The fix is obvious and the only test case I have is horrible, so I am
not including it. The problem shows up when self-hosting clang on i386
with -new-coalescer enabled.
llvm-svn: 164793
The RegisterCoalescer understands overlapping live ranges where one
register is defined as a copy of the other. With this change, register
allocators using LiveRegMatrix can do the same, at least for copies
between physical and virtual registers.
When a physreg is defined by a copy from a virtreg, allow those live
ranges to overlap:
%CL<def> = COPY %vreg11:sub_8bit; GR32_ABCD:%vreg11
%vreg13<def,tied1> = SAR32rCL %vreg13<tied0>, %CL<imp-use,kill>
We can assign %vreg11 to %ECX, overlapping the live range of %CL.
llvm-svn: 163336
The 'unused' state of a value number can be represented as an invalid
def SlotIndex. This also exposed code that shouldn't have been looking
at unused value VNInfos.
llvm-svn: 161258
The only real user of the flag was removeCopyByCommutingDef(), and it
has been switched to LiveIntervals::hasPHIKill().
All the code changed by this patch was only concerned with computing and
propagating the flag.
llvm-svn: 161255
When a live range splits into multiple connected components, we would
arbitrarily assign <undef> uses to component 0. This is wrong when the
use is tied to a def that gets assigned to a different component:
%vreg69<def> = ADD8ri %vreg68<undef>, 1
The use and def must get the same virtual register.
Fix this by assigning <undef> uses to the same component as the value
defined by the instruction, if any:
%vreg69<def> = ADD8ri %vreg69<undef>, 1
This fixes PR13402. The PR has a test case which I am not including
because it is unlikely to keep exposing this behavior in the future.
llvm-svn: 160739
generalizing its implementation sufficiently to support this value
number scenario as well.
This cuts out another significant performance hit in large functions
(over 10k basic blocks, etc), especially those with "natural" CFG
structures.
llvm-svn: 160026
back of it.
I don't have anything even remotely close to a test case for this. It
only broke two build bots, both of them doing bootstrap builds, one of
them a dragonegg bootstrap. It doesn't break for me when I bootstrap
either. It doesn't reproduce every time or on many machines during the
bootstrap. Many thanks to Duncan Sands who got the exact command (and
stage of the bootstrap) which failed on the dragonegg bootstrap and
managed to get it to trigger under valgrind with debug symbols. The fix
was then found by inspection.
llvm-svn: 159993
quadratic behavior when performing pathological merges. Fixes the core
element of PR12652.
There is only one user of addRangeFrom left: join. I'm hoping to
refactor further in a future patch and have join use this merge
operation as well.
llvm-svn: 159982
of the trick merge routines. This adds a layer of testing that was
necessary when implementing more efficient (and complex) merge logic for
this datastructure.
No functionality changed here.
llvm-svn: 159981
Don't print out the register number and spill weight, making the TRI
argument unnecessary.
This allows callers to interpret the reg field. It can currently be a
virtual register, a physical register, a spill slot, or a register unit.
llvm-svn: 158031
Dead copies cause problems because they are trivial to coalesce, but
removing them gived the live range a dangling end point. This patch
enables full dead code elimination which trims live ranges to their uses
so end points don't dangle.
DCE may erase multiple instructions. Put the pointers in an ErasedInstrs
set so we never risk visiting erased instructions in the work list.
There isn't supposed to be any dead copies entering RegisterCoalescer,
but they do slip by as evidenced by test/CodeGen/X86/coalescer-dce.ll.
llvm-svn: 157101
A live range that has an early clobber tied redef now looks like a
normal tied redef, except the early clobber def uses the early clobber
slot.
This is enough to handle any strange interference problems.
llvm-svn: 149769
more than two adjacent ranges needed to be merged. The new version should be
able to handle an arbitrary sequence of adjancent ranges.
llvm-svn: 149588
The old naming scheme (load/use/def/store) can be traced back to an old
linear scan article, but the names don't match how slots are actually
used.
The load and store slots are not needed after the deferred spill code
insertion framework was deleted.
The use and def slots don't make any sense because we are using
half-open intervals as is customary in C code, but the names suggest
closed intervals. In reality, these slots were used to distinguish
early-clobber defs from normal defs.
The new naming scheme also has 4 slots, but the names match how the
slots are really used. This is a purely mechanical renaming, but some
of the code makes a lot more sense now.
llvm-svn: 144503
It is conservatively correct to keep the hasPHIKill flags, even after
deleting PHI-defs.
The calculation can be very expensive after taildup has created a
quadratic number of indirectbr edges in the CFG, and the hasPHIKill flag
isn't used for anything after RenumberValues().
llvm-svn: 139780
There are too many compatibility problems with using mixed types in
std::upper_bound, and I don't want to spend 110 lines of boilerplate setting up
a call to a 10-line function. Binary search is not /that/ hard to implement
correctly.
I tried terminating the binary search with a linear search, but that actually
made the algorithm slower against my expectation. Most live intervals have less
than 4 segments. The early test against endIndex() does pay, and this version is
25% faster than plain std::upper_bound().
llvm-svn: 127522
The existing CompEnd predicate does not define a strict weak order as required
by the C++03 standard; therefore, its use as a predicate to std::upper_bound
is invalid. For a discussion of this issue, see
http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#270
This patch replaces the asymmetrical comparison with an iterator adaptor that
achieves the same effect while being strictly standard-conforming by ensuring
an apples-to-apples comparison.
llvm-svn: 127462
This method could probably be used by LiveIntervalAnalysis::shrinkToUses, and
now it can use extendIntervalEndTo() which coalesces ranges.
llvm-svn: 126803
Region splitting includes loop splitting as a subset, and it is more generic.
The splitting heuristics for variables that are live in more than one block are
now:
1. Try to create a region that covers multiple basic blocks.
2. Try to create a new live range for each block with multiple uses.
3. Spill.
Steps 2 and 3 are similar to what the standard spiller is doing.
llvm-svn: 123853
physical register numbers.
This makes the hack used in LiveInterval official, and lets LiveInterval be
oblivious of stack slots.
The isPhysicalRegister() and isVirtualRegister() predicates don't know about
this, so when a variable may contain a stack slot, isStackSlot() should always
be tested first.
llvm-svn: 123128
Print virtual registers numbered from 0 instead of the arbitrary
FirstVirtualRegister. The first virtual register is printed as %vreg0.
TRI::NoRegister is printed as %noreg.
llvm-svn: 123107
We don't want unused values forming their own equivalence classes, so we lump
them all together in one class, and then merge them with the class of the last
used value.
llvm-svn: 117670
connected components. These components should be allocated different virtual
registers because there is no reason for them to be allocated together.
Add the ConnectedVNInfoEqClasses class to calculate the connected components,
and move values to new LiveIntervals.
Use it from SplitKit::rewrite by creating new virtual registers for the
components.
llvm-svn: 116006
LiveInterval::MergeValueNumberInto instead of trying to extend LiveRanges and
getting it wrong.
This fixed PR8249 where a valno with a multi-segment live range was defined by
an identity copy created by RemoveCopyByCommutingDef. Some of the live
segments disappeared.
llvm-svn: 115385
