This function doesn't have anything to do with spill weights, and MRI
already has functions for manipulating the register class of a virtual
register.
llvm-svn: 137123
Remat during spilling triggers dead code elimination. If a phi-def
becomes unused, that may also cause live ranges to split into separate
connected components.
This type of splitting is different from normal live range splitting. In
particular, there may not be a common original interval.
When the split range is its own original, make sure that the new
siblings are also their own originals. The range being split cannot be
used as an original since it doesn't cover the new siblings.
llvm-svn: 134413
When an interfering live range ends at a dead slot index between two
instructions, make sure that the inserted copy instruction gets a slot index
after the dead ones. This makes it possible to avoid the interference.
Ideally, there shouldn't be interference ending at a deleted instruction, but
physical register coalescing can sometimes do that to sub-registers.
This fixes PR9823.
llvm-svn: 130687
When DCE clones a live range because it separates into connected components,
make sure that the clones enter the same register allocator stage as the
register they were cloned from.
For instance, clones may be split even when they where created during spilling.
Other registers created during spilling are not candidates for splitting or even
(re-)spilling.
llvm-svn: 128524
The instruction to be rematerialized may not be the one defining the register
that is being spilled. The traceSiblingValue() function sees through sibling
copies to find the remat candidate.
llvm-svn: 128449
I have convinced myself that it can only happen when a phi value dies. When it
happens, allocate new virtual registers for the components.
llvm-svn: 127827
LiveRangeEdit::eliminateDeadDefs() will eventually be used by coalescing,
splitting, and spilling for dead code elimination. It can delete chains of dead
instructions as long as there are no dependency loops.
llvm-svn: 127287
All registers created during splitting or spilling are assigned to the same
stack slot as the parent register.
When splitting or rematting, we may not spill at all. In that case the stack
slot is still assigned, but it will be dead.
llvm-svn: 116546
splitting or spillling, and to help with rematerialization.
Use LiveRangeEdit in InlineSpiller and SplitKit. This will eventually make it
possible to share remat code between InlineSpiller and SplitKit.
llvm-svn: 116543
