llvm-6502/lib/CodeGen
Matthias Braun 679d26ce56 MachineScheduler: Restrict macroop fusion to data-dependent instructions.
Before creating a schedule edge to encourage MacroOpFusion check that:
- The predecessor actually writes a register that the branch reads.
- The predecessor has no successors in the ScheduleDAG so we can
  schedule it in front of the branch.

This avoids skewing the scheduling heuristic in cases where macroop
fusion cannot happen.

Differential Revision: http://reviews.llvm.org/D10745

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242723 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-20 22:34:44 +00:00
..
AsmPrinter Make global aliases have symbol size equal to their type 2015-07-17 12:12:03 +00:00
MIRParser MIR Serialization: Initial serialization of machine constant pools. 2015-07-20 20:51:18 +00:00
SelectionDAG [DAGCombiner] Fixed minor typo that was missed in D9097. 2015-07-19 11:31:40 +00:00
AggressiveAntiDepBreaker.cpp [AggressiveAntiDepBreaker] Use range loops for multimap access. 2015-07-18 20:05:10 +00:00
AggressiveAntiDepBreaker.h [CodeGen] Reduce visibility of implementation details 2015-07-01 14:47:39 +00:00
AllocationOrder.cpp TargetRegisterInfo: Provide a way to check assigned registers in getRegAllocationHints() 2015-07-15 22:16:00 +00:00
AllocationOrder.h TargetRegisterInfo: Provide a way to check assigned registers in getRegAllocationHints() 2015-07-15 22:16:00 +00:00
Analysis.cpp Make TargetLowering::getPointerTy() taking DataLayout as an argument 2015-07-09 02:09:04 +00:00
AntiDepBreaker.h [CodeGen] Reduce visibility of implementation details 2015-07-01 14:47:39 +00:00
AtomicExpandPass.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
BasicTargetTransformInfo.cpp Make TargetTransformInfo keeping a reference to the Module DataLayout 2015-07-09 02:08:42 +00:00
BranchFolding.cpp [BranchFolding] Document why replacing HashMachineInstr with hash_code doesn't work 2015-06-23 14:47:36 +00:00
BranchFolding.h [CodeGen] Reduce visibility of implementation details 2015-07-01 14:47:39 +00:00
CalcSpillWeights.cpp
CallingConvLower.cpp remove function names from comments; NFC 2015-06-11 14:26:49 +00:00
CMakeLists.txt [InterleavedAccess] Add a pass InterleavedAccess to identify interleaved memory accesses and transform into target specific intrinsics. 2015-06-26 02:10:27 +00:00
CodeGen.cpp [CodeGen] Add a pass to fold null checks into nearby memory operations. 2015-06-15 18:44:27 +00:00
CodeGenPrepare.cpp Make isLegalAddressingMode() taking DataLayout as an argument 2015-07-09 02:09:40 +00:00
CoreCLRGC.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
CriticalAntiDepBreaker.cpp MachineFrameInfo: Simplify pristine register calculation. 2015-05-28 23:20:35 +00:00
CriticalAntiDepBreaker.h [CodeGen] Reduce visibility of implementation details 2015-07-01 14:47:39 +00:00
DeadMachineInstructionElim.cpp Rename llvm.frameescape and llvm.framerecover to localescape and localrecover 2015-07-07 22:25:32 +00:00
DFAPacketizer.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
DwarfEHPrepare.cpp Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
EarlyIfConversion.cpp Avoid redundant select node in early if-conversion pass 2015-06-18 22:34:09 +00:00
EdgeBundles.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
ErlangGC.cpp
ExecutionDepsFix.cpp MachineRegisterInfo: Remove UsedPhysReg infrastructure 2015-07-14 17:52:07 +00:00
ExpandISelPseudos.cpp
ExpandPostRAPseudos.cpp
FaultMaps.cpp Revert "[FaultMaps] Move FaultMapParser to Object/" 2015-06-23 20:09:03 +00:00
GCMetadata.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
GCMetadataPrinter.cpp
GCRootLowering.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
GCStrategy.cpp
GlobalMerge.cpp Redirect DataLayout from TargetMachine to Module in GlobalMerge 2015-07-07 18:49:25 +00:00
IfConversion.cpp [If Converter] Convert recursion to iteration. 2015-06-24 20:34:35 +00:00
ImplicitNullChecks.cpp [ImplicitNullChecks] Work with implicit defs. 2015-07-20 20:31:39 +00:00
InlineSpiller.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
InterferenceCache.cpp
InterferenceCache.h [CodeGen] Reduce visibility of implementation details 2015-07-01 14:47:39 +00:00
