is backtracking, it clears the hints.
This patch is more conservative than r90502, and does not break
483.xalancbmk/i686. It still breaks the PowerPC bootstrap, so it is disabled
by default, and can be enabled with the -trivial-coalesce-ends option.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91049 91177308-0d34-0410-b5e6-96231b3b80d8
When a call is placed to spill an interval this spiller will first try to
break the interval up into its component values. Single value intervals and
intervals which have already been split (or are the result of previous splits)
are spilled by the default spiller.
Splitting intervals as described above may improve the performance of generated
code in some circumstances. This work is experimental however, and it still
miscompiles many benchmarks. It's not recommended for general use yet.
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The coalescer is supposed to clean these up, but when setting up parameters
for a function call, there may be copies to physregs. If the defining
instruction has been LICM'ed far away, the coalescer won't touch it.
The register allocation hint does not always work - when the register
allocator is backtracking, it clears the hints.
This patch takes care of a few more cases that r90163 missed.
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- A valno should be set HasRedefByEC if there is an early clobber def in the middle of its live ranges. It should not be set if the def of the valno is defined by an early clobber.
- If a physical register def is tied to an use and it's an early clobber, it just means the HasRedefByEC is set since it's still one continuous live range.
- Add a couple of missing checks for HasRedefByEC in the coalescer. In general, it should not coalesce a vr with a physical register if the physical register has a early clobber def somewhere. This is overly conservative but that's the price for using such a nasty inline asm "feature".
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This helps us avoid silly copies when rematting values that are copied to a physical register:
leaq _.str44(%rip), %rcx
movq %rcx, %rsi
call _strcmp
becomes:
leaq _.str44(%rip), %rsi
call _strcmp
The coalescer will not touch the movq because that would tie down the physical register.
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A non-identity copy cannot be coalesced when the phi join destination register
is live at the copy site.
Also verify the condition that the PHI join source register is only used in
the PHI join. Otherwise the coalescing is invalid.
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This introduces a new pass, SlotIndexes, which is responsible for numbering
instructions for register allocation (and other clients). SlotIndexes numbering
is designed to match the existing scheme, so this patch should not cause any
changes in the generated code.
For consistency, and to avoid naming confusion, LiveIndex has been renamed
SlotIndex.
The processImplicitDefs method of the LiveIntervals analysis has been moved
into its own pass so that it can be run prior to SlotIndexes. This was
necessary to match the existing numbering scheme.
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is trivially rematerializable and integrate it into
TargetInstrInfo::isTriviallyReMaterializable. This way, all places that
need to know whether an instruction is rematerializable will get the
same answer.
This enables the useful parts of the aggressive-remat option by
default -- using AliasAnalysis to determine whether a memory location
is invariant, and removes the questionable parts -- rematting operations
with virtual register inputs that may not be live everywhere.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83687 91177308-0d34-0410-b5e6-96231b3b80d8
- Allocate MachineMemOperands and MachineMemOperand lists in MachineFunctions.
This eliminates MachineInstr's std::list member and allows the data to be
created by isel and live for the remainder of codegen, avoiding a lot of
copying and unnecessary translation. This also shrinks MemSDNode.
- Delete MemOperandSDNode. Introduce MachineSDNode which has dedicated
fields for MachineMemOperands.
- Change MemSDNode to have a MachineMemOperand member instead of its own
fields with the same information. This introduces some redundancy, but
it's more consistent with what MachineInstr will eventually want.
- Ignore alignment when searching for redundant loads for CSE, but remember
the greatest alignment.
Target-specific code which previously used MemOperandSDNodes with generic
SDNodes now use MemIntrinsicSDNodes, with opcodes in a designated range
so that the SelectionDAG framework knows that MachineMemOperand information
is available.
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of the defs are processed.
Also fix a implicit_def propagation bug: a implicit_def of a physical register
should be applied to uses of the sub-registers.
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we pushed the beginning of the interval back 1, so the
interval would overlap with inputs that die. We were
also pushing the end of the interval back 1, though,
which means the earlyclobber didn't overlap with other
output operands. Don't do this. PR 4964.
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The gist of this is if source of some of the copies that feed into a phi join is defined by the phi join, we'd like to eliminate them. However, if any of the non-identity source overlaps the live interval of the phi join then the coalescer won't be able to coalesce them. The early coalescer's job is to eliminate the identity copies by partially-coalescing the two live intervals.
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a new class, MachineInstrIndex, which hides arithmetic details from
most clients. This is a step towards allowing the register allocator
to update/insert code during allocation.
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MachineInstr and MachineOperand. This required eliminating a
bunch of stuff that was using DOUT, I hope that bill doesn't
mind me stealing his fun. ;-)
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- Some clients which used DOUT have moved to DEBUG. We are deprecating the
"magic" DOUT behavior which avoided calling printing functions when the
statement was disabled. In addition to being unnecessary magic, it had the
downside of leaving code in -Asserts builds, and of hiding potentially
unnecessary computations.
