sim: common: add $LINENO rewriting support to genmloop scripts

The generated mloop files can trigger compile time warnings.  It can
be difficult to see/understand where the original code is coming from
as all the diagnostics point to the generated output.  Using #line
pragmas, we can point people to the original source files.

Unfortunately, this code is written in POSIX shell, and that lacks
support for line number tracking.  The $LINENO variable, even when
available, can just be plain wrong.  For example, when using dash
and subshells, $LINENO can end up having negative values.  Add a
wrapper script that will uses awk to rewrite the $LINENO variable
to the right value to avoid all that.

Basically lineno.sh takes an input script, rewrites all uses of
$LINENO into the actual line number (and $0 into the original file
name), and then executes the temporary script.

This commit doesn't actually add #line pragmas to any files.  That
comes next.

4 files changed, 83 insertions, 22 deletions

diff --git a/sim/Makefile.in b/sim/Makefile.in
index 29ab8da..604732c 100644
--- a/sim/Makefile.in
+++ b/sim/Makefile.in
@@ -1926,8 +1926,10 @@ CGEN_GEN_CPU_DESC = \
 		$(CGEN_ARCHFILE) ignored $$opcfile
 
 CGEN_GEN_MLOOP = \
-	$(SHELL) $(srccom)/genmloop.sh \
-		-shell $(SHELL) \
+	$(SHELL) $(srccom)/lineno.sh \
+		$(srccom)/genmloop.sh \
+		$@.lineno.sh \
+		-shell $(SHELL) -awk $(AWK) -lineno $(srccom)/lineno.sh \
 		-infile $< -outfile-prefix $(@D)/
 
 
diff --git a/sim/common/genmloop.sh b/sim/common/genmloop.sh
index e9cb97d..007582e 100755
--- a/sim/common/genmloop.sh
+++ b/sim/common/genmloop.sh
@@ -142,6 +142,7 @@ infile=""
 prefix="unknown"
 outprefix=""
 outsuffix=""
+lineno=""
 
 while test $# -gt 0
 do
@@ -166,6 +167,8 @@ do
 	-cpu) shift ; cpu=$1 ;;
 	-infile) shift ; infile=$1 ;;
 	-shell) shift ; SHELL=$1 ;;
+	-awk) shift ; AWK=$1 ; export AWK ;;
+	-lineno) shift ; lineno=$1 ;;
 	*) echo "unknown option: $1" >&2 ; exit 1 ;;
 	esac
 	shift
@@ -199,6 +202,16 @@ PREFIX=`echo ${prefix} | tr "${lowercase}" "${uppercase}"`
 
 ##########################################################################
 
+load_infile_section() {
+  if [ -n "${lineno}" ]; then
+    ${SHELL} ${lineno} \
+      "${infile}" "${outprefix}mloop${outsuffix}.tmp" \
+      "$@"
+  else
+    ${SHELL} ${infile} "$@"
+  fi
+}
+
 rm -f ${outprefix}eng${outsuffix}.hin
 exec 1>${outprefix}eng${outsuffix}.hin
 
@@ -380,7 +393,7 @@ ATTRIBUTE_UNUSED static INLINE void
 
 EOF
 
-${SHELL} $infile support
+load_infile_section support
 
 ##########################################################################
 
@@ -425,7 +438,7 @@ esac
 
 # Any initialization code before looping starts.
 # Note that this code may declare some locals.
-${SHELL} $infile init
+load_infile_section init
 
 if [ x$parallel = xread ] ; then
   cat << EOF
@@ -466,7 +479,7 @@ cat << EOF
 /* begin full-exec-simple */
 EOF
 
-${SHELL} $infile full-exec-simple
+load_infile_section full-exec-simple
 
 cat << EOF
 /* end full-exec-simple */
@@ -527,7 +540,7 @@ static INLINE SCACHE *
 /* begin extract-scache */
 EOF
 
-${SHELL} $infile extract-scache
+load_infile_section extract-scache
 
 cat << EOF
 /* end extract-scache */
@@ -557,7 +570,7 @@ EOF
 
 # Any initialization code before looping starts.
 # Note that this code may declare some locals.
-${SHELL} $infile init
+load_infile_section init
 
 cat << EOF
 
@@ -580,7 +593,7 @@ cat << EOF
 /* begin full-exec-scache */
 EOF
 
-${SHELL} $infile full-exec-scache
+load_infile_section full-exec-scache
 
 cat << EOF
 /* end full-exec-scache */
@@ -618,7 +631,7 @@ EOF
 
 # Any initialization code before looping starts.
 # Note that this code may declare some locals.
-${SHELL} $infile init
+load_infile_section init
 
 cat << EOF
 
@@ -647,7 +660,7 @@ cat << EOF
 /* begin fast-exec-scache */
 EOF
 
-${SHELL} $infile fast-exec-scache
+load_infile_section fast-exec-scache
 
 cat << EOF
 /* end fast-exec-scache */
@@ -695,7 +708,7 @@ static INLINE SCACHE *
 /* begin extract-scache */
 EOF
 
