Subzero: Embed the revision string into translated output.

src/IceRevision.cpp

+//===- subzero/src/IceRevision.cpp - Revision string embedding ------------===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief Implements the function for returning the Subzero revision string.
+///
+//===----------------------------------------------------------------------===//
+
+#include "IceRevision.h"
+
+#define XSTRINGIFY(x) STRINGIFY(x)

[John, 2016/08/08 11:47:28]

why the indirection? XSTRINGIFY could just #x its argument, right?

[Jim Stichnoth, 2016/08/08 14:46:18]

I think this is one of the oddities of the preprocessor, explained in e.g.
http://stackoverflow.com/questions/16989730/stringification-how-does-it-work .

I tried various simplifications, and ended up with either a compilation error,
or the version reported as "Subzero_revision_SUBZERO_REVISION" instead of having
the git hash.

[John, 2016/08/08 14:55:36]

Oh, yeah! STRINGFY(x) #x stringfies x without expanding macros... you could
**probably** define SUBZERO_REVISION to be a string (add the escaped
double-quotes in the Makefiles), but this is better.

[Jim Stichnoth, 2016/08/08 17:48:09]

Yeah - I kind of prefer dealing with quotes in the C++ code, rather than
subjecting it to the weirdness of shell and Makefile quoting/escaping.

+#define STRINGIFY(x) #x
+
+#ifndef SUBZERO_REVISION
+#define SUBZERO_REVISION unknown
+#endif // !SUBZERO_REVISION
+
+namespace Ice {
+const char *getSubzeroRevision() {
+  return "Subzero_revision_" XSTRINGIFY(SUBZERO_REVISION);
+}
+}