[PATCH] Fix incorrect computation in fill_always_executed_in_1

[Xiong Hu Luo via Gcc-patches]

It seems to me that ALWAYS_EXECUTED_IN is not computed correctly for
nested loops.  inn_loop is updated to inner loop, so it need be restored
when exiting from innermost loop. With this patch, the store instruction
in outer loop could also be moved out of outer loop by store motion.
Any comments?  Thanks.

gcc/ChangeLog:

        * tree-ssa-loop-im.c (fill_always_executed_in_1): Restore
        inn_loop when exiting from innermost loop.

gcc/testsuite/ChangeLog:

        * gcc.dg/tree-ssa/ssa-lim-19.c: New test.
---
 gcc/testsuite/gcc.dg/tree-ssa/ssa-lim-19.c | 24 ++++++++++++++++++++++
 gcc/tree-ssa-loop-im.c                     |  6 +++++-
 2 files changed, 29 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/ssa-lim-19.c

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-lim-19.c 
b/gcc/testsuite/gcc.dg/tree-ssa/ssa-lim-19.c
new file mode 100644
index 00000000000..097a5ee4a4b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-lim-19.c
@@ -0,0 +1,24 @@
+/* PR/101293 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-lim2-details" } */
+
+struct X { int i; int j; int k;};
+
+void foo(struct X *x, int n, int l)
+{
+  for (int j = 0; j < l; j++)
+    {
+      for (int i = 0; i < n; ++i)
+       {
+         int *p = &x->j;
+         int tem = *p;
+         x->j += tem * i;
+       }
+      int *r = &x->k;
+      int tem2 = *r;
+      x->k += tem2 * j;
+    }
+}
+
+/* { dg-final { scan-tree-dump-times "Executing store motion" 2 "lim2" } } */
+
diff --git a/gcc/tree-ssa-loop-im.c b/gcc/tree-ssa-loop-im.c
index b24bc64f2a7..5ca4738b20e 100644
--- a/gcc/tree-ssa-loop-im.c
+++ b/gcc/tree-ssa-loop-im.c
@@ -3211,6 +3211,10 @@ fill_always_executed_in_1 (class loop *loop, sbitmap 
contains_call)
          if (dominated_by_p (CDI_DOMINATORS, loop->latch, bb))
            last = bb;
 
+         if (inn_loop != loop
+             && flow_loop_nested_p (bb->loop_father, inn_loop))
+           inn_loop = bb->loop_father;
+
          if (bitmap_bit_p (contains_call, bb->index))
            break;
 
@@ -3238,7 +3242,7 @@ fill_always_executed_in_1 (class loop *loop, sbitmap 
contains_call)
 
          if (bb->loop_father->header == bb)
            {
-             if (!dominated_by_p (CDI_DOMINATORS, loop->latch, bb))
+             if (!dominated_by_p (CDI_DOMINATORS, bb->loop_father->latch, bb))
                break;
 
              /* In a loop that is always entered we may proceed anyway.
-- 
2.27.0.90.geebb51ba8c