Add compiler-side support for promotion.

Author: vext01

llvm/lib/Transforms/Yk/StackMaps.cpp

@@ -28,6 +28,8 @@ void initializeYkStackmapsPass(PassRegistry &);
 } // namespace llvm
 
 namespace {
+const char *YkPromote = "__ykllvm_recognised_promote";
+
 class YkStackmaps : public ModulePass {
 public:
   static char ID;
@@ -61,7 +63,15 @@ class YkStackmaps : public ModulePass {
             // emit a stackmap in those cases too.
             if (!CI.isIndirectCall() && CI.getCalledFunction()->isIntrinsic())
               continue;
-            SMCalls.insert({&I, LA.getLiveVarsBefore(&I)});
+            std::vector<Value *> Lives = LA.getLiveVarsBefore(&I);
+            // Value guards for variable promotions, require us to also
+            // track the value generated by the call.
+            if (CI.getCalledFunction() &&
+                CI.getCalledFunction()->getName() == YkPromote) {
+              Value *RV = cast<Value>(&CI);
+              Lives.push_back(RV);
+            }
+            SMCalls.insert({&I, Lives});
           } else if ((isa<BranchInst>(I) &&
                       cast<BranchInst>(I).isConditional()) ||
                      isa<SwitchInst>(I)) {