Subzero: Embed the revision string into translated output.

src/IceGlobalContext.cpp

 //===- subzero/src/IceGlobalContext.cpp - Global context defs -------------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
 /// \brief Defines aspects of the compilation that persist across multiple
 /// functions.
 ///
 //===----------------------------------------------------------------------===//
 
 #include "IceGlobalContext.h"
 
 #include "IceCfg.h"
 #include "IceCfgNode.h"
 #include "IceClFlags.h"
 #include "IceDefs.h"
 #include "IceELFObjectWriter.h"
 #include "IceGlobalInits.h"
 #include "IceLiveness.h"
 #include "IceOperand.h"
+#include "IceRevision.h"
 #include "IceTargetLowering.h"
 #include "IceTimerTree.h"
 #include "IceTypes.def"
 #include "IceTypes.h"
 
 #ifdef __clang__
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wunused-parameter"
 #endif // __clang__
 
@@ skipping 423 matching lines @@
 void GlobalContext::lowerJumpTables() { DataLowering->lowerJumpTables(); }
 
 void GlobalContext::saveBlockInfoPtrs() {
   for (VariableDeclaration *Global : Globals) {
     if (Cfg::isProfileGlobal(*Global)) {
       ProfileBlockInfos.push_back(Global);
     }
   }
 }
 
+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 =
       BuildDefs::dump() && (getFlags().getVerbose() & IceV_GlobalInit) &&
       getFlags().matchVerboseFocusOn("", 0);
   if (DumpGlobalVariables) {
     OstreamLocker L(this);
     Ostream &Stream = getStrDump();
     for (const Ice::VariableDeclaration *Global : Globals) {
       Global->dump(Stream);
@@ skipping 562 matching lines @@
 void TimerMarker::pushCfg(const Cfg *Func) {
   Ctx = Func->getContext();
   Active = Func->getFocusedTiming() || getFlags().getSubzeroTimingEnabled();
   if (Active)
     Ctx->pushTimer(ID, StackID);
 }
 
 ICE_TLS_DEFINE_FIELD(GlobalContext::ThreadContext *, GlobalContext, TLS);
 
 } // end of namespace Ice