iverilog: add test for the vvp example mentioned in the documentation

This test was added to verify the new options
in the `iverilog` program, which allow it to
be run from a build directory.

Since `iverilog` is not compatible with the MSYS2
runtime environment used in CI, the added test is
excluded on this platform.

configure.ac

@@ -98,6 +98,22 @@ AC_SUBST(EXEEXT)
 # Combined check for Microsoft-related bogosities; sets WIN32 if found
 AX_WIN32
 
+# detect msys shell
+AC_MSG_CHECKING([whether the shell is an MSYS2 runtime shell])
+
+AS_CASE([$host_os:$MSYSTEM],
+  [*mingw*:UCRT64|*mingw*:MINGW64|*mingw*:MINGW32|*mingw*:CLANG64], [
+    MSYS_SHELL=true
+    msys_shell_result=yes
+  ],
+  [
+    MSYS_SHELL=false
+    msys_shell_result=no
+  ]
+)
+AC_MSG_RESULT([$msys_shell_result])
+AC_SUBST([MSYS_SHELL])
+
 # Check to see if we are using the Sun compiler. If so then configure
 # some of the flags to match the Sun compiler syntax. This is also used
 # in the aclocal.m4 file to configure the flags used to build and link

driver/Makefile.in

@@ -17,12 +17,18 @@
 #
 SHELL = /bin/sh
 
+EXEEXT = @EXEEXT@
+ENV_VVP=@ENV_VVP@
+MSYS_SHELL=@MSYS_SHELL@
+
 suffix = @install_suffix@
 
 prefix = @prefix@
 exec_prefix = @exec_prefix@
 srcdir = @srcdir@
 datarootdir = @datarootdir@
+builddir=@builddir@
+top_builddir=@top_builddir@
 
 VPATH = $(srcdir)
 
@@ -58,11 +64,25 @@ O = main.o substit.o cflexor.o cfparse.o
 all: dep iverilog@EXEEXT@ iverilog.man
 
 check: all
+	@if $(MSYS_SHELL); then \
+		echo "iverilog: execution from a build directory not suppported for this runtime"; \
+	else \
+		echo "iverilog: create .vpp from .v file and run it"; \
+		$(builddir)/iverilog@EXEEXT@ \
+			-B$(top_builddir)/tgt-vvp \
+			-BI$(top_builddir) \
+			-BM$(top_builddir)/vpi \
+			-BP$(top_builddir)/ivlpp \
+			-Bt$(top_builddir)/tgt-vvp \
+			$(verbose) -o top.vvp -s top $(srcdir)/hello_world.v; \
+		$(ENV_VVP) $(top_builddir)/vvp/vvp$(suffix)@EXEEXT@ top.vvp; \
+	fi
 
 clean:
 	rm -f *.o cflexor.c cfparse.c cfparse.h cfparse.output
 	rm -f iverilog@EXEEXT@ iverilog.man iverilog.pdf iverilog.ps
 	rm -rf dep
+	rm -f test.conf top.vvp
 
 distclean: clean
 	rm -f Makefile config.log

driver/hello_world.v

@@ -0,0 +1,3 @@
+module top;
+    initial $display("Hello World!");
+endmodule