Provide a drop_dead_args() function which deletes them instead.
We still need to assign a register to dead EBB arguments, so they can't
just be ignored.
When the legalizer splits a value into halves, it would previously stop
if the value was an EBB argument. With this change, we also split EBB
arguments and iteratively split arguments on branches to the EBB.
The iterative splitting stops when we hit the entry block arguments or
an instruction that isn't one of the concatenation instructions.
LiveRanges represent the live-in range of a value as a sorted
list of intervals. Each interval starts at an EBB and continues
to an instruction. Before this commit, the LiveRange would store
an interval for each EBB. This commit changes the representation
such that intervals continuing from one EBB to another are coalesced
into one.
Fixes#37.
The ProgramOrder::cmp() comparison is often used where one or both
arguments are statically known to be an Inst or Ebb. Give the compiler a
better chance to discover this via inlining and other optimizations.
- Make cmp() generic with Into<ExpandedProgramPoint> bounds.
- Implement the natural From<T> traits for ExpandedProgramPoint.
- Make Layout::pp_seq() generic with the same bound.
Now, with inlining and constant folding, passing an Inst argument to
PO::cmp() will result in a call to a monomorphized Layout::seq::<Inst>()
which can avoid the dynamic match to select a table for looking up the
sequence number.
The result is that comparing two program points of statically known type
results in two direct table lookups and a sequence number comparison.
This all uses ExpandedProgramPoint because it is more likely to be
transparent to the constant folder than the bit-packed ProgramPoint
type.
Assign sequence numbers to both instructions and EBB headers such that
their relative position can be determined in constant time simply by
comparing sequence numbers.
Implement the sequence numbers with a scheme similar to the line numbers
used in BASIC programs. Start out with 10, 20, 30, ... and pick numbers
in the gaps as long as possible. Renumber locally when needed.
Make it possible to move a cursor to a new position.
In the current implementation of Layout and Cursor, this is a trivial
operation, but if we switch to a B-tree based function layout, this
involves navigating the tree.
This is a work in progress. The 'legalizer.rs' file generated by
gen_legalizer.py is not used for anything yet.
Add PEP 484 type annotations to a bunch of Python code.
Rewrite Builder uses in test cases to use this method and construct a
new builder for each instruction. This pattern allows us to change the
InstBuilder trait to a one-shot implementation that can only create a
single instruction.
Don't re-export the Builder struct, it is less important than the
InstBuilder trait, and we may get more implementations.
Give these crates each a more standard directory layout with sources in
a 'src' sub-sirectory and Cargo.toml in the top lib/foo directory.
Add license and description fields to each.
The build script for the cretonne crate now lives in
'lib/cretonne/build.rs' separating it from the normal library sources
under 'lib/cretonne/src'.
