CodeGen: Don't crash when a lambda uses a local constexpr variable

The DeclRefExpr might be for a variable initialized by a constant
expression which hasn't been ODR used.
Emit the initializer for the variable instead of trying to capture the
variable itself.

This fixes PR22071.

llvm-svn: 225060
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 16b624a..8c04f13 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -1902,22 +1902,6 @@
   QualType T = E->getType();
 
   if (const auto *VD = dyn_cast<VarDecl>(ND)) {
-    // Check for captured variables.
-    if (E->refersToCapturedVariable()) {
-      if (auto *FD = LambdaCaptureFields.lookup(VD))
-        return EmitCapturedFieldLValue(*this, FD, CXXABIThisValue);
-      else if (CapturedStmtInfo) {
-        if (auto *V = LocalDeclMap.lookup(VD))
-          return MakeAddrLValue(V, T, Alignment);
-        else
-          return EmitCapturedFieldLValue(*this, CapturedStmtInfo->lookup(VD),
-                                         CapturedStmtInfo->getContextValue());
-      }
-      assert(isa<BlockDecl>(CurCodeDecl));
-      return MakeAddrLValue(GetAddrOfBlockDecl(VD, VD->hasAttr<BlocksAttr>()),
-                            T, Alignment);
-    }
-
     // Global Named registers access via intrinsics only
     if (VD->getStorageClass() == SC_Register &&
         VD->hasAttr<AsmLabelAttr>() && !VD->isLocalVarDecl())
@@ -1935,6 +1919,22 @@
       // FIXME: Eventually we will want to emit vector element references.
       return MakeAddrLValue(Val, T, Alignment);
     }
+
+    // Check for captured variables.
+    if (E->refersToCapturedVariable()) {
+      if (auto *FD = LambdaCaptureFields.lookup(VD))
+        return EmitCapturedFieldLValue(*this, FD, CXXABIThisValue);
+      else if (CapturedStmtInfo) {
+        if (auto *V = LocalDeclMap.lookup(VD))
+          return MakeAddrLValue(V, T, Alignment);
+        else
+          return EmitCapturedFieldLValue(*this, CapturedStmtInfo->lookup(VD),
+                                         CapturedStmtInfo->getContextValue());
+      }
+      assert(isa<BlockDecl>(CurCodeDecl));
+      return MakeAddrLValue(GetAddrOfBlockDecl(VD, VD->hasAttr<BlocksAttr>()),
+                            T, Alignment);
+    }
   }
 
   // FIXME: We should be able to assert this for FunctionDecls as well!