These low-level functions allow us to build up a list of instruction
results incrementally. They are equivalent to the existing
attach_ebb_arg and append_ebb_arg.
Instead, just return the first of the detached values, and provide a
next_secondary_result() method for traversing the list.
This is equivalent to how detach_ebb_args() works, and it allows the
data flow graph to be modified while traversing the list of results.
Now that some instruction formats put all of their value arguments in a
value list, we need to know how many value are fixed and how many are
variable_args.
CC @angusholder who may need this information in the verifier.
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.
Instruction formats are now identified by a signature that doesn't
include the ordering of value operands relative to immediate operands.
This means that the BinaryRev instruction format becomes redundant, so
delete it. The isub_imm instruction was the only one using that format.
Rename it to irsub_imm to make it clear what it does now that it is
printed as 'irsub_imm v2, 45'.
Now that variable arguments are always stored in a value list with the
fixed arguments, we no longer need the arcane [&[Value]; 2] return type.
Arguments are always stored contiguously, so just return a &[Value]
slice.
Also remove the each_arg() methods which were just trying to make it
easier to work with the old slice pair.
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.
The Branch format also stores its fixed argument in the value list. This
requires the value pool to be passed to a few more functions.
Note that this actually makes the Branch and Jump variants of
InstructionData identical. The instruction format hashing does not yet
understand that all value operands are stored in the value list. We'll
fix that in a later patch.
Also convert IndirectCall, noting that Call and IndirectCall remain
separate instruction formats because they have different immediate
fields.
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.
Add a Function::display() method which can include ISA-specific
information when printing the function.
If a test file has a unique ISA, use that in the `test cat`
implementation.
Add support for two new type variable functions: half_vector() and
double_vector().
Use these two instructions to break down unsupported SIMD types and
build them up again.
Insert conversion code that reconstructs the original function argument
types from the legalized ABI signature.
Add abi::legalize_abi_value(). This function is used when adapting code
to a legalized function signature.
These two methods can be use to rewrite the argument values to an EBB.
In particular, we need to rewrite the arguments to the entry block to be
compatible with a legalized function signature.
Reuse the put_ebb_arg() method in the implementation of
append_ebb_arg().
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.
