[PATCH 03/10] [ARC] Don't allow the last ZOL insn to be in a delay slot.

[Claudiu Zissulescu <Claudiu dot Zissulescu at synopsys dot com>]

From: Claudiu Zissulescu <claziss@gmail.com>

The ARC ZOL implementation doesn't allow the last instruction to be a
control instruction or part of a delay slot.  Thus, we add a note to
the last ZOL instruction which will prevent it to finish into a delay
slot.

2017-10-20  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/arc/arc.c (hwloop_optimize): Prevent the last
        ZOL instruction to end into a delay slot.
	* config/arc/arc.md (cond_delay_insn): Check if the instruction
	can be placed into a delay slot against reg_note.
	(in_delay_slot): Likewise.

testsuite/
2017-10-20  Claudiu Zissulescu  <claziss@synopsys.com>

	* gcc.target/arc/loop-3.c: New test.
	* gcc.target/arc/loop-4.c: Likewise.

[FIX][ZOL] fix checking for jumps
---
 gcc/config/arc/arc.c                  |  6 ++++++
 gcc/config/arc/arc.md                 |  4 ++++
 gcc/testsuite/gcc.target/arc/loop-3.c | 27 +++++++++++++++++++++++++++
 gcc/testsuite/gcc.target/arc/loop-4.c | 14 ++++++++++++++
 4 files changed, 51 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/arc/loop-3.c
 create mode 100644 gcc/testsuite/gcc.target/arc/loop-4.c

diff --git a/gcc/config/arc/arc.c b/gcc/config/arc/arc.c
index 964815a..1479a8d 100644
--- a/gcc/config/arc/arc.c
+++ b/gcc/config/arc/arc.c
@@ -7609,6 +7609,12 @@ hwloop_optimize (hwloop_info loop)
 		 loop->loop_no);
       last_insn = emit_insn_after (gen_nopv (), last_insn);
     }
+
+  /* SAVE_NOTE is used by haifa scheduler.  However, we are after it
+     and we can use it to indicate the last ZOL instruction cannot be
+     part of a delay slot.  */
+  add_reg_note (last_insn, REG_SAVE_NOTE, GEN_INT (2));
+
   loop->last_insn = last_insn;
 
   /* Get the loop iteration register.  */
diff --git a/gcc/config/arc/arc.md b/gcc/config/arc/arc.md
index 2e0ac52..6239483 100644
--- a/gcc/config/arc/arc.md
+++ b/gcc/config/arc/arc.md
@@ -472,6 +472,8 @@
 	     (symbol_ref "(arc_hazard (prev_active_insn (insn), insn)
 			   + arc_hazard (insn, next_active_insn (insn)))"))
 	 (const_string "false")
+	 (match_test "find_reg_note (insn, REG_SAVE_NOTE, GEN_INT (2))")
+	 (const_string "false")
 	 (eq_attr "iscompact" "maybe") (const_string "true")
 	 ]
 
@@ -499,6 +501,8 @@
   (cond [(eq_attr "cond" "!canuse") (const_string "no")
 	 (eq_attr "type" "call,branch,uncond_branch,jump,brcc")
 	 (const_string "no")
+	 (match_test "find_reg_note (insn, REG_SAVE_NOTE, GEN_INT (2))")
+	 (const_string "no")
 	 (eq_attr "length" "2,4") (const_string "yes")]
 	(const_string "no")))
 
diff --git a/gcc/testsuite/gcc.target/arc/loop-3.c b/gcc/testsuite/gcc.target/arc/loop-3.c
new file mode 100644
index 0000000..bf7aec9
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arc/loop-3.c
@@ -0,0 +1,27 @@
+/* { dg-do assemble } */
+/* { dg-do compile } */
+/* { dg-options "-O2 -mno-sdata" } *
+
+/* This example will fail to assemble if the last instruction is a
+   branch with delay slot.  */
+int d;
+extern char * fn2 (void);
+
+void fn1(void)
+{
+  char *a = fn2();
+  for (;;) {
+    long long b;
+    int e = 8;
+    for (; e <= 63; e += 7) {
+      long c = *a++;
+      b += c & e;
+      if (c & 28)
+        break;
+    }
+    d = b;
+  }
+}
+
+/* { dg-final { scan-assembler "bne_s @.L2" } } */
+/* { dg-final { scan-assembler-not "add.eq" } } */
diff --git a/gcc/testsuite/gcc.target/arc/loop-4.c b/gcc/testsuite/gcc.target/arc/loop-4.c
new file mode 100644
index 0000000..99a93a7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arc/loop-4.c
@@ -0,0 +1,14 @@
+/* { dg-do assemble } */
+/* { dg-do compile } */
+/* { dg-options "-Os" } */
+
+
+void fn1(void *p1, int p2, int p3)
+{
+  char *d = p1;
+  do
+    *d++ = p2;
+  while (--p3);
+}
+
+/* { dg-final { scan-assembler "lp_count" } } */
-- 
1.9.1