[PATCH] tree-optimization/106533 - loop distribution of inner loop of nest

[Richard Biener via Gcc-patches]

Loop distribution currently gives up if the outer loop of a loop
nest it analyzes contains a stmt with side-effects instead of
continuing to analyze the innermost loop.  The following fixes that
by continuing anyway.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

        PR tree-optimization/106533
        * tree-loop-distribution.cc (loop_distribution::execute): Continue
        analyzing the inner loops when find_seed_stmts_for_distribution
        fails.

        * gcc.dg/tree-ssa/ldist-39.c: New testcase.
---
 gcc/testsuite/gcc.dg/tree-ssa/ldist-39.c | 16 ++++++++++++++++
 gcc/tree-loop-distribution.cc            |  2 +-
 2 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/ldist-39.c

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ldist-39.c 
b/gcc/testsuite/gcc.dg/tree-ssa/ldist-39.c
new file mode 100644
index 00000000000..3ef72864d96
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ldist-39.c
@@ -0,0 +1,16 @@
+/* PR/106533 */
+/* { dg-options "-O2 -fdump-tree-ldist-optimized" } */
+
+void bar (int *a, int * __restrict b)
+{
+  for (int k = 0; k < 10; k++)
+    {
+      for (int j = 0; j < 100000; ++j)
+       a[j] = b[j];
+      __builtin_printf ("Foo!");
+    }
+}
+
+/* The stmt with side-effects in the outer loop should not prevent
+   distribution of the inner loop of the loop nest.  */
+/* { dg-final { scan-tree-dump "optimized: Loop . distributed: split to 0 
loops and 1 library calls" "ldist" } } */
diff --git a/gcc/tree-loop-distribution.cc b/gcc/tree-loop-distribution.cc
index 0ee441c077d..e1948fb452a 100644
--- a/gcc/tree-loop-distribution.cc
+++ b/gcc/tree-loop-distribution.cc
@@ -3829,7 +3829,7 @@ loop_distribution::execute (function *fun)
        {
          auto_vec<gimple *> work_list;
          if (!find_seed_stmts_for_distribution (loop, &work_list))
-           break;
+           continue;
 
          const char *str = loop->inner ? " nest" : "";
          dump_user_location_t loc = find_loop_location (loop);
-- 
2.35.3