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Avoid remat'ing instructions whose def have sub-register indices for now. It's just really really hard to get all the cases right.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75900 91177308-0d34-0410-b5e6-96231b3b80d8
This adds location info for all llvm_unreachable calls (which is a macro now) in
!NDEBUG builds.
In NDEBUG builds location info and the message is off (it only prints
"UREACHABLE executed").
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Make llvm_unreachable take an optional string, thus moving the cerr<< out of
line.
LLVM_UNREACHABLE is now a simple wrapper that makes the message go away for
NDEBUG builds.
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as an (index,bool) pair. The bool flag records whether the kill is a
PHI kill or not. This code will be used to enable splitting of live
intervals containing PHI-kills.
A slight change to live interval weights introduced an extra spill
into lsr-code-insertion (outside the critical sections). The test
condition has been updated to reflect this.
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Note, isUndef marker must be placed even on implicit_def def operand or else the scavenger will not ignore it. This is necessary because -O0 path does not use liveintervalanalysis, it treats implicit_def just like any other def.
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The register allocator, when it allocates a register to a virtual register defined by an implicit_def, can allocate any physical register without worrying about overlapping live ranges. It should mark all of operands of the said virtual register so later passes will do the right thing.
This is not the best solution. But it should be a lot less fragile to having the scavenger try to track what is defined by implicit_def.
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entries as there are basic blocks in the function. LiveVariables::getVarInfo
creates a VarInfo struct for every register in the function, leading to
quadratic space use. This patch changes the BitVector to a SparseBitVector,
which doesn't help the worst-case memory use but does reduce the actual use in
very long functions with short-lived variables.
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VirtRegMap keeps track of allocations so it knows what's not used. As a horrible hack, the stack coloring can color spill slots with *free* registers. That is, it replace reload and spills with copies from and to the free register. It unfold instructions that load and store the spill slot and replace them with register using variants.
Not yet enabled. This is part 1. More coming.
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This fixes a very subtle bug. vr defined by an implicit_def is allowed overlap with any register since it doesn't actually modify anything. However, if it's used as a two-address use, its live range can be extended and it can be spilled. The spiller must take care not to emit a reload for the vn number that's defined by the implicit_def. This is both a correctness and performance issue.
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%reg1498<def> = MOV32rm %reg1024, 1, %reg0, 12, %reg0, Mem:LD(4,4) [sunkaddr39 + 0]
%reg1506<def> = MOV32rm %reg1024, 1, %reg0, 8, %reg0, Mem:LD(4,4) [sunkaddr42 + 0]
%reg1486<def> = MOV32rr %reg1506
%reg1486<def> = XOR32rr %reg1486, %reg1498, %EFLAGS<imp-def,dead>
%reg1510<def> = MOV32rm %reg1024, 1, %reg0, 4, %reg0, Mem:LD(4,4) [sunkaddr45 + 0]
=>
%reg1498<def> = MOV32rm %reg2036, 1, %reg0, 12, %reg0, Mem:LD(4,4) [sunkaddr39 + 0]
%reg1506<def> = MOV32rm %reg2037, 1, %reg0, 8, %reg0, Mem:LD(4,4) [sunkaddr42 + 0]
%reg1486<def> = MOV32rr %reg1506
%reg1486<def> = XOR32rr %reg1486, %reg1498, %EFLAGS<imp-def,dead>
%reg1510<def> = MOV32rm %reg2038, 1, %reg0, 4, %reg0, Mem:LD(4,4) [sunkaddr45 + 0]
From linearscan's point of view, each of reg2036, 2037, and 2038 are separate registers, each is "killed" after a single use. The reloaded register is available and it's often clobbered right away. e.g. In thise case reg1498 is allocated EAX while reg2036 is allocated RAX. This means we end up with multiple reloads from the same stack slot in the same basic block.
Now linearscan recognize there are other reloads from same SS in the same BB. So it'll "downgrade" RAX (and its aliases) after reg2036 is allocated until the next reload (reg2037) is done. This greatly increase the likihood reloads from SS are reused.
This speeds up sha1 from OpenSSL by 5.8%. It is also an across the board win for SPEC2000 and 2006.
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register destinations that are tied to source operands. The
TargetInstrDescr::findTiedToSrcOperand method silently fails for inline
assembly. The existing MachineInstr::isRegReDefinedByTwoAddr was very
close to doing what is needed, so this revision makes a few changes to
that method and also renames it to isRegTiedToUseOperand (for consistency
with the very similar isRegTiedToDefOperand and because it handles both
two-address instructions and inline assembly with tied registers).
