WIP.

src/passes/basic_opt.rs

@@ -5,6 +5,7 @@ use crate::ir::*;
 use crate::op_traits::is_pure;
 use crate::passes::dom_pass::{dom_pass, DomtreePass};
 use crate::scoped_map::ScopedMap;
+use crate::Operator;
 
 pub fn gvn(body: &mut FunctionBody, cfg: &CFGInfo) {
     dom_pass::<GVNPass>(body, cfg, &mut GVNPass::default());
@@ -33,6 +34,150 @@ fn value_is_pure(value: Value, body: &FunctionBody) -> bool {
     }
 }
 
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+enum ConstVal {
+    I32(u32),
+    I64(u64),
+    None,
+}
+
+fn const_eval(op: &Operator, vals: &[ConstVal]) -> Option<ConstVal> {
+    match (op, vals) {
+        (Operator::I32Const { value }, []) => Some(ConstVal::I32(*value as u32)),
+        (Operator::I64Const { value }, []) => Some(ConstVal::I64(*value as u64)),
+        (Operator::I32Eqz, [ConstVal::I32(a)]) => Some(ConstVal::I32(if *a == 0 { 1 } else { 0 })),
+        (Operator::I32Eq, [ConstVal::I32(a), ConstVal::I32(b)]) => {
+            Some(ConstVal::I32(if a == b { 1 } else { 0 }))
+        }
+        (Operator::I32Ne, [ConstVal::I32(a), ConstVal::I32(b)]) => {
+            Some(ConstVal::I32(if a != b { 1 } else { 0 }))
+        }
+        (Operator::I32LtS, [ConstVal::I32(a), ConstVal::I32(b)]) => {
+            Some(ConstVal::I32(if (*a as i32) < (*b as i32) { 1 } else { 0 }))
+        }
+        (Operator::I32LtU, [ConstVal::I32(a), ConstVal::I32(b)]) => {
+            Some(ConstVal::I32(if a < b { 1 } else { 0 }))
+        }
+        (Operator::I32GtS, [ConstVal::I32(a), ConstVal::I32(b)]) => {
+            Some(ConstVal::I32(if (*a as i32) > (*b as i32) { 1 } else { 0 }))
+        }
+        (Operator::I32GtU, [ConstVal::I32(a), ConstVal::I32(b)]) => {
+            Some(ConstVal::I32(if a > b { 1 } else { 0 }))
+        }
+        (Operator::I32LeS, [ConstVal::I32(a), ConstVal::I32(b)]) => {
+            Some(ConstVal::I32(if (*a as i32) <= (*b as i32) {
+                1
+            } else {
+                0
+            }))
+        }
+        (Operator::I32LeU, [ConstVal::I32(a), ConstVal::I32(b)]) => {
+            Some(ConstVal::I32(if a <= b { 1 } else { 0 }))
+        }
+        (Operator::I32GeS, [ConstVal::I32(a), ConstVal::I32(b)]) => {
+            Some(ConstVal::I32(if (*a as i32) >= (*b as i32) {
+                1
+            } else {
+                0
+            }))
+        }
+        (Operator::I32GeU, [ConstVal::I32(a), ConstVal::I32(b)]) => {
+            Some(ConstVal::I32(if a >= b { 1 } else { 0 }))
+        }
+        (Operator::I64Eqz, [ConstVal::I64(a)]) => Some(ConstVal::I64(if *a == 0 { 1 } else { 0 })),
+        (Operator::I64Eq, [ConstVal::I64(a), ConstVal::I64(b)]) => {
+            Some(ConstVal::I64(if a == b { 1 } else { 0 }))
+        }
+        (Operator::I64Ne, [ConstVal::I64(a), ConstVal::I64(b)]) => {
+            Some(ConstVal::I64(if a != b { 1 } else { 0 }))
+        }
+        (Operator::I64LtS, [ConstVal::I64(a), ConstVal::I64(b)]) => {
+            Some(ConstVal::I64(if (*a as i64) < (*b as i64) { 1 } else { 0 }))
+        }
+        (Operator::I64LtU, [ConstVal::I64(a), ConstVal::I64(b)]) => {
+            Some(ConstVal::I64(if a < b { 1 } else { 0 }))
+        }
+        (Operator::I64GtS, [ConstVal::I64(a), ConstVal::I64(b)]) => {
+            Some(ConstVal::I64(if (*a as i64) > (*b as i64) { 1 } else { 0 }))
+        }
+        (Operator::I64GtU, [ConstVal::I64(a), ConstVal::I64(b)]) => {
+            Some(ConstVal::I64(if a > b { 1 } else { 0 }))
+        }
+        (Operator::I64LeS, [ConstVal::I64(a), ConstVal::I64(b)]) => {
+            Some(ConstVal::I64(if (*a as i64) <= (*b as i64) {
+                1
+            } else {
+                0
+            }))
+        }
+        (Operator::I64LeU, [ConstVal::I64(a), ConstVal::I64(b)]) => {
+            Some(ConstVal::I64(if a <= b { 1 } else { 0 }))
+        }
+        (Operator::I64GeS, [ConstVal::I64(a), ConstVal::I64(b)]) => {
+            Some(ConstVal::I64(if (*a as i64) >= (*b as i64) {
+                1
+            } else {
+                0
+            }))
+        }
+        (Operator::I64GeU, [ConstVal::I64(a), ConstVal::I64(b)]) => {
+            Some(ConstVal::I64(if a >= b { 1 } else { 0 }))
+        }
+
+        (Operator::I32Add, [ConstVal::I32(a), ConstVal::I32(b)]) => {
+            Some(ConstVal::I32(a.wrapping_add(*b)))
+        }
+        (Operator::I32Sub, [ConstVal::I32(a), ConstVal::I32(b)]) => {
+            Some(ConstVal::I32(a.wrapping_sub(*b)))
+        }
+        (Operator::I32Mul, [ConstVal::I32(a), ConstVal::I32(b)]) => {
+            Some(ConstVal::I32(a.wrapping_mul(*b)))
+        }
