llvm-6502/lib/CodeGen
Rafael Espindola e29887b4ee Use .cfi_sections to put the unwind info in .debug_frame when possible. With
this clang will use .debug_frame in, for example,
clang -g -c -m32 test.c
This matches gcc's behaviour. It looks like .debug_frame is a bit bigger
than .eh_frame, but has the big advantage of not being allocated.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131140 91177308-0d34-0410-b5e6-96231b3b80d8
2011-05-10 18:39:09 +00:00
..
AsmPrinter Use .cfi_sections to put the unwind info in .debug_frame when possible. With 2011-05-10 18:39:09 +00:00
SelectionDAG Look through struct wrapped types for inline asm statments. 2011-05-09 20:04:43 +00:00
AggressiveAntiDepBreaker.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
AggressiveAntiDepBreaker.h
AllocationOrder.cpp Simplify a bunch of isVirtualRegister() and isPhysicalRegister() logic. 2011-01-10 02:58:51 +00:00
AllocationOrder.h Try harder to get the hint by preferring to evict hint interference. 2011-02-25 01:04:22 +00:00
Analysis.cpp Minor code re-structuring. 2011-03-19 17:03:16 +00:00
AntiDepBreaker.h
BranchFolding.cpp Branch folding is folding a landing pad into a regular BB. 2011-04-22 01:07:09 +00:00
BranchFolding.h
CalcSpillWeights.cpp Use the new TRI->getLargestLegalSuperClass hook to constrain register class inflation. 2011-04-26 18:52:36 +00:00
CallingConvLower.cpp ARM byval support. Will be enabled by another patch to the FE. <rdar://problem/7662569> 2011-04-20 16:47:52 +00:00
CMakeLists.txt Add an InterferenceCache class for caching per-block interference ranges. 2011-04-02 06:03:35 +00:00
CodeGen.cpp
CodePlacementOpt.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
CriticalAntiDepBreaker.cpp Fix PostRA antidependence breaker. 2011-02-08 17:39:46 +00:00
CriticalAntiDepBreaker.h Typo. 2011-02-09 22:55:48 +00:00
DeadMachineInstructionElim.cpp Simplify a bunch of isVirtualRegister() and isPhysicalRegister() logic. 2011-01-10 02:58:51 +00:00
DwarfEHPrepare.cpp Remove PHINode::reserveOperandSpace(). Instead, add a parameter to 2011-03-30 11:28:46 +00:00
EdgeBundles.cpp Build the Hopfield network incrementally when splitting global live ranges. 2011-04-09 02:59:09 +00:00
ELF.h Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
ELFCodeEmitter.cpp
ELFCodeEmitter.h
ELFWriter.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
ELFWriter.h
ExpandISelPseudos.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
GCMetadata.cpp
GCMetadataPrinter.cpp
GCStrategy.cpp Rename TargetFrameInfo into TargetFrameLowering. Also, put couple of FIXMEs and fixes here and there. 2011-01-10 12:39:04 +00:00
IfConversion.cpp If converter was being too cute. It look for root BBs (which don't have 2011-04-27 19:32:43 +00:00
InlineSpiller.cpp Add some statistics to the splitting and spilling frameworks. 2011-05-05 17:22:53 +00:00
InterferenceCache.cpp Precompute interference for neighbor blocks as long as there is no interference. 2011-04-09 02:59:05 +00:00
InterferenceCache.h Precompute interference for neighbor blocks as long as there is no interference. 2011-04-09 02:59:05 +00:00
IntrinsicLowering.cpp Recognize inline asm 'rev /bin/bash, ' as a bswap intrinsic call. 2011-01-08 01:24:27 +00:00
LatencyPriorityQueue.cpp Various bits of framework needed for precise machine-level selection 2010-12-24 05:03:26 +00:00
LiveDebugVariables.cpp Remove an assertion to fix PR9872. 2011-05-08 19:21:08 +00:00
LiveDebugVariables.h Update LiveDebugVariables after live range splitting. 2011-05-06 18:00:02 +00:00
LiveInterval.cpp Replace a broken LiveInterval::MergeValueInAsValue() with something simpler. 2011-03-19 23:02:49 +00:00
