llvm-6502/lib/CodeGen
Chandler Carruth cfb75fba73 Fix up the CMake build for the new files added in r146960, they're
likely to stay either way that discussion ends up resolving itself.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146966 91177308-0d34-0410-b5e6-96231b3b80d8
2011-12-20 08:42:11 +00:00
..
AsmPrinter Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch 2011-12-20 02:50:00 +00:00
SelectionDAG Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch 2011-12-20 02:50:00 +00:00
AggressiveAntiDepBreaker.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
AggressiveAntiDepBreaker.h
AllocationOrder.cpp
AllocationOrder.h
Analysis.cpp Move Instruction::isSafeToSpeculativelyExecute out of VMCore and 2011-12-14 23:49:11 +00:00
AntiDepBreaker.h
BranchFolding.cpp - Add MachineInstrBundle.h and MachineInstrBundle.cpp. This includes a function 2011-12-14 02:11:42 +00:00
BranchFolding.h
CalcSpillWeights.cpp Move CalculateRegClass to MRI::recomputeRegClass. 2011-08-09 16:46:27 +00:00
CallingConvLower.cpp
CMakeLists.txt Fix up the CMake build for the new files added in r146960, they're 2011-12-20 08:42:11 +00:00
CodeGen.cpp Kill off the LoopSplitter. It's not being used or maintained. 2011-12-06 01:57:59 +00:00
CodePlacementOpt.cpp
CriticalAntiDepBreaker.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
CriticalAntiDepBreaker.h
DeadMachineInstructionElim.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
DFAPacketizer.cpp use space star instead of star space 2011-12-06 17:34:16 +00:00
DwarfEHPrepare.cpp This code is dead, what with the new EH model and the auto-upgraders in place. 2011-11-07 23:36:48 +00:00
EdgeBundles.cpp Twinify GraphWriter a little bit. 2011-11-15 16:26:38 +00:00
ELF.h
ELFCodeEmitter.cpp Fix asserts in CodeGen from: 2011-09-10 01:07:54 +00:00
ELFCodeEmitter.h Fix asserts in CodeGen from: 2011-09-10 01:07:54 +00:00
ELFWriter.cpp
ELFWriter.h
ExecutionDepsFix.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
ExpandISelPseudos.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
ExpandPostRAPseudos.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
GCMetadata.cpp Remove all remaining uses of Value::getNameStr(). 2011-11-15 16:27:03 +00:00
GCMetadataPrinter.cpp
GCStrategy.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
IfConversion.cpp Add a if-conversion optimization that allows 'true' side of a diamond to be 2011-12-19 22:01:30 +00:00
InlineSpiller.cpp Fixed register allocator splitting a live range on a spilling variable. 2011-12-12 22:16:27 +00:00
InterferenceCache.cpp
InterferenceCache.h
IntrinsicLowering.cpp
JITCodeEmitter.cpp Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch 2011-12-20 02:50:00 +00:00
LatencyPriorityQueue.cpp
LexicalScopes.cpp Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch 2011-12-20 02:50:00 +00:00
LiveDebugVariables.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
LiveDebugVariables.h
LiveInterval.cpp Use getVNInfoBefore() when it makes sense. 2011-11-14 01:39:36 +00:00
LiveIntervalAnalysis.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
LiveIntervalUnion.cpp Simplify the interference checking code a bit. 2011-08-12 00:22:04 +00:00
LiveIntervalUnion.h Simplify the interference checking code a bit. 2011-08-12 00:22:04 +00:00
LiveRangeCalc.cpp Switch extendInBlock() to take a kill slot instead of the last use slot. 2011-09-13 16:47:56 +00:00
LiveRangeCalc.h Unbreak msvc. 2011-09-13 03:58:34 +00:00
LiveRangeEdit.cpp Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch 2011-12-20 02:50:00 +00:00
LiveRangeEdit.h Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch 2011-12-20 02:50:00 +00:00
LiveStackAnalysis.cpp Move getCommonSubClass() into TRI. 2011-09-30 22:18:51 +00:00
LiveVariables.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
LLVMBuild.txt LLVMBuild: Introduce a common section which currently has a list of the 2011-12-12 22:45:54 +00:00
LLVMTargetMachine.cpp Move global variables in TargetMachine into new TargetOptions class. As an API 2011-12-02 22:16:29 +00:00
LocalStackSlotAllocation.cpp
MachineBasicBlock.cpp - Add MachineInstrBundle.h and MachineInstrBundle.cpp. This includes a function 2011-12-14 02:11:42 +00:00
MachineBlockFrequencyInfo.cpp
MachineBlockPlacement.cpp Remove unneeded semicolon. 2011-12-07 19:46:10 +00:00
MachineBranchProbabilityInfo.cpp Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch 2011-12-20 02:50:00 +00:00
MachineCodeEmitter.cpp Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch 2011-12-20 02:50:00 +00:00
MachineCSE.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
MachineDominators.cpp
MachineFunction.cpp Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch 2011-12-20 02:50:00 +00:00
MachineFunctionAnalysis.cpp Sink codegen optimization level into MCCodeGenInfo along side relocation model 2011-11-16 08:38:26 +00:00
MachineFunctionPass.cpp
MachineFunctionPrinterPass.cpp
MachineInstr.cpp - Add MachineInstrBundle.h and MachineInstrBundle.cpp. This includes a function 2011-12-14 02:11:42 +00:00
MachineInstrBundle.cpp - Add MachineInstrBundle.h and MachineInstrBundle.cpp. This includes a function 2011-12-14 02:11:42 +00:00
MachineLICM.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
