[gcc r14-4765] vect: don't allow fully masked loops with non-masked simd clones [PR 110485]

[Andre Simoes Dias Vieira <avieira@gcc.gnu.org>]

https://gcc.gnu.org/g:8b704ed0b8f35ec1a57e70bd8e6913ba0e9d1f24

commit r14-4765-g8b704ed0b8f35ec1a57e70bd8e6913ba0e9d1f24
Author: Andre Vieira <andre.simoesdiasvieira@arm.com>
Date:   Thu Oct 19 18:28:12 2023 +0100

    vect: don't allow fully masked loops with non-masked simd clones [PR 110485]
    
    When analyzing a loop and choosing a simdclone to use it is possible to choose
    a simdclone that cannot be used 'inbranch' for a loop that can use partial
    vectors.  This may lead to the vectorizer deciding to use partial vectors which
    are not supported for notinbranch simd clones.  This patch fixes that by
    disabling the use of partial vectors once a notinbranch simd clone has been
    selected.
    
    gcc/ChangeLog:
    
            PR tree-optimization/110485
            * tree-vect-stmts.cc (vectorizable_simd_clone_call): Disable partial
            vectors usage if a notinbranch simdclone has been selected.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.dg/gomp/pr110485.c: New test.

Diff:
---
 gcc/testsuite/gcc.dg/gomp/pr110485.c | 19 +++++++++++++++++++
 gcc/tree-vect-stmts.cc               | 11 +++++++++++
 2 files changed, 30 insertions(+)

diff --git a/gcc/testsuite/gcc.dg/gomp/pr110485.c b/gcc/testsuite/gcc.dg/gomp/pr110485.c
new file mode 100644
index 000000000000..ba6817a127f4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/gomp/pr110485.c
@@ -0,0 +1,19 @@
+/* PR 110485 */
+/* { dg-do compile } */
+/* { dg-additional-options "-Ofast -fdump-tree-vect-details" } */
+/* { dg-additional-options "-march=znver4 --param=vect-partial-vector-usage=1" { target x86_64-*-* } } */
+#pragma omp declare simd notinbranch uniform(p)
+extern double __attribute__ ((const)) bar (double a, double p);
+
+double a[1024];
+double b[1024];
+
+void foo (int n)
+{
+  #pragma omp simd
+  for (int i = 0; i < n; ++i)
+    a[i] = bar (b[i], 71.2);
+}
+
+/* { dg-final { scan-tree-dump-not "MASK_LOAD" "vect" } } */
+/* { dg-final { scan-tree-dump "can't use a fully-masked loop because a non-masked simd clone was selected." "vect" { target x86_64-*-* } } } */
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index 8abb5f17f7f1..e96ff2c8e7cc 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -4377,6 +4377,17 @@ vectorizable_simd_clone_call (vec_info *vinfo, stmt_vec_info stmt_info,
 		       ? boolean_true_node : boolean_false_node;
 	    simd_clone_info.safe_push (sll);
 	  }
+
+      if (!bestn->simdclone->inbranch && loop_vinfo)
+	{
+	  if (dump_enabled_p ()
+	      && LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo))
+	    dump_printf_loc (MSG_NOTE, vect_location,
+			     "can't use a fully-masked loop because a"
+			     " non-masked simd clone was selected.\n");
+	  LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
+	}
+
       STMT_VINFO_TYPE (stmt_info) = call_simd_clone_vec_info_type;
       DUMP_VECT_SCOPE ("vectorizable_simd_clone_call");
 /*      vect_model_simple_cost (vinfo, stmt_info, ncopies,