[src/trunk]: src/usr.bin/xlint/lint1 lint: document the difference between FA...

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

details:   https://anonhg.NetBSD.org/src/rev/0121bf8d49a3
branches:  trunk
changeset: 1022863:0121bf8d49a3
user:      rillig <rillig%NetBSD.org@localhost>
date:      Tue Aug 10 07:02:00 2021 +0000

description:
lint: document the difference between FARG and PUSH

diffstat:

 usr.bin/xlint/lint1/ops.def |  12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)

diffs (26 lines):

diff -r d62008208cfe -r 0121bf8d49a3 usr.bin/xlint/lint1/ops.def
--- a/usr.bin/xlint/lint1/ops.def       Tue Aug 10 06:47:48 2021 +0000
+++ b/usr.bin/xlint/lint1/ops.def       Tue Aug 10 07:02:00 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ops.def,v 1.21 2021/08/10 06:31:16 rillig Exp $ */
+/*     $NetBSD: ops.def,v 1.22 2021/08/10 07:02:00 rillig Exp $ */
 
 begin_ops()
 
@@ -104,6 +104,16 @@
 op(    CASE,   "case",         -,-,-,-,-,-,-,-,-,-,-,-,-,-,-,-,-,-,-,-)
 op(    FARG,   "farg",         1,-,1,-,-,-,-,-,-,-,-,-,-,-,-,-,-,1,-,-)
 
+/*
+ * Both FARG and PUSH represent function arguments.  FARG is used in the
+ * early phase of analysis, when the node is not yet part of a function call
+ * expression (CALL or ICALL).  Later, build_function_argument builds a
+ * function call expression out of the FARG nodes, where they become PUSH.
+ * In a function call expression, the PUSH nodes are ordered from right to
+ * left, that is, the function call f(17, 23) is represented as
+ * CALL(f, PUSH(23, PUSH(17, NULL))).
+ */
+
 end_ops()
 
 #ifndef NOPS