libgo: reduce overhead for memory/block/mutex profiling

    
    Revise the gccgo version of memory/block/mutex profiling to reduce
    runtime overhead. The main change is to collect raw stack traces while
    the profile is on line, then post-process the stacks just prior to the
    point where we are ready to use the final product. Memory profiling
    (at a very low sampling rate) is enabled by default, and the overhead
    of the symbolization / DWARF-reading from backtrace_full was slowing
    things down relative to the main Go runtime.
    
    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/171497

From-SVN: r271172

1 files changed, 4 insertions, 0 deletions

diff --git a/libgo/go/runtime/string.go b/libgo/go/runtime/string.go
index 025ea7a..eac94bf 100644
--- a/libgo/go/runtime/string.go
+++ b/libgo/go/runtime/string.go
@@ -360,6 +360,10 @@ func hasPrefix(s, prefix string) bool {
 	return len(s) >= len(prefix) && s[:len(prefix)] == prefix
 }
 
+func hasSuffix(s, suffix string) bool {
+	return len(s) >= len(suffix) && s[len(s)-len(suffix):] == suffix
+}
+
 const (
 	maxUint = ^uint(0)
 	maxInt  = int(maxUint >> 1)