A64: Optimization: Merge interpret blocks

src/frontend/ir/basic_block.cpp

@@ -90,6 +90,11 @@ void Block::SetTerminal(Terminal term) {
     terminal = term;
 }
 
+void Block::ReplaceTerminal(Terminal term) {
+    ASSERT_MSG(HasTerminal(), "Terminal has not been set.");
+    terminal = term;
+}
+
 bool Block::HasTerminal() const {
     return terminal.which() != 0;
 }

src/frontend/ir/basic_block.h

@@ -111,6 +111,8 @@ public:
     Terminal GetTerminal() const;
     /// Sets the terminal instruction for this basic block.
     void SetTerminal(Terminal term);
+    /// Replaces the terminal instruction for this basic block.
+    void ReplaceTerminal(Terminal term);
     /// Determines whether or not this basic block has a terminal instruction.
     bool HasTerminal() const;
 

src/frontend/ir/terminal.h

@@ -20,11 +20,12 @@ struct Invalid {};
 
 /**
  * This terminal instruction calls the interpreter, starting at `next`.
- * The interpreter must interpret exactly one instruction.
+ * The interpreter must interpret exactly `num_instructions` instructions.
  */
 struct Interpret {
     explicit Interpret(const LocationDescriptor& next_) : next(next_) {}
     LocationDescriptor next; ///< Location at which interpretation starts.
+    size_t num_instructions = 1;
 };
 
 /**