Re: [PATCH] rtlanal: Fix set_noop_p for volatile loads or stores [PR114768]

[Thomas Schwinge <tschwinge@baylibre.com>]

Hi Jakub!

On 2024-04-19T08:24:03+0200, Jakub Jelinek <jakub@redhat.com> wrote:
> --- gcc/testsuite/gcc.dg/pr114768.c.jj	2024-04-18 15:37:49.139433678 +0200
> +++ gcc/testsuite/gcc.dg/pr114768.c	2024-04-18 15:43:30.389730365 +0200
> @@ -0,0 +1,10 @@
> +/* PR rtl-optimization/114768 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-rtl-final" } */
> +/* { dg-final { scan-rtl-dump "\\\(mem/v:" "final" { target { ! { nvptx*-*-* } } } } } */
> +
> +void
> +foo (int *p)
> +{
> +  *p = *(volatile int *) p;
> +}

Why exclude nvptx target here?  As far as I can see, it does behave in
the exactly same way as expected; see 'diff' of before vs. after the
'gcc/rtlanal.cc' code changes:

    PASS: gcc.dg/pr114768.c (test for excess errors)
    [-FAIL:-]{+PASS:+} gcc.dg/pr114768.c scan-rtl-dump final "\\(mem/v:"

    --- 0/pr114768.c.347r.final	2024-04-19 11:34:34.577037596 +0200
    +++ ./pr114768.c.347r.final	2024-04-19 12:08:00.118312524 +0200
    @@ -13,15 +13,27 @@
     ;;  entry block defs 	 1 [%stack] 2 [%frame] 3 [%args]
     ;;  exit block uses 	 1 [%stack] 2 [%frame]
     ;;  regs ever live 	
    -;;  ref usage 	r1={1d,2u} r2={1d,2u} r3={1d,1u} 
    -;;    total ref usage 8{3d,5u,0e} in 1{1 regular + 0 call} insns.
    +;;  ref usage 	r1={1d,3u} r2={1d,3u} r3={1d,2u} r22={1d,1u} r23={1d,2u} 
    +;;    total ref usage 16{5d,11u,0e} in 4{4 regular + 0 call} insns.
     (note 1 0 4 NOTE_INSN_DELETED)
     (note 4 1 2 2 [bb 2] NOTE_INSN_BASIC_BLOCK)
    -(note 2 4 3 2 NOTE_INSN_DELETED)
    +(insn 2 4 3 2 (set (reg/v/f:DI 23 [ p ])
    +        (unspec:DI [
    +                (const_int 0 [0])
    +            ] UNSPEC_ARG_REG)) "source-gcc/gcc/testsuite/gcc.dg/pr114768.c":8:1 14 {load_arg_regdi}
    +     (nil))
     (note 3 2 6 2 NOTE_INSN_FUNCTION_BEG)
    -(note 6 3 10 2 NOTE_INSN_DELETED)
    -(note 10 6 11 2 NOTE_INSN_EPILOGUE_BEG)
    -(jump_insn 11 10 12 2 (return) "source-gcc/gcc/testsuite/gcc.dg/pr114768.c":10:1 289 {return}
    +(insn 6 3 7 2 (set (reg:SI 22 [ _1 ])
    +        (mem/v:SI (reg/v/f:DI 23 [ p ]) [1 MEM[(volatile int *)p_3(D)]+0 S4 A32])) "source-gcc/gcc/testsuite/gcc.dg/pr114768.c":9:8 6 {*movsi_insn}
    +     (nil))
    +(insn 7 6 10 2 (set (mem:SI (reg/v/f:DI 23 [ p ]) [1 *p_3(D)+0 S4 A32])
    +        (reg:SI 22 [ _1 ])) "source-gcc/gcc/testsuite/gcc.dg/pr114768.c":9:6 6 {*movsi_insn}
    +     (expr_list:REG_DEAD (reg/v/f:DI 23 [ p ])
    +        (expr_list:REG_DEAD (reg:SI 22 [ _1 ])
    +            (nil))))
    +(note 10 7 13 2 NOTE_INSN_EPILOGUE_BEG)
    +(note 13 10 11 3 [bb 3] NOTE_INSN_BASIC_BLOCK)
    +(jump_insn 11 13 12 3 (return) "source-gcc/gcc/testsuite/gcc.dg/pr114768.c":10:1 289 {return}
          (nil)
      -> return)
     (barrier 12 11 0)

    --- 0/pr114768.s	2024-04-19 11:34:34.577037596 +0200
    +++ ./pr114768.s	2024-04-19 12:08:00.118312524 +0200
    @@ -13,5 +13,10 @@
     {
     	.reg.u64 %ar0;
     	ld.param.u64 %ar0, [%in_ar0];
    +	.reg.u32 %r22;
    +	.reg.u64 %r23;
    +		mov.u64	%r23, %ar0;
    +		ld.u32	%r22, [%r23];
    +		st.u32	[%r23], %r22;
     	ret;
     }


Grüße
 Thomas