Re: [PR66726] Factor conversion out of COND_EXPR

[Bernhard Reutner-Fischer <rep dot dot dot nop at gmail dot com>]

On July 4, 2015 2:32:11 PM GMT+02:00, Kugan <kugan.vivekanandarajah@linaro.org> wrote:
>On 04/07/15 18:51, Bernhard Reutner-Fischer wrote:
>> On Sat, Jul 04, 2015 at 12:58:58PM +1000, Kugan wrote:
>>> Please find a patch that attempt to FIX PR66726 by factoring
>conversion
>>> out of COND_EXPR as explained in the PR.
>>>
>>> Bootstrapped and regression tested on x86-64-none-linux-gnu with no
>new
>>> regressions. Is this OK for trunk?
>>>
>>> Thanks,
>>> Kugan
>>>
>>>
>>> gcc/testsuite/ChangeLog:
>>>
>>> 2015-07-03  Kugan Vivekanandarajah  <kuganv@linaro.org>
>>> 	    Jeff Law  <law@redhat.com>
>>>
>>> 	PR middle-end/66726
>>> 	* gcc.dg/tree-ssa/pr66726.c: New test.
>> 
>> I'd have scanned the details dump for "factor CONVERT_EXPR out" 1
>> to make sure that it's this part that takes care of it.

I meant in addition, just to be sure.

Patch itself looks plausible to me but I cannot approve it.

