Re: [PR 67794] Also remap SSA_NAMEs defined in ASMs in IPA-SRA

[Richard Biener <rguenther@suse.de>]

On Thu, 8 Oct 2015, Martin Jambor wrote:

> Hi,
> 
> the following fixes PR 67794 by properly remapping SSA_NAMEs which are
> based on PARM_DECLs which are about to be removed as unnecessary.  And
> by "properly" I mean also when they are defined by a GIMPL_ASM
> statement.  In fact, it switches to using an iterator over definitions
> to make sure it always handles everything...  well,except for PHIs
> which are still handled specially because, from a quick glance over
> their source, it seemed to me that the iterator does not support them.
> 
> Bootstrapped and tested on x86_64-linux.  OK for trunk?
> The issue is most probably latent on a number of old branches, do we
> want to backport the patch to any of them?
> 
> Thanks,
> 
> Martin
> 
> 
> 2015-10-08  Martin Jambor  <mjambor@suse.cz>
> 
> 	tree-optimization/67794
> 	* tree-sra.c (replace_removed_params_ssa_names): Do not distinguish
> 	between types of state,ents but accept original definitions as a
> 	parameter.
> 	(ipa_sra_modify_function_body): Use FOR_EACH_SSA_DEF_OPERAND to
> 	iterate over definitions.
> 
> testsuite/
>         * gcc.dg/ipa/ipa-sra-10.c: Nw test.
>         * gcc.dg/torture/pr67794.c: Likewise.
> 
> diff --git a/gcc/testsuite/gcc.dg/ipa/ipa-sra-10.c b/gcc/testsuite/gcc.dg/ipa/ipa-sra-10.c
> new file mode 100644
> index 0000000..24b64d1
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/ipa/ipa-sra-10.c
> @@ -0,0 +1,34 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fipa-sra -fdump-tree-eipa_sra-details"  } */
> +
> +extern void consume (int);
> +extern int glob, glob1, glob2;
> +extern int get (void);
> +
> +
> +static void __attribute__ ((noinline))
> +foo (int a)
> +{
> +  a = glob;
> +  consume (a);
> +  a = get ();
> +  consume (a);
> +  __asm__ volatile("" : : ""(a));
> +  consume (a);
> +
> +  if (glob1)
> +    a = glob1;
> +  else
> +    a = glob2;
> +  consume (a);
> +}
> +
> +int
> +bar (int a)
> +{
> +  foo (a);
> +  glob = a;
> +  return 0;
> +}
> +
> +/* { dg-final { scan-tree-dump-times "replacing an SSA name of a removed param" 4 "eipa_sra" } } */
> diff --git a/gcc/testsuite/gcc.dg/torture/pr67794.c b/gcc/testsuite/gcc.dg/torture/pr67794.c
> new file mode 100644
> index 0000000..5489e56
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/torture/pr67794.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +
> +int *b;
> +static void fn1(int *best, int *dmin) {
> +  int a[64];
> +  dmin = a;
> +  __asm__ volatile("" : "+&r"(dmin) : ""(best));
> +}
> +
> +__attribute__((always_inline)) static inline void fn2(int *best) { fn1(best, b); }
> +
> +void fn3(void) {
> +  int c[1];
> +  fn2(c);
> +}
> diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
> index 4327990..f2a4e72 100644
> --- a/gcc/tree-sra.c
> +++ b/gcc/tree-sra.c
> @@ -4612,61 +4612,45 @@ get_adjustment_for_base (ipa_parm_adjustment_vec adjustments, tree base)
>    return NULL;
>  }
>  
> -/* If the statement STMT defines an SSA_NAME of a parameter which is to be
> -   removed because its value is not used, replace the SSA_NAME with a one
> -   relating to a created VAR_DECL together all of its uses and return true.
> -   ADJUSTMENTS is a pointer to an adjustments vector.  */
> +/* If OLD_NAME, which is being defined by statement STMT, is an SSA_NAME of a
> +   parameter which is to be removed because its value is not used, create a new
> +   SSA_NAME relating to a replacement VAR_DECL, replace all uses of the
> +   original with it and return it.  If there is no need to re-map, return true.
> +   ADJUSTMENTS is a pointer to a vector of IPA-SRA adjustments.  */

The docs still say we return a bool

Otherwise the patch looks ok to me.  I think we want to backport it
to branche(s) after a while.

Thanks,
Richard.

