T0b1/wasmtime
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Expand OpcodeConstraints to 32 bits.

Browse Source 
Make room for 255 different type sets and 2^16 entries in the operand
constraints table.
This commit is contained in:
Jakob Stoklund Olesen
2016-09-27 16:09:26 -07:00
parent d256c46f60
commit 2a4aaa3da1
2 changed files with 36 additions and 36 deletions
Download Patch File Download Diff File Expand all files Collapse all files

57
cranelift/src/libcretonne/ir/instructions.rs
View File

@@ -398,52 +398,49 @@ pub enum BranchInfo<'a> {
/// The `InstructionFormat` determines the constraints on most operands, but `Value` operands and
/// results are not determined by the format. Every `Opcode` has an associated
/// `OpcodeConstraints` object that provides the missing details.
///
/// Since there can be a lot of opcodes, the `OpcodeConstraints` object is encoded as a bit field
/// by the `meta/gen_instr.py` script.
///
/// The bit field bits are:
///
/// Bits 0-2:
/// Number of fixed result values. This does not include `variable_args` results as are
/// produced by call instructions.
///
/// Bit 3:
/// This opcode is polymorphic and the controlling type variable can be inferred from the
/// designated input operand. This is the `typevar_operand` index given to the
/// `InstructionFormat` meta language object. When bit 0 is not set, the controlling type
/// variable must be the first output value instead.
///
/// Bits 4-7:
/// Permitted set of types for the controlling type variable as an index into `TYPE_SETS`.
///
/// Bits 8-15:
/// Offset into `OPERAND_CONSTRAINT` table of the descriptors for this opcode. The first
/// `fixed_results()` entries describe the result constraints, then follows constraints for the
/// fixed `Value` input operands. The number of `Value` inputs isdetermined by the instruction
/// format.
///
#[derive(Clone, Copy)]
pub struct OpcodeConstraints(u16);
pub struct OpcodeConstraints {
/// Flags for this opcode encoded as a bit field:
///
/// Bits 0-2:
/// Number of fixed result values. This does not include `variable_args` results as are
/// produced by call instructions.
///
/// Bit 3:
/// This opcode is polymorphic and the controlling type variable can be inferred from the
/// designated input operand. This is the `typevar_operand` index given to the
/// `InstructionFormat` meta language object. When bit 0 is not set, the controlling type
/// variable must be the first output value instead.
flags: u8,
/// Permitted set of types for the controlling type variable as an index into `TYPE_SETS`.
typeset_offset: u8,
/// Offset into `OPERAND_CONSTRAINT` table of the descriptors for this opcode. The first
/// `fixed_results()` entries describe the result constraints, then follows constraints for the
/// fixed `Value` input operands. The number of `Value` inputs is determined by the instruction
/// format.
constraint_offset: u16,
}
impl OpcodeConstraints {
/// Can the controlling type variable for this opcode be inferred from the designated value
/// input operand?
/// This also implies that this opcode is polymorphic.
pub fn use_typevar_operand(self) -> bool {
(self.0 & 0x8) != 0
(self.flags & 0x8) != 0
}
/// Get the number of *fixed* result values produced by this opcode.
/// This does not include `variable_args` produced by calls.
pub fn fixed_results(self) -> usize {
(self.0 & 0x7) as usize
(self.flags & 0x7) as usize
}
/// Get the offset into `TYPE_SETS` for the controlling type variable.
/// Returns `None` if the instruction is not polymorphic.
fn typeset_offset(self) -> Option<usize> {
let offset = ((self.0 & 0xff) >> 4) as usize;
let offset = self.typeset_offset as usize;
if offset < TYPE_SETS.len() {
Some(offset)
} else {
@@ -453,7 +450,7 @@ impl OpcodeConstraints {
/// Get the offset into OPERAND_CONSTRAINTS where the descriptors for this opcode begin.
fn constraint_offset(self) -> usize {
(self.0 >> 8) as usize
self.constraint_offset as usize
}
/// Get the value type of result number `n`, having resolved the controlling type variable to