Thanks,
>
>Thanks for the comments. Please see the updated patch with the fixes.
>Kugan
>
>> 
>>>
>>> gcc/ChangeLog:
>>>
>>> 2015-07-03  Kugan Vivekanandarajah  <kuganv@linaro.org>
>>>
>>> 	PR middle-end/66726
>>> 	* tree-ssa-phiopt.c (factor_out_conditional_conversion): New
>function.
>>> 	(tree_ssa_phiopt_worker): Call factor_out_conditional_conversion.
>> 
>>> diff --git a/gcc/tree-ssa-phiopt.c b/gcc/tree-ssa-phiopt.c
>>> index d2a5cee..e8af086 100644
>>> --- a/gcc/tree-ssa-phiopt.c
>>> +++ b/gcc/tree-ssa-phiopt.c
>> 
>>> @@ -410,6 +413,108 @@ replace_phi_edge_with_variable (basic_block
>cond_block,
>>>  	      bb->index);
>>>  }
>>>  
>>> +/* PR66726: Factor conversion out of COND_EXPR.  If the argument of
>the PHI
>> 
>> s/the argument/the arguments/
>> 
>>> +   stmt are CONVERT_STMT, factor out the conversion and perform the
>conversion
>>> +   to the result of PHI stmt.  */
>>> +
>>> +static bool
>>> +factor_out_conditional_conversion (edge e0, edge e1, gphi *phi,
>>> +				   tree arg0, tree arg1)
>>> +{
>>> +  gimple def0 = NULL, def1 = NULL, new_stmt;
>>> +  tree new_arg0 = NULL_TREE, new_arg1 = NULL_TREE;
>>> +  tree temp, result;
>>> +  gimple_stmt_iterator gsi;
>>> +
>>> +  /* One of the argument has to be SSA_NAME and other argument can
>> 
>> s/the argument/the arguments/
>> 
>>> +     be an SSA_NAME of INTEGER_CST.  */
>>> +  if ((TREE_CODE (arg0) != SSA_NAME
>>> +       && TREE_CODE (arg0) != INTEGER_CST)
>>> +      || (TREE_CODE (arg1) != SSA_NAME
>>> +	  && TREE_CODE (arg1) != INTEGER_CST)
>>> +      || (TREE_CODE (arg0) == INTEGER_CST
>>> +	  && TREE_CODE (arg1) == INTEGER_CST))
>> 
>> inconsistent space for the && lines above; The first should have a
>> leading tab.
>> 
>>> +    return false;
>>> +
>>> +  /* Handle only PHI statements with two arguments.  TODO: If all
>>> +     other arguments to PHI are INTEGER_CST, we can handle more
>>> +     than two arguments too.  */
>>> +  if (gimple_phi_num_args (phi) != 2)
>>> +    return false;
>>> +
>>> +  /* If arg0 is an SSA_NAME and the stmt which defines arg0 is
>>> +     ai CONVERT_STMT, use the LHS as new_arg0.  */
>> 
>> s/ai/a/
>> 
>>> +  if (TREE_CODE (arg0) == SSA_NAME)
>>> +    {
>>> +      def0 = SSA_NAME_DEF_STMT (arg0);
>>> +      if (!is_gimple_assign (def0)
>>> +	  || !CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def0)))
>>> +	return false;
>>> +      new_arg0 = gimple_assign_rhs1 (def0);
>>> +    }
>>> +
>>> +  /* If arg1 is an SSA_NAME and the stmt which defines arg0 is
>>> +     ai CONVERT_STMT, use the LHS as new_arg1.  */
>> 
>> s/ai/a/
>> 
>>> +  if (TREE_CODE (arg1) == SSA_NAME)
>>> +    {
>>> +      def1 = SSA_NAME_DEF_STMT (arg1);
>>> +      if (!is_gimple_assign (def1)
>>> +	  || !CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def1)))
>>> +	return false;
>>> +      new_arg1 = gimple_assign_rhs1 (def1);
>>> +    }
>>> +
>>> +  /* If arg0 is an INTEGER_CST, fold it to new type.  */
>>> +  if (TREE_CODE (arg0) != SSA_NAME)
>>> +    {
>>> +      if (!POINTER_TYPE_P (TREE_TYPE (new_arg1))
>>> +	  && int_fits_type_p (arg0, TREE_TYPE (new_arg1)))
>>> +	new_arg0 = fold_convert (TREE_TYPE (new_arg1), arg0);
>>> +      else
>>> +	return false;
>>> +    }
>>> +
>>> +  /* If arg1 is an INTEGER_CST, fold it to new type.  */
>>> +  if (TREE_CODE (arg1) != SSA_NAME)
>>> +    {
>>> +      if (!POINTER_TYPE_P (TREE_TYPE (new_arg0))
>>> +	  && int_fits_type_p (arg1, TREE_TYPE (new_arg0)))
>>> +	new_arg1 = fold_convert (TREE_TYPE (new_arg0), arg1);
>>> +      else
>>> +	return false;
>>> +    }
>>> +
>>> +  /* If types of new_arg0 and new_arg1 are different bailout.  */
>>> +  if (TREE_TYPE (new_arg0) != TREE_TYPE (new_arg1))
>>> +    return false;
>>> +
>>> +  /* Replace the PHI stmt with the new_arg0 and new_arg1.  Also
>insert
>>> +     a new CONVER_STMT that converts the phi results.  */
>> 
>> s/CONVER_STMT/CONVERT_STMT/
>> 
>>> +  gsi = gsi_after_labels (gimple_bb (phi));
>>> +  result = PHI_RESULT (phi);
>>> +  temp = make_ssa_name (TREE_TYPE (new_arg0), phi);
>>> +
>>> +  if (dump_file && (dump_flags & TDF_DETAILS))
>>> +    {
>>> +      fprintf (dump_file, "PHI ");
>>> +      print_generic_expr (dump_file, gimple_phi_result (phi), 0);
>>> +      fprintf (dump_file,
>>> +	       " changed to factor CONVERT_EXPR out from COND_EXPR.\n");
>>> +      fprintf (dump_file, "New PHI_RESULT is ");
>>> +      print_generic_expr (dump_file, temp, 0);
>>> +      fprintf (dump_file, " and new stmt with CONVERT_EXPR defines
>");
>>> +      print_generic_expr (dump_file, result, 0);
>>> +      fprintf (dump_file, ".\n");
>>> +    }
>>> +
>>> +  gimple_phi_set_result (phi, temp);
>>> +  SET_PHI_ARG_DEF (phi, e0->dest_idx, new_arg0);
>>> +  SET_PHI_ARG_DEF (phi, e1->dest_idx, new_arg1);
>>> +  new_stmt = gimple_build_assign (result, CONVERT_EXPR, temp);
>>> +  gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
>>> +  return true;
>>> +}
>>> +
>>>  /*  The function conditional_replacement does the main work of
>doing the
>>>      conditional replacement.  Return true if the replacement is
>done.
>>>      Otherwise return false.
>>> @@ -2144,6 +2249,26 @@ gate_hoist_loads (void)
>>>     This pass also performs a fifth transformation of a slightly
>different
>>>     flavor.
>>>  
>>> +   Factor conversion in COND_EXPR
>>> +   ----------------------------------
>> 
>> excess trailing "----" ;)
>> 
>> thanks,
>>> +
>>> +   This transformation factors the conversion out of COND_EXPR with
>>> +   factor_out_conditional_conversion.
>>> +
>>> +   For example:
>>> +   if (a <= CST) goto <bb 3>; else goto <bb 4>;
>>> +   <bb 3>:
>>> +   tmp = (int) a;
>>> +   <bb 4>:
>>> +   tmp = PHI <tmp, CST>
>>> +
>>> +   Into:
>>> +   if (a <= CST) goto <bb 3>; else goto <bb 4>;
>>> +   <bb 3>:
>>> +   <bb 4>:
>>> +   a = PHI <a, CST>
>>> +   tmp = (int) a;
>>> +
>>>     Adjacent Load Hoisting
>>>     ----------------------
>>>  
>>