This will allow tail duplication and tail merging during layout to have a
shared threshold to make sure that they don't overlap. No observable change
intended.
llvm-svn: 278981
If AnalyzeBranch can't analyze a block and it is possible to
fallthrough, then duplicating the block doesn't make sense, as only one
block can be the layout predecessor for the un-analyzable fallthrough.
Submitted wit a test case, but NOTE: the test case doesn't currently
fail. However, the test case fails with D20505 and would have saved me
some time debugging.
llvm-svn: 278866
If AnalyzeBranch can't analyze a block and it is possible to
fallthrough, then duplicating the block doesn't make sense, as only one
block can be the layout predecessor for the un-analyzable fallthrough.
Submitted wit a test case, but NOTE: the test case doesn't currently
fail. However, the test case fails with D20505 and would have saved me
some time debugging.
llvm-svn: 278288
Add a check that the layout predecessor of a block is an actual CFG
predecssor of the block as well. No current code fails this check, but
upcoming patches can trigger this, and it makes sense to separate it
out.
llvm-svn: 276066
canTailDuplicate accepts two blocks and returns true if the first can be
duplicated into the second successfully. Use this function to
encapsulate the heuristic.
llvm-svn: 276062
This logic was introduced in r157663 and does not make any sense to me.
The motivating example in rdar://11538365 looks like this:
This is the tail:
BB#16: derived from LLVM BB %if.end68
Live Ins: %R0 %R4 %R5
Predecessors according to CFG: BB#15 BB#5
tBLXi pred:14, pred:%noreg, <ga:@CFRelease>, %R0<kill>, <regmask>, %LR<imp-def,dead>, %SP<imp-use>, %SP<imp-def>
t2B <BB#20>, pred:14, pred:%noreg
Successors according to CFG: BB#20
This is the predBB:
BB#5:
Live Ins: %R5
Predecessors according to CFG: BB#4
%R4<def> = t2MOVi 0, pred:14, pred:%noreg, opt:%noreg
t2B <BB#16>, pred:14, pred:%noreg
Successors according to CFG: BB#16
However this is invalid machine code to begin with, if %R0 is live-in to
BB#16 then it must be live-in to BB#5 as well if BB#5 does not define
it. We should not need logic to retroactively fix broken machine code
and in fact the example from r157663 passes cleanly with the code
removed and I do not see any (newly) failing tests with the machine
verifier enabled.
Differential Revision: http://reviews.llvm.org/D22031
llvm-svn: 274655
This is mostly a mechanical change to make TargetInstrInfo API take
MachineInstr& (instead of MachineInstr* or MachineBasicBlock::iterator)
when the argument is expected to be a valid MachineInstr. This is a
general API improvement.
Although it would be possible to do this one function at a time, that
would demand a quadratic amount of churn since many of these functions
call each other. Instead I've done everything as a block and just
updated what was necessary.
This is mostly mechanical fixes: adding and removing `*` and `&`
operators. The only non-mechanical change is to split
ARMBaseInstrInfo::getOperandLatencyImpl out from
ARMBaseInstrInfo::getOperandLatency. Previously, the latter took a
`MachineInstr*` which it updated to the instruction bundle leader; now,
the latter calls the former either with the same `MachineInstr&` or the
bundle leader.
As a side effect, this removes a bunch of MachineInstr* to
MachineBasicBlock::iterator implicit conversions, a necessary step
toward fixing PR26753.
Note: I updated WebAssembly, Lanai, and AVR (despite being
off-by-default) since it turned out to be easy. I couldn't run tests
for AVR since llc doesn't link with it turned on.
llvm-svn: 274189
Summary:
Split NumInstrDups statistic into separate added/removed counts to avoid
negative stat being printed as unsigned.
Subscribers: mcrosier, llvm-commits
Differential Revision: http://reviews.llvm.org/D21335
llvm-svn: 272700
This used to be free, copying and moving DebugLocs became expensive
after the metadata rewrite. Passing by reference eliminates a ton of
track/untrack operations. No functionality change intended.
llvm-svn: 272512
When a block is tail-duplicated, the PHI nodes from that block are
replaced with appropriate COPY instructions. When those PHI nodes
contained use operands with subregisters, the subregisters were
dropped from the COPY instructions, resulting in incorrect code.
Keep track of the subregister information and use this information
when remapping instructions from the duplicated block.
Differential Revision: http://reviews.llvm.org/D19337
llvm-svn: 267583
The call to processPHI already erased MI from its parent, so MI isn't
even valid here, making the getParent() call a use-after-free in
addition to being redundant.
Found by ASan with the ArrayRecycler changes in llvm.org/pr26808.
llvm-svn: 266008
This is in preparation for tail duplication during block placement. See D18226.
This needs to be a utility class for 2 reasons. No passes may run after block
placement, and also, tail-duplication affects subsequent layout decisions, so
it must be interleaved with placement, and can't be separated out into its own
pass. The original pass is still useful, and now runs by delegating to the
utility class.
llvm-svn: 265842
Matthias Braun