Add stack locals, fix current exception logic

This adds the ability to have stack locals. These are local variables, indexed purely by number, that don't follow ruby semantics. They can not be closed over, and are allocated by adding extra slots at the end of the operand stack. The only use of these stack locals is to save and restore the current exception when entering and exiting a rescue/ensure.
rubinius · Dec 27, 2009 · a609348 · a609348
1 parent bb8f168
commit a609348
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Showing 18 changed files with 163 additions and 80 deletions.
diff --git a/lib/compiler/ast/control_flow.rb b/lib/compiler/ast/control_flow.rb
@@ -461,8 +461,9 @@ def bytecode(g, force=false)
           g.push :nil
         end
 
-        if g.state.rescue?
-          g.clear_exception
+        if lcl = g.state.rescue?
+          g.push_stack_local lcl
+          g.pop_exception
         end
 
         if g.state.block?

diff --git a/lib/compiler/ast/exceptions.rb b/lib/compiler/ast/exceptions.rb
@@ -34,6 +34,11 @@ def bytecode(g)
         # TODO: ?
         g.new_label.set!
 
+        g.push_exception
+        current_exc = g.new_stack_local
+        g.set_stack_local current_exc
+        g.pop
+
         g.state.push_ensure
         @body.bytecode(g)
         g.state.pop_ensure
@@ -42,9 +47,10 @@ def bytecode(g)
         g.goto ok
 
         ex.set!
+
         g.push_exception
 
-        g.state.push_rescue
+        g.state.push_rescue(current_exc)
         @ensure.bytecode(g)
         g.state.pop_rescue
         g.pop
@@ -93,8 +99,11 @@ def bytecode(g)
           els     = g.new_label
           done    = g.new_label
 
-          # Save the current exception into a local
+          # Save the current exception into a stack local
           g.push_exception
+          current_exc = g.new_stack_local
+          g.set_stack_local current_exc
+          g.pop
 
           g.retry.set!
           ex = g.new_label
@@ -119,16 +128,17 @@ def bytecode(g)
               g.pop_unwind
 
               # Reset the outer exception
-              g.swap
+              g.push_stack_local current_exc
               g.pop_exception
+
               g.goto current_break
             end
 
             g.break = current_break
           end
 
           ex.set!
-          @rescue.bytecode(g, reraise, done)
+          @rescue.bytecode(g, reraise, done, current_exc)
           reraise.set!
           g.reraise
 
@@ -139,7 +149,7 @@ def bytecode(g)
           end
           done.set!
 
-          g.swap
+          g.push_stack_local current_exc
           g.pop_exception
         end
         g.pop_modifiers
@@ -197,7 +207,7 @@ def assignment?(node)
         return true if value.kind_of? GlobalVariableAccess and value.name == :$!
       end
 
-      def bytecode(g, reraise, done)
+      def bytecode(g, reraise, done, current_exc)
         pos(g)
         body = g.new_label
 
@@ -229,18 +239,21 @@ def bytecode(g, reraise, done)
         current_break = g.break
         g.break = g.new_label
 
-        g.state.push_rescue
+        g.state.push_rescue(current_exc)
         @body.bytecode(g)
         g.state.pop_rescue
+
         g.clear_exception
         g.goto done
 
         if g.break.used?
           g.break.set!
           g.clear_exception
 
-          g.swap
+          # Reset the outer exception
+          g.push_stack_local current_exc
           g.pop_exception
+
           if current_break
             g.goto current_break
           else
@@ -251,7 +264,7 @@ def bytecode(g, reraise, done)
         g.break = current_break
         if @next
           if_false.set!
-          @next.bytecode(g, reraise, done)
+          @next.bytecode(g, reraise, done, current_exc)
         end
       end
     end

diff --git a/lib/compiler/ast/node.rb b/lib/compiler/ast/node.rb
@@ -133,22 +133,22 @@ class State
 
       def initialize(scope)
         @scope = scope
-        @rescue = 0
         @ensure = 0
         @block = 0
         @masgn = 0
+        @rescue = []
       end
 
-      def push_rescue
-        @rescue += 1
+      def push_rescue(val)
+        @rescue.push(val)
       end
 
       def pop_rescue
-        @rescue -= 1 if rescue?
+        @rescue.pop if rescue?
       end
 
       def rescue?
-        @rescue > 0
+        @rescue.last
       end
 
       def push_ensure

diff --git a/lib/compiler/generator.rb b/lib/compiler/generator.rb
@@ -64,6 +64,8 @@ def initialize
 
       @state = []
       @generators = []
+
+      @stack_locals = 0
     end
 
     attr_reader   :ip, :stream, :iseq, :literals
@@ -147,7 +149,7 @@ def package(klass)
       cm.local_count    = @local_count
       cm.local_names    = @local_names.to_tuple if @local_names
 
-      cm.stack_size     = @stack_size
+      cm.stack_size     = @stack_size + @stack_locals
       cm.file           = @file
       cm.name           = @name
       cm.primitive      = @primitive
@@ -169,6 +171,12 @@ def set_label_positions
 
     # Helpers
 
+    def new_stack_local
+      idx = @stack_locals
+      @stack_locals += 1
+      return idx
+    end
+
     def add(instruction, arg1=nil, arg2=nil)
       @stream << InstructionSet[instruction].bytecode
       length = 1

diff --git a/lib/compiler/printers.rb b/lib/compiler/printers.rb
@@ -31,6 +31,7 @@ def match?(name)
       def print_header(cm)
         name = cm.name.inspect
         size = (SEPARATOR_SIZE - name.size - 2) / 2
+        size = 1 if size <= 0
         puts "\n#{"=" * size} #{name} #{"=" * (size + name.size % 2)}"
         print "Arguments:   "
         print "#{cm.required_args} required, #{cm.total_args} total"

diff --git a/spec/compiler/defn_spec.rb b/spec/compiler/defn_spec.rb
@@ -29,7 +29,10 @@ def m
         ensure_noexc_lbl = d.new_label
 
         d.setup_unwind ensure_exc_lbl
+
         d.new_label.set!
+        exc = d.save_exception
+
         d.push_literal :a
         d.ensure_return
         d.pop_unwind
@@ -38,7 +41,9 @@ def m
         ensure_exc_lbl.set!
         d.push_exception
         d.push_literal :b
-        d.clear_exception
+
+        d.restore_exception exc
+
         d.ret
         d.pop
         d.pop_exception

diff --git a/spec/compiler/ensure_spec.rb b/spec/compiler/ensure_spec.rb
@@ -20,6 +20,8 @@
 
       top.set!
 
+      g.save_exception
+
       g.push_modifiers
       g.push :nil
       g.pop_modifiers
@@ -129,6 +131,8 @@
 
       top.set!
 
+      saved = save_exception()
+
       g.push 14
       g.pop
       g.push 2

diff --git a/spec/compiler/iter_spec.rb b/spec/compiler/iter_spec.rb
@@ -385,8 +385,10 @@
       top_lbl = d.new_label
       top_lbl.set!
 
+      e_saved = d.save_exception
       d.push_modifiers
-      d.push_exception
+
+      r_saved = d.save_exception
 
       retry_lbl.set!
 
@@ -427,8 +429,8 @@
 
       reraise_lbl.set!
       d.clear_exception
-      d.swap
-      d.pop_exception
+
+      d.restore_exception(r_saved)
       d.raise_break
 
       next_lbl.set!
@@ -437,8 +439,8 @@
 
       else_lbl.set!
       last_lbl.set!
-      d.swap
-      d.pop_exception
+
+      d.restore_exception r_saved
       d.pop_modifiers
 
       d.pop_unwind