-static int
-record_stack_memrefs (xp, data)
- rtx *xp;
- void *data;
-{
- rtx x = *xp;
- struct record_stack_memrefs_data *d =
- (struct record_stack_memrefs_data *) data;
- if (!x)
- return 0;
- switch (GET_CODE (x))
- {
- case MEM:
- if (!reg_mentioned_p (stack_pointer_rtx, x))
- return -1;
- /* We are not able to handle correctly all possible memrefs containing
- stack pointer, so this check is necessary. */
- if (stack_memref_p (x))
- {
- d->memlist = record_one_stack_memref (d->insn, xp, d->memlist);
- return -1;
- }
- return 1;
- case REG:
- /* ??? We want be able to handle non-memory stack pointer
- references later. For now just discard all insns refering to
- stack pointer outside mem expressions. We would probably
- want to teach validate_replace to simplify expressions first.
-
- We can't just compare with STACK_POINTER_RTX because the
- reference to the stack pointer might be in some other mode.
- In particular, an explict clobber in an asm statement will
- result in a QImode clober. */
- if (REGNO (x) == STACK_POINTER_REGNUM)
- return 1;
- break;
- default:
- break;
- }
- return 0;
-}
-
-/* Subroutine of combine_stack_adjustments, called for each basic block. */
-
-static void
-combine_stack_adjustments_for_block (bb)
- basic_block bb;
-{
- HOST_WIDE_INT last_sp_adjust = 0;
- rtx last_sp_set = NULL_RTX;
- struct csa_memlist *memlist = NULL;
- rtx pending_delete;
- rtx insn, next;
- struct record_stack_memrefs_data data;
-
- for (insn = bb->head; ; insn = next)
- {
- rtx set;
-
- pending_delete = NULL_RTX;
- next = NEXT_INSN (insn);
-
- if (! INSN_P (insn))
- goto processed;
-
- set = single_set_for_csa (insn);
- if (set)
- {
- rtx dest = SET_DEST (set);
- rtx src = SET_SRC (set);
-
- /* Find constant additions to the stack pointer. */
- if (dest == stack_pointer_rtx
- && GET_CODE (src) == PLUS
- && XEXP (src, 0) == stack_pointer_rtx
- && GET_CODE (XEXP (src, 1)) == CONST_INT)
- {
- HOST_WIDE_INT this_adjust = INTVAL (XEXP (src, 1));
-
- /* If we've not seen an adjustment previously, record
- it now and continue. */
- if (! last_sp_set)
- {
- last_sp_set = insn;
- last_sp_adjust = this_adjust;
- goto processed;
- }
-
- /* If not all recorded memrefs can be adjusted, or the
- adjustment is now too large for a constant addition,
- we cannot merge the two stack adjustments.
-
- Also we need to be carefull to not move stack pointer
- such that we create stack accesses outside the allocated
- area. We can combine an allocation into the first insn,
- or a deallocation into the second insn. We can not
- combine an allocation followed by a deallocation.
-
- The only somewhat frequent occurrence of the later is when
- a function allocates a stack frame but does not use it.
- For this case, we would need to analyze rtl stream to be
- sure that allocated area is really unused. This means not
- only checking the memory references, but also all registers
- or global memory references possibly containing a stack
- frame address.
-
- Perhaps the best way to address this problem is to teach
- gcc not to allocate stack for objects never used. */
-
- /* Combine an allocation into the first instruction. */
- if (STACK_GROWS_DOWNWARD ? this_adjust <= 0 : this_adjust >= 0)
- {
- if (try_apply_stack_adjustment (last_sp_set, memlist,
- last_sp_adjust + this_adjust,
- this_adjust))
- {
- /* It worked! */
- pending_delete = insn;
- last_sp_adjust += this_adjust;
- goto processed;
- }
- }
-
- /* Otherwise we have a deallocation. Do not combine with
- a previous allocation. Combine into the second insn. */
- else if (STACK_GROWS_DOWNWARD
- ? last_sp_adjust >= 0 : last_sp_adjust <= 0)
- {
- if (try_apply_stack_adjustment (insn, memlist,
- last_sp_adjust + this_adjust,
- -last_sp_adjust))
- {
- /* It worked! */
- delete_insn (last_sp_set);
- last_sp_set = insn;
- last_sp_adjust += this_adjust;
- free_csa_memlist (memlist);
- memlist = NULL;
- goto processed;
- }
- }
-
- /* Combination failed. Restart processing from here. */
- free_csa_memlist (memlist);
- memlist = NULL;
- last_sp_set = insn;
- last_sp_adjust = this_adjust;
- goto processed;
- }
-
- /* Find a predecrement of exactly the previous adjustment and
- turn it into a direct store. Obviously we can't do this if
- there were any intervening uses of the stack pointer. */
- if (memlist == NULL
- && GET_CODE (dest) == MEM
- && ((GET_CODE (XEXP (dest, 0)) == PRE_DEC
- && (last_sp_adjust
- == (HOST_WIDE_INT) GET_MODE_SIZE (GET_MODE (dest))))
- || (GET_CODE (XEXP (dest, 0)) == PRE_MODIFY
- && GET_CODE (XEXP (XEXP (dest, 0), 1)) == PLUS
- && XEXP (XEXP (XEXP (dest, 0), 1), 0) == stack_pointer_rtx
- && (GET_CODE (XEXP (XEXP (XEXP (dest, 0), 1), 1))
- == CONST_INT)
- && (INTVAL (XEXP (XEXP (XEXP (dest, 0), 1), 1))
- == -last_sp_adjust)))
- && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx
- && ! reg_mentioned_p (stack_pointer_rtx, src)
- && memory_address_p (GET_MODE (dest), stack_pointer_rtx)
- && validate_change (insn, &SET_DEST (set),
- replace_equiv_address (dest,
- stack_pointer_rtx),
- 0))
- {
- if (last_sp_set == bb->head)
- bb->head = NEXT_INSN (last_sp_set);
- delete_insn (last_sp_set);
-
- free_csa_memlist (memlist);
- memlist = NULL;
- last_sp_set = NULL_RTX;
- last_sp_adjust = 0;
- goto processed;
- }
- }
-
- data.insn = insn;
- data.memlist = memlist;
- if (GET_CODE (insn) != CALL_INSN && last_sp_set
- && !for_each_rtx (&PATTERN (insn), record_stack_memrefs, &data))
- {
- memlist = data.memlist;
- goto processed;
- }
- memlist = data.memlist;
-
- /* Otherwise, we were not able to process the instruction.
- Do not continue collecting data across such a one. */
- if (last_sp_set
- && (GET_CODE (insn) == CALL_INSN
- || reg_mentioned_p (stack_pointer_rtx, PATTERN (insn))))
- {
- free_csa_memlist (memlist);
- memlist = NULL;
- last_sp_set = NULL_RTX;
- last_sp_adjust = 0;
- }
-
- processed:
- if (insn == bb->end)
- break;
-
- if (pending_delete)
- delete_insn (pending_delete);
- }
-
- if (pending_delete)
- delete_insn (pending_delete);
-}