[binutils-gdb] sim: pru: Fix behaviour when loop count is zero

[binutils-gdb] sim: pru: Fix behaviour when loop count is zero

[Dimitar Dimitrov]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=7bee555bb712b74749b749d80566f9c0d2094312

commit 7bee555bb712b74749b749d80566f9c0d2094312
Author: Dimitar Dimitrov <dimitar@dinux.eu>
Date:   Fri Nov 11 20:14:13 2022 +0200

    sim: pru: Fix behaviour when loop count is zero
    
    If the counter for LOOP instruction is provided by a register with
    value zero, then the instruction must cause a PC jump directly to the
    loop end.  But in that particular case simulator must not initialize
    its internal loop variables, because loop body will not be executed.
    Instead, simulator must obtain the loop's end address directly from
    the LOOP instruction.
    
    Signed-off-by: Dimitar Dimitrov <dimitar@dinux.eu>

Diff:
---
 sim/pru/pru.isa               |  4 ++--
 sim/testsuite/pru/loop-zero.s | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/sim/pru/pru.isa b/sim/pru/pru.isa
index b7d8b4af8b9..be8cdfd27fb 100644
--- a/sim/pru/pru.isa
+++ b/sim/pru/pru.isa
@@ -222,7 +222,7 @@ INSTRUCTION (loop,
 	     OP2 = (IO ? IMM8 + 1 : RS2_w0);
 	     if (OP2 == 0)
 	      {
-		PC = LOOPEND;
+		PC = PC + LOOP_JMPOFFS;
 	      }
 	     else
 	      {
@@ -237,7 +237,7 @@ INSTRUCTION (iloop,
 	     OP2 = (IO ? IMM8 + 1 : RS2_w0);
 	     if (OP2 == 0)
 	      {
-		PC = LOOPEND;
+		PC = PC + LOOP_JMPOFFS;
 	      }
 	     else
 	      {
diff --git a/sim/testsuite/pru/loop-zero.s b/sim/testsuite/pru/loop-zero.s
new file mode 100644
index 00000000000..65330f27beb
--- /dev/null
+++ b/sim/testsuite/pru/loop-zero.s
@@ -0,0 +1,41 @@
+# Check that loop insn works if register value is zero.
+# mach: pru
+
+# Copyright (C) 2022 Free Software Foundation, Inc.
+# Contributed by Dimitar Dimitrov <dimitar@dinux.eu>
+#
+# This file is part of the GNU simulators.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+.include "testutils.inc"
+
+	start
+
+	ldi r25, 0
+	ldi r27, 0
+	ldi r28, 10
+
+	loop 1f, r25
+	add r27, r27, 1
+	add r28, r28, 1
+1:
+
+	qbne F, r25, 0
+	qbne F, r27, 0
+	qbne F, r28, 10
+
+	pass
+
+F:	fail