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ir_opt.odin 19.5 KB · Plain text
package shader

import "core:fmt"

// IR optimization passes

optimize :: proc(module: ^IR_Module, level: Opt_Level) {
	if level == .None do return

	opt_constant_fold(module)
	opt_copy_propagation(module)
	opt_cse(module)
	opt_dead_code_elim(module)

	if level == .Aggressive {
		// Second pass catches new opportunities
		opt_constant_fold(module)
		opt_copy_propagation(module)
		opt_cse(module)
		opt_dead_code_elim(module)
	}
}

// -- Constant Folding --

opt_constant_fold :: proc(module: ^IR_Module) {
	for &fn in module.functions {
		opt_fold_stmts(fn.body[:])
	}
}

@(private = "file")
opt_fold_stmts :: proc(stmts: []IR_Stmt) {
	for &stmt in stmts {
		switch s in stmt {
		case ^IR_Let:
			s.value = opt_fold_expr(s.value)
		case ^IR_Assign:
			s.value = opt_fold_expr(s.value)
		case ^IR_Return:
			s.value = opt_fold_expr(s.value)
		case ^IR_Store_Output:
			s.value = opt_fold_expr(s.value)
		case ^IR_If:
			s.condition = opt_fold_expr(s.condition)
			opt_fold_stmts(s.then_body[:])
			for &ei in s.elseif_clauses {
				ei.condition = opt_fold_expr(ei.condition)
				opt_fold_stmts(ei.body[:])
			}
			opt_fold_stmts(s.else_body[:])
		case ^IR_For:
			s.start = opt_fold_expr(s.start)
			s.stop = opt_fold_expr(s.stop)
			s.step = opt_fold_expr(s.step)
			opt_fold_stmts(s.body[:])
		case ^IR_While:
			s.condition = opt_fold_expr(s.condition)
			opt_fold_stmts(s.body[:])
		case ^IR_Expr_Stmt:
			s.expr = opt_fold_expr(s.expr)
		case ^IR_Barrier:
			// no-op
		case ^IR_Discard:
			// no-op
		case ^IR_Break:
			// no-op
		case ^IR_Continue:
			// no-op
		}
	}
}

@(private = "file")
opt_fold_expr :: proc(expr: ^IR_Expr) -> ^IR_Expr {
	if expr == nil do return nil

	switch d in expr.derived {
	case ^IR_Binary:
		d.left = opt_fold_expr(d.left)
		d.right = opt_fold_expr(d.right)

		// Try to fold constant binary ops
		left_lit := get_literal(d.left)
		right_lit := get_literal(d.right)
		if left_lit != nil && right_lit != nil {
			if result, ok := fold_binary(d.op, left_lit, right_lit); ok {
				return make_literal_expr(result, expr.type)
			}
		}

		// Algebraic simplifications
		if right_lit != nil {
			// x * 1.0 -> x
			if d.op == .Mul {
				if is_float_one(right_lit) do return d.left
				if is_float_zero(right_lit) do return make_literal_expr(f64(0.0), expr.type)
			}
			// x + 0.0 -> x, x - 0.0 -> x
			if (d.op == .Add || d.op == .Sub) && is_float_zero(right_lit) {
				return d.left
			}
		}
		if left_lit != nil {
			// 1.0 * x -> x
			if d.op == .Mul && is_float_one(left_lit) {
				return d.right
			}
			// 0.0 * x -> 0
			if d.op == .Mul && is_float_zero(left_lit) {
				return make_literal_expr(f64(0.0), expr.type)
			}
			// 0.0 + x -> x
			if d.op == .Add && is_float_zero(left_lit) {
				return d.right
			}
		}

	case ^IR_Unary:
		d.operand = opt_fold_expr(d.operand)
		lit := get_literal(d.operand)
		if lit != nil {
			if result, ok := fold_unary(d.op, lit); ok {
				return make_literal_expr(result, expr.type)
			}
		}

	case ^IR_Call:
		for &arg in d.args {
			arg = opt_fold_expr(arg)
		}

	case ^IR_Field_Access:
		d.object = opt_fold_expr(d.object)

	case ^IR_Swizzle:
		d.object = opt_fold_expr(d.object)

	case ^IR_Composite_Extract:
		d.object = opt_fold_expr(d.object)

	case ^IR_Vector_Shuffle:
		d.object = opt_fold_expr(d.object)

