llvm-6502/lib/CodeGen
Eric Christopher 6eebe47060 Split out abbreviations for the skeleton info from the rest of
the abbreviations. Part of implementing split dwarf.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170589 91177308-0d34-0410-b5e6-96231b3b80d8
2012-12-19 22:02:53 +00:00
..
AsmPrinter Split out abbreviations for the skeleton info from the rest of 2012-12-19 22:02:53 +00:00
SelectionDAG Change AsmOperandInfo::ConstraintVT to MVT, instead of EVT. 2012-12-19 15:19:11 +00:00
AggressiveAntiDepBreaker.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
AggressiveAntiDepBreaker.h Sort includes for all of the .h files under the 'lib' tree. These were 2012-12-04 07:12:27 +00:00
AllocationOrder.cpp Speed up the AllocationOrder class a bit. 2012-12-04 22:25:16 +00:00
AllocationOrder.h Speed up the AllocationOrder class a bit. 2012-12-04 22:25:16 +00:00
Analysis.cpp Rename the 'Attributes' class to 'Attribute'. It's going to represent a single attribute in the future. 2012-12-19 07:18:57 +00:00
AntiDepBreaker.h
BranchFolding.cpp Rename the 'Attributes' class to 'Attribute'. It's going to represent a single attribute in the future. 2012-12-19 07:18:57 +00:00
BranchFolding.h
CalcSpillWeights.cpp
CallingConvLower.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
CMakeLists.txt Move the guts of TargetInstrInfoImpl into the TargetInstrInfo class. 2012-11-28 02:35:13 +00:00
CodeGen.cpp
CodePlacementOpt.cpp Rename the 'Attributes' class to 'Attribute'. It's going to represent a single attribute in the future. 2012-12-19 07:18:57 +00:00
CriticalAntiDepBreaker.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
CriticalAntiDepBreaker.h Sort includes for all of the .h files under the 'lib' tree. These were 2012-12-04 07:12:27 +00:00
DeadMachineInstructionElim.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
DFAPacketizer.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
DwarfEHPrepare.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
EarlyIfConversion.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
EdgeBundles.cpp
ExecutionDepsFix.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
ExpandISelPseudos.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
ExpandPostRAPseudos.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
GCMetadata.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
GCMetadataPrinter.cpp
GCStrategy.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
IfConversion.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
InlineSpiller.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
InterferenceCache.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
InterferenceCache.h Make the LiveRegMatrix analysis available to targets. 2012-11-28 19:13:06 +00:00
IntrinsicLowering.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
JITCodeEmitter.cpp
LatencyPriorityQueue.cpp
LexicalScopes.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
LiveDebugVariables.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
LiveDebugVariables.h
LiveInterval.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
LiveIntervalAnalysis.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
LiveIntervalUnion.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
LiveRangeCalc.cpp
LiveRangeCalc.h
LiveRangeEdit.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
LiveRegMatrix.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
LiveStackAnalysis.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
LiveVariables.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
LLVMBuild.txt
LLVMTargetMachine.cpp Defer call to InitSections until after MCContext has been initialized. If 2012-12-10 22:49:11 +00:00
LocalStackSlotAllocation.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
MachineBasicBlock.cpp Tighten up the splice() API for bundled instructions. 2012-12-18 20:59:41 +00:00
MachineBlockFrequencyInfo.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
MachineBlockPlacement.cpp Rename the 'Attributes' class to 'Attribute'. It's going to represent a single attribute in the future. 2012-12-19 07:18:57 +00:00
MachineBranchProbabilityInfo.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
MachineCodeEmitter.cpp
MachineCopyPropagation.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
MachineCSE.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
MachineDominators.cpp
MachineFunction.cpp Rename the 'Attributes' class to 'Attribute'. It's going to represent a single attribute in the future. 2012-12-19 07:18:57 +00:00
MachineFunctionAnalysis.cpp
MachineFunctionPass.cpp
MachineFunctionPrinterPass.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
MachineInstr.cpp Use bidirectional bundle flags to simplify important functions. 2012-12-18 23:21:49 +00:00
MachineInstrBundle.cpp Use the new MI bundling API in MachineInstrBundle itself. 2012-12-13 23:23:46 +00:00
MachineLICM.cpp Change TargetLowering::getRepRegClassFor to take an MVT, instead of 2012-12-13 18:45:35 +00:00
MachineLoopInfo.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
MachineModuleInfo.cpp Make the MCStreamer have a reset method and call that after finalization of the asm printer, 2012-12-12 22:59:46 +00:00
MachineModuleInfoImpls.cpp
MachinePassRegistry.cpp
MachinePostDominators.cpp
MachineRegisterInfo.cpp Revert r168630, r168631, and r168633 as these are causing nightly test failures. 2012-11-28 00:21:29 +00:00
MachineScheduler.cpp MISched: Cleanup, redundant statement. 2012-12-18 20:52:58 +00:00
MachineSink.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
MachineSSAUpdater.cpp Remove the explicit MachineInstrBuilder(MI) constructor. 2012-12-19 21:31:56 +00:00
MachineTraceMetrics.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
MachineTraceMetrics.h
MachineVerifier.cpp Verify bundle flags for consistency in MachineVerifier. 2012-12-18 22:55:07 +00:00
Makefile
OcamlGC.cpp
OptimizePHIs.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
Passes.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
PeepholeOptimizer.cpp Add debug prints for when optimizeLoadInstr folds a load. 2012-12-17 03:56:00 +00:00
PHIElimination.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
PHIEliminationUtils.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
PHIEliminationUtils.h
PostRASchedulerList.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
ProcessImplicitDefs.cpp
PrologEpilogInserter.cpp Rename the 'Attributes' class to 'Attribute'. It's going to represent a single attribute in the future. 2012-12-19 07:18:57 +00:00
PrologEpilogInserter.h Sort includes for all of the .h files under the 'lib' tree. These were 2012-12-04 07:12:27 +00:00
PseudoSourceValue.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
README.txt
RegAllocBase.cpp Make the LiveRegMatrix analysis available to targets. 2012-11-28 19:13:06 +00:00
RegAllocBase.h Sort includes for all of the .h files under the 'lib' tree. These were 2012-12-04 07:12:27 +00:00
RegAllocBasic.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
RegAllocFast.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
RegAllocGreedy.cpp Speed up the AllocationOrder class a bit. 2012-12-04 22:25:16 +00:00
RegAllocPBQP.cpp Use MRI::getSimpleHint() instead of getRegAllocPref() in remaining cases. 2012-12-04 00:30:22 +00:00
RegisterClassInfo.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
RegisterCoalescer.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
RegisterCoalescer.h
RegisterPressure.cpp RegPressureTracker::dump(): Remove unnecessary argument. 2012-12-05 23:05:22 +00:00
RegisterScavenging.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
ScheduleDAG.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
ScheduleDAGInstrs.cpp MISched: add dependence to ExitSU to model live-out latency. 2012-12-18 20:53:01 +00:00
ScheduleDAGPrinter.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
ScoreboardHazardRecognizer.cpp
ShadowStackGC.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
ShrinkWrapping.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
SjLjEHPrepare.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
SlotIndexes.cpp
Spiller.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
Spiller.h
SpillPlacement.cpp
SpillPlacement.h
SplitKit.cpp Make the LiveRegMatrix analysis available to targets. 2012-11-28 19:13:06 +00:00
SplitKit.h
StackColoring.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
StackProtector.cpp Rename the 'Attributes' class to 'Attribute'. It's going to represent a single attribute in the future. 2012-12-19 07:18:57 +00:00
StackSlotColoring.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
StrongPHIElimination.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
TailDuplication.cpp Rename the 'Attributes' class to 'Attribute'. It's going to represent a single attribute in the future. 2012-12-19 07:18:57 +00:00
TargetFrameLoweringImpl.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
TargetInstrInfo.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
TargetLoweringObjectFileImpl.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
TargetOptionsImpl.cpp
TargetRegisterInfo.cpp Add a new hook for providing register allocator hints more flexibly. 2012-12-03 21:17:00 +00:00
TargetSchedule.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
TwoAddressInstructionPass.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
UnreachableBlockElim.cpp Use the new script to sort the includes of every file under lib. 2012-12-03 16:50:05 +00:00
VirtRegMap.cpp Remove VirtRegMap::getRegAllocPref(). 2012-12-04 00:35:59 +00:00

