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[PATCH] Fix slow and non-deterministic behavior of isspace() and tolower()
- From: Shawn Landden <shawn at git dot icu>
- To: gdb-patches at sourceware dot org
- Cc: Shawn Landden <shawn at git dot icu>
- Date: Sun, 9 Jun 2019 10:17:04 -0500
- Subject: [PATCH] Fix slow and non-deterministic behavior of isspace() and tolower()
I was getting 8% and 6% cpu usage in tolower() and isspace(),
respectively, waiting for a breakpoint on ppc64el.
Also, gdb doesn't want non-deterministic behavior here.
---
gdb/utils.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/gdb/utils.c b/gdb/utils.c
index 9686927473..d36b942cc5 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -2626,10 +2626,29 @@ strcmp_iw (const char *string1, const char *string2)
user searches for "foo", then strcmp will sort "foo" before "foo$".
Then lookup_partial_symbol will notice that strcmp_iw("foo$",
"foo") is false, so it won't proceed to the actual match of
"foo(int)" with "foo". */
+/* glibc versions of these have non-deterministic locale-dependant behavior,
+ and are very slow, taking 8% and 6% of total CPU time with some use-cases */
+#undef isspace
+static int isspace(int c)
+{
+ return c == ' ' || (unsigned)c-'\t' < 5;
+}
+#undef isupper
+static int isupper(int c)
+{
+ return (unsigned)c-'A' < 26;
+}
+#undef tolower
+static int tolower(int c)
+{
+ if (isupper(c)) return c | 32;
+ return c;
+}
+
int
strcmp_iw_ordered (const char *string1, const char *string2)
{
const char *saved_string1 = string1, *saved_string2 = string2;
enum case_sensitivity case_pass = case_sensitive_off;
--
2.20.1