From bf32992748c9849c38c089477d04b546e43ccdd1 Mon Sep 17 00:00:00 2001
From: Richard Biener <rguenther@suse.de>
Date: Wed, 24 Oct 2018 06:52:45 +0000
Subject: [PATCH] re PR tree-optimization/87665 (gcc HEAD (svn: 265340) breaks
elements on resize)
2018-10-24 Richard Biener <rguenther@suse.de>
PR tree-optimization/87665
* tree-vect-data-refs.c (vect_preserves_scalar_order_p): Adjust
to reflect reality.
* gcc.dg/torture/pr87665.c: New testcase.
From-SVN: r265452
---
gcc/ChangeLog | 6 ++++++
gcc/testsuite/ChangeLog | 5 +++++
gcc/testsuite/gcc.dg/torture/pr87665.c | 27 +++++++++++++++++++++++++
gcc/tree-vect-data-refs.c | 28 +++++++++++++++++---------
4 files changed, 57 insertions(+), 9 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/torture/pr87665.c
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5fe8205a94cc..33c906afb094 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-10-24 Richard Biener <rguenther@suse.de>
+
+ PR tree-optimization/87665
+ * tree-vect-data-refs.c (vect_preserves_scalar_order_p): Adjust
+ to reflect reality.
+
2018-10-12 Jeff Law <law@redhat.com>
* config/h8300/h8300.c (h8300_expand_prologue): Fix stm generation
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 1e992733ef12..fd437f58a13e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-10-24 Richard Biener <rguenther@suse.de>
+
+ PR tree-optimization/87665
+ * gcc.dg/torture/pr87665.c: New testcase.
+
2018-10-23 Jakub Jelinek <jakub@redhat.com>
* g++.dg/cpp2a/lambda-this3.C: Limit dg-bogus directives to c++17_down
diff --git a/gcc/testsuite/gcc.dg/torture/pr87665.c b/gcc/testsuite/gcc.dg/torture/pr87665.c
new file mode 100644
index 000000000000..6f5e968b6284
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr87665.c
@@ -0,0 +1,27 @@
+/* { dg-do run } */
+
+struct X { long x; long y; };
+
+struct X a[1024], b[1024];
+
+void foo ()
+{
+ for (int i = 0; i < 1024; ++i)
+ {
+ long tem = a[i].x;
+ a[i].x = 0;
+ b[i].x = tem;
+ b[i].y = a[i].y;
+ }
+}
+
+int main()
+{
+ for (int i = 0; i < 1024; ++i)
+ a[i].x = i;
+ foo ();
+ for (int i = 0; i < 1024; ++i)
+ if (b[i].x != i)
+ __builtin_abort();
+ return 0;
+}
diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c
index 4b3711442e68..a24e1853e038 100644
--- a/gcc/tree-vect-data-refs.c
+++ b/gcc/tree-vect-data-refs.c
@@ -210,16 +210,26 @@ vect_preserves_scalar_order_p (dr_vec_info *dr_info_a, dr_vec_info *dr_info_b)
return true;
/* STMT_A and STMT_B belong to overlapping groups. All loads in a
- group are emitted at the position of the first scalar load and all
+ group are emitted at the position of the last scalar load and all
stores in a group are emitted at the position of the last scalar store.
- Thus writes will happen no earlier than their current position
- (but could happen later) while reads will happen no later than their
- current position (but could happen earlier). Reordering is therefore
- only possible if the first access is a write. */
- stmtinfo_a = vect_orig_stmt (stmtinfo_a);
- stmtinfo_b = vect_orig_stmt (stmtinfo_b);
- stmt_vec_info earlier_stmt_info = get_earlier_stmt (stmtinfo_a, stmtinfo_b);
- return !DR_IS_WRITE (STMT_VINFO_DATA_REF (earlier_stmt_info));
+ Compute that position and check whether the resulting order matches
+ the current one. */
+ stmt_vec_info last_a = DR_GROUP_FIRST_ELEMENT (stmtinfo_a);
+ if (last_a)
+ for (stmt_vec_info s = DR_GROUP_NEXT_ELEMENT (last_a); s;
+ s = DR_GROUP_NEXT_ELEMENT (s))
+ last_a = get_later_stmt (last_a, s);
+ else
+ last_a = stmtinfo_a;
+ stmt_vec_info last_b = DR_GROUP_FIRST_ELEMENT (stmtinfo_b);
+ if (last_b)
+ for (stmt_vec_info s = DR_GROUP_NEXT_ELEMENT (last_b); s;
+ s = DR_GROUP_NEXT_ELEMENT (s))
+ last_b = get_later_stmt (last_b, s);
+ else
+ last_b = stmtinfo_b;
+ return ((get_later_stmt (last_a, last_b) == last_a)
+ == (get_later_stmt (stmtinfo_a, stmtinfo_b) == stmtinfo_a));
}
/* A subroutine of vect_analyze_data_ref_dependence. Handle
--
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