This entry point will be used for controlling ABI conventions when
legalizing.
Provide an empty implementation for RISC-V and let the other ISAs crash
in legalization.
This is just the scaffolding. We still need to:
- Rewrite the entry block arguments to match the legalized signature.
- Rewrite call and return instructions.
- Implement the legalize_signature() function for all ISAs.
- Add shared generic types to help with the legalize_signature()
functions.
Specify the location of arguments as well as the size of stack argument
array needed. The ABI annotations are optional, just like the value
locations.
Remove the Eq implementation for Signature which was only used by a
single parser test.
Some polymorphic instructions don't return the controlling type
variable, so it has to be computed from the designated operand instead.
- Add a requires_typevar_operand() method to the operand constraints
which indicates that.
- Add a ctrl_typevar(dfg) method to InstructionData which computes the
controlling type variable correctly, and returns VOID for monomorphic
instructions.
- Use ctrl_typevar(dfg) to drive the level-1 encoding table lookups.
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.
- Remove NO_VALUE and ExpandedValue::None.
- Remove the Default implelmentation for Value.
- InstructionData::second_result() returns an Option<Value>.
- InstructionData::second_result() returns a reference to the packed
option.
This was only used for the comment rewrite mechanism, and we can just
predict the next allocated instruction number instead. See the other
uses of next_key() for gather_comments().
We will track live ranges separately for each SSA value, rather than per
virtual register like LLVM does.
This is the basis for a register allocator, so place it in a new
regalloc module.
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.
for InstructionData. Use generated `is_terminator()` for `Opcode`
instead. `is_terminator`, `can_trap` and `is_branch` functions are now
public.
fix syntax error
When the extended_values table is empty, the value to resolve is
definitely not an alias, but we still need as least one trip in the loop
to determine that.
Provide a generic way of accessing the value arguments on an
instruction. This is provided as two slice references. One for the fixed
arguments and one for any VariableArgs.
The arguments() methods return an array of two slices which is a bit
awkward. Also provide an each_arg() method which passes each argument
value to a closure.
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.
A extended value can now be changed to a third form: An alias of another
value. This is like a copy instruction, but implicit in the value table.
Value aliases are used in lieu of use-def chains which would be used to
implement replace-all-uses-with.
Added new DFG methods:
- change_to_alias() changes an existing extended value into an alias.
Primay values can't be changed, replace their definition with a copy
instruction instead.
- resolve_aliases() find the original non-alias value.
- resolve_copies() like resolve_aliases(), but also sees through
copy/spill/fill instructions.
Polymorphic single-result instructions don't always return the
controlling type variable as their first result. They may use a derived
type variable, as for example icmp does.
All scalar types are mapped to b1 which is usually what you want for a
scalar. Vector types have their lanes mapped to the wider boolean types.
Add an as_bool_pedantic() methos that produces the scalar sized boolean
types as before.
Also add a friendlier Debug implementation for Type.
The DataFlowGraph::replace(inst) method returns an instruction builder
that will replace an instruction in-place.
This will be used when transforming instructions, replacing an old
instruction with a new (legal) way of computing its primary value. Since
primary result values are essentially instruction pointers, this is the
only way of replacing the definition of a value.
If secondary result values match the old instruction in both number and
types, they can be reused. If not, added a detach_secondary_results()
method for detaching old secondary values.
All the InstrBuilder methods now consume the builder, and the non-leaf
methods return the dfg mutable reference they were holding.
This makes it possible to construct instruction builders that are only
safe to use once because they are doing more advanced value rewriting.
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.
Distinguish the lifetime of the Cursor and its referenced function
layout.
Use two separate function lifetimes: 'fc and 'fd. The borrow checker
seems to get confused if we don't.
All of the instruction format an opcode methods are emitted as an
InstBuilder trait instead of adding them to the Bulder struct directly.
The methods only make use of the InstBuilderBase methods to create new
instructions.
This makes it possible to reuse the InstBuilder trait for different ways
of inserting instructions.