LiveIntervalAnalysis.cpp When a physreg is live-in and live through a basic block, make sure its live 2011-04-30 19:12:33 +00:00
LiveIntervalUnion.cpp Speed up eviction by stopping collectInterferingVRegs as soon as the spill 2011-04-11 21:47:01 +00:00
LiveIntervalUnion.h Reuse live interval union between functions. This saves a bit of compile time 2011-04-11 23:57:14 +00:00
LiveRangeEdit.cpp Add some statistics to the splitting and spilling frameworks. 2011-05-05 17:22:53 +00:00
LiveRangeEdit.h Update LiveDebugVariables after live range splitting. 2011-05-06 18:00:02 +00:00
LiveStackAnalysis.cpp Teach TargetRegisterInfo how to cram stack slot indexes in with the virtual and 2011-01-09 21:17:37 +00:00
LiveVariables.cpp Reduce vector reallocations. 2011-03-08 17:28:36 +00:00
LLVMTargetMachine.cpp Remove the DwarfTable enum. 2011-05-05 22:14:31 +00:00
LocalStackSlotAllocation.cpp Rename TargetFrameInfo into TargetFrameLowering. Also, put couple of FIXMEs and fixes here and there. 2011-01-10 12:39:04 +00:00
LowerSubregs.cpp Trailing whitespace. 2011-02-25 22:53:20 +00:00
MachineBasicBlock.cpp Simplify declarations slightly by using typedefs. 2011-04-18 21:21:37 +00:00
MachineCSE.cpp Re-revert r130877; it's apparently causing a regression on 197.parser, 2011-05-06 05:23:07 +00:00
MachineDominators.cpp
MachineFunction.cpp Make the logic for determining function alignment more explicit. No functionality change. 2011-05-06 20:34:06 +00:00
MachineFunctionAnalysis.cpp Clean up a funky pass registration that got passed over when I got rid of static constructors. 2011-01-04 00:55:21 +00:00
MachineFunctionPass.cpp
MachineFunctionPrinterPass.cpp
MachineInstr.cpp Remove an assertion to fix PR9872. 2011-05-08 19:21:08 +00:00
MachineLICM.cpp Look pass copies when determining whether hoisting would end up inserting more copies. rdar://9266679 2011-04-11 21:09:18 +00:00
MachineLoopInfo.cpp
MachineLoopRanges.cpp Add MachineLoopRange comparators for sorting loop lists by number and by area. 2010-12-17 18:13:52 +00:00
MachineModuleInfo.cpp
MachineModuleInfoImpls.cpp
MachinePassRegistry.cpp
MachineRegisterInfo.cpp Revert r124611 - "Keep track of incoming argument's location while emitting LiveIns." 2011-02-21 23:21:26 +00:00
MachineSink.cpp Fix a couple of places where changes are made but not tracked. 2011-04-11 18:47:20 +00:00
MachineSSAUpdater.cpp
MachineVerifier.cpp SjLj EH could produce a machine basic block that legitimately has more than one 2011-05-04 22:54:05 +00:00
Makefile
ObjectCodeEmitter.cpp
OcamlGC.cpp
OptimizePHIs.cpp
Passes.cpp Update comment. 2011-04-30 03:13:08 +00:00
PeepholeOptimizer.cpp Add a peephole optimization to optimize pairs of bitcasts. e.g. 2011-03-15 05:13:13 +00:00
PHIElimination.cpp Remove unused STL header includes. 2011-04-23 19:53:52 +00:00
PHIEliminationUtils.cpp
PHIEliminationUtils.h
PostRASchedulerList.cpp Typo: Reviewed by Alistair. 2011-05-06 18:14:32 +00:00
PreAllocSplitting.cpp Remove some checks for StrongPHIElim. These checks make it impossible to use an 2010-12-19 18:03:27 +00:00
ProcessImplicitDefs.cpp Place context in member variables instead of passing around pointers. 2011-03-14 20:57:14 +00:00
PrologEpilogInserter.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
PrologEpilogInserter.h
PseudoSourceValue.cpp
README.txt Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
RegAllocBase.h Fix PR9883. Make sure all caches are invalidated when a live range is repaired. 2011-05-10 17:37:41 +00:00
RegAllocBasic.cpp Fix PR9883. Make sure all caches are invalidated when a live range is repaired. 2011-05-10 17:37:41 +00:00
