The length returned by vect_get_loop_len is REALLEN + BIAS, but was
assumed to be REALLEN - BIAS. If BIAS is -1, this leads to wrong
code.
Bootstrapped and regtested on s390. Ok for trunk?
gcc/ChangeLog:
* tree-vect-loop.cc (vectorizable_live_operation_1): Fix
load/store bias handling.
gcc/testsuite/ChangeLog:
* gcc.dg/vect/nodump-extractlast-1.c: New test.
Signed-off-by: Juergen Christ <jchr...@linux.ibm.com>
---
.../gcc.dg/vect/nodump-extractlast-1.c | 21 ++++++++++++++++++
gcc/tree-vect-loop.cc | 22 ++++++++++---------
2 files changed, 33 insertions(+), 10 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/vect/nodump-extractlast-1.c
diff --git a/gcc/testsuite/gcc.dg/vect/nodump-extractlast-1.c
b/gcc/testsuite/gcc.dg/vect/nodump-extractlast-1.c
new file mode 100644
index 000000000000..980ac3e42188
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/nodump-extractlast-1.c
@@ -0,0 +1,21 @@
+/* Check for a bung in the treatment of LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS when
+ using VEC_EXTRACT. */
+/* { dg-require-effective-target vect_int } */
+
+char c = 4;
+
+__attribute__((noipa))
+int
+foo ()
+{
+ for ( ; c > 3; c -= 3);
+ return c - 1;
+}
+
+int
+main ()
+{
+ if (foo() != 0)
+ __builtin_abort();
+ return 0;
+}
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 3b56f865ec7c..78256904dcea 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -10155,10 +10155,12 @@ vectorizable_live_operation_1 (loop_vec_info
loop_vinfo, basic_block exit_bb,
{
/* Emit:
- SCALAR_RES = VEC_EXTRACT <VEC_LHS, LEN + BIAS - 1>
+ SCALAR_RES = VEC_EXTRACT <VEC_LHS, LEN - (BIAS + 1)>
- where VEC_LHS is the vectorized live-out result and MASK is
- the loop mask for the final iteration. */
+ where VEC_LHS is the vectorized live-out result, LEN is the length of
+ the vector, BIAS is the load-store bias. The bias should not be used
+ at all since we are not using load/store operations, but LEN will be
+ REALLEN + BIAS, so subtract it to get to the correct position. */
gcc_assert (SLP_TREE_LANES (slp_node) == 1);
gimple_seq tem = NULL;
gimple_stmt_iterator gsi = gsi_last (tem);
@@ -10167,18 +10169,18 @@ vectorizable_live_operation_1 (loop_vec_info
loop_vinfo, basic_block exit_bb,
1, vectype, 0, 1);
gimple_seq_add_seq (&stmts, tem);
- /* BIAS - 1. */
+ /* BIAS + 1. */
signed char biasval = LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo);
- tree bias_minus_one
- = int_const_binop (MINUS_EXPR,
+ tree bias_plus_one
+ = int_const_binop (PLUS_EXPR,
build_int_cst (TREE_TYPE (len), biasval),
build_one_cst (TREE_TYPE (len)));
- /* LAST_INDEX = LEN + (BIAS - 1). */
- tree last_index = gimple_build (&stmts, PLUS_EXPR, TREE_TYPE (len),
- len, bias_minus_one);
+ /* LAST_INDEX = LEN - (BIAS + 1). */
+ tree last_index = gimple_build (&stmts, MINUS_EXPR, TREE_TYPE (len),
+ len, bias_plus_one);
- /* SCALAR_RES = VEC_EXTRACT <VEC_LHS, LEN + BIAS - 1>. */
+ /* SCALAR_RES = VEC_EXTRACT <VEC_LHS, LEN - (BIAS + 1)>. */
tree scalar_res
= gimple_build (&stmts, CFN_VEC_EXTRACT, TREE_TYPE (vectype),
vec_lhs_phi, last_index);
--
2.43.7
