From 52e35469f0a057ce31c04a36116e7a5563c2665b Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Mon, 18 Nov 2013 02:29:58 +0000
Subject: 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.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43702 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 vm_core.h | 18 +++++++++++-------
 vm_exec.c |  9 +++++++++
 vm_exec.h |  9 ++-------
 3 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/vm_core.h b/vm_core.h
index 94527bbfa6..1011df7276 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -889,13 +889,17 @@ int rb_autoloading_value(VALUE mod, ID id, VALUE* value);
 
 #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 */
 
diff --git a/vm_exec.c b/vm_exec.c
index c914a8bcca..c7057cd445 100644
--- a/vm_exec.c
+++ b/vm_exec.c
@@ -29,6 +29,15 @@ static void vm_analysis_insn(int insn);
 #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)
diff --git a/vm_exec.h b/vm_exec.h
index c92f715594..7e2b60a359 100644
--- a/vm_exec.h
+++ b/vm_exec.h
@@ -169,12 +169,7 @@ default:                        \
 #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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