Hi,
Current pcom implementation rewrites into lcssa form after all loops are
transformed, this is
not enough because unrolling of later loop checks lcssa form in function
tree_transform_and_unroll_loop.
This simple patch rewrites loop into lcssa form if store-store chain is
handled. I think it doesn't
affect compilation time since rewrite_into_loop_closed_ssa_1 is only called for
store-store chain
transformation and only the transformed loop is rewritten.
Bootstrap and test ongoing on x86_64. is it OK if no failures?
Thanks,
bin
2017-09-14 Bin Cheng <bin.ch...@arm.com>
PR tree-optimization/82163
* tree-predcom.c (tree_predictive_commoning_loop): Rewrite into
loop closed ssa instantly. Return boolean true if loop is unrolled.
(tree_predictive_commoning): Return TODO_cleanup_cfg if loop is
unrolled.
gcc/testsuite
2017-09-14 Bin Cheng <bin.ch...@arm.com>
PR tree-optimization/82163
* gcc.dg/tree-ssa/pr82163.c: New test.diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr82163.c
b/gcc/testsuite/gcc.dg/tree-ssa/pr82163.c
new file mode 100644
index 0000000..fef2b1d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr82163.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O3" } */
+
+int a, b, c[4], d, e, f, g;
+
+void h ()
+{
+ for (; a; a++)
+ {
+ c[a + 3] = g;
+ if (b)
+ c[a] = f;
+ else
+ {
+ for (; d; d++)
+ c[d + 3] = c[d];
+ for (e = 1; e == 2; e++)
+ ;
+ if (e)
+ break;
+ }
+ }
+}
diff --git a/gcc/tree-predcom.c b/gcc/tree-predcom.c
index e7b10cb..ffbe332 100644
--- a/gcc/tree-predcom.c
+++ b/gcc/tree-predcom.c
@@ -3014,11 +3014,10 @@ insert_init_seqs (struct loop *loop, vec<chain_p>
chains)
}
}
-/* Performs predictive commoning for LOOP. Sets bit 1<<0 of return value
- if LOOP was unrolled; Sets bit 1<<1 of return value if loop closed ssa
- form was corrupted. */
+/* Performs predictive commoning for LOOP. Returns true if LOOP was
+ unrolled. */
-static unsigned
+static bool
tree_predictive_commoning_loop (struct loop *loop)
{
vec<data_reference_p> datarefs;
@@ -3154,7 +3153,13 @@ end: ;
free_affine_expand_cache (&name_expansions);
- return (unroll ? 1 : 0) | (loop_closed_ssa ? 2 : 0);
+ /* Rewrite loop into loop closed ssa form if necessary. We can not do it
+ after all loops are transformed because unrolling of later loop checks
+ loop closed ssa form. */
+ if (loop_closed_ssa)
+ rewrite_into_loop_closed_ssa_1 (NULL, 0, SSA_OP_USE, loop);
+
+ return unroll;
}
/* Runs predictive commoning. */
@@ -3163,7 +3168,7 @@ unsigned
tree_predictive_commoning (void)
{
struct loop *loop;
- unsigned ret = 0, changed = 0;
+ bool changed = 0;
initialize_original_copy_tables ();
FOR_EACH_LOOP (loop, LI_ONLY_INNERMOST)
@@ -3173,17 +3178,13 @@ tree_predictive_commoning (void)
}
free_original_copy_tables ();
- if (changed > 0)
+ if (changed)
{
scev_reset ();
-
- if (changed > 1)
- rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa);
-
- ret = TODO_cleanup_cfg;
+ return TODO_cleanup_cfg;
}
- return ret;
+ return 0;
}
/* Predictive commoning Pass. */
