cmd/compile: move stringtoslicebytetmp to the backend

- removes the runtime function stringtoslicebytetmp
- removes the generation of calls to stringtoslicebytetmp from the frontend
- adds handling of OSTRARRAYBYTETMP in the backend

This reduces binary sizes and avoids function call overhead.

Change-Id: Ib9988d48549cee663b685b4897a483f94727b940
Reviewed-on: https://go-review.googlesource.com/32158
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Martin Möhrmann <martisch@uos.de>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 0 insertions, 12 deletions

diff --git a/src/runtime/string.go b/src/runtime/string.go
index c7a9d27711..4cf165bb87 100644
--- a/src/runtime/string.go
+++ b/src/runtime/string.go
@@ -147,18 +147,6 @@ func stringtoslicebyte(buf *tmpBuf, s string) []byte {
 	return b
 }
 
-func stringtoslicebytetmp(s string) []byte {
-	// Return a slice referring to the actual string bytes.
-	// This is only for use by internal compiler optimizations
-	// that know that the slice won't be mutated.
-	// The only such case today is:
-	// for i, c := range []byte(str)
-
-	str := stringStructOf(&s)
-	ret := slice{array: str.str, len: str.len, cap: str.len}
-	return *(*[]byte)(unsafe.Pointer(&ret))
-}
-
 func stringtoslicerune(buf *[tmpStringBufSize]rune, s string) []rune {
 	// two passes.
 	// unlike slicerunetostring, no race because strings are immutable.