	case ^IR_Index:
		d.object = opt_fold_expr(d.object)
		d.index = opt_fold_expr(d.index)

	case ^IR_Construct:
		for &arg in d.args {
			arg = opt_fold_expr(arg)
		}

	case ^IR_Type_Cast:
		d.value = opt_fold_expr(d.value)

	case ^IR_Select:
		d.condition = opt_fold_expr(d.condition)
		d.true_val = opt_fold_expr(d.true_val)
		d.false_val = opt_fold_expr(d.false_val)

	case ^IR_Literal, ^IR_Var_Ref, ^IR_Load_Binding, ^IR_Input_Field, ^IR_Builtin_Var, ^IR_Shared_Ref:
		// leaf nodes, nothing to fold
	}

	return expr
}

@(private = "file")
get_literal :: proc(expr: ^IR_Expr) -> ^IR_Literal {
	if expr == nil do return nil
	lit, ok := expr.derived.(^IR_Literal)
	return ok ? lit : nil
}

@(private = "file")
is_float_zero :: proc(lit: ^IR_Literal) -> bool {
	switch v in lit.value {
	case f64:  return v == 0.0
	case i64:  return v == 0
	case bool: return false
	}
	return false
}

@(private = "file")
is_float_one :: proc(lit: ^IR_Literal) -> bool {
	switch v in lit.value {
	case f64:  return v == 1.0
	case i64:  return v == 1
	case bool: return false
	}
	return false
}

@(private = "file")
fold_binary :: proc(op: IR_Op, left, right: ^IR_Literal) -> (IR_Literal_Value, bool) {
	// Float-float ops
	lf, l_is_f := left.value.(f64)
	rf, r_is_f := right.value.(f64)
	if l_is_f && r_is_f {
		#partial switch op {
		case .Add: return lf + rf, true
		case .Sub: return lf - rf, true
		case .Mul: return lf * rf, true
		case .Div: if rf != 0 do return lf / rf, true
		case .Mod:
			if rf != 0 {
				// SPIR-V FMod semantics: result has same sign as divisor
				q := lf / rf
				// Truncate toward zero
				trunc_q: f64 = q >= 0 ? f64(i64(q)) : -f64(i64(-q))
				return lf - trunc_q * rf, true
			}
		case .Eq:  return lf == rf, true
		case .Neq: return lf != rf, true
		case .Lt:  return lf < rf, true
		case .Gt:  return lf > rf, true
		case .Lte: return lf <= rf, true
		case .Gte: return lf >= rf, true
		case: // fall through
		}
	}

	// Int-int ops
	li, l_is_i := left.value.(i64)
	ri, r_is_i := right.value.(i64)
	if l_is_i && r_is_i {
		#partial switch op {
		case .Add: return li + ri, true
		case .Sub: return li - ri, true
		case .Mul: return li * ri, true
		case .Div: if ri != 0 do return li / ri, true
		case .Mod: if ri != 0 do return li % ri, true
		case .Eq:  return li == ri, true
		case .Neq: return li != ri, true
		case .Lt:  return li < ri, true
		case .Gt:  return li > ri, true
		case .Lte: return li <= ri, true
		case .Gte: return li >= ri, true
		case: // fall through
		}
	}

	// Bool-bool ops
	lb, l_is_b := left.value.(bool)
	rb, r_is_b := right.value.(bool)
	if l_is_b && r_is_b {
		#partial switch op {
		case .And: return lb && rb, true
		case .Or:  return lb || rb, true
		case .Eq:  return lb == rb, true
		case .Neq: return lb != rb, true
		case: // fall through
		}
	}

	return nil, false
}

@(private = "file")
fold_unary :: proc(op: IR_Op, operand: ^IR_Literal) -> (IR_Literal_Value, bool) {
	#partial switch op {
	case .Neg:
		switch v in operand.value {
		case f64:  return -v, true
		case i64:  return -v, true
		case bool: return nil, false
		}
	case .Not:
		if b, ok := operand.value.(bool); ok {
			return !b, true
		}
	case: // fall through
	}
	return nil, false
}

@(private = "file")
make_literal_expr :: proc(value: IR_Literal_Value, type: ^Resolved_Type) -> ^IR_Expr {
	lit := new(IR_Literal)
	lit.value = value
	e := new(IR_Expr)
	e.kind = .Literal
	e.type = type
	e.derived = lit
	return e
}

