fix incorrect ifcvt data flow computation

[Joern Rennecke <joern dot rennecke at superh dot com>]

ifcvt.c:dead_or_predicable uses local_set as computed by propagate_block
to determine which registers are changed in a piece of code.  However,
propagate_one_insn doesn't include updates of a stack pointer where a
CONST_INT is added to the stack pointer.  This resulted in the wrong
value of the stack pointer when branching to label 432 in the exapmle
below after if-conversion (r15 is the stack pointer):

test.ii.29.peephole2:

(jump_insn:HI 333 733 705 7 (set (pc)
        (if_then_else (ne (reg:SI 147 t)
                (const_int 0 [0x0]))
            (label_ref 432)
            (pc))) 195 {branch_true} (insn_list 332 (nil))
    (expr_list:REG_DEAD (reg:SI 147 t)
        (expr_list:REG_BR_PROB (const_int 7900 [0x1edc])
            (nil))))
;; End of basic block 7, registers live:
 1 [r1] 8 [r8] 9 [r9] 10 [r10] 11 [r11] 12 [r12] 15 [r15] 151 []
;; Register highparts live:


;; Start of basic block 8, registers live: 1 [r1] 8 [r8] 9 [r9] 10 [r10] 11 [r11] 12 [r12] 15 [r15] 151 []
;; register highparts live:
(note:HI 705 333 353 8 [bb 8] NOTE_INSN_BASIC_BLOCK)

(insn:HI 353 705 885 8 (set (reg/f:SI 15 r15)
        (plus:SI (reg/f:SI 15 r15)
            (const_int -4 [0xfffffffc]))) 39 {*addsi3_compact} (nil)
    (nil))

(jump_insn 885 353 886 8 (set (pc)
        (label_ref 884)) -1 (nil)
    (nil))
;; End of basic block 8, registers live:
 1 [r1] 8 [r8] 9 [r9] 10 [r10] 11 [r11] 12 [r12] 15 [r15] 151 []

**************************************************************************
test.ii.30.ce3:

(insn:HI 353 733 333 7 (set (reg/f:SI 15 r15)
        (plus:SI (reg/f:SI 15 r15)
            (const_int -4 [0xfffffffc]))) 39 {*addsi3_compact} (nil)
    (nil))

(jump_insn:HI 333 353 899 7 (set (pc)
        (if_then_else (eq (reg:SI 147 t)
                (const_int 0 [0x0]))
            (label_ref:SI 884)
            (pc))) 196 {branch_false} (insn_list 332 (nil))
    (expr_list:REG_DEAD (reg:SI 147 t)
        (expr_list:REG_BR_PROB (const_int 2100 [0x834])
            (nil))))
;; End of basic block 7, registers live:
 1 [r1] 8 [r8] 9 [r9] 10 [r10] 11 [r11] 12 [r12] 15 [r15] 151 []
;; Register highparts live:
 1 [r1] 8 [r8] 9 [r9] 10 [r10] 12 [r12] 15 [r15] 151 []

;; Start of basic block 8, registers live: 1 [r1] 8 [r8] 9 [r9] 10 [r10] 12 [r12] 15 [r15] 151 []
;; register highparts live:
(note 899 333 900 8 [bb 8] NOTE_INSN_BASIC_BLOCK)

(jump_insn 900 899 901 8 (set (pc)
        (label_ref 432)) -1 (nil)
    (nil))
;; End of basic block 8, registers live:
 1 [r1] 8 [r8] 9 [r9] 10 [r10] 12 [r12] 15 [r15] 151 []

Currently regression testing on i686-px-linux-gnu X sh-elf and native.

2004-04-20  J"orn Rennecke <joern.rennecke@superh.com>

	* flow.c (propagate_one_insn): Call mark_set_regs for stack pointer
	updates too.

Index: flow.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/flow.c,v
retrieving revision 1.584
diff -p -r1.584 flow.c
*** flow.c	3 Mar 2004 11:41:47 -0000	1.584
--- flow.c	20 Apr 2004 15:12:57 -0000
*************** propagate_one_insn (struct propagate_blo
*** 1707,1718 ****
  	   && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
  	   && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
  	   && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
!     /* We have an insn to pop a constant amount off the stack.
!        (Such insns use PLUS regardless of the direction of the stack,
!        and any insn to adjust the stack by a constant is always a pop.)
!        These insns, if not dead stores, have no effect on life, though
!        they do have an effect on the memory stores we are tracking.  */
!     invalidate_mems_from_set (pbi, stack_pointer_rtx);
    else
      {
        rtx note;
--- 1707,1724 ----
  	   && GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
  	   && XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
  	   && GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
!     {
!       /* We have an insn to pop a constant amount off the stack.
!          (Such insns use PLUS regardless of the direction of the stack,
!          and any insn to adjust the stack by a constant is always a pop
! 	 or part of a push.)
!          These insns, if not dead stores, have no effect on life, though
!          they do have an effect on the memory stores we are tracking.  */
!       invalidate_mems_from_set (pbi, stack_pointer_rtx);
!       /* Still, we need to update local_set, lest ifcvt.c:dead_or_predicable
! 	 concludes that the stack pointer is not modified.  */
!       mark_set_regs (pbi, PATTERN (insn), insn);
!     }
    else
      {
        rtx note;