[gcc r12-5608] vect: Fix vect_is_reduction

[gcc r12-5608] vect: Fix vect_is_reduction

[Richard Sandiford]

https://gcc.gnu.org/g:9b577047eec65936a5299cac13dd7b73cdfc4ae4

commit r12-5608-g9b577047eec65936a5299cac13dd7b73cdfc4ae4
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Tue Nov 30 09:52:27 2021 +0000

    vect: Fix vect_is_reduction
    
    The current definition of vect_is_reduction (provided for target
    costing) misses some pattern statements.
    
    gcc/
            * tree-vectorizer.h (vect_is_reduction): Use STMT_VINFO_REDUC_IDX.
    
    gcc/testsuite/
            * gcc.target/aarch64/sve/cost_model_13.c: New test.

Diff:
---
 gcc/testsuite/gcc.target/aarch64/sve/cost_model_13.c | 16 ++++++++++++++++
 gcc/tree-vectorizer.h                                |  3 +--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/gcc/testsuite/gcc.target/aarch64/sve/cost_model_13.c b/gcc/testsuite/gcc.target/aarch64/sve/cost_model_13.c
new file mode 100644
index 00000000000..95f2ce91f80
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/cost_model_13.c
@@ -0,0 +1,16 @@
+/* { dg-options "-O3 -mtune=neoverse-v1" } */
+
+int
+f11 (short *restrict x, int n)
+{
+  short res = 0;
+  for (int i = 0; i < n; ++i)
+    res += x[i];
+  return res;
+}
+
+/* We should use SVE rather than Advanced SIMD.  */
+/* { dg-final { scan-assembler {\tld1h\tz[0-9]+\.h,} } } */
+/* { dg-final { scan-assembler {\tadd\tz[0-9]+\.h,} } } */
+/* { dg-final { scan-assembler-not {\tldr\tq[0-9]+,} } } */
+/* { dg-final { scan-assembler-not {\tv[0-9]+\.8h,} } } */
diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
index 0eb13d6cc74..76e81ea546a 100644
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -2372,8 +2372,7 @@ vect_is_store_elt_extraction (vect_cost_for_stmt kind, stmt_vec_info stmt_info)
 inline bool
 vect_is_reduction (stmt_vec_info stmt_info)
 {
-  return (STMT_VINFO_REDUC_DEF (stmt_info)
-	  || VECTORIZABLE_CYCLE_DEF (STMT_VINFO_DEF_TYPE (stmt_info)));
+  return STMT_VINFO_REDUC_IDX (stmt_info) >= 0;
 }
 
 /* If STMT_INFO describes a reduction, return the vect_reduction_type