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with SUBREG_TO_REG, teach SimpleRegisterCoalescing to coalesce
SUBREG_TO_REG instructions (which are similar to INSERT_SUBREG
instructions), and teach the DAGCombiner to take advantage of this on
targets which support it. This eliminates many redundant
zero-extension operations on x86-64.
This adds a new TargetLowering hook, isZExtFree. It's similar to
isTruncateFree, except it only applies to actual definitions, and not
no-op truncates which may not zero the high bits.
Also, this adds a new optimization to SimplifyDemandedBits: transform
operations like x+y into (zext (add (trunc x), (trunc y))) on targets
where all the casts are no-ops. In contexts where the high part of the
add is explicitly masked off, this allows the mask operation to be
eliminated. Fix the DAGCombiner to avoid undoing these transformations
to eliminate casts on targets where the casts are no-ops.
Also, this adds a new two-address lowering heuristic. Since
two-address lowering runs before coalescing, it helps to be able to
look through copies when deciding whether commuting and/or
three-address conversion are profitable.
Also, fix a bug in LiveInterval::MergeInClobberRanges. It didn't handle
the case that a clobber range extended both before and beyond an
existing live range. In that case, multiple live ranges need to be
added. This was exposed by the new subreg coalescing code.
Remove 2008-05-06-SpillerBug.ll. It was bugpoint-reduced, and the
spiller behavior it was looking for no longer occurrs with the new
instruction selection.
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- Make type declarations match the struct/class keyword of the definition.
- Move AddSignalHandler into the namespace where it belongs.
- Correctly call functions from template base.
- Some other small changes.
With this patch, LLVM and Clang should build properly and with far less noise under VS2008.
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v1024 = EDI // not killed
=
= EDI
One possible solution is for the coalescer to examine the sub-register live intervals in the same manner as the physical register. Another possibility is to examine defs and uses (when needed) of sub-registers. Both solutions are too expensive. For now, look for "short virtual intervals" and scan instructions to look for conflict instead.
This is a small win on x86-64. e.g. It shaves 403.gcc by ~80 instructions.
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172 %ECX<def> = MOV32rr %reg1039<kill>
180 INLINEASM <es:subl $5,$1
sbbl $3,$0>, 10, %EAX<def>, 14, %ECX<earlyclobber,def>, 9, %EAX<kill>,
36, <fi#0>, 1, %reg0, 0, 9, %ECX<kill>, 36, <fi#1>, 1, %reg0, 0
188 %EAX<def> = MOV32rr %EAX<kill>
196 %ECX<def> = MOV32rr %ECX<kill>
204 %ECX<def> = MOV32rr %ECX<kill>
212 %EAX<def> = MOV32rr %EAX<kill>
220 %EAX<def> = MOV32rr %EAX
228 %reg1039<def> = MOV32rr %ECX<kill>
The early clobber operand ties ECX input to the ECX def.
The live interval of ECX is represented as this:
%reg20,inf = [46,47:1)[174,230:0) 0@174-(230) 1@46-(47)
The right way to represent this is something like
%reg20,inf = [46,47:2)[174,182:1)[181:230:0) 0@174-(182) 1@181-230 @2@46-(47)
Of course that won't work since that means overlapping live ranges defined by two val#.
The workaround for now is to add a bit to val# which says the val# is redefined by a early clobber def somewhere. This prevents the move at 228 from being optimized away by SimpleRegisterCoalescing::AdjustCopiesBackFrom.
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and the LiveInterval.h top-level comment and accordingly. This fixes blocks
having spurious live-in registers in boundary cases.
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can give it the same stack slot as the spilled interval if it is folded.
This prevents the fold/unfold code from pointing to the wrong register.
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"If a re-materializable instruction has a register
operand, the spiller will change the register operand's
spill weight to HUGE_VAL to avoid it being spilled.
However, if the operand is already in the queue ready
to be spilled, avoid re-materializing it".
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RA problem by expanding the live interval of an
earlyclobber def back one slot. Remove
overlap-earlyclobber throughout. Remove
earlyclobber bits and their handling from
live internals.
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with an earlyclobber operand elsewhere. Propagate
this bit and the earlyclobber bit through SDISel.
Change linear-scan RA not to allocate regs in a way
that conflicts with an earlyclobber. See also comments.
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instruction. Also, their valno's should have an unknown def. This has no effect currently, but was
causing issues when StrongPHIElimination was enabled.
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isImmediate(), isRegister(), and friends, to avoid confusion
about having two different names with the same meaning. I'm
not attached to the longer names, and would be ok with
changing to the shorter names if others prefer it.
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With this patch, all of MultiSource/Applications and all of SPEC2000/2006 pass with
the SimpleSpiller and this fast-path enabled.
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1) Assign stack slots to new temporaries.
2) Don't insert an interval into the return vector more than once.
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1) Remove an incorrect assertion.
2) Set the stack slot weight properly.
3) Resize the VirtRegMap when needed.
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