MachineLoopInfo.cpp
MachineLoopRanges.cpp
MachineModuleInfo.cpp Add an ivar that maps a landing pad's EH symbol to the call sites that may jump 2011-10-05 22:20:38 +00:00
MachineModuleInfoImpls.cpp
MachinePassRegistry.cpp Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch 2011-12-20 02:50:00 +00:00
MachineRegisterInfo.cpp Handle sub-register operands in recomputeRegClass(). 2011-12-19 16:53:37 +00:00
MachineSink.cpp Do not sink instruction, if it is not profitable. 2011-12-14 23:20:38 +00:00
MachineSSAUpdater.cpp Mix some minor misuse of MachineBasicBlock iterator. 2011-12-06 02:49:06 +00:00
MachineVerifier.cpp - Add MachineInstrBundle.h and MachineInstrBundle.cpp. This includes a function 2011-12-14 02:11:42 +00:00
Makefile
ObjectCodeEmitter.cpp
OcamlGC.cpp
OptimizePHIs.cpp When deleting a phi cycle after looking through copies, constrain the register 2011-10-17 21:54:46 +00:00
Passes.cpp Delete the linear scan register allocator. 2011-11-12 22:39:45 +00:00
PeepholeOptimizer.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
PHIElimination.cpp First chunk of MachineInstr bundle support. 2011-12-06 22:12:01 +00:00
PHIEliminationUtils.cpp
PHIEliminationUtils.h
PostRASchedulerList.cpp - Add MachineInstrBundle.h and MachineInstrBundle.cpp. This includes a function 2011-12-14 02:11:42 +00:00
ProcessImplicitDefs.cpp
PrologEpilogInserter.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
PrologEpilogInserter.h
PseudoSourceValue.cpp
README.txt
RegAllocBase.h
RegAllocBasic.cpp Privatize an unused part of the LiveIntervalUnion::Query interface. 2011-08-11 21:00:42 +00:00
RegAllocFast.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
RegAllocGreedy.cpp Stop tracking spill slot uses in VirtRegMap. 2011-11-13 01:23:30 +00:00
RegAllocPBQP.cpp Kill off the LoopSplitter. It's not being used or maintained. 2011-12-06 01:57:59 +00:00
RegisterClassInfo.cpp Detect proper register sub-classes. 2011-08-05 21:28:14 +00:00
RegisterClassInfo.h Detect proper register sub-classes. 2011-08-05 21:28:14 +00:00
RegisterCoalescer.cpp Reverting r145899 as it breaks clang self-hosting 2011-12-08 03:24:10 +00:00
RegisterCoalescer.h Rename member variables to follow coding standards. 2011-08-09 01:01:27 +00:00
RegisterScavenging.cpp Silence a bunch (but not all) "variable written but not read" warnings 2011-08-12 14:54:45 +00:00
RenderMachineFunction.cpp Rename SlotIndexes to match how they are used. 2011-11-13 20:45:27 +00:00
RenderMachineFunction.h
ScheduleDAG.cpp Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch 2011-12-20 02:50:00 +00:00
ScheduleDAGEmit.cpp
ScheduleDAGInstrs.cpp Model ARM predicated write as read-mod-write. e.g. 2011-12-14 20:00:08 +00:00
ScheduleDAGInstrs.h PostRA scheduler fix. Clear stale loop dependencies. 2011-10-07 06:33:09 +00:00
ScheduleDAGPrinter.cpp Twinify GraphWriter a little bit. 2011-11-15 16:26:38 +00:00
ScoreboardHazardRecognizer.cpp Remove an invalid assert that is really just asserting when the scheduler emits 2011-09-27 21:59:16 +00:00
ShadowStackGC.cpp Use the C personality function instead of the C++ personality function. 2011-09-22 17:56:40 +00:00
ShrinkWrapping.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
SjLjEHPrepare.cpp Reapply r146481 with a fix to create the Builder value in the correct place and 2011-12-14 22:45:33 +00:00
SlotIndexes.cpp Rename SlotIndexes to match how they are used. 2011-11-13 20:45:27 +00:00
Spiller.cpp Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch 2011-12-20 02:50:00 +00:00
Spiller.h Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch 2011-12-20 02:50:00 +00:00
SpillPlacement.cpp Be more conservative when forming compact regions. 2011-08-03 23:09:38 +00:00
SpillPlacement.h Be more conservative when forming compact regions. 2011-08-03 23:09:38 +00:00
SplitKit.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
SplitKit.h Hoist back-copies to the least busy dominator. 2011-09-14 16:45:39 +00:00
StackProtector.cpp Enable stack protectors for all arrays, not just char arrays. rdar://5875909 2011-11-23 07:13:56 +00:00
StackSlotColoring.cpp Allow inlining of functions with returns_twice calls, if they have the 2011-12-18 20:35:43 +00:00
StrongPHIElimination.cpp Rename SlotIndexes to match how they are used. 2011-11-13 20:45:27 +00:00
TailDuplication.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
TargetFrameLoweringImpl.cpp Move parts of lib/Target that use CodeGen into lib/CodeGen. 2011-12-15 22:58:58 +00:00
TargetInstrInfoImpl.cpp Attempt to fix PR11607 by shuffling around which class defines which methods. 2011-12-19 20:06:03 +00:00
TargetLoweringObjectFileImpl.cpp On MachO, the pointer to the personality function should always be in the 2011-11-29 01:43:20 +00:00
TargetOptionsImpl.cpp Move parts of lib/Target that use CodeGen into lib/CodeGen. 2011-12-15 22:58:58 +00:00
TwoAddressInstructionPass.cpp Add bundle aware API for querying instruction properties and switch the code 2011-12-07 07:15:52 +00:00
UnreachableBlockElim.cpp
VirtRegMap.cpp More dead code elimination in VirtRegMap. 2011-11-13 01:23:34 +00:00
VirtRegMap.h More dead code elimination in VirtRegMap. 2011-11-13 01:23:34 +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.