// -- Copy Propagation --
// For immutable `let x = y` where y is a simple Var_Ref, replace uses of x with y.
// Conservative: invalidates all mappings at control flow boundaries.

opt_copy_propagation :: proc(module: ^IR_Module) {
	for &fn in module.functions {
		copy_map := make(map[IR_Var_Id]IR_Var_Id)
		name_map := make(map[IR_Var_Id]string) // id -> name for updating name field
		defer delete(copy_map)
		defer delete(name_map)
		// Populate name_map from var_decls
		for decl in fn.var_decls {
			name_map[decl.id] = decl.name
		}
		opt_copy_prop_stmts(fn.body[:], &copy_map, &name_map)
	}
}

@(private = "file")
opt_copy_prop_stmts :: proc(stmts: []IR_Stmt, copy_map: ^map[IR_Var_Id]IR_Var_Id, name_map: ^map[IR_Var_Id]string) {
	for &stmt in stmts {
		switch s in stmt {
		case ^IR_Let:
			s.value = opt_copy_prop_expr(s.value, copy_map, name_map)
			// If value is a simple var ref, record the mapping
			if vr, ok := s.value.derived.(^IR_Var_Ref); ok {
				copy_map[s.id] = vr.id
			}
		case ^IR_Assign:
			s.value = opt_copy_prop_expr(s.value, copy_map, name_map)
			// Assignment to a variable invalidates any copies pointing to it
			if vr, ok := s.target.derived.(^IR_Var_Ref); ok {
				// Invalidate anything that copies FROM this var
				keys_to_remove := make([dynamic]IR_Var_Id, context.temp_allocator)
				for k, v in copy_map {
					if v == vr.id {
						append(&keys_to_remove, k)
					}
				}
				for k in keys_to_remove {
					delete_key(copy_map, k)
				}
				// Also invalidate if this var was a copy target
				delete_key(copy_map, vr.id)
			}
		case ^IR_Return:
			s.value = opt_copy_prop_expr(s.value, copy_map, name_map)
		case ^IR_Store_Output:
			s.value = opt_copy_prop_expr(s.value, copy_map, name_map)
		case ^IR_If:
			s.condition = opt_copy_prop_expr(s.condition, copy_map, name_map)
			// Conservative: don't propagate into/across branches
			then_map := make(map[IR_Var_Id]IR_Var_Id)
			defer delete(then_map)
			opt_copy_prop_stmts(s.then_body[:], &then_map, name_map)
			for &ei in s.elseif_clauses {
				ei.condition = opt_copy_prop_expr(ei.condition, copy_map, name_map)
				ei_map := make(map[IR_Var_Id]IR_Var_Id)
				defer delete(ei_map)
				opt_copy_prop_stmts(ei.body[:], &ei_map, name_map)
			}
			else_map := make(map[IR_Var_Id]IR_Var_Id)
			defer delete(else_map)
			opt_copy_prop_stmts(s.else_body[:], &else_map, name_map)
		case ^IR_For:
			s.start = opt_copy_prop_expr(s.start, copy_map, name_map)
			s.stop = opt_copy_prop_expr(s.stop, copy_map, name_map)
			s.step = opt_copy_prop_expr(s.step, copy_map, name_map)
			for_map := make(map[IR_Var_Id]IR_Var_Id)
			defer delete(for_map)
			opt_copy_prop_stmts(s.body[:], &for_map, name_map)
		case ^IR_While:
			s.condition = opt_copy_prop_expr(s.condition, copy_map, name_map)
			while_map := make(map[IR_Var_Id]IR_Var_Id)
			defer delete(while_map)
			opt_copy_prop_stmts(s.body[:], &while_map, name_map)
		case ^IR_Expr_Stmt:
			s.expr = opt_copy_prop_expr(s.expr, copy_map, name_map)
		case ^IR_Barrier:
			// no-op
		case ^IR_Discard:
			// no-op
		case ^IR_Break:
			// no-op
		case ^IR_Continue:
			// no-op
		}
	}
}

