followup for cid 1004EE408E1382C1752 and 1004EE40DDD498FBB0D:

do a mirtoconf run-time check (ugh) to see whether the CPU designers
smoked/were brain-dead or if we don’t actually need the manual check

Build.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
-srcversion='$MirOS: src/bin/mksh/Build.sh,v 1.500 2011/12/31 00:31:25 tg Exp $'
+srcversion='$MirOS: src/bin/mksh/Build.sh,v 1.501 2011/12/31 02:04:16 tg Exp $'
 #-
 # Copyright (c) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
 #	Thorsten Glaser <tg@mirbsd.org>
@@ -147,7 +147,7 @@ ac_testinit() {
 }
 
 # pipe .c | ac_test[n] [!] label [!] checkif[!]0 [setlabelifcheckis[!]0] useroutput
-ac_testn() {
+ac_testnnd() {
 	if test x"$1" = x"!"; then
 		fr=1
 		shift
@@ -173,6 +173,9 @@ ac_testn() {
 		test $ct = sunpro && vscan='-e ignored -e turned.off'
 	fi
 	test -n "$vscan" && grep $vscan vv.out >/dev/null 2>&1 && fv=$fr
+}
+ac_testn() {
+	ac_testnnd "$@"
 	rmf conftest.c conftest.o ${tcfn}* vv.out
 	ac_testdone
 }
@@ -1171,7 +1174,7 @@ else
 		#define EXTERN
 		#define MKSH_INCLUDES_ONLY
 		#include "sh.h"
-		__RCSID("$MirOS: src/bin/mksh/Build.sh,v 1.500 2011/12/31 00:31:25 tg Exp $");
+		__RCSID("$MirOS: src/bin/mksh/Build.sh,v 1.501 2011/12/31 02:04:16 tg Exp $");
 		int main(void) { printf("Hello, World!\n"); return (0); }
 EOF
 	case $cm in
@@ -1535,6 +1538,61 @@ EOF
 CFLAGS=$save_CFLAGS
 eval test 1 = \$HAVE_COMPILE_TIME_ASSERTS_$$ || exit 1
 
+#
+# runtime checks
+# once this is more than one, check if we can do runtime
+# checks (not cross-compiling) first to save on warnings
+#
+$e "${bi}run-time checks follow$ao, please ignore any weird errors"
+
+ac_testnnd silent_idivwrapv '' '(run-time) whether signed integer division overflows wrap silently' <<-'EOF'
+	#define MKSH_INCLUDES_ONLY
+	#include "sh.h"
+	#ifdef SIGFPE
+	static void fpe_catcher(int) MKSH_A_NORETURN;
+	#endif
+	int main(int ac, char **av) {
+		mksh_ari_t o1, o2, r1, r2;
+
+	#ifdef SIGFPE
+		signal(SIGFPE, fpe_catcher);
+	#endif
+		o1 = ((mksh_ari_t)1 << 31);
+		o2 = -ac;
+		r1 = o1 / o2;
+		r2 = o1 % o2;
+		if (r1 == o1 && r2 == 0) {
+			printf("si");
+			return (0);
+		}
+		printf("no %d %d %d %d %s", o1, o2, r1, r2, av[0]);
+		return (1);
+	}
+	#ifdef SIGFPE
+	static const char fpe_msg[] = "no, got SIGFPE, what were they smoking?";
+	static void fpe_catcher(int sig MKSH_A_UNUSED) {
+		write(1, fpe_msg, sizeof(fpe_msg) - 1);
+		_exit(2);
+	}
+	#endif
+EOF
+if test $fv = 0; then
+	echo "| hrm, compiling this failed, but we will just failback"
+else
+	echo "| running test programme; this will fail if cross-compiling"
+	echo "| in which case we will gracefully degrade to the default"
+	./$tcfn >vv.out 2>&1
+	rv=$?
+	echo "| result: `cat vv.out`"
+	fv=0
+	test $rv = 0 && test x"`cat vv.out`" = x"si" && fv=1
+fi
+rmf conftest.c conftest.o ${tcfn}* vv.out
+ac_testdone
+ac_cppflags
+
+$e "${bi}end of run-time checks$ao"
+
 #
 # Compiler: Praeprocessor (only if needed)
 #

Makefile

@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/Makefile,v 1.91 2011/12/08 22:19:16 tg Exp $
+# $MirOS: src/bin/mksh/Makefile,v 1.92 2011/12/31 02:04:17 tg Exp $
 #-
 # Copyright (c) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
 #	Thorsten Glaser <tg@mirbsd.org>
@@ -46,6 +46,8 @@ CPPFLAGS+=	-DMKSH_ASSUME_UTF8 -DMKSH_DISABLE_DEPRECATED \
 		-DHAVE_STRCASESTR=1 -DHAVE_STRLCPY=1 -DHAVE_FLOCK_DECL=1 \
 		-DHAVE_REVOKE_DECL=1 -DHAVE_SYS_SIGLIST_DECL=1 \
 		-DHAVE_PERSISTENT_HISTORY=1
+# probably differs between i386 and sparc
+CPPFLAGS+=	-DHAVE_SILENT_IDIVWRAPV=0
 COPTS+=		-std=gnu99 -Wall
 .endif
 

expr.c

@@ -22,7 +22,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/expr.c,v 1.52 2011/12/16 20:03:02 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/expr.c,v 1.53 2011/12/31 02:04:18 tg Exp $");
 
 /* The order of these enums is constrained by the order of opinfo[] */
 enum token {
@@ -366,21 +366,25 @@ evalexpr(Expr_state *es, int prec)
 			break;
 		case O_DIV:
 		case O_DIVASN:
+#if !HAVE_SILENT_IDIVWRAPV
 			if (!es->natural && vr->val.i == -1 &&
 			    vl->val.i == ((mksh_ari_t)1 << 31)) {
 				/* -2147483648 / -1 = 2147483648 */
 				/* 80000000 / FFFFFFFF = 80000000 */
 				res = ((mksh_ari_t)1 << 31);
 			} else
+#endif
 				res = bivui(vl, /, vr);
 			break;
 		case O_MOD:
 		case O_MODASN:
+#if !HAVE_SILENT_IDIVWRAPV
 			if (!es->natural && vr->val.i == -1 &&
 			    vl->val.i == ((mksh_ari_t)1 << 31)) {
 				/* -2147483648 % -1 = 0 */
 				res = 0;
 			} else
+#endif
 				res = bivui(vl, %, vr);
 			break;
 		case O_PLUS: