* unroll.c (reg_dead_after_loop): Check for reg in REG_EQUAL and

	REG_EQUIV notes as well.

	* g++.dg/opt/strength-reduce.C: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@69076 138bc75d-0d04-0410-961f-82ee72b054a4

4 files changed, 65 insertions, 1 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 84a6e50e080..c2621df17df 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2003-07-08  Jakub Jelinek  <jakub@redhat.com>
+
+	* unroll.c (reg_dead_after_loop): Check for reg in REG_EQUAL and
+	REG_EQUIV notes as well.
+
 2003-07-08  Kazu Hirata  <kazu@cs.umass.edu>
 
 	* doc/md.texi: Fix the description of addmodecc.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 5ee11fb1bab..79d98c1e9db 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2003-07-08  Jakub Jelinek  <jakub@redhat.com>
+
+	* g++.dg/opt/strength-reduce.C: New test.
+
 2003-07-07  Roger Sayle  <roger@eyesopen.com>
 
 	PR target/10979
diff --git a/gcc/testsuite/g++.dg/opt/strength-reduce.C b/gcc/testsuite/g++.dg/opt/strength-reduce.C
new file mode 100644
index 00000000000..7c4619a36fa
--- /dev/null
+++ b/gcc/testsuite/g++.dg/opt/strength-reduce.C
@@ -0,0 +1,51 @@
+// This testcase was miscompiled on s390x, because strength-reduction
+// did not see biv in C::foo as used after loop, but it was used
+// in a REG_EQUAL note.
+// { dg-do run }
+// { dg-options "-O2" }
+
+extern "C" void abort (void);
+
+struct C
+{
+  int foo (char ch, int offset = 0x7fffffff) const;
+  int bar (int offset, char c) const;
+  char *a;
+};
+
+int C::bar (int offset, char c) const
+{
+  char ch = a[offset];
+  if (ch < c)
+    return -1;
+  if (ch > c)
+    return 1;
+  return 0;
+}
+
+int C::foo (char ch, int offset) const
+{
+  int len = __builtin_strlen (a);
+  if (len == 0)
+    return 0x7fffffff;
+  if (offset >= len)
+    offset = len - 1;
+
+  while (bar (offset, ch) != 0)
+    {
+      if (offset == 0)
+        return 0x7fffffff;
+      offset--;
+    }
+
+  return offset;
+}
+
+int main (void)
+{
+  C c;
+  c.a = "/some/dir/file.ext";
+  if (c.foo ('/') != 9)
+    abort ();
+  return 0;
+}
diff --git a/gcc/unroll.c b/gcc/unroll.c
index 955136e0b03..e557cb2c1e5 100644
--- a/gcc/unroll.c
+++ b/gcc/unroll.c
@@ -2899,11 +2899,15 @@ reg_dead_after_loop (const struct loop *loop, rtx reg)
 	  code = GET_CODE (insn);
 	  if (GET_RTX_CLASS (code) == 'i')
 	    {
-	      rtx set;
+	      rtx set, note;
 
 	      if (reg_referenced_p (reg, PATTERN (insn)))
 		return 0;
 
+	      note = find_reg_equal_equiv_note (insn);
+	      if (note && reg_overlap_mentioned_p (reg, XEXP (note, 0)))
+		return 0;
+
 	      set = single_set (insn);
 	      if (set && rtx_equal_p (SET_DEST (set), reg))
 		break;