libgo: update to Go1.12beta2

    
    Reviewed-on: https://go-review.googlesource.com/c/158019

gotools/:
	* Makefile.am (go_cmd_vet_files): Update for Go1.12beta2 release.
	(GOTOOLS_TEST_TIMEOUT): Increase to 600.
	(check-runtime): Export LD_LIBRARY_PATH before computing GOARCH
	and GOOS.
	(check-vet): Copy golang.org/x/tools into check-vet-dir.
	* Makefile.in: Regenerate.

gcc/testsuite/:
	* go.go-torture/execute/names-1.go: Stop using debug/xcoff, which
	is no longer externally visible.

From-SVN: r268084

1 files changed, 12 insertions, 11 deletions

diff --git a/libgo/go/bytes/buffer.go b/libgo/go/bytes/buffer.go
index a2eca2e..aff2db5 100644
--- a/libgo/go/bytes/buffer.go
+++ b/libgo/go/bytes/buffer.go
@@ -12,13 +12,15 @@ import (
 	"unicode/utf8"
 )
 
+// smallBufferSize is an initial allocation minimal capacity.
+const smallBufferSize = 64
+
 // A Buffer is a variable-sized buffer of bytes with Read and Write methods.
 // The zero value for Buffer is an empty buffer ready to use.
 type Buffer struct {
-	buf       []byte   // contents are the bytes buf[off : len(buf)]
-	off       int      // read at &buf[off], write at &buf[len(buf)]
-	bootstrap [64]byte // memory to hold first slice; helps small buffers avoid allocation.
-	lastRead  readOp   // last read operation, so that Unread* can work correctly.
+	buf      []byte // contents are the bytes buf[off : len(buf)]
+	off      int    // read at &buf[off], write at &buf[len(buf)]
+	lastRead readOp // last read operation, so that Unread* can work correctly.
 
 	// FIXME: it would be advisable to align Buffer to cachelines to avoid false
 	// sharing.
@@ -66,7 +68,7 @@ func (b *Buffer) String() string {
 	return string(b.buf[b.off:])
 }
 
-// empty returns whether the unread portion of the buffer is empty.
+// empty reports whether the unread portion of the buffer is empty.
 func (b *Buffer) empty() bool { return len(b.buf) <= b.off }
 
 // Len returns the number of bytes of the unread portion of the buffer;
@@ -125,9 +127,8 @@ func (b *Buffer) grow(n int) int {
 	if i, ok := b.tryGrowByReslice(n); ok {
 		return i
 	}
-	// Check if we can make use of bootstrap array.
-	if b.buf == nil && n <= len(b.bootstrap) {
-		b.buf = b.bootstrap[:n]
+	if b.buf == nil && n <= smallBufferSize {
+		b.buf = make([]byte, n, smallBufferSize)
 		return 0
 	}
 	c := cap(b.buf)
@@ -441,9 +442,9 @@ func (b *Buffer) ReadString(delim byte) (line string, err error) {
 // NewBuffer creates and initializes a new Buffer using buf as its
 // initial contents. The new Buffer takes ownership of buf, and the
 // caller should not use buf after this call. NewBuffer is intended to
-// prepare a Buffer to read existing data. It can also be used to size
-// the internal buffer for writing. To do that, buf should have the
-// desired capacity but a length of zero.
+// prepare a Buffer to read existing data. It can also be used to set
+// the initial size of the internal buffer for writing. To do that,
+// buf should have the desired capacity but a length of zero.
 //
 // In most cases, new(Buffer) (or just declaring a Buffer variable) is
 // sufficient to initialize a Buffer.