nobu	2013-11-18 11:29:58 +0900 (Mon, 18 Nov 2013)

  New Revision: 43702

  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=rev&revision=43702

  Log:
    vm_core.h: extract VM_STACK_OVERFLOWED_P
    
    * vm_core.h (VM_STACK_OVERFLOWED_P, WHEN_VM_STACK_OVERFLOWED): extract
      condition from CHECK_VM_STACK_OVERFLOW.
    
    * vm_exec.c (vm_stack_overflow_for_insn): move rb_bug call.
    
    * vm_exec.h (CHECK_VM_STACK_OVERFLOW_FOR_INSN): share the condition
      with CHECK_VM_STACK_OVERFLOW.

  Modified files:
    trunk/vm_core.h
    trunk/vm_exec.c
    trunk/vm_exec.h
Index: vm_core.h
===================================================================
--- vm_core.h	(revision 43701)
+++ vm_core.h	(revision 43702)
@@ -889,13 +889,17 @@ int rb_autoloading_value(VALUE mod, ID i https://github.com/ruby/ruby/blob/trunk/vm_core.h#L889
 
 #define sysstack_error GET_VM()->special_exceptions[ruby_error_sysstack]
 
-#define CHECK_VM_STACK_OVERFLOW0(cfp, sp, margin) do { \
-    if ((VALUE *)((char *)((VALUE *)(sp) + (margin)) + sizeof(rb_control_frame_t)) >= ((VALUE *)(cfp))) { \
-	vm_stackoverflow(); \
-    } \
-} while (0)
-
-#define CHECK_VM_STACK_OVERFLOW(cfp, margin) CHECK_VM_STACK_OVERFLOW0((cfp), (cfp)->sp, margin)
+#define RUBY_CONST_ASSERT(expr) (1/!!(expr)) /* expr must be a compile-time constant */
+#define VM_STACK_OVERFLOWED_P(cfp, sp, margin) \
+    (!RUBY_CONST_ASSERT(sizeof(*(sp)) == sizeof(VALUE)) || \
+     !RUBY_CONST_ASSERT(sizeof(*(cfp)) == sizeof(rb_control_frame_t)) || \
+     ((rb_control_frame_t *)((sp) + (margin)) + 1) >= (cfp))
+#define WHEN_VM_STACK_OVERFLOWED(cfp, sp, margin) \
+    if (LIKELY(!VM_STACK_OVERFLOWED_P(cfp, sp, margin))) {(void)0;} else /* overflowed */
+#define CHECK_VM_STACK_OVERFLOW0(cfp, sp, margin) \
+    WHEN_VM_STACK_OVERFLOWED(cfp, sp, margin) vm_stackoverflow()
+#define CHECK_VM_STACK_OVERFLOW(cfp, margin) \
+    WHEN_VM_STACK_OVERFLOWED(cfp, (cfp)->sp, margin) vm_stackoverflow()
 
 /* for thread */
 
Index: vm_exec.c
===================================================================
--- vm_exec.c	(revision 43701)
+++ vm_exec.c	(revision 43702)
@@ -29,6 +29,15 @@ static void vm_analysis_insn(int insn); https://github.com/ruby/ruby/blob/trunk/vm_exec.c#L29
 #endif
 /* #define DECL_SC_REG(r, reg) VALUE reg_##r */
 
+NORETURN(static void vm_stack_overflow_for_insn(void));
+static void
+vm_stack_overflow_for_insn(void)
+{
+    rb_bug("CHECK_VM_STACK_OVERFLOW_FOR_INSN: should not overflow here. "
+	   "Please contact ruby-core/dev with your (a part of) script. "
+	   "This check will be removed soon.");
+}
+
 #if !OPT_CALL_THREADED_CODE
 static VALUE
 vm_exec_core(rb_thread_t *th, VALUE initial)
Index: vm_exec.h
===================================================================
--- vm_exec.h	(revision 43701)
+++ vm_exec.h	(revision 43702)
@@ -169,12 +169,7 @@ default:                        \ https://github.com/ruby/ruby/blob/trunk/vm_exec.h#L169
 #endif
 
 #define SCREG(r) (reg_##r)
-#define CHECK_VM_STACK_OVERFLOW_FOR_INSN(cfp, margin) do { \
-    if (((rb_control_frame_t *)(((cfp)->sp) + (margin)) + 1) >= (cfp)) { \
-	rb_bug("CHECK_VM_STACK_OVERFLOW_FOR_INSN: should not overflow here. " \
-	       "Please contact ruby-core/dev with your (a part of) script. " \
-	       "This check will be removed soon."); \
-    } \
-} while (0)
+#define CHECK_VM_STACK_OVERFLOW_FOR_INSN(cfp, margin) \
+    WHEN_VM_STACK_OVERFLOWED(cfp, (cfp)->sp, margin) vm_stack_overflow_for_insn()
 
 #endif /* RUBY_VM_EXEC_H */

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