1 files changed, 47 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index ee8fdaebbda..e31bbc7fe57 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -36,6 +36,7 @@
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/ValueHandle.h"
+#include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -1603,12 +1604,57 @@ static bool TryToShrinkGlobalToBoolean(GlobalVariable *GV, Constant *OtherVal) {
   assert(InitVal->getType() != Type::getInt1Ty(GV->getContext()) &&
          "No reason to shrink to bool!");
 
+  SmallVector<DIGlobalVariableExpression *, 1> GVs;
+  GV->getDebugInfo(GVs);
+
   // If initialized to zero and storing one into the global, we can use a cast
   // instead of a select to synthesize the desired value.
   bool IsOneZero = false;
-  if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal))
+  bool EmitOneOrZero = true;
+  if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)){
     IsOneZero = InitVal->isNullValue() && CI->isOne();
 
+    if (ConstantInt *CIInit = dyn_cast<ConstantInt>(GV->getInitializer())){
+      uint64_t ValInit = CIInit->getZExtValue();
+      uint64_t ValOther = CI->getZExtValue();
+      uint64_t ValMinus = ValOther - ValInit;
+
+      for(auto *GVe : GVs){
+        DIGlobalVariable *DGV = GVe->getVariable();
+        DIExpression *E = GVe->getExpression();
+
+        // It is expected that the address of global optimized variable is on
+        // top of the stack. After optimization, value of that variable will
+        // be ether 0 for initial value or 1 for other value. The following
+        // expression should return constant integer value depending on the
+        // value at global object address:
+        // val * (ValOther - ValInit) + ValInit:
+        // DW_OP_deref DW_OP_constu <ValMinus>
+        // DW_OP_mul DW_OP_constu <ValInit> DW_OP_plus DW_OP_stack_value
+        E = DIExpression::get(NewGV->getContext(),
+                             {dwarf::DW_OP_deref,
+                              dwarf::DW_OP_constu,
+                              ValMinus,
+                              dwarf::DW_OP_mul,
+                              dwarf::DW_OP_constu,
+                              ValInit,
+                              dwarf::DW_OP_plus,
+                              dwarf::DW_OP_stack_value});
+        DIGlobalVariableExpression *DGVE =
+          DIGlobalVariableExpression::get(NewGV->getContext(), DGV, E);
+        NewGV->addDebugInfo(DGVE);
+     }
+     EmitOneOrZero = false;
+    }
+  }
+
+  if (EmitOneOrZero) {
+     // FIXME: This will only emit address for debugger on which will
+     // be written only 0 or 1.
+     for(auto *GV : GVs)
+       NewGV->addDebugInfo(GV);
+   }
+
   while (!GV->use_empty()) {
     Instruction *UI = cast<Instruction>(GV->user_back());
     if (StoreInst *SI = dyn_cast<StoreInst>(UI)) {