This is the mail archive of the
gdb-patches@sourceware.org
mailing list for the GDB project.
[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: Pedro Alves <palves at redhat dot com>, jhb at freebsd dot org, eliz at gnu dot org, Shawn Landden <shawn at git dot icu>
- Date: Fri, 21 Jun 2019 15:19:59 -0400
- Subject: [PATCH] Fix slow and non-deterministic behavior of isspace() and tolower()
- References: <20190610213017.2021-1-shawn@git.icu>
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.
v2: do not touch C namespace
v3: Turns out there are two places using these in performance-critical
parts.
Follow GNU coding standards.
Signed-off-by: Shawn Landden <shawn@git.icu>
Co-Author: Pedro Alves <palves@redhat.com>
Mailing-list: https://sourceware.org/ml/gdb-patches/2019-06/threads.html#00187
---
gdb/common/common-utils.c | 6 +++---
gdb/common/common-utils.h | 22 ++++++++++++++++++++++
gdb/utils.c | 8 ++++----
3 files changed, 29 insertions(+), 7 deletions(-)
diff --git a/gdb/common/common-utils.c b/gdb/common/common-utils.c
index ae2dd9db2b..8215f505e8 100644
--- a/gdb/common/common-utils.c
+++ b/gdb/common/common-utils.c
@@ -338,7 +338,7 @@ skip_spaces (char *chp)
{
if (chp == NULL)
return NULL;
- while (*chp && isspace (*chp))
+ while (*chp && gdb_isspace (*chp))
chp++;
return chp;
}
@@ -350,7 +350,7 @@ skip_spaces (const char *chp)
{
if (chp == NULL)
return NULL;
- while (*chp && isspace (*chp))
+ while (*chp && gdb_isspace (*chp))
chp++;
return chp;
}
@@ -362,7 +362,7 @@ skip_to_space (const char *chp)
{
if (chp == NULL)
return NULL;
- while (*chp && !isspace (*chp))
+ while (*chp && !gdb_isspace (*chp))
chp++;
return chp;
}
diff --git a/gdb/common/common-utils.h b/gdb/common/common-utils.h
index 2320318de7..5e6e0afb9c 100644
--- a/gdb/common/common-utils.h
+++ b/gdb/common/common-utils.h
@@ -146,4 +146,26 @@ in_inclusive_range (T value, T low, T high)
return value >= low && value <= high;
}
+static inline
+int
+gdb_isspace (int c)
+{
+ return c == ' ' || (unsigned)c - '\t' < 5;
+}
+
+static inline
+int
+gdb_isupper (int c)
+{
+ return (unsigned)c - 'A' < 26;
+}
+
+static inline
+int
+gdb_tolower (int c)
+{
+ if (isupper(c)) return c | 32;
+ return c;
+}
+
#endif
diff --git a/gdb/utils.c b/gdb/utils.c
index c531748fe4..f92e8f5346 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -2572,16 +2572,16 @@ strcmp_iw_ordered (const char *string1, const char *string2)
while (*string1 != '\0' && *string2 != '\0')
{
- while (isspace (*string1))
+ while (gdb_isspace (*string1))
string1++;
- while (isspace (*string2))
+ while (gdb_isspace (*string2))
string2++;
switch (case_pass)
{
case case_sensitive_off:
- c1 = tolower ((unsigned char) *string1);
- c2 = tolower ((unsigned char) *string2);
+ c1 = gdb_tolower ((unsigned char) *string1);
+ c2 = gdb_tolower ((unsigned char) *string2);
break;
case case_sensitive_on:
c1 = *string1;
--
2.20.1