I'm testing the attached fix.
>From 6de0603f3a5c86396d44250cb34d4451528681b1 Mon Sep 17 00:00:00 2001
From: Andrea Corallo <andrea.cora...@arm.com>
Date: Wed, 3 Feb 2021 15:21:54 +0100
Subject: [PATCH] arm: Add low overhead loop address range check [PR98931]
2021-02-03 Andrea Corallo <andrea.cora...@arm.com>
* config/arm/arm.c (arm_target_insn_ok_for_lob): Add address range
check.
---
gcc/config/arm/arm.c | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index e22396dbcd5..85c96cdb156 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -33769,10 +33769,22 @@ arm_target_insn_ok_for_lob (rtx insn)
supported for 'low over head loop' making sure that LE target is
above LE itself in the generated code. */
- return single_succ_p (bb)
- && single_pred_p (bb)
- && single_succ_edge (bb)->dest == single_pred_edge (bb)->src
- && contains_no_active_insn_p (bb);
+ if (!single_succ_p (bb)
+ || !single_pred_p (bb)
+ || single_succ_edge (bb)->dest != single_pred_edge (bb)->src
+ || !contains_no_active_insn_p (bb))
+ return false;
+
+ unsigned int distance = 0;
+ rtx_insn *curr_insn = BB_HEAD (single_succ_edge (bb)->dest);
+ while ((curr_insn = NEXT_INSN (curr_insn)))
+ distance += get_attr_length (curr_insn);
+
+ /* LE encodes the PC relative jump address in 12 bits. */
+ if (distance >= (1 << 11))
+ return false;
+
+ return true;
}
#if CHECKING_P
--
2.20.1
