These instructions have a fixed register constraint; the shift amount is
passed in CL.
Add meta language syntax so a fixed register can be specified as
"GPR.rcx".
Tabulate the Intel opcode representations and implement an OP() function
which computes the encoding bits.
Implement the single-byte opcode with a reg-reg ModR/M byte.
These special-purpose arguments and return values are only relevant for
the function being compiled, so add a `current` flag to
legalize_signature().
- Add the necessary argument values to the entry block to represent
the special-purpose arguments.
- Propagate the link and sret arguments to return instructions if the
legalized signature asks for it.
When converting from ABI types to original program types, the final
conversion instruction can place its result into the original value, so
it doesn't need to be changed to an alias.
Now that we can detach and reuse all values, there is no longer a need
to create a lot of alias values during pattern expansion. Instead, reuse
the values from the source pattern when emitting instructions in the
destination pattern.
If a destination instruction produces the exact same values as a source
instruction, simply leave the values attached and replace the
instruction it. Otherwise, detach the source values, reuse them in the
expansion, and remove the source instruction afterwards.
All values are now references into the value table, so drop the
distinction between direct and table values. Direct values don't exist
any more.
Also remove the parser support for the 'vxNN' syntax. Only 'vNN' values
can be parsed now.
We only ever create table values now.
Simplify legalizer::legalize_inst_results. Instead of calling
detach_secondary_results, just detach all the results and don't treat
the first result specially.
This affects the comparison instructions which now read "icmp ult a, b".
This mimics LLVM's style and makes it simpler to add instruction flags
in the future, such as "load v1" -> "load aligned v1".
These enumerated operands and flags feel like opcode modifiers rather
than value operands, so displaying them differently makes sense.
Value and numeric operands are still comma separated.
Not all br_icmp opcodes are present in the ISA. The missing ones can be
reached by commuting operands.
Don't attempt to encode EBB offsets yet. For now just emit an EBB
relocation for the branch instruction.
The carry and borrow values are boolean, so we have to convert them to
an integer type with bint(c) before we can add them to the result.
Also tweak the default legalizer action for unsupported types: Only
attempt a narrowing pattern for lane types > 32 bits.
This was found by @angusholder's new type checks in the verifier.
If an instruction doesn't have an associated encoding, use the standard
TargetIsa hook to encode it.
The test still fails if an instruction can't be encoded. There is no
legalization step.
The EBB argument splitting may generate concat-split dependencies when
it repairs branch arguments in EBBs that have not yet been fully
legalized. Add a branch argument simplification step that can resolve
these dependency chains.
This means that all split and concatenation instructions will be dead
after legalization for types that have no legal instructions using them.
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.
The legalizer often splits values into parts with the vsplit and
isplit_lohi instructions. Avoid doing that for values that are already
defined by the corresponding concatenation instructions.
This reduces the number of instructions created during legalization, and
it simplifies later optimizations. A number of dead concatenation
instructions are left behind. They can be trivially cleaned up by a dead
code elimination pass.
The call arguments on call_indirect should not include the fixed callee
argument.
Add legalizer assertions to verify that signatures are actually valid
after legalization. If not, we would get infinite legalizer loops.
Like the entry block arguments, the return values from a call
instruction need to be converted back from their ABI representation.
Add tests of call instruction legalization.
- abi.cton is for testing the actual RISC-V ABI.
- legalize-abi.cton is for testing the legalizer around ABI boundaries.
- parse-encoding.cton is for testing the parser's handling of RISC-V
encoding and register annotations.
The type signatures of functions can change when they are legalized for
a specific ABI. This means that all call and return instructions need to
be rewritten to use the correct arguments.
- Fix arguments to call instructions.
- Fix arguments to return instructions.
TBD:
- Fix return values from call instructions.
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.
Add an abi module with code that is probably useful to all ISAs when
implementing this function.
Add a unit() method to RegClassData which can be used to index the
register units in a class.
Since we're deconstructing an instruction anyway, go ahead and resolve
any value aliases on its arguments before we construct the replacement
instructions.
If a secondary value in the source pattern becomes a primary value in
the destination pattern, it is not possible to overwrite the definition
of the source value.
Instead, change the original source value to an alias to the new promary
value.
When expanding iadd_cout, the original instruction is replaced with an
iadd, and an icmp is inserted after the iadd.
Make sure we advance the insertion position after replacing iadd_cout so
the icmp gets inserted *after* iadd.
Include the test file preamble comments when building a filecheck
instance for every function in the file.
This makes it possible to define common regex variables in the preamble
and use these definitions for all the functions.
When an illegal instruction is replaced with other instructions, back up
and revisit the expanded instructions. The new instructions need to have
encodings assigned too.
This also allows for expansions to contain illegal instructions that
need to be legalized themselves.