InterleavedAccessPass.cpp [InterleavedAccess] Fix failures "undefined type 'llvm::raw_ostream'" on windows. 2015-06-26 04:38:21 +00:00
IntrinsicLowering.cpp
LatencyPriorityQueue.cpp
LexicalScopes.cpp
LiveDebugVariables.cpp
LiveDebugVariables.h [CodeGen] Reduce visibility of implementation details 2015-07-01 14:47:39 +00:00
LiveInterval.cpp LiveInterval: Document and enforce rules about empty subranges. 2015-07-16 18:55:35 +00:00
LiveIntervalAnalysis.cpp LiveInterval: Document and enforce rules about empty subranges. 2015-07-16 18:55:35 +00:00
LiveIntervalUnion.cpp
LivePhysRegs.cpp LivePhysRegs: Add support to add pristine registers when populating with live-in/live-out registers. 2015-07-01 17:17:17 +00:00
LiveRangeCalc.cpp LiveRangeCalc: Improve error messages on malformed IR 2015-05-11 18:47:47 +00:00
LiveRangeCalc.h
LiveRangeEdit.cpp LiveRangeEdit: Fix liveranges not shrinking on subrange kill. 2015-06-01 21:26:26 +00:00
LiveRegMatrix.cpp MachineRegisterInfo: Remove UsedPhysReg infrastructure 2015-07-14 17:52:07 +00:00
LiveStackAnalysis.cpp
LiveVariables.cpp [LiveVariables] Improve isLiveOut runtime performances. NFC. 2015-06-11 07:50:21 +00:00
LLVMBuild.txt Protection against stack-based memory corruption errors using SafeStack 2015-06-15 21:07:11 +00:00
LLVMTargetMachine.cpp llc: Add a 'run-pass' option. 2015-07-06 17:44:26 +00:00
LocalStackSlotAllocation.cpp
MachineBasicBlock.cpp CodeGen: Push the ModuleSlotTracker through MachineOperands 2015-06-26 22:06:47 +00:00
MachineBlockFrequencyInfo.cpp Rename doFunction() in BFI to calculate() and change its parameters from pointers to references. 2015-07-15 19:58:26 +00:00
MachineBlockPlacement.cpp Test commit. 2015-07-15 17:58:15 +00:00
MachineBranchProbabilityInfo.cpp
MachineCombiner.cpp [MachineCombiner] Work with itineraries 2015-07-15 08:22:23 +00:00
MachineCopyPropagation.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
MachineCSE.cpp MachineCSE: Add a target query for the LookAheadLimit heurisitic 2015-05-09 00:56:07 +00:00
MachineDominanceFrontier.cpp
MachineDominators.cpp Remove macro guards for extern template instantiations. 2015-07-13 17:21:31 +00:00
MachineFunction.cpp Redirect DataLayout from TargetMachine to Module in MachineFunction 2015-07-07 18:20:57 +00:00
MachineFunctionAnalysis.cpp MIR Serialization: Connect the machine function analysis pass to the MIR parser. 2015-06-15 20:30:22 +00:00
MachineFunctionPass.cpp
MachineFunctionPrinterPass.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
MachineInstr.cpp CodeGen: Create a proper ModuleSlotTracker for MachineInstr 2015-06-26 23:18:44 +00:00
MachineInstrBundle.cpp [ARM] Pass a callback to FunctionPass constructors to enable skipping execution 2015-06-08 18:50:43 +00:00
MachineLICM.cpp MachineLICM: Use TargetSchedModel instead of just itineraries 2015-06-13 03:42:11 +00:00
MachineLoopInfo.cpp Rename LoopInfo::Analyze() to LoopInfo::analyze() and turn its parameter type to const&. 2015-07-16 18:23:57 +00:00
MachineModuleInfo.cpp [CodeGen] Force emission of personality directive if explicitly specified 2015-07-14 19:22:51 +00:00
MachineModuleInfoImpls.cpp
MachinePassRegistry.cpp
MachinePostDominators.cpp
MachineRegionInfo.cpp
MachineRegisterInfo.cpp MachineRegisterInfo: Remove UsedPhysReg infrastructure 2015-07-14 17:52:07 +00:00
MachineScheduler.cpp MachineScheduler: Restrict macroop fusion to data-dependent instructions. 2015-07-20 22:34:44 +00:00
MachineSink.cpp [MachineSink] Address post-commit review comments 2015-06-16 08:57:21 +00:00
MachineSSAUpdater.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
MachineTraceMetrics.cpp use range-based for loops; NFCI 2015-07-06 16:27:35 +00:00
MachineVerifier.cpp LiveInterval: Document and enforce rules about empty subranges. 2015-07-16 18:55:35 +00:00
Makefile Resubmit r237954 (MIR Serialization: print and parse LLVM IR using MIR format). 2015-05-27 18:02:19 +00:00
MIRPrinter.cpp MIR Serialization: Initial serialization of machine constant pools. 2015-07-20 20:51:18 +00:00
MIRPrinter.h MIR Serialization: move the MIR printer out of the MIR printing pass. 2015-06-15 23:52:35 +00:00
MIRPrintingPass.cpp MIR Serialization: move the MIR printer out of the MIR printing pass. 2015-06-15 23:52:35 +00:00
module.modulemap
OcamlGC.cpp
OptimizePHIs.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
