67 lines
2.2 KiB
Rust
67 lines
2.2 KiB
Rust
//! Peephole optimizations that can be performed while creating clif ir.
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use cranelift_codegen::ir::{condcodes::IntCC, InstructionData, Opcode, Value, ValueDef};
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use cranelift_frontend::FunctionBuilder;
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/// If the given value was produced by a `bint` instruction, return it's input, otherwise return the
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/// given value.
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pub(crate) fn maybe_unwrap_bint(bcx: &mut FunctionBuilder<'_>, arg: Value) -> Value {
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if let ValueDef::Result(arg_inst, 0) = bcx.func.dfg.value_def(arg) {
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match bcx.func.dfg[arg_inst] {
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InstructionData::Unary { opcode: Opcode::Bint, arg } => arg,
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_ => arg,
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}
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} else {
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arg
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}
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}
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/// If the given value was produced by the lowering of `Rvalue::Not` return the input and true,
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/// otherwise return the given value and false.
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pub(crate) fn maybe_unwrap_bool_not(bcx: &mut FunctionBuilder<'_>, arg: Value) -> (Value, bool) {
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if let ValueDef::Result(arg_inst, 0) = bcx.func.dfg.value_def(arg) {
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match bcx.func.dfg[arg_inst] {
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// This is the lowering of `Rvalue::Not`
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InstructionData::IntCompareImm {
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opcode: Opcode::IcmpImm,
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cond: IntCC::Equal,
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arg,
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imm,
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} if imm.bits() == 0 => (arg, true),
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_ => (arg, false),
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}
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} else {
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(arg, false)
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}
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}
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/// Returns whether the branch is statically known to be taken or `None` if it isn't statically known.
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pub(crate) fn maybe_known_branch_taken(
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bcx: &FunctionBuilder<'_>,
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arg: Value,
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test_zero: bool,
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) -> Option<bool> {
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let arg_inst = if let ValueDef::Result(arg_inst, 0) = bcx.func.dfg.value_def(arg) {
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arg_inst
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} else {
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return None;
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};
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match bcx.func.dfg[arg_inst] {
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InstructionData::UnaryBool { opcode: Opcode::Bconst, imm } => {
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if test_zero {
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Some(!imm)
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} else {
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Some(imm)
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}
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}
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InstructionData::UnaryImm { opcode: Opcode::Iconst, imm } => {
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if test_zero {
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Some(imm.bits() == 0)
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} else {
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Some(imm.bits() != 0)
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}
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}
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_ => None,
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}
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}
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