+        (Operator::I32And, [ConstVal::I32(a), ConstVal::I32(b)]) => Some(ConstVal::I32(a & b)),
+        (Operator::I32Or, [ConstVal::I32(a), ConstVal::I32(b)]) => Some(ConstVal::I32(a | b)),
+        (Operator::I32Xor, [ConstVal::I32(a), ConstVal::I32(b)]) => Some(ConstVal::I32(a ^ b)),
+        (Operator::I32Shl, [ConstVal::I32(a), ConstVal::I32(b)]) => Some(ConstVal::I32(a << b)),
+        (Operator::I32ShrS, [ConstVal::I32(a), ConstVal::I32(b)]) => {
+            Some(ConstVal::I32(((*a as i32) >> (*b as i32)) as u32))
+        }
+
+        (Operator::I32ShrU, [ConstVal::I32(a), ConstVal::I32(b)]) => Some(ConstVal::I32(a >> b)),
+
+        (Operator::I64Add, [ConstVal::I64(a), ConstVal::I64(b)]) => {
+            Some(ConstVal::I64(a.wrapping_add(*b)))
+        }
+        (Operator::I64Sub, [ConstVal::I64(a), ConstVal::I64(b)]) => {
+            Some(ConstVal::I64(a.wrapping_sub(*b)))
+        }
+        (Operator::I64Mul, [ConstVal::I64(a), ConstVal::I64(b)]) => {
+            Some(ConstVal::I64(a.wrapping_mul(*b)))
+        }
+        (Operator::I64And, [ConstVal::I64(a), ConstVal::I64(b)]) => Some(ConstVal::I64(a & b)),
+        (Operator::I64Or, [ConstVal::I64(a), ConstVal::I64(b)]) => Some(ConstVal::I64(a | b)),
+        (Operator::I64Xor, [ConstVal::I64(a), ConstVal::I64(b)]) => Some(ConstVal::I64(a ^ b)),
+        (Operator::I64Shl, [ConstVal::I64(a), ConstVal::I64(b)]) => Some(ConstVal::I64(a << b)),
+        (Operator::I64ShrS, [ConstVal::I64(a), ConstVal::I64(b)]) => {
+            Some(ConstVal::I64(((*a as i64) >> (*b as i64)) as u64))
+        }
+
+        (Operator::I64ShrU, [ConstVal::I64(a), ConstVal::I64(b)]) => Some(ConstVal::I64(a >> b)),
+
+        (Operator::I32Extend8S, [ConstVal::I32(a)]) => Some(ConstVal::I32(*a as i8 as i32 as u32)),
+        (Operator::I32Extend16S, [ConstVal::I32(a)]) => {
+            Some(ConstVal::I32(*a as i16 as i32 as u32))
+        }
+        (Operator::I64Extend8S, [ConstVal::I64(a)]) => Some(ConstVal::I64(*a as i8 as i64 as u64)),
+        (Operator::I64Extend16S, [ConstVal::I64(a)]) => {
+            Some(ConstVal::I64(*a as i16 as i64 as u64))
+        }
+        (Operator::I64Extend32S, [ConstVal::I64(a)]) => {
+            Some(ConstVal::I64(*a as i32 as i64 as u64))
+        }
+
+        _ => None,
+    }
+}
+
 impl GVNPass {
     fn optimize(&mut self, block: Block, body: &mut FunctionBody) {
         let mut i = 0;
@@ -42,14 +187,51 @@ impl GVNPass {
             if value_is_pure(inst, body) {
                 let mut value = body.values[inst].clone();
                 value.update_uses(|val| *val = body.resolve_alias(*val));
+
+                if let ValueDef::Operator(op, args, ..) = &value {
+                    let arg_values = args
+                        .iter()
+                        .map(|&arg| match body.values[arg] {
+                            ValueDef::Operator(Operator::I32Const { value }, _, _) => {
+                                ConstVal::I32(value as u32)
+                            }
+                            ValueDef::Operator(Operator::I64Const { value }, _, _) => {
+                                ConstVal::I64(value as u64)
+                            }
+                            _ => ConstVal::None,
+                        })
+                        .collect::<Vec<_>>();
+                    let const_val = const_eval(op, &arg_values[..]);
+                    match const_val {
+                        Some(ConstVal::I32(val)) => {
+                            value = ValueDef::Operator(
+                                Operator::I32Const { value: val as i32 },
+                                vec![],
+                                vec![Type::I32],
+                            );
+                            body.values[inst] = value.clone();
+                        }
+                        Some(ConstVal::I64(val)) => {
+                            value = ValueDef::Operator(
+                                Operator::I64Const { value: val as i64 },
+                                vec![],
+                                vec![Type::I64],
+                            );
+                            body.values[inst] = value.clone();
+                        }
+                        _ => {}
+                    }
+                }
+
                 if let Some(value) = self.map.get(&value) {
                     body.set_alias(inst, *value);
                     i -= 1;
                     body.blocks[block].insts.remove(i);
-                } else {
+                    continue;
+                }
+
                 self.map.insert(value, inst);
             }
         }
     }
-    }
 }