Passes.cpp Redirect DataLayout from TargetMachine to Module in SjLjEHPrepare 2015-07-08 01:00:31 +00:00
PeepholeOptimizer.cpp Revert "Refactor optimizeUncoalescable logic" 2015-07-15 18:10:46 +00:00
PHIElimination.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
PHIEliminationUtils.cpp
PHIEliminationUtils.h
PostRASchedulerList.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
ProcessImplicitDefs.cpp CodeGen: Use mop_iterator instead of MIOperands/ConstMIOperands 2015-05-29 02:56:46 +00:00
PrologEpilogInserter.cpp MachineRegisterInfo: Remove UsedPhysReg infrastructure 2015-07-14 17:52:07 +00:00
PseudoSourceValue.cpp
README.txt
RegAllocBase.cpp
RegAllocBase.h
RegAllocBasic.cpp TargetRegisterInfo: Provide a way to check assigned registers in getRegAllocationHints() 2015-07-15 22:16:00 +00:00
RegAllocFast.cpp MachineRegisterInfo: Remove UsedPhysReg infrastructure 2015-07-14 17:52:07 +00:00
RegAllocGreedy.cpp [RAGreedy] Add an experimental deferred spilling feature. 2015-07-17 23:04:06 +00:00
RegAllocPBQP.cpp
RegisterClassInfo.cpp
RegisterCoalescer.cpp RegisterCoalescer: Cleanup empty subranges after shrinkToUses() 2015-06-30 00:33:44 +00:00
RegisterCoalescer.h Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
RegisterPressure.cpp RegisterPressure: Add PressureDiff::dump() 2015-07-08 23:40:27 +00:00
RegisterScavenging.cpp [RegisterScavenger] Fix handling of predicated instructions 2015-06-09 22:10:58 +00:00
ScheduleDAG.cpp
ScheduleDAGInstrs.cpp Move most user of TargetMachine::getDataLayout to the Module one 2015-07-16 06:11:10 +00:00
ScheduleDAGPrinter.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
ScoreboardHazardRecognizer.cpp
ShadowStackGC.cpp
ShadowStackGCLowering.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
ShrinkWrap.cpp [ShrinkWrap] Add a target hook to check whether or not 2015-05-27 06:25:48 +00:00
SjLjEHPrepare.cpp Fix __builtin_setjmp in combination with sjlj exception handling. 2015-07-16 22:34:16 +00:00
SlotIndexes.cpp
Spiller.h Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
SpillPlacement.cpp
SpillPlacement.h
SplitKit.cpp
SplitKit.h [CodeGen] Reduce visibility of implementation details 2015-07-01 14:47:39 +00:00
StackColoring.cpp Remove MCInstrItineraries includes in parts that don't use them anymore 2015-05-14 18:01:11 +00:00
StackMapLivenessAnalysis.cpp [StackMap Liveness] Calling the base class' getAnalysisUsage method. NFCI. 2015-07-07 02:05:18 +00:00
StackMaps.cpp Move most user of TargetMachine::getDataLayout to the Module one 2015-07-16 06:11:10 +00:00
StackProtector.cpp Redirect DataLayout from TargetMachine to Module in StackProtector 2015-07-07 23:38:49 +00:00
StackSlotColoring.cpp
StatepointExampleGC.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
TailDuplication.cpp [MachineBasicBlock] Add getFirstNonDebugInstr to complement getLastNonDebugInstr 2015-06-23 14:47:29 +00:00
TargetFrameLoweringImpl.cpp PrologEpilogInserter: Rewrite API to determine callee save regsiters. 2015-07-14 17:17:13 +00:00
TargetInstrInfo.cpp Remove TargetInstrInfo::canFoldMemoryOperand 2015-07-19 10:50:53 +00:00
TargetLoweringBase.cpp [Codegen] Add intrinsics 'absdiff' and corresponding SDNodes for absolute difference operation 2015-07-16 15:22:46 +00:00
TargetLoweringObjectFileImpl.cpp Remove DataLayout from TargetLoweringObjectFile, redirect to Module 2015-07-16 06:04:17 +00:00
TargetOptionsImpl.cpp Use function attribute "trap-func-name" and remove TargetOptions::TrapFuncName. 2015-07-02 22:13:27 +00:00
TargetRegisterInfo.cpp TargetRegisterInfo: Provide a way to check assigned registers in getRegAllocationHints() 2015-07-15 22:16:00 +00:00
TargetSchedule.cpp Use llvm_unreachable() instead of report_fatal_error() if the machine model is incomplete 2015-07-17 17:50:11 +00:00
TwoAddressInstructionPass.cpp [TwoAddressInstructionPass] Rename a variable to match the coding style. 2015-07-06 20:12:54 +00:00
UnreachableBlockElim.cpp Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
VirtRegMap.cpp MachineRegisterInfo: Remove UsedPhysReg infrastructure 2015-07-14 17:52:07 +00:00
WinEHPrepare.cpp [SEH] Push reloads of the SEH code past phi nodes 2015-07-10 22:21:54 +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 r4, [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.