Re: [PATCH] rs6000: Expand vec_insert in expander instead of gimple [PR79251]

[luoxhu <luoxhu@linux.ibm.com>]

Hi,

On 2020/9/1 00:47, will schmidt wrote:
>> +  tmode = TYPE_MODE (TREE_TYPE (arg0));
>> +  mode1 = TYPE_MODE (TREE_TYPE (TREE_TYPE (arg0)));
>> +  mode2 = TYPE_MODE ((TREE_TYPE (arg2)));
>> +  gcc_assert (VECTOR_MODE_P (tmode));
>> +
>> +  op0 = expand_expr (arg0, NULL_RTX, tmode, EXPAND_NORMAL);
>> +  op1 = expand_expr (arg1, NULL_RTX, mode1, EXPAND_NORMAL);
>> +  op2 = expand_expr (arg2, NULL_RTX, mode2, EXPAND_NORMAL);
>> +
>> +  if (GET_MODE (op1) != mode1 && GET_MODE (op1) != VOIDmode)
>> +    op1 = convert_modes (mode1, GET_MODE (op1), op1, true);
>> +
>> +  op0 = force_reg (tmode, op0);
>> +  op1 = force_reg (mode1, op1);
>> +  op2 = force_reg (mode2, op2);
>> +
>> +  target = gen_reg_rtx (V16QImode);
> Should that be tmode, or is V16QImode always correct here?


Thanks for the review.
Yes, the target should be TImode here, but the followed call
rs6000_expand_vector_insert needs a lot of emit_insns in it, 
using V16QI could reuse most of patterns in existed md files,
after returning from this function, there will be a convert from
V16QImode to TImode to make the type same:

expr.c: convert_move (target, temp, TYPE_UNSIGNED (TREE_TYPE (exp))); 

and I've tested this with V2DI, V2DF V4SI, V4SF, V8HI, V16QI on
Power9-LE and Power8-BE, the result correctness is ensured.
Other comments are modified.  Will update it later if no disagreements
about the implementation.


Thanks,
Xionghu

> 
>> +  rs6000_expand_vector_insert (target, op0, op1, op2);
>> +
>> +  return target;
>> +}