More benchmarks.
Add a hand-rolled maps line parser as something to compare our realistic
sscanf benchmark against. Also add benchmarks for the ato*/strto* family.
This patch doesn't fix the tests, which seem to have been broken by
the recent google-benchmark upgrade despite the benchmarks themselves
all working just fine. To me that's a final strike against these tests
which are hard to maintain and not obviously useful, but we can worry
about what to do with them -- whether to just delete them or to try to
turn them into tests that actually have some value -- in a separate CL.
Bug: N/A
Test: ran benchmarks
Change-Id: I6c9a77ece98d624baeb049b360876ef5c35ea7f2
diff --git a/benchmarks/stdio_benchmark.cpp b/benchmarks/stdio_benchmark.cpp
index 872725d..965a3ae 100644
--- a/benchmarks/stdio_benchmark.cpp
+++ b/benchmarks/stdio_benchmark.cpp
@@ -223,6 +223,7 @@
}
BIONIC_BENCHMARK(BM_stdio_scanf_d);
+// Parsing maps is a common use of sscanf with a relatively complex format string.
static void BM_stdio_scanf_maps(benchmark::State& state) {
while (state.KeepRunning()) {
uintptr_t start;
@@ -236,3 +237,71 @@
}
}
BIONIC_BENCHMARK(BM_stdio_scanf_maps);
+
+// Hard-coded equivalent of the maps sscanf from libunwindstack/Maps.cpp for a baseline.
+static int ParseMap(const char* line, const char* /*fmt*/, uintptr_t* start, uintptr_t* end,
+ char* permissions, uintptr_t* offset, int* name_pos) __attribute__((noinline)) {
+ char* str;
+ const char* old_str = line;
+
+ // "%" PRIxPTR "-"
+ *start = strtoul(old_str, &str, 16);
+ if (old_str == str || *str++ != '-') return 0;
+
+ // "%" PRIxPTR " "
+ old_str = str;
+ *end = strtoul(old_str, &str, 16);
+ if (old_str == str || !std::isspace(*str++)) return 0;
+ while (std::isspace(*str)) str++;
+
+ // "%4s "
+ if (*str == '\0') return 0;
+ permissions[0] = *str;
+ str++;
+ permissions[1] = *str;
+ str++;
+ permissions[2] = *str;
+ str++;
+ permissions[3] = *str;
+ str++;
+ permissions[4] = 0;
+ if (!std::isspace(*str++)) return 0;
+
+ // "%" PRIxPTR " "
+ old_str = str;
+ *offset = strtoul(old_str, &str, 16);
+ if (old_str == str || !std::isspace(*str)) return 0;
+
+ // "%*x:%*x "
+ old_str = str;
+ (void)strtoul(old_str, &str, 16);
+ if (old_str == str || *str++ != ':') return 0;
+ if (std::isspace(*str)) return 0;
+ old_str = str;
+ (void)strtoul(str, &str, 16);
+ if (old_str == str || !std::isspace(*str++)) return 0;
+
+ // "%*d "
+ old_str = str;
+ (void)strtoul(old_str, &str, 10);
+ if (old_str == str || (!std::isspace(*str) && *str != '\0')) return 0;
+ while (std::isspace(*str)) str++;
+
+ // "%n"
+ *name_pos = (str - line);
+ return 4;
+}
+
+static void BM_stdio_scanf_maps_baseline(benchmark::State& state) {
+ while (state.KeepRunning()) {
+ uintptr_t start;
+ uintptr_t end;
+ uintptr_t offset;
+ char permissions[5];
+ int name_pos;
+ if (ParseMap("6f000000-6f01e000 rwxp 00000000 00:0c 16389419 /system/lib/libcomposer.so",
+ "%" PRIxPTR "-%" PRIxPTR " %4s %" PRIxPTR " %*x:%*x %*d %n",
+ &start, &end, permissions, &offset, &name_pos) != 4) abort();
+ }
+}
+BIONIC_BENCHMARK(BM_stdio_scanf_maps_baseline);