RegAllocFast.cpp Typo 2011-04-22 01:40:20 +00:00
RegAllocGreedy.cpp Fix PR9883. Make sure all caches are invalidated when a live range is repaired. 2011-05-10 17:37:41 +00:00
RegAllocLinearScan.cpp Remove unused STL header includes. 2011-04-23 19:53:52 +00:00
RegAllocPBQP.cpp Make SpillIs an optional pointer. Avoid creating a bunch of temporary SmallVectors. 2011-03-10 01:21:58 +00:00
RegisterCoalescer.cpp
RegisterScavenging.cpp Handle <def,undef> in the second loop as well. 2011-05-02 20:36:53 +00:00
RenderMachineFunction.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
RenderMachineFunction.h
ScheduleDAG.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
ScheduleDAGEmit.cpp Change all self assignments X=X to (void)X, so that we can turn on a 2010-12-23 00:58:24 +00:00
ScheduleDAGInstrs.cpp Added an assertion, and updated a comment. 2011-05-06 21:52:52 +00:00
ScheduleDAGInstrs.h
ScheduleDAGPrinter.cpp Pass the graph to the DOTGraphTraits.getEdgeAttributes(). 2011-02-27 04:11:03 +00:00
ScoreboardHazardRecognizer.cpp Convert -enable-sched-cycles and -enable-sched-hazard to -disable 2011-01-21 05:51:33 +00:00
ShadowStackGC.cpp
ShrinkWrapping.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
SimpleRegisterCoalescing.cpp Disable physical register coalescing by default. 2011-05-04 23:59:00 +00:00
SimpleRegisterCoalescing.h Extract physreg joining policy to a separate method. 2011-04-04 20:59:59 +00:00
SjLjEHPrepare.cpp The default of the dispatch switch statement was to branch to a BB that executed 2011-04-11 21:32:34 +00:00
SlotIndexes.cpp Use basic block numbers as indexes when mapping slot index ranges. 2011-04-02 06:03:31 +00:00
Spiller.cpp Remove unused STL header includes. 2011-04-23 19:53:52 +00:00
Spiller.h Change the Spiller interface to take a LiveRangeEdit reference. 2011-03-10 01:51:42 +00:00
SpillPlacement.cpp Build the Hopfield network incrementally when splitting global live ranges. 2011-04-09 02:59:09 +00:00
SpillPlacement.h Build the Hopfield network incrementally when splitting global live ranges. 2011-04-09 02:59:09 +00:00
SplitKit.cpp Fix PR9883. Make sure all caches are invalidated when a live range is repaired. 2011-05-10 17:37:41 +00:00
SplitKit.h Gracefully handle invalid live ranges. Fix PR9831. 2011-05-03 20:42:13 +00:00
Splitter.cpp
Splitter.h
StackProtector.cpp Inline check that's used only once. 2011-03-29 17:12:55 +00:00
StackSlotColoring.cpp Teach TargetRegisterInfo how to cram stack slot indexes in with the virtual and 2011-01-09 21:17:37 +00:00
StrongPHIElimination.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
TailDuplication.cpp Update comments. 2011-02-04 01:10:12 +00:00
TargetInstrInfoImpl.cpp Permit remat when a virtual register has multiple defs. 2011-04-20 22:14:17 +00:00
TargetLoweringObjectFileImpl.cpp Remove a flag that would set the ".eh" symbol as .globl. MachO was the only one 2011-05-05 06:49:15 +00:00
TwoAddressInstructionPass.cpp Catch more cases where 2-address pass should 3-addressify instructions. rdar://9002648. 2011-03-02 01:08:17 +00:00
UnreachableBlockElim.cpp Make more passes preserve dominators (or state that they preserve dominators if 2011-01-08 17:01:52 +00:00
VirtRegMap.cpp Also count identity copies. 2011-05-06 17:59:57 +00:00
VirtRegMap.h This method belonged in VirtRegMap. 2011-02-19 00:38:43 +00:00
VirtRegRewriter.cpp Fix a ton of comment typos found by codespell. Patch by 2011-04-15 05:18:47 +00:00
VirtRegRewriter.h

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

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.