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//! Peephole optimizations that can be performed while creating clif ir.
use cranelift_codegen::ir::{
condcodes::IntCC, types, InstBuilder, InstructionData, Opcode, Value, ValueDef,
};
use cranelift_frontend::FunctionBuilder;
/// If the given value was produced by a `bint` instruction, return it's input, otherwise return the
/// given value.
pub(crate) fn maybe_unwrap_bint(bcx: &mut FunctionBuilder<'_>, arg: Value) -> Value {
if let ValueDef::Result(arg_inst, 0) = bcx.func.dfg.value_def(arg) {
match bcx.func.dfg[arg_inst] {
InstructionData::Unary {
opcode: Opcode::Bint,
arg,
} => arg,
_ => arg,
}
} else {
arg
}
}
/// If the given value was produced by the lowering of `Rvalue::Not` return the input and true,
/// otherwise return the given value and false.
pub(crate) fn maybe_unwrap_bool_not(bcx: &mut FunctionBuilder<'_>, arg: Value) -> (Value, bool) {
if let ValueDef::Result(arg_inst, 0) = bcx.func.dfg.value_def(arg) {
match bcx.func.dfg[arg_inst] {
// This is the lowering of `Rvalue::Not`
InstructionData::IntCompareImm {
opcode: Opcode::IcmpImm,
cond: IntCC::Equal,
arg,
imm,
} if imm.bits() == 0 => (arg, true),
_ => (arg, false),
}
} else {
(arg, false)
}
}
pub(crate) fn make_branchable_value(bcx: &mut FunctionBuilder<'_>, arg: Value) -> Value {
if bcx.func.dfg.value_type(arg).is_bool() {
return arg;
}
(|| {
let arg_inst = if let ValueDef::Result(arg_inst, 0) = bcx.func.dfg.value_def(arg) {
arg_inst
} else {
return None;
};
match bcx.func.dfg[arg_inst] {
// This is the lowering of Rvalue::Not
InstructionData::Load {
opcode: Opcode::Load,
arg: ptr,
flags,
offset,
} => {
// Using `load.i8 + uextend.i32` would legalize to `uload8 + ireduce.i8 +
// uextend.i32`. Just `uload8` is much faster.
match bcx.func.dfg.ctrl_typevar(arg_inst) {
types::I8 => Some(bcx.ins().uload8(types::I32, flags, ptr, offset)),
types::I16 => Some(bcx.ins().uload16(types::I32, flags, ptr, offset)),
_ => None,
}
}
_ => None,
}
})()
.unwrap_or_else(|| {
match bcx.func.dfg.value_type(arg) {
types::I8 | types::I16 => {
// WORKAROUND for brz.i8 and brnz.i8 not yet being implemented
bcx.ins().uextend(types::I32, arg)
}
_ => arg,
}
})
}
/// Returns whether the branch is statically known to be taken or `None` if it isn't statically known.
pub(crate) fn maybe_known_branch_taken(
bcx: &FunctionBuilder<'_>,
arg: Value,
test_zero: bool,
) -> Option<bool> {
let arg_inst = if let ValueDef::Result(arg_inst, 0) = bcx.func.dfg.value_def(arg) {
arg_inst
} else {
return None;
};
match bcx.func.dfg[arg_inst] {
InstructionData::UnaryBool {
opcode: Opcode::Bconst,
imm,
} => {
if test_zero {
Some(!imm)
} else {
Some(imm)
}
}
InstructionData::UnaryImm {
opcode: Opcode::Iconst,
imm,
} => {
if test_zero {
Some(imm.bits() == 0)
} else {
Some(imm.bits() != 0)
}
}
_ => None,
}
}
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