From bc598864289b942b1ebe13d025c4299a32d4c536 Mon Sep 17 00:00:00 2001 From: mlokr Date: Sun, 12 May 2024 14:56:59 +0200 Subject: [PATCH] adding per function dead code elimination --- hblang/examples/structs.hb | 4 +- hblang/src/codegen.rs | 106 +++++++++++++++++++++++-------------- hblang/test.bin | Bin 309 -> 0 bytes 3 files changed, 68 insertions(+), 42 deletions(-) delete mode 100644 hblang/test.bin diff --git a/hblang/examples/structs.hb b/hblang/examples/structs.hb index 68915ee..a91391d 100644 --- a/hblang/examples/structs.hb +++ b/hblang/examples/structs.hb @@ -1,6 +1,6 @@ Ty := struct { - a: int - b: int + a: int, + b: int, } main := fn(): int { diff --git a/hblang/src/codegen.rs b/hblang/src/codegen.rs index ce1bc50..617906d 100644 --- a/hblang/src/codegen.rs +++ b/hblang/src/codegen.rs @@ -42,7 +42,7 @@ pub mod bt { builtin_type! { VOID; - UNREACHABLE; + NEVER; INT; BOOL; } @@ -393,6 +393,8 @@ impl<'a> Codegen<'a> { match *expr { E::Ident { name: "int", .. } => bt::INT, E::Ident { name: "bool", .. } => bt::BOOL, + E::Ident { name: "void", .. } => bt::VOID, + E::Ident { name: "never", .. } => bt::NEVER, E::Ident { id, .. } => { let index = self .records @@ -418,8 +420,9 @@ impl<'a> Codegen<'a> { let stack = self.alloc_stack(size as u32); let mut field_values = fields .iter() - .map(|(name, field)| (*name, self.expr(field, None).unwrap())) - .collect::>(); + .map(|(name, field)| self.expr(field, None).map(|v| (*name, v))) + .collect::>>()?; + let decl_fields = self.records[idx as usize].fields.clone(); let mut offset = 0; for (name, ty) in decl_fields.as_ref() { @@ -442,7 +445,7 @@ impl<'a> Codegen<'a> { }) } E::Field { target, field } => { - let target = self.expr(target, None).unwrap(); + let target = self.expr(target, None)?; let TypeKind::Struct(idx) = TypeKind::from_ty(target.ty) else { panic!("expected struct, got {:?}", target.ty); }; @@ -479,12 +482,12 @@ impl<'a> Codegen<'a> { .map(|&(name, ty)| (name.into(), self.ty(&ty))) .collect(); self.records.push(Struct { id: *id, fields }); - None + Some(Value::VOID) } E::UnOp { op: T::Amp, val, .. } => { - let val = self.expr(val, None).unwrap(); + let val = self.expr(val, None)?; match val.loc { Loc::StackRef(off) => { let reg = self.gpa.allocate(); @@ -504,7 +507,7 @@ impl<'a> Codegen<'a> { E::UnOp { op: T::Star, val, .. } => { - let val = self.expr(val, None).unwrap(); + let val = self.expr(val, None)?; let reg = self.loc_to_reg(val.loc); match TypeKind::from_ty(val.ty) { TypeKind::Pointer(ty) => Some(Value { @@ -542,7 +545,9 @@ impl<'a> Codegen<'a> { self.gpa.init_callee(); self.ret = self.ty(ret); log::dbg!("fn-body"); - self.expr(body, None); + if self.expr(body, None).is_some() { + panic!("expected all paths in the fucntion {name} to return"); + } self.vars.clear(); log::dbg!("fn-relocs"); self.reloc_stack(); @@ -553,28 +558,28 @@ impl<'a> Codegen<'a> { self.ret(); self.stack_size = 0; self.vars.clear(); - None + Some(Value::VOID) } E::BinOp { left: E::Ident { id, .. }, op: T::Decl, right, } => { - let val = self.expr(right, None).unwrap(); + let val = self.expr(right, None)?; let loc = self.make_loc_owned(val.loc, val.ty); let loc = self.ensure_spilled(loc); self.vars.push(Variable { id: *id, value: Value { ty: val.ty, loc }, }); - None + Some(Value::VOID) } E::Call { func: E::Ident { id, .. }, args, } => { for (i, arg) in args.iter().enumerate() { - let arg = self.expr(arg, None).unwrap(); + let arg = self.expr(arg, None)?; let reg = self.loc_to_reg(arg.loc); self.code.encode(instrs::cp(i as Reg + 2, reg.0)); self.gpa.free(reg); @@ -601,7 +606,7 @@ impl<'a> Codegen<'a> { } E::Return { val, .. } => { if let Some(val) = val { - let val = self.expr(val, Some(self.ret)).unwrap(); + let val = self.expr(val, Some(self.ret))?; if val.ty != self.ret { panic!("expected {:?}, got {:?}", self.ret, val.ty); } @@ -623,11 +628,11 @@ impl<'a> Codegen<'a> { } E::Block { stmts, .. } => { for stmt in stmts { - if let Some(Loc::Reg(reg)) = self.expr(stmt, None).map(|v| v.loc) { + if let Loc::Reg(reg) = self.expr(stmt, None)?.loc { self.gpa.free(reg); } } - None + Some(Value::VOID) } E::Number { value, .. } => Some(Value { ty: expeted.unwrap_or(bt::INT), @@ -635,58 +640,68 @@ impl<'a> Codegen<'a> { }), E::If { cond, then, else_, .. - } => { + } => 'b: { log::dbg!