add new instruction attribute called leaf

An instruction is leaf if it has no rb_funcall inside.  In order to
check this property, we introduce stack canary which is a random
number collected at runtime.  Stack top is always filled with this
number and checked for stack smashing operations, when VM_CHECK_MODE.
[GH-1947]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64677 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 8 insertions, 0 deletions

diff --git a/tool/ruby_vm/models/bare_instructions.rb b/tool/ruby_vm/models/bare_instructions.rb
index d2ff1341a0..5c27af3a38 100755
--- a/tool/ruby_vm/models/bare_instructions.rb
+++ b/tool/ruby_vm/models/bare_instructions.rb
@@ -105,6 +105,10 @@ class RubyVM::BareInstructions
     /\b(false|0)\b/ !~ @attrs['handles_sp'].expr.expr
   end
 
+  def complicated_return_values?
+    @sig[:ret].any? {|i| i == '...' }
+  end
+
   def inspect
     sprintf "#<%s %s@%s:%d>", self.class.name, @name, @loc[0], @loc[1]
   end
@@ -130,6 +134,10 @@ class RubyVM::BareInstructions
     generate_attribute 'rb_num_t', 'width', width
     generate_attribute 'rb_snum_t', 'sp_inc', rets.size - pops.size
     generate_attribute 'bool', 'handles_sp', false
+    generate_attribute 'bool', 'leaf', opes.all? {|o|
+      # Insn with ISEQ should yield it; can never be a leaf.
+      o[:type] != 'ISEQ'
+    }
   end
 
   def typesplit a