[LLVM-C] Add an accessor for the "value type" of a global

[CodaFi]

Summary

Before this, there was no reasonable way to retrieve the type of a global value (most notably, a function) that was created with the C API.

include/llvm-c/Core.h

 void LLVMSetSection(LLVMValueRef Global, const char *Section);
 LLVMVisibility LLVMGetVisibility(LLVMValueRef Global);
 void LLVMSetVisibility(LLVMValueRef Global, LLVMVisibility Viz);
 LLVMDLLStorageClass LLVMGetDLLStorageClass(LLVMValueRef Global);
 void LLVMSetDLLStorageClass(LLVMValueRef Global, LLVMDLLStorageClass Class);
 LLVMUnnamedAddr LLVMGetUnnamedAddress(LLVMValueRef Global);
 void LLVMSetUnnamedAddress(LLVMValueRef Global, LLVMUnnamedAddr UnnamedAddr);
 
+/**
+ * Returns the "value type" of a global value.  This differs from the formal
+ * type of a global value which is always a pointer type.
+ *
+ * @see llvm::GlobalValue::getValueType()
+ */
+LLVMTypeRef LLVMGlobalGetValueType(LLVMValueRef Global);
+
 /** Deprecated: Use LLVMGetUnnamedAddress instead. */
 LLVMBool LLVMHasUnnamedAddr(LLVMValueRef Global);
 /** Deprecated: Use LLVMSetUnnamedAddress instead. */
 void LLVMSetUnnamedAddr(LLVMValueRef Global, LLVMBool HasUnnamedAddr);
 
 /**
  * @defgroup LLVMCCoreValueWithAlignment Values with alignment
  *

lib/IR/Core.cpp

 }
 
 void LLVMSetUnnamedAddr(LLVMValueRef Global, LLVMBool HasUnnamedAddr) {
   unwrap<GlobalValue>(Global)->setUnnamedAddr(
       HasUnnamedAddr ? GlobalValue::UnnamedAddr::Global
                      : GlobalValue::UnnamedAddr::None);
 }
 
+LLVMTypeRef LLVMGlobalGetValueType(LLVMValueRef Global) {
+  return wrap(unwrap<GlobalValue>(Global)->getValueType());
+}
+
 /*--.. Operations on global variables, load and store instructions .........--*/
 
 unsigned LLVMGetAlignment(LLVMValueRef V) {
   Value *P = unwrap<Value>(V);
   if (GlobalValue *GV = dyn_cast<GlobalValue>(P))
     return GV->getAlignment();
   if (AllocaInst *AI = dyn_cast<AllocaInst>(P))
     return AI->getAlignment();