The following fixes a reported slowdown in 171.swim due to "better"
loop distribution dependence analysis. We really should apply
the (weak) costing model also to builtin partitions.
(and work on a better one so we can enable loop distribution by
default at -O3)
Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
Richard.
2017-01-27 Richard Biener <rguent...@suse.de>
PR tree-optimization/79245
* tree-loop-distribution.c (distribute_loop): Apply cost
modeling also to detected patterns.
* gcc.dg/tree-ssa/ldist-23.c: XFAIL.
* gcc.dg/tree-ssa/ldist-25.c: New testcase.
Index: gcc/tree-loop-distribution.c
===================================================================
--- gcc/tree-loop-distribution.c (revision 244963)
+++ gcc/tree-loop-distribution.c (working copy)
@@ -1548,8 +1548,7 @@ distribute_loop (struct loop *loop, vec<
for (int j = i + 1;
partitions.iterate (j, &partition); ++j)
{
- if (!partition_builtin_p (partition)
- && similar_memory_accesses (rdg, into, partition))
+ if (similar_memory_accesses (rdg, into, partition))
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
Index: gcc/testsuite/gcc.dg/tree-ssa/ldist-23.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/ldist-23.c (revision 244963)
+++ gcc/testsuite/gcc.dg/tree-ssa/ldist-23.c (working copy)
@@ -29,5 +29,6 @@ int main()
return 0;
}
-/* { dg-final { scan-tree-dump "split to 1 loops and 1 library call" "ldist" }
} */
-/* { dg-final { scan-tree-dump "generated memcpy" "ldist" } } */
+/* XFAILed due to the fix for PR79245. */
+/* { dg-final { scan-tree-dump "split to 1 loops and 1 library call" "ldist" {
xfail *-*-* } } } */
+/* { dg-final { scan-tree-dump "generated memcpy" "ldist" { xfail *-*-* } } }
*/
Index: gcc/testsuite/gcc.dg/tree-ssa/ldist-25.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/ldist-25.c (nonexistent)
+++ gcc/testsuite/gcc.dg/tree-ssa/ldist-25.c (working copy)
@@ -0,0 +1,25 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -ftree-loop-distribute-patterns
-fdump-tree-ldist-details" } */
+
+#define k 128000
+double a[k][k];
+double b[k][k];
+double c[k][k];
+
+int x;
+int y;
+
+void
+foo (void)
+{
+ for (int j = 0; j < x; j++)
+ {
+ for (int i = 0; i < y; i++)
+ {
+ c[j][i] = b[j][i] - a[j][i];
+ a[j][i] = b[j][i];
+ }
+ }
+}
+
+/* { dg-final { scan-tree-dump "Loop . is the same" "ldist" } } */
