re PR target/55023 (hppa: wrong code generated with tail call optimisation)

	PR target/55023
	* dse.c (scan_insn): Treat sibling call as though it does a wild read.
	* testsuite/gcc.dg/pr55023.c: New file.

From-SVN: r219037

gcc/ChangeLog

+2014-12-22  John David Anglin  <danglin@gcc.gnu.org>
+
+	PR target/55023
+	* dse.c (scan_insn): Treat sibling call as though it does a wild read.
+
 2014-12-22  Bin Cheng  <bin.cheng@arm.com>
 
 	PR rtl-optimization/62151

gcc/dse.c

@@ -2483,6 +2483,17 @@ scan_insn (bb_info_t bb_info, rtx_insn *insn)
 
       insn_info->cannot_delete = true;
 
+      /* Arguments for a sibling call that are pushed to memory are passed
+	 using the incoming argument pointer of the current function.  These
+	 may or may not be frame related depending on the target.  Since
+	 argument pointer related stores are not currently tracked, we treat
+	 a sibling call as though it does a wild read.  */
+      if (SIBLING_CALL_P (insn))
+	{
+	  add_wild_read (bb_info);
+	  return;
+	}
+
       /* Const functions cannot do anything bad i.e. read memory,
 	 however, they can read their parameters which may have
 	 been pushed onto the stack.

gcc/testsuite/ChangeLog

+2014-12-22  John David Anglin  <danglin@gcc.gnu.org>
+
+	* gcc.dg/pr55023.c: New file.
+
 2014-12-22  Francois-Xavier Coudert  <fxcoudert@gcc.gnu.org>
 
 	* lib/ubsan-dg.exp: Add library path for libstdc++.

gcc/testsuite/gcc.dg/pr55023.c

+/* PR rtl-optimization/55023 */
+/* { dg-do run } */
+/* { dg-options "-O2 -fno-inline" } */
+
+extern void abort (void);
+typedef long long int64_t;
+
+struct foo {
+    int x;
+    int y;
+};
+
+int64_t foo(int64_t a, int64_t b, int64_t c)
+{
+    return a + b + c;
+}
+
+int64_t bar(int64_t a, struct foo bq, struct foo cq)
+{
+    int64_t b = bq.x + bq.y;
+    int64_t c = cq.x + cq.y;
+    return foo(a, b, c);
+}
+
+int main(void)
+{
+  int64_t a = 1;
+  struct foo b = { 2, 3 };
+  struct foo c = { 4, 5 };
+  if (bar (a, b, c) != 15)
+    abort ();
+  return 0;
+}