llvm-svn: 139892

The leaveIntvAfter() function normally inserts a back-copy after the
requested instruction, making the back-copy kill the live range.

In spill mode, try to insert the back-copy before the last use instead.
That means the last use becomes the kill instead of the back-copy.  This
lowers the register pressure because the last use can now redefine the
same register it was reading.

This will also improve compile time: The back-copy isn't a kill, so
hoisting it in hoistCopiesForSize() won't force a recomputation of the
source live range.  Similarly, if the back-copy isn't hoisted by the
splitter, the spiller will not attempt hoisting it locally.

llvm-svn: 139883

If the source register is live after the copy being spilled, there is no
point to hoisting it.  Hoisting inside a basic block only serves to
resolve interferences by shortening the live range of the source.

llvm-svn: 139882

llvm-svn: 139851

When -split-spill-mode is enabled, spill hoisting is performed by
SplitKit instead of by InlineSpiller.  This hidden command line option
is for testing the splitter spill mode.

llvm-svn: 139845

Fix the stats counters to reflect that.

llvm-svn: 139819

The number of spills could go negative since a folded COPY is just a
spill, and it may be eliminated.

llvm-svn: 139815

Adjust counters when removing spill and reload instructions.

We still don't account for reloads being removed by eliminateDeadDefs().

llvm-svn: 139806

When traceSiblingValue() encounters a PHI-def value created by live
range splitting, don't look at all the predecessor blocks.  That can be
very expensive in a complicated CFG.

Instead, consider that all the non-PHI defs jointly dominate all the
PHI-defs.  Tracing directly to all the non-PHI defs is much faster that
zipping around in the CFG when there are many PHIs with many
predecessors.

This significantly improves compile time for indirectbr interpreters.

llvm-svn: 139797

Blocks with multiple PHI successors only need to go on the worklist
once.  Use a SmallPtrSet to track the live-out blocks that have already
been handled.  This is a lot faster than the two live range check we
would otherwise do.

Also stop recomputing hasPHIKill flags.  Like RenumberValues(), it is
conservatively correct to leave them in, and they are not used for
anything important.

llvm-svn: 139792

It does, after all.

RemoveCopyByCommutingDef rewrites the uses of one particular value
number in A. It doesn't know how to rewrite phi uses, so there can't be
any.

llvm-svn: 139787

There is only one legitimate use remaining, in addIntervalsForSpills().
All other calls to hasPHIKill() are only used to update PHIKill flags.

The addIntervalsForSpills() function is part of the old spilling
framework, only used by linearscan.

llvm-svn: 139783

Instead, let HasOtherReachingDefs() test for defs in B that overlap any
phi-defs in A as well.  This test is slightly different, but almost
identical.

A perfectly precise test would only check those phi-defs in A that are
reachable from AValNo.

llvm-svn: 139782

The source live range is recomputed using shrinkToUses() which does
handle phis correctly.  The hasPHIKill() condition was relevant in the
old days when ReMaterializeTrivialDef() tried to recompute the live
range itself.

The shrinkToUses() function will mark the original def as dead when no
more uses and phi kills remain.  It is then removed by
runOnMachineFunction().

llvm-svn: 139781

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

An improper SlotIndex->VNInfo lookup was leading to unsafe copy removal.
Fixes PR10920 401.bzip2 miscompile with no IV rewrite.

llvm-svn: 139765

llvm-svn: 139751

THe LRE_DidCloneVirtReg callback may be called with vitual registers
that RAGreedy doesn't even know about yet.  In that case, there are no
data structures to update.

llvm-svn: 139702

When a back-copy is hoisted to the nearest common dominator, keep
looking up the dominator tree for a less loopy dominator, and place the
back-copy there instead.

Don't do this when a single existing back-copy dominates all the others.
Assume the client knows what he is doing, and keep the dominating
back-copy.

