Hi!
On the following testcase, a = a / 8; looks like reasonable reduction
statement, but we pattern recognize it as
patt_1 = a < 0 ? 7 : 0;
patt_2 = a + patt_1;
a = patt2 >> 3;
and in the first pattern stmt the reduction operand is in the condition of
COND_EXPR, not operands as vectorizable_reduction was asserting. Generally,
it couldn't be used anywhere in a pattern stmt, it could be just some
preparation statement.
Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?
2013-02-18 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/56350
* tree-vect-loop.c (vectorizable_reduction): If orig_stmt, return false
if haven't found reduction or nested cycle operand, rather than
asserting we must find it.
* gcc.dg/pr56350.c: New test.
--- gcc/tree-vect-loop.c.jj 2013-01-15 10:30:19.000000000 +0100
+++ gcc/tree-vect-loop.c 2013-02-18 11:32:30.306566358 +0100
@@ -4692,7 +4692,7 @@ vectorizable_reduction (gimple stmt, gim
The last use is the reduction variable. In case of nested cycle this
assumption is not true: we use reduc_index to record the index of the
reduction variable. */
- for (i = 0; i < op_type-1; i++)
+ for (i = 0; i < op_type - 1; i++)
{
/* The condition of COND_EXPR is checked in vectorizable_condition(). */
if (i == 0 && code == COND_EXPR)
@@ -4724,11 +4724,18 @@ vectorizable_reduction (gimple stmt, gim
if (!vectype_in)
vectype_in = tem;
gcc_assert (is_simple_use);
- gcc_assert (dt == vect_reduction_def
- || dt == vect_nested_cycle
- || ((dt == vect_internal_def || dt == vect_external_def
- || dt == vect_constant_def || dt == vect_induction_def)
- && nested_cycle && found_nested_cycle_def));
+ if (!(dt == vect_reduction_def
+ || dt == vect_nested_cycle
+ || ((dt == vect_internal_def || dt == vect_external_def
+ || dt == vect_constant_def || dt == vect_induction_def)
+ && nested_cycle && found_nested_cycle_def)))
+ {
+ /* For pattern recognized stmts, orig_stmt might be a reduction,
+ but some helper statements for the pattern might not, or
+ might be COND_EXPRs with reduction uses in the condition. */
+ gcc_assert (orig_stmt);
+ return false;
+ }
if (!found_nested_cycle_def)
reduc_def_stmt = def_stmt;
--- gcc/testsuite/gcc.dg/pr56350.c.jj 2013-02-18 11:30:12.117327599 +0100
+++ gcc/testsuite/gcc.dg/pr56350.c 2013-02-18 11:29:59.000000000 +0100
@@ -0,0 +1,13 @@
+/* PR tree-optimization/56350 */
+/* { dg-do compile } */
+/* { dg-options "-O -ftree-vectorize" } */
+
+int a, b, c;
+
+void
+f (void)
+{
+ for (; c; c++)
+ for (b = 0; b < 2; b++)
+ a /= 8;
+}
Jakub
