llvm2alive: add support for weird automatic splat of constants into vectors

LLVM API support is very poor for this, hence the long code..

Author: nunoplopes

llvm_util/utils.cpp

@@ -286,6 +286,32 @@ Value* get_operand(llvm::Value *v,
   if (!ty)
     return nullptr;
 
+  // automatic splat of constant values
+  if (auto vty = dyn_cast<llvm::FixedVectorType>(v->getType());
+      vty && !isa<llvm::ConstantAggregate, llvm::ConstantAggregateZero,
+                  llvm::ConstantDataSequential>(v)) {
+    llvm::Value *llvm_splat = nullptr;
+    if (auto cnst = dyn_cast<llvm::ConstantInt>(v)) {
+      llvm_splat
+        = llvm::ConstantInt::get(vty->getElementType(), cnst->getValue());
+    } else if (auto cnst = dyn_cast<llvm::ConstantFP>(v)) {
+      llvm_splat
+        = llvm::ConstantFP::get(vty->getElementType(), cnst->getValue());
+    } else
+      return nullptr;
+
+    auto splat = get_operand(llvm_splat, constexpr_conv, copy_inserter,
+                             register_fn_decl);
+    if (!splat)
+      return nullptr;
+
+    vector<Value*> vals(vty->getNumElements(), splat);
+    auto val = make_unique<AggregateValue>(*ty, std::move(vals));
+    auto ret = val.get();
+    current_fn->addConstant(std::move(val));
+    RETURN_CACHE(ret);
+  }
+
   if (auto cnst = dyn_cast<llvm::ConstantInt>(v)) {
     RETURN_CACHE(make_intconst(cnst->getValue()));
   }