[Bug tree-optimization/40073] Vector short/char shifts generate sub-optimal code

[amylaar at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40073

--- Comment #16 from Jorn Wolfgang Rennecke <amylaar at gcc dot gnu.org> ---
Going from gcc 8.2 to gcc 9.1, I find the following two test cases are now
autovectorized:

/* { dg-do compile } */
/* { dg-options "-O3" } */

/* Test auto-vectorization */

#include "vector-types.h"

#define LENGTH 256

__attribute__((aligned (VECTOR_SIZE))) short a[LENGTH], b[LENGTH];
short c;

void foo (void) {
  int i;

  for (i=0; i<LENGTH; i++){
    a[i] = b[i] >> (c & 0xf);
  }
}




/* { dg-do compile } */
/* { dg-options "-O3" } */

/* Test auto-vectorization */

#include "vector-types.h"

#define LENGTH 256

__attribute__((aligned (VECTOR_SIZE))) unsigned short a[LENGTH], b[LENGTH];
unsigned short c;

void foo (void) {
  int i;

  for (i=0; i<LENGTH; i++){
    a[i] = b[i] >> (c & 0xf);
  }
}