@(private = "file")
opt_copy_prop_expr :: proc(expr: ^IR_Expr, copy_map: ^map[IR_Var_Id]IR_Var_Id, name_map: ^map[IR_Var_Id]string) -> ^IR_Expr {
	if expr == nil do return nil

	switch d in expr.derived {
	case ^IR_Var_Ref:
		// Follow the copy chain to the original
		resolved := d.id
		for {
			next, ok := copy_map[resolved]
			if !ok do break
			resolved = next
		}
		if resolved != d.id {
			d.id = resolved
			if name, ok := name_map[resolved]; ok {
				d.name = name
			}
		}
	case ^IR_Binary:
		d.left = opt_copy_prop_expr(d.left, copy_map, name_map)
		d.right = opt_copy_prop_expr(d.right, copy_map, name_map)
	case ^IR_Unary:
		d.operand = opt_copy_prop_expr(d.operand, copy_map, name_map)
	case ^IR_Call:
		for &arg in d.args {
			arg = opt_copy_prop_expr(arg, copy_map, name_map)
		}
	case ^IR_Field_Access:
		d.object = opt_copy_prop_expr(d.object, copy_map, name_map)
	case ^IR_Swizzle:
		d.object = opt_copy_prop_expr(d.object, copy_map, name_map)
	case ^IR_Composite_Extract:
		d.object = opt_copy_prop_expr(d.object, copy_map, name_map)
	case ^IR_Vector_Shuffle:
		d.object = opt_copy_prop_expr(d.object, copy_map, name_map)
	case ^IR_Index:
		d.object = opt_copy_prop_expr(d.object, copy_map, name_map)
		d.index = opt_copy_prop_expr(d.index, copy_map, name_map)
	case ^IR_Construct:
		for &arg in d.args {
			arg = opt_copy_prop_expr(arg, copy_map, name_map)
		}
	case ^IR_Type_Cast:
		d.value = opt_copy_prop_expr(d.value, copy_map, name_map)
	case ^IR_Select:
		d.condition = opt_copy_prop_expr(d.condition, copy_map, name_map)
		d.true_val = opt_copy_prop_expr(d.true_val, copy_map, name_map)
		d.false_val = opt_copy_prop_expr(d.false_val, copy_map, name_map)
	case ^IR_Literal, ^IR_Load_Binding, ^IR_Input_Field, ^IR_Builtin_Var, ^IR_Shared_Ref:
		// leaf nodes
	}
	return expr
}

// -- Common Subexpression Elimination --
// Within flat blocks, hash IR_Let value expressions and replace duplicates
// with references to the first computation. DCE cleans up unused originals.

opt_cse :: proc(module: ^IR_Module) {
	for &fn in module.functions {
		opt_cse_stmts(fn.body[:])
	}
}

@(private = "file")
opt_cse_stmts :: proc(stmts: []IR_Stmt) {
	// Map from expression string → var that holds that value
	seen_id := make(map[string]IR_Var_Id)
	seen_name := make(map[string]string)
	defer delete(seen_id)
	defer delete(seen_name)

	for &stmt in stmts {
		switch s in stmt {
		case ^IR_Let:
			if !expr_has_side_effects(s.value) {
				key := cse_expr_key(s.value)
				if len(key) > 0 {
					if existing_id, ok := seen_id[key]; ok {
						// Replace with reference to existing variable
						ref := new(IR_Var_Ref)
						ref.id = existing_id
						ref.name = seen_name[key]
						s.value = new(IR_Expr)
						s.value.kind = .Var_Ref
						s.value.type = s.type
						s.value.derived = ref
					} else {
						seen_id[key] = s.id
						seen_name[key] = s.name
					}
				}
			}
		case ^IR_If:
			// Recurse into sub-blocks with fresh scope
			opt_cse_stmts(s.then_body[:])
			for &ei in s.elseif_clauses {
				opt_cse_stmts(ei.body[:])
			}
			opt_cse_stmts(s.else_body[:])
		case ^IR_For:
			opt_cse_stmts(s.body[:])
		case ^IR_While:
			opt_cse_stmts(s.body[:])
		case ^IR_Assign, ^IR_Return, ^IR_Store_Output, ^IR_Expr_Stmt, ^IR_Barrier, ^IR_Discard, ^IR_Break, ^IR_Continue:
			// no CSE opportunities in these
		}
	}
}

// Build a structural key string for an expression for CSE comparison
@(private = "file")
cse_expr_key :: proc(expr: ^IR_Expr) -> string {
	if expr == nil do return ""

	b := make([dynamic]u8, context.temp_allocator)
	cse_expr_key_build(&b, expr)
	return string(b[:])
}

