On 12/09/18 15:51, Richard Biener wrote:
On Wed, Sep 12, 2018 at 2:56 PM Kyrill Tkachov
<kyrylo.tkac...@foss.arm.com> wrote:
Hi all,
This PR is an SSA validation error where the definition ends up not dominating
a use.
This appeared after my recip_sqrt optimisation. Though the optimisation doesn't
get triggered
as there is no sqrt involved it prevents execute_cse_reciprocals_1 from running
as it's currently
an either/or situation. I think execute_cse_reciprocals_1 doesn't like it when
some divisions get
execute_cse_reciprocals_1 called on them and some don't.
This patch changes optimize_recip_sqrt to return a boolean indicating success
and call execute_cse_reciprocals_1
if no transform was made so that execute_cse_reciprocals_1 has a chance to
optimise it as well.
Bootstrapped and tested on x86_64-unknown-linux-gnu.
Ok for trunk?
OK. But your analysis suggests to do it the other way around - call
execute_cse_reciprocals_1 and if that
leaves a division at *gsi process it with optimize_recip_sqrt?
Ah, that's a shorter approach, this version implements that.
Bootstrapped and tested on x86_64-unknown-linux-gnu.
Is this preferable?
Thanks,
Kyrill
2018-09-12 Kyrylo Tkachov <kyrylo.tkac...@arm.com>
PR tree-optimization/87259
PR lto/87283
(pass_cse_reciprocals::execute): Run optimize_recip_sqrt after
execute_cse_reciprocals_1 has tried transforming.
2018-09-12 Kyrylo Tkachov <kyrylo.tkac...@arm.com>
PR tree-optimization/87259
* gcc.dg/pr87259.c: New test.
diff --git a/gcc/testsuite/gcc.dg/pr87259.c b/gcc/testsuite/gcc.dg/pr87259.c
new file mode 100644
index 0000000000000000000000000000000000000000..527a60a37adb520591ff40a52a12706aa1582068
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr87259.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-Ofast" } */
+
+int a, b, c;
+int *e;
+float f;
+void h() {
+ for (int g;;) {
+ float d = b, i = 0 / f, j = a / (f * f), k, l = 0 / d;
+ c = i + j;
+ g = l;
+ e[g] = c / d * k / d;
+ }
+}
diff --git a/gcc/tree-ssa-math-opts.c b/gcc/tree-ssa-math-opts.c
index 055b4e08e97469bac3ba7e26d61193512c234575..2b3ee887ad047b6e1430efe901965e2aeccf163a 100644
--- a/gcc/tree-ssa-math-opts.c
+++ b/gcc/tree-ssa-math-opts.c
@@ -547,7 +547,7 @@ free_bb (struct occurrence *occ)
depending on the uses of x, r1, r2. This removes one multiplication and
allows the sqrt and division operations to execute in parallel.
DEF_GSI is the gsi of the initial division by sqrt that defines
- DEF (x in the example abovs). */
+ DEF (x in the example above). */
static void
optimize_recip_sqrt (gimple_stmt_iterator *def_gsi, tree def)
@@ -947,13 +947,13 @@ pass_cse_reciprocals::execute (function *fun)
&& FLOAT_TYPE_P (TREE_TYPE (def))
&& TREE_CODE (def) == SSA_NAME)
{
+ execute_cse_reciprocals_1 (&gsi, def);
+ stmt = gsi_stmt (gsi);
if (flag_unsafe_math_optimizations
&& is_gimple_assign (stmt)
&& !stmt_can_throw_internal (stmt)
&& gimple_assign_rhs_code (stmt) == RDIV_EXPR)
optimize_recip_sqrt (&gsi, def);
- else
- execute_cse_reciprocals_1 (&gsi, def);
}
}