//===---------------------------------------------------------------------===//

Common register allocation / spilling problem:

        mul lr, r4, lr
        str lr, [sp, #+52]
        ldr lr, [r1, #+32]
        sxth r3, r3
        ldr r4, [sp, #+52]
        mla r4, r3, lr, r4

can be:

        mul lr, r4, lr
        mov r4, lr
        str lr, [sp, #+52]
        ldr lr, [r1, #+32]
        sxth r3, r3
        mla r4, r3, lr, r4

and then "merge" mul and mov:

        mul r4, r4, lr
        str lr, [sp, #+52]
        ldr lr, [r1, #+32]
        sxth r3, r3
        mla r4, r3, lr, r4

It also increase the likelihood the store may become dead.

//===---------------------------------------------------------------------===//

bb27 ...
        ...
        %reg1037 = ADDri %reg1039, 1
        %reg1038 = ADDrs %reg1032, %reg1039, %NOREG, 10
    Successors according to CFG: 0x8b03bf0 (#5)

bb76 (0x8b03bf0, LLVM BB @0x8b032d0, ID#5):
    Predecessors according to CFG: 0x8b0c5f0 (#3) 0x8b0a7c0 (#4)
        %reg1039 = PHI %reg1070, mbb<bb76.outer,0x8b0c5f0>, %reg1037, mbb<bb27,0x8b0a7c0>

Note ADDri is not a two-address instruction. However, its result %reg1037 is an
operand of the PHI node in bb76 and its operand %reg1039 is the result of the
PHI node. We should treat it as a two-address code and make sure the ADDri is
scheduled after any node that reads %reg1039.