@(private = "file")
cse_expr_key_build :: proc(b: ^[dynamic]u8, expr: ^IR_Expr) {
	if expr == nil do return

	switch d in expr.derived {
	case ^IR_Literal:
		append(b, 'L')
		switch v in d.value {
		case i64:
			s := fmt.tprintf("%d", v)
			append(b, ..transmute([]u8)s)
		case f64:
			s := fmt.tprintf("%f", v)
			append(b, ..transmute([]u8)s)
		case bool:
			append(b, v ? '1' : '0')
		}
	case ^IR_Var_Ref:
		append(b, 'V')
		s := fmt.tprintf("%d", int(d.id))
		append(b, ..transmute([]u8)s)
	case ^IR_Binary:
		append(b, '(')
		cse_expr_key_build(b, d.left)
		s := ir_op_to_string(d.op)
		append(b, ..transmute([]u8)s)
		cse_expr_key_build(b, d.right)
		append(b, ')')
	case ^IR_Unary:
		append(b, 'U')
		s := ir_op_to_string(d.op)
		append(b, ..transmute([]u8)s)
		cse_expr_key_build(b, d.operand)
	case ^IR_Call:
		append(b, 'C')
		append(b, ..transmute([]u8)d.name)
		append(b, '(')
		for arg, i in d.args {
			if i > 0 do append(b, ',')
			cse_expr_key_build(b, arg)
		}
		append(b, ')')
	case ^IR_Field_Access:
		cse_expr_key_build(b, d.object)
		append(b, '.')
		append(b, ..transmute([]u8)d.field_name)
	case ^IR_Swizzle:
		cse_expr_key_build(b, d.object)
		append(b, '.')
		append(b, ..transmute([]u8)d.components)
	case ^IR_Composite_Extract:
		cse_expr_key_build(b, d.object)
		append(b, '@')
		s := fmt.tprintf("%d", d.index)
		append(b, ..transmute([]u8)s)
	case ^IR_Vector_Shuffle:
		cse_expr_key_build(b, d.object)
		append(b, 'S')
		for c, i in d.components {
			if i > 0 do append(b, ',')
			s := fmt.tprintf("%d", c)
			append(b, ..transmute([]u8)s)
		}
	case ^IR_Index:
		cse_expr_key_build(b, d.object)
		append(b, '[')
		cse_expr_key_build(b, d.index)
		append(b, ']')
	case ^IR_Construct:
		append(b, 'K')
		append(b, ..transmute([]u8)d.type_name)
		append(b, '(')
		for arg, i in d.args {
			if i > 0 do append(b, ',')
			cse_expr_key_build(b, arg)
		}
		append(b, ')')
	case ^IR_Type_Cast:
		append(b, 'T')
		s := type_to_string(expr.type)
		append(b, ..transmute([]u8)s)
		append(b, '(')
		cse_expr_key_build(b, d.value)
		append(b, ')')
	case ^IR_Load_Binding:
		append(b, 'B')
		append(b, ..transmute([]u8)d.name)
	case ^IR_Input_Field:
		append(b, 'I')
		append(b, ..transmute([]u8)d.param_name)
		append(b, '.')
		append(b, ..transmute([]u8)d.field_name)
	case ^IR_Builtin_Var:
		append(b, 'G')
		append(b, ..transmute([]u8)d.name)
	case ^IR_Shared_Ref:
		append(b, 'H')
		append(b, ..transmute([]u8)d.name)
	case ^IR_Select:
		append(b, 'Q')
		cse_expr_key_build(b, d.condition)
		append(b, '?')
		cse_expr_key_build(b, d.true_val)
		append(b, ':')
		cse_expr_key_build(b, d.false_val)
	}
}

// -- Dead Code Elimination --

opt_dead_code_elim :: proc(module: ^IR_Module) {
	for &fn in module.functions {
		// Count variable uses
		uses := make(map[IR_Var_Id]int)
		count_uses_stmts(fn.body[:], &uses)

		// Remove unused lets (that have no side effects)
		fn.body = dce_filter_stmts(fn.body, &uses)
	}
}

