i386: Allow some V32HImode and V64QImode permutations even without AVX512BW [PR80355]

When working on the PR, I've noticed we generate terrible code for
V32HImode or V64QImode permutations for -mavx512f -mno-avx512bw.
Generally we can't do much with such permutations, but since PR68655
we can handle at least some, those expressible using V16SImode or V8DImode
permutations, but that wasn't reachable, because ix86_vectorize_vec_perm_const
didn't even try, it said without TARGET_AVX512BW it can't do anything, and
with it can do everything, no d.testing_p attempts.

This patch makes it try it for TARGET_AVX512F && !TARGET_AVX512BW.

The first hunk is to avoid ICE, expand_vec_perm_even_odd_1 asserts d->vmode
isn't V32HImode because expand_vec_perm_1 for AVX512BW handles already
all permutations, but when we let it through without !TARGET_AVX512BW,
expand_vec_perm_1 doesn't handle it.

If we want, that hunk can be dropped if we implement in
expand_vec_perm_even_odd_1 and its helper the even permutation as
vpmovdw + vpmovdw + vinserti64x4 and odd permutation as
vpsrld $16 + vpsrld $16 + vpmovdw + vpmovdw + vinserti64x4.

2021-08-10  Jakub Jelinek  <jakub@redhat.com>

	PR target/80355
	* config/i386/i386-expand.c (expand_vec_perm_even_odd): Return false
	for V32HImode if !TARGET_AVX512BW.
	(ix86_vectorize_vec_perm_const) <case E_V32HImode, case E_V64QImode>:
	If !TARGET_AVX512BW and TARGET_AVX512F and d.testing_p, don't fail
	early, but actually check the permutation.

	* gcc.target/i386/avx512f-pr80355-2.c: New test.

diff --git a/gcc/config/i386/i386-expand.c b/gcc/config/i386/i386-expand.c
index bd21efa..c708b33 100644 (file)
--- a/gcc/config/i386/i386-expand.c
+++ b/gcc/config/i386/i386-expand.c
@@ -20337,6 +20337,11 @@ expand_vec_perm_even_odd (struct expand_vec_perm_d *d)
     if (d->perm[i] != 2 * i + odd)
       return false;
 
+  if (d->vmode == E_V32HImode
+      && d->testing_p
+      && !TARGET_AVX512BW)
+    return false;
+
   return expand_vec_perm_even_odd_1 (d, odd);
 }
 
@@ -20877,16 +20882,16 @@ ix86_vectorize_vec_perm_const (machine_mode vmode, rtx target, rtx op0,
        return true;
       break;
     case E_V32HImode:
-      if (!TARGET_AVX512BW)
+      if (!TARGET_AVX512F)
        return false;
-      if (d.testing_p)
+      if (d.testing_p && TARGET_AVX512BW)
        /* All implementable with a single vperm[it]2 insn.  */
        return true;
       break;
     case E_V64QImode:
-      if (!TARGET_AVX512BW)
+      if (!TARGET_AVX512F)
        return false;
-      if (d.testing_p)
+      if (d.testing_p && TARGET_AVX512BW)
        /* Implementable with 2 vperm[it]2, 2 vpshufb and 1 or insn.  */
        return true;
       break;

diff --git a/gcc/testsuite/gcc.target/i386/avx512f-pr80355-2.c b/gcc/testsuite/gcc.target/i386/avx512f-pr80355-2.c
new file mode 100644 (file)
index 0000000..c510b2f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/avx512f-pr80355-2.c
@@ -0,0 +1,23 @@
+/* PR target/80355 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -mavx512f -mno-avx512vl -mno-avx512dq -mno-avx512bw" } */
+/* { dg-final { scan-assembler-times "\tvshufi(?:32x4|64x2)\t" 2 } } */
+
+typedef short V __attribute__((vector_size (64)));
+typedef char W __attribute__((vector_size (64)));
+
+W
+f0 (W x)
+{
+  return __builtin_shuffle (x, (W) { 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
+                                    48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
+                                    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
+                                    17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 });
+}
+
+V
+f1 (V x)
+{
+  return __builtin_shuffle (x, (V) { 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+                                    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 });
+}