This method could probably be used by LiveIntervalAnalysis::shrinkToUses, and
now it can use extendIntervalEndTo() which coalesces ranges.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126803 91177308-0d34-0410-b5e6-96231b3b80d8
The greedy register allocator revealed some problems with the value mapping in
SplitKit. We would sometimes start mapping values before all defs were known,
and that could change a value from a simple 1-1 mapping to a multi-def mapping
that requires ssa update.
The new approach collects all defs and register assignments first without
filling in any live intervals. Only when finish() is called, do we compute
liveness and mapped values. At this time we know with certainty which values map
to multiple values in a split range.
This also has the advantage that we can compute live ranges based on the
remaining uses after rematerializing at split points.
The current implementation has many opportunities for compile time optimization.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124765 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123128 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116006 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115385 91177308-0d34-0410-b5e6-96231b3b80d8
instead of calling lower_bound or upper_bound directly.
This cleans up the search logic a bit because {lower,upper}_bound compare
LR->start by default, and it is usually simpler to search LR->end.
Funnelling all searches through one function also makes it possible to replace
the search algorithm with something faster than binary search.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114448 91177308-0d34-0410-b5e6-96231b3b80d8
Clobber ranges are no longer used when joining physical registers.
Instead, all aliases are checked for interference.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113084 91177308-0d34-0410-b5e6-96231b3b80d8
register at a time. This turns out to be slightly faster than iterating over
instructions, but more importantly, it allows us to compute spill weights for
new registers created after the spill weight pass has run.
Also compute the allocation hint at the same time as the spill weight. This
allows us to use the spill weight as a cost metric for copies, and choose the
most profitable hint if there is more than one possibility.
The new hints provide a very small (< 0.1%) but universal code size improvement.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110631 91177308-0d34-0410-b5e6-96231b3b80d8
After heavy editing of a live interval, it is much easier to simply renumber the
live values instead of trying to keep track of the unused ones.
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This allows us to recognize the common case where all uses could be
rematerialized, and no stack slot allocation is necessary.
If some values could be fully rematerialized, remove them from the live range
before allocating a stack slot for the rest.
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The VNInfo.kills vector was almost unused except for all the code keeping it
updated. The few places using it were easily rewritten to check for interval
ends instead.
The two new methods LiveInterval::killedAt and killedInRange are replacements.
This brings us down to 3 independent data structures tracking kills.
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This introduces a new pass, SlotIndexes, which is responsible for numbering
instructions for register allocation (and other clients). SlotIndexes numbering
is designed to match the existing scheme, so this patch should not cause any
changes in the generated code.
For consistency, and to avoid naming confusion, LiveIndex has been renamed
SlotIndex.
The processImplicitDefs method of the LiveIntervals analysis has been moved
into its own pass so that it can be run prior to SlotIndexes. This was
necessary to match the existing numbering scheme.
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The gist of this is if source of some of the copies that feed into a phi join is defined by the phi join, we'd like to eliminate them. However, if any of the non-identity source overlaps the live interval of the phi join then the coalescer won't be able to coalesce them. The early coalescer's job is to eliminate the identity copies by partially-coalescing the two live intervals.
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linear scan reg alloc. This fixes a problem I ran into where extracting
a function from a larger file caused the generated code to change (masking
the problem I was trying to debug) because the allocator behaved differently.
This changes the results for two X86 regression checks. stack-color-with-reg
is improved, with one less instruction, but pr3495 is worse, with one more
copy. As far as I can tell, these tests were just getting lucky or unlucky,
so I've changed the expected results.
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a new class, MachineInstrIndex, which hides arithmetic details from
most clients. This is a step towards allowing the register allocator
to update/insert code during allocation.
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