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Simple preopt: fold binary opcodes chains together;

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This commit is contained in:
Benjamin Bouvier
2019-07-05 12:24:35 +02:00
parent dc58a5fc5c
commit 141b45e0e1
1 changed files with 44 additions and 0 deletions
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44
cranelift/codegen/src/simple_preopt.rs
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@@ -501,6 +501,9 @@ fn simplify(pos: &mut FuncCursor, inst: Inst) {
.dfg
.replace(inst)
.BinaryImm(new_opcode, ty, imm, args[0]);
// Repeat for BinaryImm simplification.
simplify(pos, inst);
} else if let Some(imm) = resolve_imm64_value(&pos.func.dfg, args[0]) {
let new_opcode = match opcode {
Opcode::Isub => Opcode::IrsubImm,
@@ -524,6 +527,47 @@ fn simplify(pos: &mut FuncCursor, inst: Inst) {
_ => {}
},
InstructionData::BinaryImm { opcode, arg, imm } => match opcode {
Opcode::IaddImm
| Opcode::ImulImm
| Opcode::BorImm
| Opcode::BandImm
| Opcode::BxorImm => {
// Fold binary_op(C2, binary_op(C1, x)) into binary_op(binary_op(C1 | C2), x)
if let ValueDef::Result(arg_inst, _) = pos.func.dfg.value_def(arg) {
if let InstructionData::BinaryImm {
opcode: prev_opcode,
arg: prev_arg,
imm: prev_imm,
} = &pos.func.dfg[arg_inst]
{
if opcode == *prev_opcode {
let ty = pos.func.dfg.ctrl_typevar(inst);
if ty == pos.func.dfg.ctrl_typevar(arg_inst) {
let lhs: i64 = imm.into();
let rhs: i64 = (*prev_imm).into();
let new_imm = match opcode {
Opcode::BorImm => lhs | rhs,
Opcode::BandImm => lhs & rhs,
Opcode::BxorImm => lhs ^ rhs,
Opcode::IaddImm => lhs.wrapping_add(rhs),
Opcode::ImulImm => lhs.wrapping_mul(rhs),
_ => panic!("can't happen"),
};
let new_imm = immediates::Imm64::from(new_imm);
let arg = *prev_arg;
pos.func
.dfg
.replace(inst)
.BinaryImm(opcode, ty, new_imm, arg);
}
}
}
}
}
_ => {}
},
InstructionData::IntCompare { opcode, cond, args } => {
debug_assert_eq!(opcode, Opcode::Icmp);
if let Some(imm) = resolve_imm64_value(&pos.func.dfg, args[1]) {