tree-optimization/115723 - ICE with .COND_ADD reduction

The following fixes an ICE with a .COND_ADD discovered as reduction
even though its else value isn't the reduction chain link but a
constant.  This would be wrong-code with --disable-checking I think.

	PR tree-optimization/115723
	* tree-vect-loop.cc (check_reduction_path): For a .COND_ADD
	verify the else value also refers to the reduction chain op.

	* gcc.dg/vect/pr115723.c: New testcase.

diff --git a/gcc/testsuite/gcc.dg/vect/pr115723.c b/gcc/testsuite/gcc.dg/vect/pr115723.c
new file mode 100644 (file)
index 0000000..b98b29d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr115723.c
@@ -0,0 +1,25 @@
+/* { dg-additional-options "-ffast-math -fno-unsafe-math-optimizations" } */
+
+#include "tree-vect.h"
+
+double __attribute__((noipa))
+foo (double *x, double *y, int n)
+{
+  double res = 0.;
+  for (int i = 0; i < n; ++i)
+    if (y[i] > 0.)
+      res += x[i];
+    else
+      res = 64.;
+  return res;
+}
+
+double y[16] = { 1., 1., 1., 1., 0., 1., 1., 1.,
+                 1., 1., 1., 1., 1., 1., 1., 1. };
+int main ()
+{
+  check_vect ();
+  if (foo (y, y, 16) != 64. + 11.)
+    abort ();
+  return 0;
+}

diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 3095ff5ab6b6d5630d583ae991eb538d26d81781..a64b5082bd18c09ab99685fce953adaf77f8d3ca 100644 (file)
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -4163,15 +4163,19 @@ pop:
 
       FOR_EACH_IMM_USE_STMT (op_use_stmt, imm_iter, op.ops[opi])
        {
-       /* In case of a COND_OP (mask, op1, op2, op1) reduction we might have
-          op1 twice (once as definition, once as else) in the same operation.
-          Allow this.  */
+         /* In case of a COND_OP (mask, op1, op2, op1) reduction we should
+            have op1 twice (once as definition, once as else) in the same
+            operation.  Enforce this.  */
          if (cond_fn_p && op_use_stmt == use_stmt)
            {
              gcall *call = as_a<gcall *> (use_stmt);
              unsigned else_pos
                = internal_fn_else_index (internal_fn (op.code));
-
+             if (gimple_call_arg (call, else_pos) != op.ops[opi])
+               {
+                 fail = true;
+                 break;
+               }
              for (unsigned int j = 0; j < gimple_call_num_args (call); ++j)
                {
                  if (j == else_pos)