> -static bool
> -replace_removed_params_ssa_names (gimple *stmt,
> +static tree
> +replace_removed_params_ssa_names (tree old_name, gimple *stmt,
>  				  ipa_parm_adjustment_vec adjustments)
>  {
>    struct ipa_parm_adjustment *adj;
> -  tree lhs, decl, repl, name;
> -
> -  if (gimple_code (stmt) == GIMPLE_PHI)
> -    lhs = gimple_phi_result (stmt);
> -  else if (is_gimple_assign (stmt))
> -    lhs = gimple_assign_lhs (stmt);
> -  else if (is_gimple_call (stmt))
> -    lhs = gimple_call_lhs (stmt);
> -  else
> -    gcc_unreachable ();
> +  tree decl, repl, new_name;
>  
> -  if (TREE_CODE (lhs) != SSA_NAME)
> -    return false;
> +  if (TREE_CODE (old_name) != SSA_NAME)
> +    return NULL;
>  
> -  decl = SSA_NAME_VAR (lhs);
> +  decl = SSA_NAME_VAR (old_name);
>    if (decl == NULL_TREE
>        || TREE_CODE (decl) != PARM_DECL)
> -    return false;
> +    return NULL;
>  
>    adj = get_adjustment_for_base (adjustments, decl);
>    if (!adj)
> -    return false;
> +    return NULL;
>  
>    repl = get_replaced_param_substitute (adj);
> -  name = make_ssa_name (repl, stmt);
> +  new_name = make_ssa_name (repl, stmt);
>  
>    if (dump_file)
>      {
>        fprintf (dump_file, "replacing an SSA name of a removed param ");
> -      print_generic_expr (dump_file, lhs, 0);
> +      print_generic_expr (dump_file, old_name, 0);
>        fprintf (dump_file, " with ");
> -      print_generic_expr (dump_file, name, 0);
> +      print_generic_expr (dump_file, new_name, 0);
>        fprintf (dump_file, "\n");
>      }
>  
> -  if (is_gimple_assign (stmt))
> -    gimple_assign_set_lhs (stmt, name);
> -  else if (is_gimple_call (stmt))
> -    gimple_call_set_lhs (stmt, name);
> -  else
> -    gimple_phi_set_result (as_a <gphi *> (stmt), name);
> -
> -  replace_uses_by (lhs, name);
> -  release_ssa_name (lhs);
> -  return true;
> +  replace_uses_by (old_name, new_name);
> +  return new_name;
>  }
>  
>  /* If the statement STMT contains any expressions that need to replaced with a
> @@ -4745,7 +4729,16 @@ ipa_sra_modify_function_body (ipa_parm_adjustment_vec adjustments)
>        gimple_stmt_iterator gsi;
>  
>        for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
> -	replace_removed_params_ssa_names (gsi_stmt (gsi), adjustments);
> +	{
> +	  gphi *phi = as_a <gphi *> (gsi_stmt (gsi));
> +	  tree new_lhs, old_lhs = gimple_phi_result (phi);
> +	  new_lhs = replace_removed_params_ssa_names (old_lhs, phi, adjustments);
> +	  if (new_lhs)
> +	    {
> +	      gimple_phi_set_result (phi, new_lhs);
> +	      release_ssa_name (old_lhs);
> +	    }
> +	}
>  
>        gsi = gsi_start_bb (bb);
>        while (!gsi_end_p (gsi))
> @@ -4765,7 +4758,6 @@ ipa_sra_modify_function_body (ipa_parm_adjustment_vec adjustments)
>  
>  	    case GIMPLE_ASSIGN:
>  	      modified |= sra_ipa_modify_assign (stmt, &gsi, adjustments);
> -	      modified |= replace_removed_params_ssa_names (stmt, adjustments);
>  	      break;
>  
>  	    case GIMPLE_CALL:
> @@ -4780,8 +4772,6 @@ ipa_sra_modify_function_body (ipa_parm_adjustment_vec adjustments)
>  		{
>  		  t = gimple_call_lhs_ptr (stmt);
>  		  modified |= ipa_modify_expr (t, false, adjustments);
> -		  modified |= replace_removed_params_ssa_names (stmt,
> -								adjustments);
>  		}
>  	      break;
>  
> @@ -4805,6 +4795,20 @@ ipa_sra_modify_function_body (ipa_parm_adjustment_vec adjustments)
>  	      break;
>  	    }
>  
> +	  def_operand_p defp;
> +	  ssa_op_iter iter;
> +	  FOR_EACH_SSA_DEF_OPERAND (defp, stmt, iter, SSA_OP_DEF)
> +	    {
> +	      tree old_def = DEF_FROM_PTR (defp);
> +	      if (tree new_def = replace_removed_params_ssa_names (old_def, stmt,
> +								   adjustments))
> +		{
> +		  SET_DEF (defp, new_def);
> +		  release_ssa_name (old_def);
> +		  modified = true;
> +		}
> +	    }
> +
>  	  if (modified)
>  	    {
>  	      update_stmt (stmt);
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)