shyouhei	2018-09-13 12:46:46 +0900 (Thu, 13 Sep 2018)

  New Revision: 64709

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=64709

  Log:
    move canary-related statements into macros
    
    This is mostly cosmetic.  Should generate a slightly readable
    vm.inc output.

  Modified files:
    trunk/tool/ruby_vm/models/bare_instructions.rb
    trunk/tool/ruby_vm/views/_insn_entry.erb
    trunk/vm_insnhelper.h
Index: tool/ruby_vm/views/_insn_entry.erb
===================================================================
--- tool/ruby_vm/views/_insn_entry.erb	(revision 64708)
+++ tool/ruby_vm/views/_insn_entry.erb	(revision 64709)
@@ -13,16 +13,11 @@ INSN_ENTRY(<%= insn.name %>) https://github.com/ruby/ruby/blob/trunk/tool/ruby_vm/views/_insn_entry.erb#L13
 %#  NAME_OF_CURRENT_INSN is used in vm_exec.h
 #   define NAME_OF_CURRENT_INSN <%= insn.name %>
 #   define INSN_ATTR(x) <%= insn.call_attribute(' ## x ## ') %>
-% unless insn.complicated_return_values?
-#   if VM_CHECK_MODE > 0
-    bool leaf;
-    VALUE *canary;
-#   endif
-% end
 % unless insn.declarations.empty?
     <%= insn.declarations.join(";\n    ") %>;
 
 % end
+<%= insn.handle_canary "DECLARE_CANARY" -%>
     START_OF_ORIGINAL_INSN(<%= insn.name %>);
 % insn.preamble.each do |konst|
 <%= render_c_expr konst -%>
@@ -39,27 +34,14 @@ INSN_ENTRY(<%= insn.name %>) https://github.com/ruby/ruby/blob/trunk/tool/ruby_vm/views/_insn_entry.erb#L34
 % if insn.handles_sp?
     POPN(INSN_ATTR(popn));
 % end
-% unless insn.complicated_return_values?
-#if VM_CHECK_MODE > 0
-    if ((leaf = INSN_ATTR(leaf))) {
-        canary = STACK_ADDR_FROM_TOP(-1);
-        *canary = vm_stack_canary;
-    }
-#endif
-% end
+<%= insn.handle_canary "SETUP_CANARY()" -%>
     COLLECT_USAGE_INSN(INSN_ATTR(bin));
 % insn.opes.each_with_index do |ope, i|
     COLLECT_USAGE_OPERAND(INSN_ATTR(bin), <%= i %>, <%= ope[:name] %>);
 % end
 <%= render_c_expr insn.expr -%>
     CHECK_VM_STACK_OVERFLOW_FOR_INSN(VM_REG_CFP, INSN_ATTR(retn));
-% unless insn.complicated_return_values?
-#if VM_CHECK_MODE > 0
-    if (leaf && (*canary != vm_stack_canary)) {
-        vm_canary_is_found_dead(INSN_ATTR(bin), *canary);
-    }
-#endif
-% end
+<%= insn.handle_canary "CHECK_CANARY()" -%>
 % if insn.handles_sp?
 %   insn.rets.reverse_each do |ret|
     PUSH(<%= insn.cast_to_VALUE ret %>);
Index: tool/ruby_vm/models/bare_instructions.rb
===================================================================
--- tool/ruby_vm/models/bare_instructions.rb	(revision 64708)
+++ tool/ruby_vm/models/bare_instructions.rb	(revision 64709)
@@ -109,8 +109,20 @@ class RubyVM::BareInstructions https://github.com/ruby/ruby/blob/trunk/tool/ruby_vm/models/bare_instructions.rb#L109
     @attrs.fetch('leaf').expr.expr == 'true;'
   end
 
-  def complicated_return_values?
-    @sig[:ret].any? {|i| i == '...' }
+  def handle_canary stmt
+    # Stack canary is basically a good thing that we want to add, however:
+    #
+    # - When the instruction returns variadic number of return values,
+    #   it is not easy to tell where is the stack top.  We can't but
+    #   skip it.
+    #
+    # - When the instruction body is empty (like putobject), we can
+    #   say for 100% sure that canary is a waste of time.
+    #
+    # So we skip canary for those cases.
+    return '' if @sig[:ret].any? {|i| i == '...' }
+    return '' if @expr.blank?
+    return "    #{stmt};\n"
   end
 
   def inspect
Index: vm_insnhelper.h
===================================================================
--- vm_insnhelper.h	(revision 64708)
+++ vm_insnhelper.h	(revision 64709)
@@ -201,6 +201,27 @@ enum vm_regan_acttype { https://github.com/ruby/ruby/blob/trunk/vm_insnhelper.h#L201
 
 
 /**********************************************************/
+/* deal with stack canary                                 */
+/**********************************************************/
+
+#if VM_CHECK_MODE > 0
+#define DECLARE_CANARY bool leaf; VALUE *canary
+#define SETUP_CANARY() \
+    if ((leaf = INSN_ATTR(leaf))) { \
+        canary = GET_SP(); \
+        SET_SV(vm_stack_canary); \
+    }
+#define CHECK_CANARY() \
+    if (leaf && (*canary != vm_stack_canary)) { \
+        vm_canary_is_found_dead(INSN_ATTR(bin), *canary); \
+    }
+#else
+#define DECLARE_CANARY          /* void */
+#define SETUP_CANARY()          /* void */
+#define CHECK_CANARY()          /* void */
+#endif
+
+/**********************************************************/
 /* others                                                 */
 /**********************************************************/
 

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