-${SHELL} $infile extract-scache
+load_infile_section extract-scache
 
 cat << EOF
 /* end extract-scache */
@@ -726,7 +739,7 @@ EOF
 
 # Any initialization code before looping starts.
 # Note that this code may declare some locals.
-${SHELL} $infile init
+load_infile_section init
 
 if [ x$parallel = xread ] ; then
 cat << EOF
@@ -762,7 +775,7 @@ cat << EOF
 /* begin full-exec-scache */
 EOF
 
-${SHELL} $infile full-exec-scache
+load_infile_section full-exec-scache
 
 cat << EOF
 /* end full-exec-scache */
@@ -798,7 +811,7 @@ EOF
 
 # Any initialization code before looping starts.
 # Note that this code may declare some locals.
-${SHELL} $infile init
+load_infile_section init
 
 if [ x$parallel = xread ] ; then
 cat << EOF
@@ -841,7 +854,7 @@ cat << EOF
 /* begin fast-exec-scache */
 EOF
 
-${SHELL} $infile fast-exec-scache
+load_infile_section fast-exec-scache
 
 cat << EOF
 /* end fast-exec-scache */
@@ -948,7 +961,7 @@ INLINE SEM_PC
 /* begin extract-pbb */
 EOF
 
-${SHELL} $infile extract-pbb
+load_infile_section extract-pbb
 
 cat << EOF
 /* end extract-pbb */
@@ -1181,7 +1194,7 @@ esac
 
 # Any initialization code before looping starts.
 # Note that this code may declare some locals.
-${SHELL} $infile init
+load_infile_section init
 
 cat << EOF
 
@@ -1224,7 +1237,7 @@ cat << EOF
 /* begin full-exec-pbb */
 EOF
 
-${SHELL} $infile full-exec-pbb
+load_infile_section full-exec-pbb
 
 cat << EOF
 /* end full-exec-pbb */
@@ -1271,7 +1284,7 @@ esac
 
 # Any initialization code before looping starts.
 # Note that this code may declare some locals.
-${SHELL} $infile init
+load_infile_section init
 
 cat << EOF
 
@@ -1314,7 +1327,7 @@ cat << EOF
 /* begin fast-exec-pbb */
 EOF
 
-${SHELL} $infile fast-exec-pbb
+load_infile_section fast-exec-pbb
 
 cat << EOF
 /* end fast-exec-pbb */
diff --git a/sim/common/lineno.sh b/sim/common/lineno.sh
new file mode 100755
index 0000000..3332f37
--- /dev/null
+++ b/sim/common/lineno.sh
@@ -0,0 +1,44 @@
+#!/bin/sh
+# Replace $LINENO on the fly.
+# Copyright (C) 2023 Free Software Foundation, Inc.
+#
+# 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/>.
+
+# Since $LINENO is not reliable in shells/subshells, generate it on the fly.
+
+if [ $# -lt 2 ]; then
+  cat <<EOF >&2
+Usage: $0 <script> <tempfile> [script args]
+
+Rewrite the $LINENO usage in <script> with the line number.  The temp script is
+written to <tempfile>, and then removed when done.
+EOF
+  exit 1
+fi
+
+input=$1
+shift
+output=$1
+shift
+
+${AWK:-awk} '{
+  gsub("[$]LINENO", NR + 1)
+  gsub("\"[$]0\"", "\"" FILENAME "\"")
+  print
+}' "${input}" >"${output}"
+${SHELL} "${output}" "$@"
+
+rm -f "${output}"
diff --git a/sim/common/local.mk b/sim/common/local.mk
index 8124910..6414ad1 100644
--- a/sim/common/local.mk
+++ b/sim/common/local.mk
@@ -234,6 +234,8 @@ CGEN_GEN_CPU_DESC = \
 		$(CGEN_ARCHFILE) ignored $$opcfile
 
 CGEN_GEN_MLOOP = \
-	$(SHELL) $(srccom)/genmloop.sh \
-		-shell $(SHELL) \
+	$(SHELL) $(srccom)/lineno.sh \
+		$(srccom)/genmloop.sh \
+		$@.lineno.sh \
+		-shell $(SHELL) -awk $(AWK) -lineno $(srccom)/lineno.sh \
 		-infile $< -outfile-prefix $(@D)/