[llgo] Roll gofrontend forward

Switch gofrontend to using go.googlesource.com, and
update to 81eb6a3f425b2158c67ee32c0cc973a72ce9d6be.

There are various changes required to update to the
go 1.5 runtime:

typemap.go is changed to accommodate the change in representation for equal/hash algorithms, and the removal of the zero value/type.
CMakeLists.txt is updated to add the build tree to the package search path, so internal packages, which are not installed, are found.
various files changes due to removal of __go_new_nopointers; the same change as in D11863, but with NoUnwindAttribute added to the added runtime functions which are called with "callOnly".
minor cleanups in ssa.go while investigating issues with unwinding/panic handling.

Differential Revisision: http://reviews.llvm.org/D15188

llvm-svn: 263536

1 files changed, 28 insertions, 0 deletions

diff --git a/llgo/third_party/gofrontend/libgo/go/strings/compare.go b/llgo/third_party/gofrontend/libgo/go/strings/compare.go
new file mode 100644
index 00000000000..b84dddea74e
--- /dev/null
+++ b/llgo/third_party/gofrontend/libgo/go/strings/compare.go
@@ -0,0 +1,28 @@
+// Copyright 2015 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package strings
+
+// Compare returns an integer comparing two strings lexicographically.
+// The result will be 0 if a==b, -1 if a < b, and +1 if a > b.
+//
+// Compare is included only for symmetry with package bytes.
+// It is usually clearer and always faster to use the built-in
+// string comparison operators ==, <, >, and so on.
+func Compare(a, b string) int {
+	// NOTE(rsc): This function does NOT call the runtime cmpstring function,
+	// because we do not want to provide any performance justification for
+	// using strings.Compare. Basically no one should use strings.Compare.
+	// As the comment above says, it is here only for symmetry with package bytes.
+	// If performance is important, the compiler should be changed to recognize
+	// the pattern so that all code doing three-way comparisons, not just code
+	// using strings.Compare, can benefit.
+	if a == b {
+		return 0
+	}
+	if a < b {
+		return -1
+	}
+	return +1
+}