This prevents us from hoisting back-copies into loops in most cases.  If
a value is defined in a loop with multiple exits, we may still hoist
back-copies into that loop.  That is the speed/size tradeoff.

llvm-svn: 139698

llvm-svn: 139692

When a ParentVNI maps to multiple defs in a new interval, its live range
may still be derived directly from RegAssign by transferValues().

On the other hand, when instructions have been rematerialized or
hoisted, it may be necessary to completely recompute live ranges using
LiveRangeCalc::extend() to all uses.

Use a bit in the value map to indicate that a live range must be
recomputed.  Rename markComplexMapped() to forceRecompute().

This fixes some live range verification errors when
-split-spill-mode=size hoists back-copies by recomputing source ranges
when RegAssign kills can't be moved.

llvm-svn: 139660

Whenever the complement interval is defined by multiple copies of the
same value, hoist those back-copies to the nearest common dominator.

This ensures that at most one copy is inserted per value in the
complement inteval, and no phi-defs are needed.

llvm-svn: 139651

llvm-svn: 139649

llvm-svn: 139641

llvm-svn: 139633

xor/and/or (For example SSE2).

llvm-svn: 139623

llvm-svn: 139616

This function is used to flag values where the complement interval may
overlap other intervals.  Call it from overlapIntv, and use the flag to
fully recompute those live ranges in transferValues().

llvm-svn: 139612

llvm-svn: 139608

Three out of four clients prefer this interface which is consistent with
extendIntervalEndTo() and LiveRangeCalc::extend().

llvm-svn: 139604

The complement interval may overlap the other intervals created, so use
a separate LiveRangeCalc instance to compute its live range.

A LiveRangeCalc instance can only be shared among non-overlapping
intervals.

llvm-svn: 139603

llvm-svn: 139581

SplitKit will soon need two copies of these data structures, and the
algorithms will also be useful when LiveIntervalAnalysis becomes
independent of LiveVariables.

llvm-svn: 139572

Splitting a landing pad takes considerable care because of PHIs and other
nasties. The problem is that the jump table needs to jump to the landing pad
block. However, the landing pad block can be jumped to only by an invoke
instruction. So we clone the landingpad instruction into its own basic block,
have the invoke jump to there. The landingpad instruction's basic block's
successor is now the target for the jump table.

But because of PHI nodes, we need to create another basic block for the jump
table to jump to. This is definitely a hack, because the values for the PHI
nodes may not be defined on the edge from the jump table. But that's okay,
because the jump table is simply a construct to mimic what is happening in the
CFG. So the values are mysteriously there, even though there is no value for the
PHI from the jump table's edge (hence calling this a hack).

llvm-svn: 139545

It has been enabled by default for a while, it was only there to allow
performance comparisons.

llvm-svn: 139501

SplitKit always computes a complement live range to cover the places
where the original live range was live, but no explicit region has been
allocated.

Currently, the complement live range is created to be as small as
possible - it never overlaps any of the regions.  This minimizes
register pressure, but if the complement is going to be spilled anyway,
that is not very important.  The spiller will eliminate redundant
spills, and hoist others by making the spill slot live range overlap
some of the regions created by splitting.  Stack slots are cheap.

This patch adds the interface to enable spill modes in SplitKit.  In
spill mode, SplitKit will assume that the complement is going to spill,
so it will allow it to overlap regions in order to avoid back-copies.
By doing some of the spiller's work early, the complement live range
becomes simpler.  In some cases, it can become much simpler because no
extra PHI-defs are required.  This will speed up both splitting and
spilling.

This is only the interface to enable spill modes, no implementation yet.

llvm-svn: 139500

llvm-svn: 139498

  assert("error");

to:

  assert(0 && "error");

llvm-svn: 139449

llvm-svn: 139419

Make the SelectionDAG verify that all the operands of BUILD_VECTOR have the same type.  Teach DAGCombiner::visitINSERT_VECTOR_ELT not to make invalid BUILD_VECTORs.  Fixes PR10897.

llvm-svn: 139407