Remove configuration option --disable-vm-evaluator

The `--disable-vm-evaluator` flag was being used only to selectively
allow/disallow the `make check-vm` option, but the VM was being
built and could be used whether that flag was passed or not.
This changeset removes that flag, allowing the VM to always be
built and available to the end user. To anyone building Octave
from source, this makes both `make check` and `make check-vm`
available. (The VM is still disabled when Octave starts, and the
user must explicitly invoke it with `__vm_enable__ (1)`.)

* configure.ac: Remove flag and corresponding variables.
* Makefile.am, test/Makefile.am: Remove use of flag,
allow `check-vm` to be available always.
* compile.cc: Edit FIXME and docstring to not mention the flag.

Makefile.am

@@ -349,10 +349,8 @@ run-octave: run-octave.in build-aux/subst-script-vals.sh
 	$(AM_V_GEN)$(call simple-filter-rule,build-aux/subst-script-vals.sh) && \
 	chmod a+rx $@
 
-if AMCOND_ENABLE_VM_EVALUATOR
 check-vm:
 	$(MAKE) -C test check-vm
-endif
 
 octave-config.h: config.h build-aux/mk-octave-config-h.sh
 	$(AM_V_GEN)$(SHELL) $(srcdir)/build-aux/mk-octave-config-h.sh $< > $@-t && \

configure.ac

@@ -1408,21 +1408,9 @@ if test $ENABLE_COMMAND_LINE_PUSH_PARSER = yes; then
     [Define to 1 to use Bison's push parser interface in the command line REPL.])
 fi
 
-### Configure compilation of *experimental* Virtual Machine evaluator.
-
+## FIXME: The next line is needed for VM-related ifdefs in pt-bytecode-vm.cc.
 AC_C_BIGENDIAN()
 
-ENABLE_VM_EVALUATOR=yes
-AC_ARG_ENABLE([vm-evaluator],
-  [AS_HELP_STRING([--disable-vm-evaluator],
-    [don't compile *experimental* virtual machine evaluator])],
-  [if test "$enableval" = no; then ENABLE_VM_EVALUATOR=no; fi], [])
-if test $ENABLE_VM_EVALUATOR = yes; then
-  AC_DEFINE(OCTAVE_ENABLE_VM_EVALUATOR, 1,
-    [Define to 1 to build experimental Virtual Machine evaluator.])
-fi
-AM_CONDITIONAL([AMCOND_ENABLE_VM_EVALUATOR], [test $ENABLE_VM_EVALUATOR = yes])
-
 ### Check for PCRE2 or PCRE regex library, requiring one to exist.
 
 have_pcre2=no

libinterp/corefcn/compile.cc

@@ -39,8 +39,6 @@
 OCTAVE_BEGIN_NAMESPACE(octave)
 
 // If TRUE, use VM evaluator rather than tree walker.
-// FIXME: Use OCTAVE_ENABLE_VM_EVALUATOR define to set it to true when
-// the VM has been tested properly.
 bool V__vm_enable__ = false;
 
 // Cleverly hidden in pt-bytecode-vm.cc to prevent inlining here
@@ -576,8 +574,6 @@ Note that the virtual machine feature is experimental.
 
 The default value is currently false, while the VM is still experimental.
 Users need to explicitly call @code{__vm_enable__ (1)} to enable it.
-In future, this will be set to the value of  the OCTAVE_ENABLE_VM_EVALUATOR
-flag that was set when building Octave.
 
 When false, Octave uses a traditional tree walker
 to evaluate statements parsed from m-code.  When true, Octave translates parsed

test/Makefile.am

@@ -150,10 +150,8 @@ endef
 check-local: $(GENERATED_TEST_FILES) $(MEX_TEST_FUNCTIONS) | $(OCTAVE_INTERPRETER_TARGETS) $(octave_dirstamp)
 	$(AM_V_at)$(call run-octave-tests)
 
-if AMCOND_ENABLE_VM_EVALUATOR
 check-vm: $(BUILT_SOURCES) $(GENERATED_TEST_FILES) $(MEX_TEST_FUNCTIONS) | $(OCTAVE_INTERPRETER_TARGETS) $(octave_dirstamp)
 	$(AM_V_at)$(call run-octave-tests,__vm_enable__ (1))
-endif
 
 COVERAGE_DIR = coverage
 COVERAGE_INFO = $(COVERAGE_DIR)/$(PACKAGE).info