[RFC PATCH v2 15/17] lib: getopt: Hoist the arg_index==1 guard

[Simon Glass]

The '--' termination test, the non-option bubble loop and the
'out of options' check are all guarded by gs->arg_index == 1: they
make sense only when we are at the start of a fresh argv[] element.
The current code repeats the guard on each one.

Pull the three out under a single 'if (gs->arg_index == 1)' so the
condition is evaluated once per outer-loop iteration. No functional
change; the compiler produces fewer compare-and-branch sequences.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

(no changes since v1)

 lib/getopt.c | 55 ++++++++++++++++++++++++++--------------------------
 1 file changed, 28 insertions(+), 27 deletions(-)

diff --git a/lib/getopt.c b/lib/getopt.c
index b3ad6968f8d..d2ccefc616e 100644
--- a/lib/getopt.c
+++ b/lib/getopt.c
@@ -44,38 +44,39 @@ int getopt(struct getopt_state *gs, const char *optstring)
 		log_debug("arg_index: %d index: %d nonopts: %d\n",
 			  gs->arg_index, gs->index, gs->nonopts);
 
-		/* `--` indicates the end of options */
-		if (gs->arg_index == 1 && gs->index < argc &&
-		    !strcmp(argv[gs->index], "--")) {
-			gs->index++;
-			return -1;
-		}
-
-		/*
-		 * Permute non-options to the end so we can keep scanning
-		 * for options past them. In '+' mode (POSIX), stop at the
-		 * first non-option instead.
-		 */
-		while (gs->arg_index == 1 &&
-		       gs->index + gs->nonopts < argc) {
+		if (gs->arg_index == 1) {
 			char *cur = argv[gs->index];
-			int i;
 
-			if (*cur == '-')
-				break;
-			if (stop_nonopt)
+			/* `--` indicates the end of options */
+			if (gs->index < argc && !strcmp(cur, "--")) {
+				gs->index++;
+				return -1;
+			}
+
+			/*
+			 * Permute non-options to the end so we can keep
+			 * scanning for options past them. In '+' mode
+			 * (POSIX), stop at the first non-option instead.
+			 */
+			while (gs->index + gs->nonopts < argc) {
+				int i;
+
+				if (*cur == '-')
+					break;
+				if (stop_nonopt)
+					return -1;
+
+				gs->nonopts++;
+				for (i = gs->index; i + 1 < argc; i++)
+					argv[i] = argv[i + 1];
+				argv[argc - 1] = cur;
+				cur = argv[gs->index];
+			}
+
+			if (gs->index + gs->nonopts >= argc)
 				return -1;
-
-			gs->nonopts++;
-			for (i = gs->index; i + 1 < argc; i++)
-				argv[i] = argv[i + 1];
-			argv[argc - 1] = cur;
 		}
 
-		/* Out of options to scan */
-		if (gs->index + gs->nonopts >= argc)
-			return -1;
-
 		/* We have found an option */
 		curopt = argv[gs->index][gs->arg_index];
 		if (curopt)
-- 
2.43.0