Re: [PATCH] i386[stv]: Handle REG_EH_REGION note

[Uros Bizjak <ubizjak@gmail.com>]

On Thu, Mar 14, 2024 at 2:33 AM liuhongt <hongtao.liu@intel.com> wrote:
>
> When we split
> (insn 37 36 38 10 (set (reg:DI 104 [ _18 ])
>         (mem:DI (reg/f:SI 98 [ CallNative_nclosure.0_1 ]) [6 MEM[(struct SQRefCounted *)CallNative_nclosure.0_1]._uiRef+0 S8 A32])) "test.C":22:42 84 {*movdi_internal}
>      (expr_list:REG_EH_REGION (const_int -11 [0xfffffffffffffff5])
>
> into
>
> (insn 104 36 37 10 (set (subreg:V2DI (reg:DI 124) 0)
>         (vec_concat:V2DI (mem:DI (reg/f:SI 98 [ CallNative_nclosure.0_1 ]) [6 MEM[(struct SQRefCounted *)CallNative_nclosure.0_1]._uiRef+0 S8 A32])
>             (const_int 0 [0]))) "test.C":22:42 -1
>         (nil)))
> (insn 37 104 105 10 (set (subreg:V2DI (reg:DI 104 [ _18 ]) 0)
>         (subreg:V2DI (reg:DI 124) 0)) "test.C":22:42 2024 {movv2di_internal}
>      (expr_list:REG_EH_REGION (const_int -11 [0xfffffffffffffff5])
>         (nil)))
>
> we must copy the REG_EH_REGION note to the first insn and split the block
> after the newly added insn.  The REG_EH_REGION on the second insn will be
> removed later since it no longer traps.
>
> Currently we only handle memory_operand, are there any other insns
> need to be handled???

I think memory access is the only thing that can trap.

> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,} for trunk and gcc-13/gcc-12 release branch.
> Ok for trunk and backport?
>
> gcc/ChangeLog:
>
>         * config/i386/i386-features.cc
>         (general_scalar_chain::convert_op): Handle REG_EH_REGION note.
>         (convert_scalars_to_vector): Ditto.
>         * config/i386/i386-features.h (class scalar_chain): New
>         memeber control_flow_insns.
>
> gcc/testsuite/ChangeLog:
>
>         * g++.target/i386/pr111822.C: New test.
> ---
>  gcc/config/i386/i386-features.cc         | 48 ++++++++++++++++++++++--
>  gcc/config/i386/i386-features.h          |  1 +
>  gcc/testsuite/g++.target/i386/pr111822.C | 45 ++++++++++++++++++++++
>  3 files changed, 90 insertions(+), 4 deletions(-)
>  create mode 100644 gcc/testsuite/g++.target/i386/pr111822.C
>
> diff --git a/gcc/config/i386/i386-features.cc b/gcc/config/i386/i386-features.cc
> index 1de2a07ed75..2ed27a9ebdd 100644
> --- a/gcc/config/i386/i386-features.cc
> +++ b/gcc/config/i386/i386-features.cc
> @@ -998,20 +998,36 @@ general_scalar_chain::convert_op (rtx *op, rtx_insn *insn)
>      }
>    else if (MEM_P (*op))
>      {
> +      rtx_insn* eh_insn, *movabs = NULL;
>        rtx tmp = gen_reg_rtx (GET_MODE (*op));
>
>        /* Handle movabs.  */
>        if (!memory_operand (*op, GET_MODE (*op)))
>         {
>           rtx tmp2 = gen_reg_rtx (GET_MODE (*op));
> +         movabs = emit_insn_before (gen_rtx_SET (tmp2, *op), insn);
>
> -         emit_insn_before (gen_rtx_SET (tmp2, *op), insn);
>           *op = tmp2;
>         }

I may be missing something, but isn't the above a dead code? We have
if (MEM_p(*op)) and then if (!memory_operand (*op, ...)).

Uros.

