Hi!
record_increment failed to verify that initializer is usable, which it is
only if cand_stmt is an addition (CAND_ADD can be e.g. even on a cast of
addition to some type of the same precision etc.) and one of the operands is
c->base_expr (because then the other operand necessarily has to be the rest,
but the code was only checking one of the operands, but cand_stmt e.g. can
be a sum of two SSA_NAMEs where each of those adds some multiply of one of
base_expr operands and some multiply of the c->stride. If we set
initializer to randomly chosen operand of such stmt, while we'll have the
right multiply of c->stride, the base_expr might be wrong.
Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk/4.8?
2013-04-15 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/56962
* gimple-ssa-strength-reduction.c (record_increment): Only set
initializer if gimple_assign_rhs_code is {,POINTER_}PLUS_EXPR and
either rhs1 or rhs2 is equal to c->base_expr.
* gcc.c-torture/execute/pr56962.c: New test.
--- gcc/gimple-ssa-strength-reduction.c.jj 2013-01-11 09:02:50.000000000
+0100
+++ gcc/gimple-ssa-strength-reduction.c 2013-04-15 11:59:46.668463873 +0200
@@ -1829,16 +1829,20 @@ record_increment (slsr_cand_t c, double_
if (c->kind == CAND_ADD
&& c->index == increment
&& (increment.sgt (double_int_one)
- || increment.slt (double_int_minus_one)))
+ || increment.slt (double_int_minus_one))
+ && (gimple_assign_rhs_code (c->cand_stmt) == PLUS_EXPR
+ || gimple_assign_rhs_code (c->cand_stmt) == POINTER_PLUS_EXPR))
{
- tree t0;
+ tree t0 = NULL_TREE;
tree rhs1 = gimple_assign_rhs1 (c->cand_stmt);
tree rhs2 = gimple_assign_rhs2 (c->cand_stmt);
if (operand_equal_p (rhs1, c->base_expr, 0))
t0 = rhs2;
- else
+ else if (operand_equal_p (rhs2, c->base_expr, 0))
t0 = rhs1;
- if (SSA_NAME_DEF_STMT (t0) && gimple_bb (SSA_NAME_DEF_STMT (t0)))
+ if (t0
+ && SSA_NAME_DEF_STMT (t0)
+ && gimple_bb (SSA_NAME_DEF_STMT (t0)))
{
incr_vec[incr_vec_len].initializer = t0;
incr_vec[incr_vec_len++].init_bb
--- gcc/testsuite/gcc.c-torture/execute/pr56962.c.jj 2013-04-15
12:09:24.781355085 +0200
+++ gcc/testsuite/gcc.c-torture/execute/pr56962.c 2013-04-15
12:09:19.985381802 +0200
@@ -0,0 +1,30 @@
+/* PR tree-optimization/56962 */
+
+extern void abort (void);
+long long v[144];
+
+__attribute__((noinline, noclone)) void
+bar (long long *x)
+{
+ if (x != &v[29])
+ abort ();
+}
+
+__attribute__((noinline, noclone)) void
+foo (long long *x, long y, long z)
+{
+ long long a, b, c;
+ a = x[z * 4 + y * 3];
+ b = x[z * 5 + y * 3];
+ c = x[z * 5 + y * 4];
+ x[y * 4] = a;
+ bar (&x[z * 5 + y]);
+ x[z * 5 + y * 5] = b + c;
+}
+
+int
+main ()
+{
+ foo (v, 24, 1);
+ return 0;
+}
Jakub