//===---------------------------------------------------------------------===//

Use local info (i.e. register scavenger) to assign it a free register to allow
reuse:
        ldr r3, [sp, #+4]
        add r3, r3, #3
        ldr r2, [sp, #+8]
        add r2, r2, #2
        ldr r1, [sp, #+4]  <==
        add r1, r1, #1
        ldr r0, [sp, #+4]
        add r0, r0, #2

//===---------------------------------------------------------------------===//

LLVM aggressively lift CSE out of loop. Sometimes this can be negative side-
effects:

R1 = X + 4
R2 = X + 7
R3 = X + 15

loop:
load [i + R1]
...
load [i + R2]
...
load [i + R3]

Suppose there is high register pressure, R1, R2, R3, can be spilled. We need
to implement proper re-materialization to handle this:

R1 = X + 4
R2 = X + 7
R3 = X + 15

loop:
R1 = X + 4  @ re-materialized
load [i + R1]
...
R2 = X + 7 @ re-materialized
load [i + R2]
...
R3 = X + 15 @ re-materialized
load [i + R3]

Furthermore, with re-association, we can enable sharing:

R1 = X + 4
R2 = X + 7
R3 = X + 15

loop:
T = i + X
load [T + 4]
...
load [T + 7]
...
load [T + 15]
//===---------------------------------------------------------------------===//

It's not always a good idea to choose rematerialization over spilling. If all
the load / store instructions would be folded then spilling is cheaper because
it won't require new live intervals / registers. See 2003-05-31-LongShifts for
an example.

//===---------------------------------------------------------------------===//

With a copying garbage collector, derived pointers must not be retained across
collector safe points; the collector could move the objects and invalidate the
derived pointer. This is bad enough in the first place, but safe points can
crop up unpredictably. Consider:

        %array = load { i32, [0 x %obj] }** %array_addr
        %nth_el = getelementptr { i32, [0 x %obj] }* %array, i32 0, i32 %n
        %old = load %obj** %nth_el
        %z = div i64 %x, %y
        store %obj* %new, %obj** %nth_el

If the i64 division is lowered to a libcall, then a safe point will (must)
appear for the call site. If a collection occurs, %array and %nth_el no longer
point into the correct object.

The fix for this is to copy address calculations so that dependent pointers
are never live across safe point boundaries. But the loads cannot be copied
like this if there was an intervening store, so may be hard to get right.

Only a concurrent mutator can trigger a collection at the libcall safe point.
So single-threaded programs do not have this requirement, even with a copying
collector. Still, LLVM optimizations would probably undo a front-end's careful
work.

//===---------------------------------------------------------------------===//

The ocaml frametable structure supports liveness information. It would be good
to support it.

//===---------------------------------------------------------------------===//

The FIXME in ComputeCommonTailLength in BranchFolding.cpp needs to be
revisited. The check is there to work around a misuse of directives in inline
assembly.

//===---------------------------------------------------------------------===//

It would be good to detect collector/target compatibility instead of silently
doing the wrong thing.

//===---------------------------------------------------------------------===//

It would be really nice to be able to write patterns in .td files for copies,
which would eliminate a bunch of explicit predicates on them (e.g. no side 
effects).  Once this is in place, it would be even better to have tblgen 
synthesize the various copy insertion/inspection methods in TargetInstrInfo.

//===---------------------------------------------------------------------===//

Stack coloring improvements:

1. Do proper LiveStackAnalysis on all stack objects including those which are
   not spill slots.
2. Reorder objects to fill in gaps between objects.
   e.g. 4, 1, <gap>, 4, 1, 1, 1, <gap>, 4 => 4, 1, 1, 1, 1, 4, 4

//===---------------------------------------------------------------------===//

The scheduler should be able to sort nearby instructions by their address. For
example, in an expanded memset sequence it's not uncommon to see code like this:

  movl $0, 4(%rdi)
  movl $0, 8(%rdi)
  movl $0, 12(%rdi)
  movl $0, 0(%rdi)

Each of the stores is independent, and the scheduler is currently making an
arbitrary decision about the order.

//===---------------------------------------------------------------------===//

Another opportunitiy in this code is that the $0 could be moved to a register:

  movl $0, 4(%rdi)
  movl $0, 8(%rdi)
  movl $0, 12(%rdi)
  movl $0, 0(%rdi)

This would save substantial code size, especially for longer sequences like
this. It would be easy to have a rule telling isel to avoid matching MOV32mi
if the immediate has more than some fixed number of uses. It's more involved
to teach the register allocator how to do late folding to recover from
excessive register pressure.