[PATCH] sim: pru: Add support for LMBD instruction

[Dimitar Dimitrov <dimitar@dinux.eu>]

Binutils support for LMBD instruction was merged [1]. So add it also
to simulator.

LMBD instruction does left-most-bit-detection. It returns 32 if
the given bit value is not found in the provided word value.

[1] https://sourceware.org/pipermail/binutils/2020-October/113901.html

sim/pru/ChangeLog:

	* pru.h (RS1SEL): New macro.
	(RS1_WIDTH): New macro.
	* pru.isa: Describe the LMBD instruction.

sim/testsuite/sim/pru/ChangeLog:

	* lmbd.s: New test.

Signed-off-by: Dimitar Dimitrov <dimitar@dinux.eu>
---
 sim/pru/pru.h                |  2 ++
 sim/pru/pru.isa              | 15 +++++++++
 sim/testsuite/sim/pru/lmbd.s | 61 ++++++++++++++++++++++++++++++++++++
 3 files changed, 78 insertions(+)
 create mode 100644 sim/testsuite/sim/pru/lmbd.s

diff --git a/sim/pru/pru.h b/sim/pru/pru.h
index 240fc30010..cbcc3ef9d7 100644
--- a/sim/pru/pru.h
+++ b/sim/pru/pru.h
@@ -58,6 +58,8 @@
 
 #define XBBO_BASEREG (CPU.regs[GET_INSN_FIELD (RS1, inst)])
 
+#define RS1SEL GET_INSN_FIELD (RS1SEL, inst)
+#define RS1_WIDTH regsel_width (RS1SEL)
 #define RDSEL GET_INSN_FIELD (RDSEL, inst)
 #define RD_WIDTH regsel_width (RDSEL)
 #define RD_REGN GET_INSN_FIELD (RD, inst)
diff --git a/sim/pru/pru.isa b/sim/pru/pru.isa
index 050154560b..c7860d0191 100644
--- a/sim/pru/pru.isa
+++ b/sim/pru/pru.isa
@@ -247,3 +247,18 @@ INSTRUCTION (iloop,
 		LOOP_IN_PROGRESS = 1;
 		PC++;
 	     })
+
+INSTRUCTION (lmbd,
+	     {
+	     int lmbd_i;
+
+	     OP2 = (IO ? IMM8 : RS2);
+
+	     for (lmbd_i = RS1_WIDTH - 1; lmbd_i >= 0; lmbd_i--)
+	       {
+		 if (!(((RS1 >> lmbd_i) ^ OP2) & 1))
+		   break;
+	       }
+	     RD = (lmbd_i < 0) ? 32 : lmbd_i;
+	     PC++;
+	     })
diff --git a/sim/testsuite/sim/pru/lmbd.s b/sim/testsuite/sim/pru/lmbd.s
new file mode 100644
index 0000000000..9a9e7827b2
--- /dev/null
+++ b/sim/testsuite/sim/pru/lmbd.s
@@ -0,0 +1,61 @@
+# Check that lmbd insn works.
+# mach: pru
+
+# Copyright (C) 2020 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
+
+	ldi32 r14, 0xffffffff
+	ldi32 r15, 0x0
+	ldi32 r16, 0x40000000
+	ldi32 r17, 8
+
+	lmbd r0, r14, 0
+	qbne 2f, r0, 32
+
+	lmbd r0, r14, 1
+	qbne 2f, r0, 31
+
+	lmbd r0, r15, 1
+	qbne 2f, r0, 32
+
+	lmbd r0, r15, 0
+	qbne 2f, r0, 31
+
+	lmbd r0, r16, r15
+	qbne 2f, r0, 31
+
+	lmbd r0, r16, 1
+	qbne 2f, r0, 30
+
+	lmbd r0, r14.w1, 1
+	qbne 2f, r0, 15
+
+	lmbd r0, r17.b0, 1
+	qbne 2f, r0, 3
+
+	lmbd r0, r17.b0, r15
+	qbne 2f, r0, 7
+
+
+1:
+	pass
+2:	fail
-- 
2.20.1