("if-cond"); - let cond = self.expr(cond, Some(bt::BOOL)).unwrap(); + let cond = self.expr(cond, Some(bt::BOOL))?; let reg = self.loc_to_reg(cond.loc); let jump_offset = self.code.code.len() as u32; self.code.encode(instrs::jeq(reg.0, 0, 0)); self.gpa.free(reg); log::dbg!("if-then"); - self.expr(then, None); + let then_unreachable = self.expr(then, None).is_none(); + let mut else_unreachable = false; - let jump; + let mut jump = self.code.code.len() as i16 - jump_offset as i16; if let Some(else_) = else_ { log::dbg!("if-else"); let else_jump_offset = self.code.code.len() as u32; - self.code.encode(instrs::jmp(0)); + if !then_unreachable { + self.code.encode(instrs::jmp(0)); + jump = self.code.code.len() as i16 - jump_offset as i16; + } - jump = self.code.code.len() as i16 - jump_offset as i16; + else_unreachable = self.expr(else_, None).is_none(); - self.expr(else_, None); - - let jump = self.code.code.len() as i32 - else_jump_offset as i32; - log::dbg!("if-else-jump: {}", jump); - self.code.code[else_jump_offset as usize + 1..][..4] - .copy_from_slice(&jump.to_ne_bytes()); - } else { - jump = self.code.code.len() as i16 - jump_offset as i16; + if !then_unreachable { + let jump = self.code.code.len() as i32 - else_jump_offset as i32; + log::dbg!("if-else-jump: {}", jump); + self.code.code[else_jump_offset as usize + 1..][..4] + .copy_from_slice(&jump.to_ne_bytes()); + } } log::dbg!("if-then-jump: {}", jump); self.code.code[jump_offset as usize + 3..][..2] .copy_from_slice(&jump.to_ne_bytes()); - None + if then_unreachable && else_unreachable { + break 'b None; + } + + Some(Value::VOID) } - E::Loop { body, .. } => { + E::Loop { body, .. } => 'a: { log::dbg!("loop"); let loop_start = self.code.code.len() as u32; self.loops.push(Loop { offset: loop_start, relocs: Default::default(), }); - self.expr(body, None); + let body_unreachable = self.expr(body, None).is_none(); log::dbg!("loop-end"); - let loop_end = self.code.code.len(); - self.code - .encode(instrs::jmp(loop_start as i32 - loop_end as i32)); + if !body_unreachable { + let loop_end = self.code.code.len(); + self.code + .encode(instrs::jmp(loop_start as i32 - loop_end as i32)); + } + let loop_end = self.code.code.len() as u32; let loop_ = self.loops.pop().unwrap(); + let is_unreachable = loop_.relocs.is_empty(); for reloc in loop_.relocs { let dest = &mut self.code.code [reloc.offset as usize + reloc.instr_offset as usize..] @@ -695,7 +710,12 @@ impl<'a> Codegen<'a> { dest.copy_from_slice(&offset.to_ne_bytes()); } - None + if is_unreachable { + log::dbg!("infinite loop"); + break 'a None; + } + + Some(Value::VOID) } E::Break { .. } => { let loop_ = self.loops.last_mut().unwrap(); @@ -716,8 +736,8 @@ impl<'a> Codegen<'a> { None } E::BinOp { left, op, right } => { - let left = self.expr(left, expeted).unwrap(); - let right = self.expr(right, Some(left.ty)).unwrap(); + let left = self.expr(left, expeted)?; + let right = self.expr(right, Some(left.ty))?; if op == T::Assign { return self.assign(left, right); } @@ -776,7 +796,7 @@ impl<'a> Codegen<'a> { _ => unimplemented!(), } self.gpa.free(rhs); - None + Some(Value::VOID) } fn get_or_reserve_label(&mut self, name: Ident) -> LabelId { @@ -912,6 +932,13 @@ pub struct Value { loc: Loc, } +impl Value { + const VOID: Self = Self { + ty: bt::VOID, + loc: Loc::Imm(0), + }; +} + #[derive(Debug)] enum Loc { Reg(LinReg), @@ -1001,7 +1028,6 @@ mod tests { let mut out = Vec::new(); codegen.dump(&mut out).unwrap(); - std::fs::write("test.bin", &out).unwrap(); use std::fmt::Write; let mut stack = [0_u64; 128]; diff --git a/hblang/test.bin b/hblang/test.bin deleted file mode 100644 index aa3916fb2747c74e24b797a5be5377bf5b8ec918..0000000000000000000000000000000000000000 GIT binary patch literal 0 HcmV?d00001 literal 309 zcmZ{fF%Ezr3`L8HhB$cxuHY$L2rTOTui)rFs|Bfu(T*?wzYmK64FGB++K=nJAtvcG zJURaGQ1dN&EUK*WNW*Qk*c2SM<7seJCP=kI3{}0#xj@Cxb97QTx9sC*%OYpeL|S1k P1r~kt*Y_pAf|2|QaiCZK