[src/trunk]: src/usr.bin/xlint/lint1 lint: flatten has_side_effect

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/e214cf80b8e0
branches:  trunk
changeset: 980294:e214cf80b8e0
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sat Jan 30 23:15:32 2021 +0000

description:
lint: flatten has_side_effect

Since GCC performs tail call optimization, the generated code is
practically the same.

Replace redundant comments with open questions.

No functional change.

diffstat:

 usr.bin/xlint/lint1/tree.c |  48 ++++++++++++++++++++++-----------------------
 1 files changed, 23 insertions(+), 25 deletions(-)

diffs (72 lines):

diff -r c42fa49edadc -r e214cf80b8e0 usr.bin/xlint/lint1/tree.c
--- a/usr.bin/xlint/lint1/tree.c        Sat Jan 30 23:05:08 2021 +0000
+++ b/usr.bin/xlint/lint1/tree.c        Sat Jan 30 23:15:32 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: tree.c,v 1.198 2021/01/30 23:05:08 rillig Exp $        */
+/*     $NetBSD: tree.c,v 1.199 2021/01/30 23:15:32 rillig Exp $        */
 
 /*
  * Copyright (c) 1994, 1995 Jochen Pohl
@@ -37,7 +37,7 @@
 
 #include <sys/cdefs.h>
 #if defined(__RCSID) && !defined(lint)
-__RCSID("$NetBSD: tree.c,v 1.198 2021/01/30 23:05:08 rillig Exp $");
+__RCSID("$NetBSD: tree.c,v 1.199 2021/01/30 23:15:32 rillig Exp $");
 #endif
 
 #include <float.h>
@@ -3771,32 +3771,30 @@
 }
 
 static bool
-has_side_effect(const tnode_t *tn)
+has_side_effect(const tnode_t *tn) // NOLINT(misc-no-recursion)
 {
-       while (!modtab[tn->tn_op].m_has_side_effect) {
-               if (tn->tn_op == CVT && tn->tn_type->t_tspec == VOID) {
-                       tn = tn->tn_left;
-               } else if (tn->tn_op == LOGAND || tn->tn_op == LOGOR) {
-                       /*
-                        * && and || have a side effect if the right operand
-                        * has a side effect.
-                        */
-                       tn = tn->tn_right;
-               } else if (tn->tn_op == QUEST) {
-                       /*
-                        * ? has a side effect if at least one of its right
-                        * operands has a side effect
-                        */
-                       tn = tn->tn_right;
-               } else if (tn->tn_op == COLON || tn->tn_op == COMMA) {
-                       return has_side_effect(tn->tn_left) ||
-                              has_side_effect(tn->tn_right);
-               } else {
-                       return false;
-               }
+       op_t op = tn->tn_op;
+
+       if (modtab[op].m_has_side_effect)
+               return true;
+
+       if (op == CVT && tn->tn_type->t_tspec == VOID)
+               return has_side_effect(tn->tn_left);
+
+       /* XXX: Why not has_side_effect(tn->tn_left) as well? */
+       if (op == LOGAND || op == LOGOR)
+               return has_side_effect(tn->tn_right);
+
+       /* XXX: Why not has_side_effect(tn->tn_left) as well? */
+       if (op == QUEST)
+               return has_side_effect(tn->tn_right);
+
+       if (op == COLON || op == COMMA) {
+               return has_side_effect(tn->tn_left) ||
+                      has_side_effect(tn->tn_right);
        }
 
-       return modtab[tn->tn_op].m_has_side_effect;
+       return false;
 }
 
 static void