Allow some flexibility in the signature matching for instruction
formats. In particular, look for a value list format as a second chance
option.
The Return, ReturnReg, and TernaryOverflow formats all fit the single
MultiAry catch-all format for instructions without immediate operands.
No instruction sets actually have single instructions for materializing
vector constants. You always need to use a constant pool.
Cretonne doesn't have constant pools yet, but it will in the future, and
that is how vector constants should be represented.
With the Return and ReturnReg formats converted to using value lists for
storing their arguments, thee are no remaining instruction formats with
variable argument lists in boxed storage.
The Return and ReturnReg formats are also going to be merged since
they are identical now.
Add a new kind of instruction format that keeps all of its value
arguments in a value list. These value lists are all allocated out of
the dfg.value_lists memory pool.
Instruction formats with the value_list property set store *all* of
their value arguments in a single value list. There is no distinction
between fixed arguments and variable arguments.
Change the Call instruction format to use the value list representation
for its arguments.
This change is only the beginning. The intent is to eliminate the
boxed_storage instruction formats completely. Value lists use less
memory, and when the transition is complete, InstructionData will have a
trivial Drop implementation.
- 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.
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.
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.
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.
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'.