@(private = "file")
count_uses_stmts :: proc(stmts: []IR_Stmt, uses: ^map[IR_Var_Id]int) {
	for stmt in stmts {
		switch s in stmt {
		case ^IR_Let:
			count_uses_expr(s.value, uses)
		case ^IR_Assign:
			count_uses_expr(s.target, uses)
			count_uses_expr(s.value, uses)
		case ^IR_Return:
			count_uses_expr(s.value, uses)
		case ^IR_Store_Output:
			count_uses_expr(s.value, uses)
		case ^IR_If:
			count_uses_expr(s.condition, uses)
			count_uses_stmts(s.then_body[:], uses)
			for ei in s.elseif_clauses {
				count_uses_expr(ei.condition, uses)
				count_uses_stmts(ei.body[:], uses)
			}
			count_uses_stmts(s.else_body[:], uses)
		case ^IR_For:
			count_uses_expr(s.start, uses)
			count_uses_expr(s.stop, uses)
			count_uses_expr(s.step, uses)
			count_uses_stmts(s.body[:], uses)
		case ^IR_While:
			count_uses_expr(s.condition, uses)
			count_uses_stmts(s.body[:], uses)
		case ^IR_Expr_Stmt:
			count_uses_expr(s.expr, uses)
		case ^IR_Barrier:
			// no variable references
		case ^IR_Discard:
			// no variable references
		case ^IR_Break:
			// no variable references
		case ^IR_Continue:
			// no variable references
		}
	}
}

@(private = "file")
count_uses_expr :: proc(expr: ^IR_Expr, uses: ^map[IR_Var_Id]int) {
	if expr == nil do return

	switch d in expr.derived {
	case ^IR_Var_Ref:
		uses[d.id] = (d.id in uses^) ? uses[d.id] + 1 : 1
	case ^IR_Binary:
		count_uses_expr(d.left, uses)
		count_uses_expr(d.right, uses)
	case ^IR_Unary:
		count_uses_expr(d.operand, uses)
	case ^IR_Call:
		for arg in d.args do count_uses_expr(arg, uses)
	case ^IR_Field_Access:
		count_uses_expr(d.object, uses)
	case ^IR_Swizzle:
		count_uses_expr(d.object, uses)
	case ^IR_Composite_Extract:
		count_uses_expr(d.object, uses)
	case ^IR_Vector_Shuffle:
		count_uses_expr(d.object, uses)
	case ^IR_Index:
		count_uses_expr(d.object, uses)
		count_uses_expr(d.index, uses)
	case ^IR_Construct:
		for arg in d.args do count_uses_expr(arg, uses)
	case ^IR_Type_Cast:
		count_uses_expr(d.value, uses)
	case ^IR_Select:
		count_uses_expr(d.condition, uses)
		count_uses_expr(d.true_val, uses)
		count_uses_expr(d.false_val, uses)
	case ^IR_Literal, ^IR_Load_Binding, ^IR_Input_Field, ^IR_Builtin_Var, ^IR_Shared_Ref:
		// no variable references
	}
}

@(private = "file")
dce_filter_stmts :: proc(stmts: [dynamic]IR_Stmt, uses: ^map[IR_Var_Id]int) -> [dynamic]IR_Stmt {
	result := make([dynamic]IR_Stmt)
	for stmt in stmts {
		#partial switch s in stmt {
		case ^IR_Let:
			// Remove if unused and no side effects in the value
			if !(s.id in uses^) && !expr_has_side_effects(s.value) {
				continue
			}
			append(&result, stmt)
			continue
		case ^IR_If:
			s.then_body = dce_filter_stmts(s.then_body, uses)
			for &ei in s.elseif_clauses {
				ei.body = dce_filter_stmts(ei.body, uses)
			}
			s.else_body = dce_filter_stmts(s.else_body, uses)
		case ^IR_For:
			s.body = dce_filter_stmts(s.body, uses)
		case ^IR_While:
			s.body = dce_filter_stmts(s.body, uses)
		}
		append(&result, stmt)
	}
	return result
}

@(private = "file")
expr_has_side_effects :: proc(expr: ^IR_Expr) -> bool {
	if expr == nil do return false
	#partial switch d in expr.derived {
	case ^IR_Call:
		return true // calls may have side effects
	case ^IR_Binary:
		return expr_has_side_effects(d.left) || expr_has_side_effects(d.right)
	case ^IR_Unary:
		return expr_has_side_effects(d.operand)
	case ^IR_Construct:
		for arg in d.args {
			if expr_has_side_effects(arg) do return true
		}
		return false
	case:
		return false
	}
}