[2/3] IBM zSystems: Make stack_tie to work with hard frame-pointer
Commit Message
With this patch a scheduling barrier is created to prevent the insn
setting up the frame-pointer and instructions which save GPRs to the
stack to be swapped. Otherwise broken CFI information would be
generated since the stack save insns would use a base register which
is not currently declared as holding the CFA.
Without -mpreserve-args this did not happen because the store multiple
we used for saving the GPRs would also cover the frame-pointer
register and therefore creates a dependency on the frame-pointer
hardreg. However, with this patch the stack_tie is emitted regardless
of -mpreserve-args since this in general appears to be the safer
approach.
* config/s390/s390.cc (save_gprs): Use gen_frame_mem.
(restore_gprs): Likewise.
(s390_emit_stack_tie): Make the stack_tie to be dependent on the
frame pointer if a frame-pointer is used.
(s390_emit_prologue): Emit stack_tie when frame-pointer is needed.
* config/s390/s390.md (stack_tie): Add a register operand and
rename to ...
(@stack_tie<mode>): ... this.
---
gcc/config/s390/s390.cc | 17 ++++++++---------
gcc/config/s390/s390.md | 5 +++--
2 files changed, 11 insertions(+), 11 deletions(-)
@@ -10898,9 +10898,7 @@ save_gprs (rtx base, int offset, int first, int last)
int i;
addr = plus_constant (Pmode, base, offset);
- addr = gen_rtx_MEM (Pmode, addr);
-
- set_mem_alias_set (addr, get_frame_alias_set ());
+ addr = gen_frame_mem (Pmode, addr);
/* Special-case single register. */
if (first == last)
@@ -11012,8 +11010,7 @@ restore_gprs (rtx base, int offset, int first, int last)
rtx addr, insn;
addr = plus_constant (Pmode, base, offset);
- addr = gen_rtx_MEM (Pmode, addr);
- set_mem_alias_set (addr, get_frame_alias_set ());
+ addr = gen_frame_mem (Pmode, addr);
/* Special-case single register. */
if (first == last)
@@ -11062,10 +11059,11 @@ s390_load_got (void)
static void
s390_emit_stack_tie (void)
{
- rtx mem = gen_frame_mem (BLKmode,
- gen_rtx_REG (Pmode, STACK_POINTER_REGNUM));
-
- emit_insn (gen_stack_tie (mem));
+ rtx mem = gen_frame_mem (BLKmode, stack_pointer_rtx);
+ if (frame_pointer_needed)
+ emit_insn (gen_stack_tie (Pmode, mem, hard_frame_pointer_rtx));
+ else
+ emit_insn (gen_stack_tie (Pmode, mem, stack_pointer_rtx));
}
/* Copy GPRS into FPR save slots. */
@@ -11676,6 +11674,7 @@ s390_emit_prologue (void)
if (frame_pointer_needed)
{
+ s390_emit_stack_tie ();
insn = emit_move_insn (hard_frame_pointer_rtx, stack_pointer_rtx);
RTX_FRAME_RELATED_P (insn) = 1;
}
@@ -11590,9 +11590,10 @@
; This is used in s390_emit_prologue in order to prevent insns
; adjusting the stack pointer to be moved over insns writing stack
; slots using a copy of the stack pointer in a different register.
-(define_insn "stack_tie"
+(define_insn "@stack_tie<mode>"
[(set (match_operand:BLK 0 "memory_operand" "+m")
- (unspec:BLK [(match_dup 0)] UNSPEC_TIE))]
+ (unspec:BLK [(match_dup 0)
+ (match_operand:P 1 "register_operand" "r")] UNSPEC_TIE))]
""
""
[(set_attr "length" "0")])