Hi!
As the comment say, we want to insert (if should_insert_square_recip
is true) new_square_stmt right after new_stmt. The current code does
that correctly if new_stmt is inserted with
gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
because the following
gsi_insert_before (&gsi, new_square_stmt, GSI_SAME_STMT);
will keep inserting before whatever gsi points to.
But one of the 3 cases inserts new_stmt instead after def_gsi, and the
current
gsi = *def_gsi;
gsi_insert_after (def_gsi, new_stmt, GSI_NEW_STMT);
gsi_insert_before (&gsi, new_square_stmt, GSI_SAME_STMT);
certainly doesn't do that, it inserts new_stmt after the def_gsi stmt and
then inserts new_square_stmt before the def_gsi stmt, so we have order of:
new_square_stmt
whatever-def_gsi-pointed-to-stmt
new_stmt
where new_square_stmt uses the lhs of new_stmt.
Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?
2018-08-03 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/86835
* tree-ssa-math-opts.c (insert_reciprocals): Even when inserting
new_stmt after def_gsi, make sure to insert new_square_stmt after
that stmt, not 2 stmts before it.
* gcc.dg/pr86835.c: New test.
--- gcc/tree-ssa-math-opts.c.jj 2018-07-12 21:31:27.698410833 +0200
+++ gcc/tree-ssa-math-opts.c 2018-08-03 12:58:27.475961037 +0200
@@ -422,6 +422,8 @@ insert_reciprocals (gimple_stmt_iterator
gsi_next (&gsi);
gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
+ if (should_insert_square_recip)
+ gsi_insert_before (&gsi, new_square_stmt, GSI_SAME_STMT);
}
else if (def_gsi && occ->bb == def_gsi->bb)
{
@@ -429,21 +431,19 @@ insert_reciprocals (gimple_stmt_iterator
never happen if the definition statement can throw, because in
that case the sole successor of the statement's basic block will
dominate all the uses as well. */
- gsi = *def_gsi;
gsi_insert_after (def_gsi, new_stmt, GSI_NEW_STMT);
+ if (should_insert_square_recip)
+ gsi_insert_after (def_gsi, new_square_stmt, GSI_NEW_STMT);
}
else
{
/* Case 3: insert in a basic block not containing defs/uses. */
gsi = gsi_after_labels (occ->bb);
gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
+ if (should_insert_square_recip)
+ gsi_insert_before (&gsi, new_square_stmt, GSI_SAME_STMT);
}
- /* Regardless of which case the reciprocal as inserted in,
- we insert the square immediately after the reciprocal. */
- if (should_insert_square_recip)
- gsi_insert_before (&gsi, new_square_stmt, GSI_SAME_STMT);
-
reciprocal_stats.rdivs_inserted++;
occ->recip_def_stmt = new_stmt;
--- gcc/testsuite/gcc.dg/pr86835.c.jj 2018-08-03 13:07:28.834159126 +0200
+++ gcc/testsuite/gcc.dg/pr86835.c 2018-08-03 13:07:14.119126559 +0200
@@ -0,0 +1,29 @@
+/* PR tree-optimization/86835 */
+/* { dg-do run } */
+/* { dg-options "-O2 -ffast-math -Wuninitialized" } */
+
+__attribute__((noipa)) void
+foo (int n, double *x, double *y)
+{ /* { dg-bogus "is used uninitialized in this function" "" {
target *-*-* } 0 } */
+ int i;
+ double b = y[4];
+ for (i = 0; i < n; ++i)
+ y[3] += __builtin_sin (x[i] / b);
+ y[0] /= b;
+ y[1] /= b * b;
+ y[2] /= b;
+}
+
+int
+main ()
+{
+ double y[] = { 16.0, 64.0, 128.0, 0.0, 2.0 };
+ foo (0, y, y);
+ if (__builtin_fabs (y[0] - 8.0) > 0.0001
+ || __builtin_fabs (y[1] - 16.0) > 0.0001
+ || __builtin_fabs (y[2] - 64.0) > 0.0001
+ || y[3] != 0.0
+ || y[4] != 2.0)
+ __builtin_abort ();
+ return 0;
+}
Jakub
