1 files changed, 75 insertions, 1 deletions

diff --git a/src/mir/from_hir.hpp b/src/mir/from_hir.hpp
index c5fd105c..d4690936 100644
--- a/src/mir/from_hir.hpp
+++ b/src/mir/from_hir.hpp
@@ -10,9 +10,38 @@
 #include <hir/type.hpp>
 #include <hir/expr.hpp> // for ExprNode_Match
 
+class MirBuilder;
+
+class ScopeHandle
+{
+    friend class MirBuilder;
+    
+    const MirBuilder& m_builder;
+    unsigned int    idx;
+    
+    ScopeHandle(const MirBuilder& builder, unsigned int idx):
+        m_builder(builder),
+        idx(idx)
+    {
+    }
+public:
+    ScopeHandle(const ScopeHandle& x) = delete;
+    ScopeHandle(ScopeHandle&& x):
+        m_builder(x.m_builder),
+        idx(x.idx)
+    {
+        x.idx = ~0;
+    }
+    ScopeHandle& operator=(const ScopeHandle& x) = delete;
+    ScopeHandle& operator=(ScopeHandle&& x) = delete;
+    ~ScopeHandle();
+};
+
 /// Helper class to construct MIR
 class MirBuilder
 {
+    friend class ScopeHandle;
+    
     ::MIR::Function&    m_output;
     
     unsigned int    m_current_block;
@@ -20,15 +49,41 @@ class MirBuilder
     
     ::MIR::RValue   m_result;
     bool    m_result_valid;
+    
+    ::std::vector<bool> variables_valid;
+    ::std::vector<bool> temporaries_valid;
+    
+    struct ScopeDef
+    {
+        bool complete = false;
+        ::std::vector<unsigned int> variables;  // Variables to be dropped at the end of this scope
+        ::std::vector<unsigned int> temporaries;  // Temporaries introduced during this scope
+        
+        bool is_conditional = false;
+        #if 0
+        ::std::vector<bool> moved_vars; // Bitmap of variables moved in the current branch
+        ::std::vector<bool> all_moved_vars; // Bitmap of variables moved in at least one branch
+        ::std::vector<bool> all_unmoved_vars; // Bitmap of variables NOT moved in at least one branch
+        #endif
+    };
+    
+    ::std::vector<ScopeDef> m_scopes;
+    ::std::vector<unsigned int> m_scope_stack;
+    ScopeHandle m_fcn_scope;
 public:
     MirBuilder(::MIR::Function& output):
         m_output(output),
         m_block_active(false),
-        m_result_valid(false)
+        m_result_valid(false),
+        m_fcn_scope(*this, 0)
     {
         set_cur_block( new_bb_unlinked() );
+        m_scopes.push_back( ScopeDef {} );
+        m_scope_stack.push_back( 0 );
     }
+    ~MirBuilder();
     
+    // - Values
     ::MIR::LValue new_temporary(const ::HIR::TypeRef& ty);
     ::MIR::LValue lvalue_or_temp(const ::HIR::TypeRef& ty, ::MIR::RValue val);
     
@@ -39,9 +94,13 @@ public:
     ::MIR::LValue get_result_lvalue(const Span& sp);
     void set_result(const Span& sp, ::MIR::RValue val);
     
+    // - Statements
+    // Push an assignment. NOTE: This also marks the rvalue as moved
     void push_stmt_assign(::MIR::LValue dst, ::MIR::RValue val);
+    // Push a drop (likely only used by scope cleanup)
     void push_stmt_drop(::MIR::LValue val);
     
+    // - Block management
     bool block_active() const {
         return m_block_active;
     }
@@ -52,6 +111,21 @@ public:
     
     ::MIR::BasicBlockId new_bb_linked();
     ::MIR::BasicBlockId new_bb_unlinked();
+    
+    // --- Scopes ---
+    /// `is_conditional`: If true, this scope is the contents of a conditional branch of the parent scope
+    ScopeHandle new_scope(const Span& sp, bool is_conditional=false);
+    void terminate_scope(const Span& sp, ScopeHandle );
+    void terminate_scope_early(const Span& sp, const ScopeHandle& );
+    
+    const ScopeHandle& fcn_scope() const {
+        return m_fcn_scope;
+    }
+
+private:
+    void drop_scope_values(const ScopeDef& sd);
+    // Helper - Marks a variable/... as moved (and checks if the move is valid)
+    void moved_lvalue(const ::MIR::LValue& lv);
 };
 
 class MirConverter: