Add an expr::operation_up to struct expression

This adds an expr::operation_up to struct expression, and then
modifies various parts of GDB to use this member when it is non-null.
The list of such spots was a bit surprising to me, and found only
after writing most of the code and then noticing what no longer
compiled.

In a few spots, new accessor methods are added to operation
subclasses, so that code that dissects an expression will work with
the new scheme.

After this change, code that constructs an expression can be switched
to the new form without breaking.

gdb/ChangeLog
2021-03-08  Tom Tromey  <tom@tromey.com>

	* ada-exp.h (class ada_var_value_operation) <get_symbol>: Remove;
	now in superclass.
	* value.h (fetch_subexp_value): Add "op" parameter.
	* value.c (init_if_undefined_command): Update.
	* tracepoint.c (validate_actionline, encode_actions_1): Update.
	* stap-probe.c (stap_probe::compile_to_ax): Update.
	* printcmd.c (set_command): Update.
	* ppc-linux-nat.c (ppc_linux_nat_target::check_condition):
	Update.
	* parser-defs.h (struct expr_builder) <set_operation>: New
	method.
	* parse.c (parse_exp_in_context, exp_uses_objfile): Update.
	* expression.h (struct expression) <first_opcode>: Update.
	<op>: New member.
	* expprint.c (dump_raw_expression, dump_prefix_expression):
	Update.
	* expop.h (class var_value_operation) <get_symbol>: New method.
	(class register_operation) <get_name>: New method.
	(class equal_operation): No longer a typedef, now a subclass.
	(class unop_memval_operation) <get_type>: New method.
	(class assign_operation) <get_lhs>: New method.
	(class unop_cast_operation) <get_type>: New method.
	* eval.c (evaluate_expression, evaluate_type)
	(evaluate_subexpression_type): Update.
	(fetch_subexp_value): Add "op" parameter.
	(parse_and_eval_type): Update.
	* dtrace-probe.c (dtrace_probe::compile_to_ax): Update.
	* breakpoint.c (update_watchpoint, watchpoint_check)
	(watchpoint_exp_is_const, watch_command_1): Update.
	* ax-gdb.c (gen_trace_for_expr, gen_eval_for_expr, gen_printf):
	Update.

1 files changed, 9 insertions, 4 deletions

diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index e9aba79..aa2abce 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -1903,7 +1903,8 @@ update_watchpoint (struct watchpoint *b, int reparse)
       struct value *v, *result;
       struct program_space *frame_pspace;
 
-      fetch_subexp_value (b->exp.get (), &pc, &v, &result, &val_chain, false);
+      fetch_subexp_value (b->exp.get (), &pc, b->exp->op.get (), &v, &result,
+			  &val_chain, false);
 
       /* Avoid setting b->val if it's already set.  The meaning of
 	 b->val is 'the last value' user saw, and we should update
@@ -5022,7 +5023,8 @@ watchpoint_check (bpstat bs)
 	return WP_VALUE_CHANGED;
 
       mark = value_mark ();
-      fetch_subexp_value (b->exp.get (), &pc, &new_val, NULL, NULL, false);
+      fetch_subexp_value (b->exp.get (), &pc, b->exp->op.get (), &new_val,
+			  NULL, NULL, false);
 
       if (b->val_bitsize != 0)
 	new_val = extract_bitfield_from_watchpoint_value (b, new_val);
@@ -10122,6 +10124,9 @@ break_range_command (const char *arg, int from_tty)
 static bool
 watchpoint_exp_is_const (const struct expression *exp)
 {
+  if (exp->op != nullptr)
+    return exp->op->constant_p ();
+
   int i = exp->nelts;
 
   while (i > 0)
@@ -10842,8 +10847,8 @@ watch_command_1 (const char *arg, int accessflag, int from_tty,
   exp_valid_block = tracker.block ();
   struct value *mark = value_mark ();
   struct value *val_as_value = nullptr;
-  fetch_subexp_value (exp.get (), &pc, &val_as_value, &result, NULL,
-		      just_location);
+  fetch_subexp_value (exp.get (), &pc, exp->op.get (), &val_as_value, &result,
+		      NULL, just_location);
 
   if (val_as_value != NULL && just_location)
     {