[gcc r15-7802] tree-optimization/119096 - bogus conditional reduction vectorization

[Richard Biener]

https://gcc.gnu.org/g:10e4107dfcf9fe324d0902f16411a75c596dab91

commit r15-7802-g10e4107dfcf9fe324d0902f16411a75c596dab91
Author: Richard Biener <rguenther@suse.de>
Date:   Mon Mar 3 14:12:37 2025 +0100

    tree-optimization/119096 - bogus conditional reduction vectorization
    
    When we vectorize a .COND_ADD reduction and apply the single-use-def
    cycle optimization we can end up chosing the wrong else value for
    subsequent .COND_ADD.  The following rectifies this.
    
            PR tree-optimization/119096
            * tree-vect-loop.cc (vect_transform_reduction): Use the
            correct else value for .COND_fn.
    
            * gcc.dg/vect/pr119096.c: New testcase.

Diff:
---
 gcc/testsuite/gcc.dg/vect/pr119096.c | 21 +++++++++++++++++++++
 gcc/tree-vect-loop.cc                |  2 +-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/gcc/testsuite/gcc.dg/vect/pr119096.c b/gcc/testsuite/gcc.dg/vect/pr119096.c
new file mode 100644
index 000000000000..2c03a5936831
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr119096.c
@@ -0,0 +1,21 @@
+#include "tree-vect.h"
+
+long __attribute__((noipa))
+sum(int* A, int* B)
+{
+        long total = 0;
+        for(int j = 0; j < 16; j++)
+                if((A[j] > 0) & (B[j] > 0))
+                        total += (long)A[j];
+        return total;
+}
+int main()
+{
+  int A[16] = { 1,1,1,1, 1,1,1,1, 1,1,1,1, 1,1,1,1 };
+  int B[16] = { };
+  check_vect ();
+  if (sum (A, B) != 0)
+    abort ();
+  return 0;
+}
+
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index dc15b955aadf..52533623cab9 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -9064,7 +9064,7 @@ vect_transform_reduction (loop_vec_info loop_vinfo,
 	    new_stmt = gimple_build_call_internal (internal_fn (code),
 						   op.num_ops,
 						   vop[0], vop[1], vop[2],
-						   vop[1]);
+						   vop[reduc_index]);
 	  else
 	    new_stmt = gimple_build_assign (vec_dest, tree_code (op.code),
 					    vop[0], vop[1], vop[2]);