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Prepare for moveable stacks in the VM.

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* libguile/vm-engine.c (CHECK_OVERFLOW, ALLOC_FRAME, vm_engine): Prepare
  for moveable stacks.
This commit is contained in:
Andy Wingo 2013-11-21 10:23:35 +01:00
parent f593117165
commit eadd9eb4c9
1 changed files with 19 additions and 8 deletions
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23
libguile/vm-engine.c
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@ -168,10 +168,18 @@
#define SYNC_ALL() /* FP already saved */ \ #define SYNC_ALL() /* FP already saved */ \
SYNC_IP() SYNC_IP()
#define CHECK_OVERFLOW(sp) \ /* After advancing vp->sp, but before writing any stack slots, check
that it is actually in bounds. If it is not in bounds, currently we
signal an error. In the future we may expand the stack instead,
possibly by moving it elsewhere, therefore no pointer into the stack
besides FP is valid across a CHECK_OVERFLOW call. Be careful! */
#define CHECK_OVERFLOW() \
do { \ do { \
if (SCM_UNLIKELY ((sp) >= vp->stack_limit)) \ if (SCM_UNLIKELY (vp->sp >= vp->stack_limit)) \
{ \
vm_error_stack_overflow (vp); \ vm_error_stack_overflow (vp); \
CACHE_REGISTER(); \
} \
} while (0) } while (0)
/* Reserve stack space for a frame. Will check that there is sufficient /* Reserve stack space for a frame. Will check that there is sufficient
@ -179,8 +187,8 @@
preparing the new frame and setting the fp and ip. */ preparing the new frame and setting the fp and ip. */
#define ALLOC_FRAME(n) \ #define ALLOC_FRAME(n) \
do { \ do { \
SCM *new_sp = vp->sp = LOCAL_ADDRESS (n - 1); \ vp->sp = LOCAL_ADDRESS (n - 1); \
CHECK_OVERFLOW (new_sp); \ CHECK_OVERFLOW (); \
} while (0) } while (0)
/* Reset the current frame to hold N locals. Used when we know that no /* Reset the current frame to hold N locals. Used when we know that no
@ -479,12 +487,15 @@ VM_NAME (SCM vm, SCM program, SCM *argv, size_t nargs_)
/* Initialization */ /* Initialization */
{ {
SCM *base; SCM *base;
ptrdiff_t base_frame_size;
/* Check that we have enough space: 3 words for the boot /* Check that we have enough space: 3 words for the boot
continuation, 3 + nargs for the procedure application, and 3 for continuation, 3 + nargs for the procedure application, and 3 for
setting up a new frame. */ setting up a new frame. */
base = vp->sp + 1; base_frame_size = 3 + 3 + nargs_ + 3;
CHECK_OVERFLOW (vp->sp + 3 + 3 + nargs_ + 3); vp->sp += base_frame_size;
CHECK_OVERFLOW ();
base = vp->sp + 1 - base_frame_size;
/* Since it's possible to receive the arguments on the stack itself, /* Since it's possible to receive the arguments on the stack itself,
and indeed the regular VM invokes us that way, shuffle up the and indeed the regular VM invokes us that way, shuffle up the