Subzero: Embed the revision string into translated output.

src/IceGlobalContext.cpp

Index: src/IceGlobalContext.cpp
diff --git a/src/IceGlobalContext.cpp b/src/IceGlobalContext.cpp
index 349db7cc4ff4bb7db75c5233ce3d3ec1f318a91b..7a77575e6b2fec28d61998476e65113f7bd61581 100644
--- a/src/IceGlobalContext.cpp
+++ b/src/IceGlobalContext.cpp
@@ -23,6 +23,7 @@
 #include "IceGlobalInits.h"
 #include "IceLiveness.h"
 #include "IceOperand.h"
+#include "IceRevision.h"
 #include "IceTargetLowering.h"
 #include "IceTimerTree.h"
 #include "IceTypes.def"
@@ -466,6 +467,27 @@ void GlobalContext::saveBlockInfoPtrs() {
   }
 }
 
+void GlobalContext::lowerGlobalsIfNoCodeHasBeenSeen() {
+  if (HasSeenCode)
+    return;
+
+  if (getFlags().getEmitRevision()) {

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

This method is supposed to emit globals, but it also may add something to the
global variable list. Is this really the best place to add this?

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

A side effect of lowering globals is that Globals is cleared or "consumed".  See
the end of lowerGlobals().

Tying in here seems simplest given that:
  (1) lowering is initiated from different places depending on whether threads=0
or threads!=0
  (2) each target has to implement its own lowerGlobals()

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

Or maybe just add the global in the GlobalContext's ctor/initialization?

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

Brilliant!  Done.

+    // Embed the Subzero revision into the compiled binary by creating a special
+    // global variable initialized with the revision string.
+    auto *Revision = VariableDeclaration::create(&Globals, true);
+    Revision->setName(this, "__Sz_revision");
+    Revision->setIsConstant(true);
+    const char *RevisionString = getSubzeroRevision();
+    Revision->addInitializer(VariableDeclaration::DataInitializer::create(
+        &Globals, RevisionString, 1 + strlen(RevisionString)));
+    Globals.push_back(Revision);
+  }
+
+  constexpr char NoSuffix[] = "";
+  lowerGlobals(NoSuffix);
+  HasSeenCode = true;
+}
+
 void GlobalContext::lowerGlobals(const std::string &SectionSuffix) {
   TimerMarker T(TimerStack::TT_emitGlobalInitializers, this);
   const bool DumpGlobalVariables =