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 --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__" } } */
--
2.4.11
