irgen: Embed parent module and None only once per module

this descreases the number of symbols / stackmap constants size slightly

src/codegen/irgen/irgenerator.cpp

@@ -910,14 +910,13 @@ private:
     }
 
     ConcreteCompilerVariable* getNone() {
-        ConcreteCompilerVariable* v = new ConcreteCompilerVariable(
-            typeFromClass(none_cls), embedRelocatablePtr(None, g.llvm_value_type_ptr), false);
-        return v;
+        llvm::Constant* none = embedRelocatablePtr(None, g.llvm_value_type_ptr, "cNone");
+        return new ConcreteCompilerVariable(typeFromClass(none_cls), none, false);
     }
 
     llvm::Constant* embedParentModulePtr() {
-        // TODO: We could reuse the name to reduce the number of relocatable pointers.
-        return embedRelocatablePtr(irstate->getSourceInfo()->parent_module, g.llvm_module_type_ptr);
+        BoxedModule* parent_module = irstate->getSourceInfo()->parent_module;
+        return embedRelocatablePtr(parent_module, g.llvm_module_type_ptr, "cParentModule");
     }
 
     ConcreteCompilerVariable* _getGlobal(AST_Name* node, UnwindInfo unw_info) {
@@ -2150,7 +2149,7 @@ private:
                 v->decvref(emitter);
                 args.push_back(converted->getValue());
             } else {
-                args.push_back(embedRelocatablePtr(None, g.llvm_value_type_ptr));
+                args.push_back(embedRelocatablePtr(None, g.llvm_value_type_ptr, "cNone"));
             }
         }
 

src/codegen/irgen/util.cpp

@@ -106,13 +106,23 @@ const void* getValueOfRelocatableSym(const std::string& str) {
     return NULL;
 }
 
-llvm::Constant* embedRelocatablePtr(const void* addr, llvm::Type* type) {
+llvm::Constant* embedRelocatablePtr(const void* addr, llvm::Type* type, llvm::StringRef shared_name) {
     assert(addr);
 
     if (!ENABLE_JIT_OBJECT_CACHE)
         return embedConstantPtr(addr, type);
 
-    std::string name = (llvm::Twine("c") + llvm::Twine(relocatable_syms.size())).str();
+    std::string name;
+    if (!shared_name.empty()) {
+        llvm::GlobalVariable* gv = g.cur_module->getGlobalVariable(shared_name, true);
+        if (gv)
+            return gv;
+        assert(!relocatable_syms.count(name));
+        name = shared_name;
+    } else {
+        name = (llvm::Twine("c") + llvm::Twine(relocatable_syms.size())).str();
+    }
+
     relocatable_syms[name] = addr;
 
     llvm::Type* var_type = type->getPointerElementType();

src/codegen/irgen/util.h

@@ -17,6 +17,8 @@
 
 #include <string>
 
+#include "llvm/ADT/StringRef.h"
+
 namespace llvm {
 class Constant;
 class Function;
@@ -27,7 +29,7 @@ namespace pyston {
 
 llvm::Constant* getStringConstantPtr(const std::string& str);
 llvm::Constant* getStringConstantPtr(const char* str);
-llvm::Constant* embedRelocatablePtr(const void* addr, llvm::Type*);
+llvm::Constant* embedRelocatablePtr(const void* addr, llvm::Type*, llvm::StringRef shared_name = llvm::StringRef());
 llvm::Constant* embedConstantPtr(const void* addr, llvm::Type*);
 llvm::Constant* getConstantInt(int64_t val);
 llvm::Constant* getConstantDouble(double val);