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* eval.c (FUNCTION_CALL_MAY_RETURN_TWICE): DUMMY_SETJMP is replaced

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because setjmp is not enough to fix getcontext and SPARC register
  window problem.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@8651 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
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akr 2005-06-20 10:00:23 +00:00
parent b03649bc2a
commit 258f9f49d6
2 changed files with 35 additions and 11 deletions
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6
ChangeLog
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@ -1,3 +1,9 @@
Mon Jun 20 18:44:04 2005 Tanaka Akira <akr@m17n.org>
* eval.c (FUNCTION_CALL_MAY_RETURN_TWICE): DUMMY_SETJMP is replaced
because setjmp is not enough to fix getcontext and SPARC register
window problem.
Mon Jun 20 17:15:51 2005 NAKAMURA Usaku <usa@ruby-lang.org>
* ext/dbm/dbm.c (fdbm_closed): new method DBM#closed?

40
eval.c
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@ -108,36 +108,54 @@ rb_jump_context(env, val)
abort(); /* ensure noreturn */
}
/*
* DUMMY_SETJMP is a magic for getcontext, gcc and IA64 register stack
* combination problem.
* FUNCTION_CALL_MAY_RETURN_TWICE is a magic for getcontext, gcc,
* IA64 register stack and SPARC register window combination problem.
*
* Assume following code sequence.
*
* 1. set a register in the register stack such as r32.
* 1. set a register in the register stack/window such as r32/l0.
* 2. call getcontext.
* 3. use the register.
* 4. update the register for other use.
* 5. call setcontext directly or indirectly.
* 5. call setcontext indirectly (or directly).
*
* This code should be run as 1->2->3->4->5->3->4.
* But after second getcontext return (second 3),
* the register is broken (updated).
* It's because getcontext/setcontext doesn't preserve the content of the
* register stack.
* register stack/window.
*
* setjmp also doesn't preserve the content of the register stack.
* setjmp also doesn't preserve the content of the register stack/window.
* But it has not the problem because gcc knows setjmp may return twice.
* gcc detects setjmp and generates setjmp safe code.
*
* So setjmp call before getcontext call fix the problem.
* So setjmp call before getcontext call makes the code somewhat safe.
* It fix the problem on IA64.
* It is not required that setjmp is called at run time, since the problem is
* register usage.
*
* Since the magic setjmp is not enough for SPARC,
* inline asm is used to prohibit registers in register windows.
*/
static jmp_buf dummy_setjmp_jmp_buf;
int dummy_setjmp_false = 0;
#define DUMMY_SETJMP (dummy_setjmp_false ? setjmp(dummy_setjmp_jmp_buf) : 0)
#if defined (__GNUC__) && (defined(sparc) || defined(__sparc__))
#define FUNCTION_CALL_MAY_RETURN_TWICE \
({ __asm__ volatile ("" : : : \
"%o0", "%o1", "%o2", "%o3", "%o4", "%o5", "%o7", \
"%l0", "%l1", "%l2", "%l3", "%l4", "%l5", "%l6", "%l7", \
"%i0", "%i1", "%i2", "%i3", "%i4", "%i5", "%i7"); })
#else
static jmp_buf function_call_may_return_twice_jmp_buf;
int function_call_may_return_twice_false = 0;
#define FUNCTION_CALL_MAY_RETURN_TWICE \
(function_call_may_return_twice_false ? \
setjmp(function_call_may_return_twice_jmp_buf) : \
0)
#endif
#define ruby_longjmp(env, val) rb_jump_context(env, val)
#define ruby_setjmp(j) ((j)->status = 0, DUMMY_SETJMP, getcontext(&(j)->context), (j)->status)
#define ruby_setjmp(j) ((j)->status = 0, \
FUNCTION_CALL_MAY_RETURN_TWICE, \
getcontext(&(j)->context), \
(j)->status)
#else
typedef jmp_buf rb_jmpbuf_t;
#if !defined(setjmp) && defined(HAVE__SETJMP)