diff mbox

[2/2] arc: Fix for loop end detection

Message ID 60f778afbc7621347ff1e817bbf78c113dd8c83b.1492010055.git.andrew.burgess@embecosm.com
State New
Headers show

Commit Message

Andrew Burgess April 12, 2017, 3:23 p.m. UTC 
We use a negative ID number to link together the doloop_begin and
doloop_end instructions.  This negative ID number is setup within
doloop_begin, at this point the ID is stored into the loop end
instruction (doloop_end_i) and placed into the doloop_begin_i
instruction.

In arc.c (arc_reorg) we extract the ID from the doloop_end_i
instruction in order to find the matching doloop_begin_i instruction,
though the ID is only used in some cases.

Currently in arc_reorg when we extract the ID we negate it.  This
negation is invalid.  The ID stored in both doloop_end_i and
doloop_begin_i is already negative, the negation in arc_reorg means
that if we need to use the ID to find the doloop_begin_i then we will
never find it (as the IDs will never match).

This commit removes the unneeded negation, moves the extraction of the
ID into a more appropriately scoped block and adds a new test for this
issue.

gcc/ChangeLog:

	* config/arc/arc.c (arc_reorg): Move loop_end_id into a more local
	block, and do not negate it, the stored id is already negative.

gcc/testsuite/ChangeLog:

	* gcc.target/arc/loop-1.c: New file.
---
 gcc/ChangeLog                         |  6 +++++
 gcc/config/arc/arc.c                  |  5 ++--
 gcc/testsuite/ChangeLog               |  4 ++++
 gcc/testsuite/gcc.target/arc/loop-1.c | 45 +++++++++++++++++++++++++++++++++++
 4 files changed, 58 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/arc/loop-1.c
diff mbox

Patch

diff --git a/gcc/config/arc/arc.c b/gcc/config/arc/arc.c
index 0563a74..39b198d 100644
--- a/gcc/config/arc/arc.c
+++ b/gcc/config/arc/arc.c
@@ -6573,8 +6573,6 @@  arc_reorg (void)
 	  rtx_insn *lp_simple = NULL;
 	  rtx_insn *next = NULL;
 	  rtx op0 = XEXP (XVECEXP (PATTERN (insn), 0, 1), 0);
-	  HOST_WIDE_INT loop_end_id
-	    = -INTVAL (XEXP (XVECEXP (PATTERN (insn), 0, 4), 0));
 	  int seen_label = 0;
 
 	  for (lp = prev;
@@ -6585,6 +6583,9 @@  arc_reorg (void)
 	  if (!lp || !NONJUMP_INSN_P (lp)
 	      || dead_or_set_regno_p (lp, LP_COUNT))
 	    {
+	      HOST_WIDE_INT loop_end_id
+		= INTVAL (XEXP (XVECEXP (PATTERN (insn), 0, 4), 0));
+
 	      for (prev = next = insn, lp = NULL ; prev || next;)
 		{
 		  if (prev)
diff --git a/gcc/testsuite/gcc.target/arc/loop-1.c b/gcc/testsuite/gcc.target/arc/loop-1.c
new file mode 100644
index 0000000..1afe8eb
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arc/loop-1.c
@@ -0,0 +1,45 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+/* This case would fail to make use of the zero-overhead loop
+   instruction at one time due to a bug.  */
+
+extern char a[];
+
+struct some_t
+{
+  struct
+  {
+    int aaa;
+    short bbb;
+    char ccc;
+    char ddd;
+  } ppp[8];
+
+  int www[1];
+};
+
+int b;
+
+void
+some_function ()
+{
+  struct some_t *tmp = (struct some_t *) a;
+
+  while ((*tmp).ppp[b].ccc)
+    while(0);
+
+  for (; b; b++)
+    {
+      if (tmp->ppp[b].ccc)
+        {
+          int c = tmp->ppp[b].bbb;
+          int d = tmp->ppp[b].aaa;
+          int e = d - tmp->www[c];
+          if (e)
+            tmp->ppp[b].ddd = 1;
+        }
+    }
+}
+
+/* { dg-final { scan-assembler "\[^\n\]+lp \\.L__GCC__" } } */