ifcvt: Improve tests for predicated operations

-msve-vector-bits=128 causes the AArch64 port to list 128-bit Advanced
SIMD as the first-choice mode for vectorisation, with SVE being used for
things that Advanced SIMD can't handle as easily.  However, ifcvt would
not then try to use SVE's predicated FP arithmetic, leading to tests
like TSVC ControlFlow-flt failing to vectorise.

The mask load/store code did try other vector modes, but could also be
improved to make sure that SVEness sticks when computing derived modes.

(Unlike mode_for_vector, related_vector_mode always returns a vector
mode, so there's no need to check VECTOR_MODE_P as well.)

gcc/
	* internal-fn.c (vectorized_internal_fn_supported_p): Handle
	vector types first.  For scalar types, consider both the preferred
	vector mode and the alternative vector modes.
	* optabs-query.c (can_vec_mask_load_store_p): Use the same
	structure as above, in particular using related_vector_mode
	for modes provided by autovectorize_vector_modes.

gcc/testsuite/
	* gcc.target/aarch64/sve/cond_arith_6.c: New test.

3 files changed, 43 insertions, 22 deletions

diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
index fb8b43d..cd5e63f 100644
--- a/gcc/internal-fn.c
+++ b/gcc/internal-fn.c
@@ -4109,16 +4109,32 @@ expand_internal_call (gcall *stmt)
 bool
 vectorized_internal_fn_supported_p (internal_fn ifn, tree type)
 {
+  if (VECTOR_MODE_P (TYPE_MODE (type)))
+    return direct_internal_fn_supported_p (ifn, type, OPTIMIZE_FOR_SPEED);
+
   scalar_mode smode;
-  if (!VECTOR_TYPE_P (type) && is_a <scalar_mode> (TYPE_MODE (type), &smode))
+  if (!is_a <scalar_mode> (TYPE_MODE (type), &smode))
+    return false;
+
+  machine_mode vmode = targetm.vectorize.preferred_simd_mode (smode);
+  if (VECTOR_MODE_P (vmode))
     {
-      machine_mode vmode = targetm.vectorize.preferred_simd_mode (smode);
-      if (VECTOR_MODE_P (vmode))
-	type = build_vector_type_for_mode (type, vmode);
+      tree vectype = build_vector_type_for_mode (type, vmode);
+      if (direct_internal_fn_supported_p (ifn, vectype, OPTIMIZE_FOR_SPEED))
+	return true;
     }
 
-  return (VECTOR_MODE_P (TYPE_MODE (type))
-	  && direct_internal_fn_supported_p (ifn, type, OPTIMIZE_FOR_SPEED));
+  auto_vector_modes vector_modes;
+  targetm.vectorize.autovectorize_vector_modes (&vector_modes, true);
+  for (machine_mode base_mode : vector_modes)
+    if (related_vector_mode (base_mode, smode).exists (&vmode))
+      {
+	tree vectype = build_vector_type_for_mode (type, vmode);
+	if (direct_internal_fn_supported_p (ifn, vectype, OPTIMIZE_FOR_SPEED))
+	  return true;
+      }
+
+  return false;
 }
 
 void
diff --git a/gcc/optabs-query.c b/gcc/optabs-query.c
index 3248ce2..05ee5f5 100644
--- a/gcc/optabs-query.c
+++ b/gcc/optabs-query.c
@@ -582,27 +582,18 @@ can_vec_mask_load_store_p (machine_mode mode,
     return false;
 
   vmode = targetm.vectorize.preferred_simd_mode (smode);
-  if (!VECTOR_MODE_P (vmode))
-    return false;
-
-  if (targetm.vectorize.get_mask_mode (vmode).exists (&mask_mode)
+  if (VECTOR_MODE_P (vmode)
+      && targetm.vectorize.get_mask_mode (vmode).exists (&mask_mode)
       && convert_optab_handler (op, vmode, mask_mode) != CODE_FOR_nothing)
     return true;
 
   auto_vector_modes vector_modes;
   targetm.vectorize.autovectorize_vector_modes (&vector_modes, true);
-  for (unsigned int i = 0; i < vector_modes.length (); ++i)
-    {
-      poly_uint64 cur = GET_MODE_SIZE (vector_modes[i]);
-      poly_uint64 nunits;
-      if (!multiple_p (cur, GET_MODE_SIZE (smode), &nunits))
-	continue;
-      if (mode_for_vector (smode, nunits).exists (&vmode)
-	  && VECTOR_MODE_P (vmode)
-	  && targetm.vectorize.get_mask_mode (vmode).exists (&mask_mode)
-	  && convert_optab_handler (op, vmode, mask_mode) != CODE_FOR_nothing)
-	return true;
-    }
+  for (machine_mode base_mode : vector_modes)
+    if (related_vector_mode (base_mode, smode).exists (&vmode)
+	&& targetm.vectorize.get_mask_mode (vmode).exists (&mask_mode)
+	&& convert_optab_handler (op, vmode, mask_mode) != CODE_FOR_nothing)
+      return true;
   return false;
 }
 
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/cond_arith_6.c b/gcc/testsuite/gcc.target/aarch64/sve/cond_arith_6.c
new file mode 100644
index 0000000..4085ab1
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/cond_arith_6.c
@@ -0,0 +1,14 @@
+/* { dg-options "-O3 -msve-vector-bits=128" } */
+
+void
+f (float *x)
+{
+  for (int i = 0; i < 100; ++i)
+    if (x[i] > 1.0f)
+      x[i] -= 1.0f;
+}
+
+/* { dg-final { scan-assembler {\tld1w\tz} } } */
+/* { dg-final { scan-assembler {\tfcmgt\tp} } } */
+/* { dg-final { scan-assembler {\tfsub\tz} } } */
+/* { dg-final { scan-assembler {\tst1w\tz} } } */