>
> -      emit_insn_before (gen_rtx_SET (gen_rtx_SUBREG (vmode, tmp, 0),
> -                                    gen_gpr_to_xmm_move_src (vmode, *op)),
> -                       insn);
> +      eh_insn
> +       = emit_insn_before (gen_rtx_SET (gen_rtx_SUBREG (vmode, tmp, 0),
> +                                        gen_gpr_to_xmm_move_src (vmode, *op)),
> +                           insn);
> +
> +      if (cfun->can_throw_non_call_exceptions)
> +       {
> +         /* Handle REG_EH_REGION note.  */
> +         rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
> +         if (note)
> +           {
> +             if (movabs)
> +               eh_insn = movabs;
> +             control_flow_insns.safe_push (eh_insn);
> +             add_reg_note (eh_insn, REG_EH_REGION, XEXP (note, 0));
> +           }
> +       }
> +
>        *op = gen_rtx_SUBREG (vmode, tmp, 0);
>
>        if (dump_file)
> @@ -2494,6 +2510,7 @@ convert_scalars_to_vector (bool timode_p)
>  {
>    basic_block bb;
>    int converted_insns = 0;
> +  auto_vec<rtx_insn *> control_flow_insns;
>
>    bitmap_obstack_initialize (NULL);
>    const machine_mode cand_mode[3] = { SImode, DImode, TImode };
> @@ -2575,6 +2592,11 @@ convert_scalars_to_vector (bool timode_p)
>                          chain->chain_id);
>             }
>
> +         rtx_insn* iter_insn;
> +         unsigned int ii;
> +         FOR_EACH_VEC_ELT (chain->control_flow_insns, ii, iter_insn)
> +           control_flow_insns.safe_push (iter_insn);
> +
>           delete chain;
>         }
>      }
> @@ -2643,6 +2665,24 @@ convert_scalars_to_vector (bool timode_p)
>                   DECL_INCOMING_RTL (parm) = gen_rtx_SUBREG (TImode, r, 0);
>               }
>           }
> +
> +      if (!control_flow_insns.is_empty ())
> +       {
> +         free_dominance_info (CDI_DOMINATORS);
> +
> +         unsigned int i;
> +         rtx_insn* insn;
> +         FOR_EACH_VEC_ELT (control_flow_insns, i, insn)
> +           if (control_flow_insn_p (insn))
> +             {
> +               /* Split the block after insn.  There will be a fallthru
> +                  edge, which is OK so we keep it.  We have to create
> +                  the exception edges ourselves.  */
> +               bb = BLOCK_FOR_INSN (insn);
> +               split_block (bb, insn);
> +               rtl_make_eh_edge (NULL, bb, BB_END (bb));
> +             }
> +       }
>      }
>
>    return 0;
> diff --git a/gcc/config/i386/i386-features.h b/gcc/config/i386/i386-features.h
> index 8bab2d8666d..b259cf679af 100644
> --- a/gcc/config/i386/i386-features.h
> +++ b/gcc/config/i386/i386-features.h
> @@ -155,6 +155,7 @@ class scalar_chain
>    hash_map<rtx, rtx> defs_map;
>    unsigned n_sse_to_integer;
>    unsigned n_integer_to_sse;
> +  auto_vec<rtx_insn *> control_flow_insns;
>
>    bool build (bitmap candidates, unsigned insn_uid, bitmap disallowed);
>    virtual int compute_convert_gain () = 0;
> diff --git a/gcc/testsuite/g++.target/i386/pr111822.C b/gcc/testsuite/g++.target/i386/pr111822.C
> new file mode 100644
> index 00000000000..d405387b23c
> --- /dev/null
> +++ b/gcc/testsuite/g++.target/i386/pr111822.C
> @@ -0,0 +1,45 @@
> +/* PR target/111822 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -flive-range-shrinkage -fno-dce -fnon-call-exceptions" } */
> +
> +typedef union {
> +  int *pNativeClosure;
> +  struct SQRefCounted *pRefCounted;
> +} SQObjectValue;
> +typedef struct {
> +  SQObjectValue _unVal;
> +} SQObject;
> +typedef long SQFUNCTION(struct SQVM *);
> +struct SQVM {
> +  void CallNative();
> +};
> +struct SQRefCounted {
> +  long long _uiRef;
> +};
> +void Null();
> +struct SQObjectPtr : SQObject {
> +  SQObjectPtr() {}
> +  SQObjectPtr(int *pNativeClosure) {
> +    _unVal.pNativeClosure = pNativeClosure;
> +    _unVal.pRefCounted->_uiRef++;
> +  }
> +  ~SQObjectPtr() { --_unVal.pRefCounted->_uiRef; }
> +};
> +struct CallInfo {
> +  SQObjectPtr _closure;
> +};
> +long long _top;
> +SQFUNCTION _function;
> +int *CallNative_nclosure;
> +void SQVM::CallNative() {
> +  long long oldtop = _top;
> +  CallInfo lci;
> +  lci._closure = CallNative_nclosure;
> +  try {
> +    _function(this);
> +  } catch (...) {
> +    _top = oldtop;
> +  }
> +  while (oldtop)
> +    Null();
> +}
> --
> 2.31.1
>