s390: Avoid CAS boolean output inefficiency
Ulrich Weigand
uweigand@de.ibm.com
Wed Aug 8 18:05:00 GMT 2012
Richard Henderson wrote:
> On 08/07/2012 10:02 AM, Ulrich Weigand wrote:
> > The following patch changes the builtin expander to pass a MEM oldval
> > as-is to the back-end expander, so that the back-end can move the
> > store to before the CC operation. With that patch I'm also seeing
> > all the IPMs disappear.
> ...
> > What do you think about this solution? It has the advantage that
> > we still get the same xor code if we actually do need the ipm ...
>
> I'm ok with that patch.
Thanks! I've checked in the following version.
Tested on s390x-ibm-linux with no regressions.
Bye,
Ulrich
ChangeLog:
* builtins.c (expand_builtin_atomic_compare_exchange): Pass old
value operand as MEM to expand_atomic_compare_and_swap.
* config/s390/s390.md ("atomic_compare_and_swap<mode>"): Accept
nonimmediate_operand for old value; generate load and store if
needed.
* config/s390/s390.c (s390_expand_cs_hqi): Accept any operand
as vtarget.
Index: gcc/builtins.c
===================================================================
*** gcc/builtins.c (revision 190226)
--- gcc/builtins.c (working copy)
*************** expand_builtin_atomic_compare_exchange (
*** 5376,5381 ****
--- 5376,5382 ----
expect = expand_normal (CALL_EXPR_ARG (exp, 1));
expect = convert_memory_address (Pmode, expect);
+ expect = gen_rtx_MEM (mode, expect);
desired = expand_expr_force_mode (CALL_EXPR_ARG (exp, 2), mode);
weak = CALL_EXPR_ARG (exp, 3);
*************** expand_builtin_atomic_compare_exchange (
*** 5383,5396 ****
if (host_integerp (weak, 0) && tree_low_cst (weak, 0) != 0)
is_weak = true;
! oldval = copy_to_reg (gen_rtx_MEM (mode, expect));
!
if (!expand_atomic_compare_and_swap ((target == const0_rtx ? NULL : &target),
&oldval, mem, oldval, desired,
is_weak, success, failure))
return NULL_RTX;
! emit_move_insn (gen_rtx_MEM (mode, expect), oldval);
return target;
}
--- 5384,5398 ----
if (host_integerp (weak, 0) && tree_low_cst (weak, 0) != 0)
is_weak = true;
! oldval = expect;
if (!expand_atomic_compare_and_swap ((target == const0_rtx ? NULL : &target),
&oldval, mem, oldval, desired,
is_weak, success, failure))
return NULL_RTX;
! if (oldval != expect)
! emit_move_insn (expect, oldval);
!
return target;
}
Index: gcc/config/s390/s390.c
===================================================================
*** gcc/config/s390/s390.c (revision 190226)
--- gcc/config/s390/s390.c (working copy)
*************** s390_expand_cs_hqi (enum machine_mode mo
*** 4825,4831 ****
rtx res = gen_reg_rtx (SImode);
rtx csloop = NULL, csend = NULL;
- gcc_assert (register_operand (vtarget, VOIDmode));
gcc_assert (MEM_P (mem));
init_alignment_context (&ac, mem, mode);
--- 4825,4830 ----
Index: gcc/config/s390/s390.md
===================================================================
*** gcc/config/s390/s390.md (revision 190226)
--- gcc/config/s390/s390.md (working copy)
***************
*** 8870,8876 ****
(define_expand "atomic_compare_and_swap<mode>"
[(match_operand:SI 0 "register_operand") ;; bool success output
! (match_operand:DGPR 1 "register_operand") ;; oldval output
(match_operand:DGPR 2 "memory_operand") ;; memory
(match_operand:DGPR 3 "register_operand") ;; expected intput
(match_operand:DGPR 4 "register_operand") ;; newval intput
--- 8870,8876 ----
(define_expand "atomic_compare_and_swap<mode>"
[(match_operand:SI 0 "register_operand") ;; bool success output
! (match_operand:DGPR 1 "nonimmediate_operand");; oldval output
(match_operand:DGPR 2 "memory_operand") ;; memory
(match_operand:DGPR 3 "register_operand") ;; expected intput
(match_operand:DGPR 4 "register_operand") ;; newval intput
***************
*** 8879,8887 ****
(match_operand:SI 7 "const_int_operand")] ;; failure model
""
{
! rtx cc, cmp;
emit_insn (gen_atomic_compare_and_swap<mode>_internal
! (operands[1], operands[2], operands[3], operands[4]));
cc = gen_rtx_REG (CCZ1mode, CC_REGNUM);
cmp = gen_rtx_EQ (SImode, cc, const0_rtx);
emit_insn (gen_cstorecc4 (operands[0], cmp, cc, const0_rtx));
--- 8879,8900 ----
(match_operand:SI 7 "const_int_operand")] ;; failure model
""
{
! rtx cc, cmp, output = operands[1];
!
! if (!register_operand (output, <MODE>mode))
! output = gen_reg_rtx (<MODE>mode);
!
emit_insn (gen_atomic_compare_and_swap<mode>_internal
! (output, operands[2], operands[3], operands[4]));
!
! /* We deliberately accept non-register operands in the predicate
! to ensure the write back to the output operand happens *before*
! the store-flags code below. This makes it easier for combine
! to merge the store-flags code with a potential test-and-branch
! pattern following (immediately!) afterwards. */
! if (output != operands[1])
! emit_move_insn (operands[1], output);
!
cc = gen_rtx_REG (CCZ1mode, CC_REGNUM);
cmp = gen_rtx_EQ (SImode, cc, const0_rtx);
emit_insn (gen_cstorecc4 (operands[0], cmp, cc, const0_rtx));
***************
*** 8890,8896 ****
(define_expand "atomic_compare_and_swap<mode>"
[(match_operand:SI 0 "register_operand") ;; bool success output
! (match_operand:HQI 1 "register_operand") ;; oldval output
(match_operand:HQI 2 "memory_operand") ;; memory
(match_operand:HQI 3 "general_operand") ;; expected intput
(match_operand:HQI 4 "general_operand") ;; newval intput
--- 8903,8909 ----
(define_expand "atomic_compare_and_swap<mode>"
[(match_operand:SI 0 "register_operand") ;; bool success output
! (match_operand:HQI 1 "nonimmediate_operand") ;; oldval output
(match_operand:HQI 2 "memory_operand") ;; memory
(match_operand:HQI 3 "general_operand") ;; expected intput
(match_operand:HQI 4 "general_operand") ;; newval intput
--
Dr. Ulrich Weigand
GNU Toolchain for Linux on System z and Cell BE
Ulrich.Weigand@de.ibm.com
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