[PATCH] [ARC][ZOL] Account for empty body loops

[Claudiu Zissulescu <Claudiu.Zissulescu@synopsys.com>]

From: claziss <claziss@synopsys.com>

Hi Andrew,

By mistake I've pushed an incoplete ZOL-rework patch, and it missing the attached parts. Please can you check if it is ok?

Thank you,
Claudiu

gcc/
2017-09-01  Claudiu Zissulescu <claziss@synopsys.com>

	    * config/arc/arc.c (hwloop_optimize): Account for empty
	    body loops.

testsuite/
2017-09-01  Claudiu Zissulescu <claziss@synopsys.com>

 	        * gcc.target/arc/loop-1.c: Add test.
---
 gcc/config/arc/arc.c                  | 13 +++++++++++--
 gcc/testsuite/gcc.target/arc/loop-1.c | 12 ++++++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100755 gcc/testsuite/gcc.target/arc/loop-1.c

diff --git a/gcc/config/arc/arc.c b/gcc/config/arc/arc.c
index 52a9b24..d519063 100644
--- a/gcc/config/arc/arc.c
+++ b/gcc/config/arc/arc.c
@@ -7240,6 +7240,12 @@ hwloop_optimize (hwloop_info loop)
 	fprintf (dump_file, ";; loop %d too long\n", loop->loop_no);
       return false;
     }
+  else if (!loop->length)
+    {
+      if (dump_file)
+	fprintf (dump_file, ";; loop %d is empty\n", loop->loop_no);
+      return false;
+    }
 
   /* Check if we use a register or not.  */
   if (!REG_P (loop->iter_reg))
@@ -7311,8 +7317,11 @@ hwloop_optimize (hwloop_info loop)
       && INSN_P (last_insn)
       && (JUMP_P (last_insn) || CALL_P (last_insn)
 	  || GET_CODE (PATTERN (last_insn)) == SEQUENCE
-	  || get_attr_type (last_insn) == TYPE_BRCC
-	  || get_attr_type (last_insn) == TYPE_BRCC_NO_DELAY_SLOT))
+	  /* At this stage we can have (insn (clobber (mem:BLK
+	     (reg)))) instructions, ignore them.  */
+	  || (GET_CODE (PATTERN (last_insn)) != CLOBBER
+	      && (get_attr_type (last_insn) == TYPE_BRCC
+		  || get_attr_type (last_insn) == TYPE_BRCC_NO_DELAY_SLOT))))
     {
       if (loop->length + 2 > ARC_MAX_LOOP_LENGTH)
 	{
diff --git a/gcc/testsuite/gcc.target/arc/loop-1.c b/gcc/testsuite/gcc.target/arc/loop-1.c
new file mode 100755
index 0000000..274bb46
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arc/loop-1.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+/* Check how we handle empty body loops.  */
+
+int a;
+void fn1(void) {
+  int i;
+  for (; i < 8; i++) {
+    double A[a];
+  }
+}
-- 
1.9.1