Introduce --basedir to insns2vm.rb

and leverage that to preserve the directory structure under tool/ruby_vm/views

template/Makefile.in

@@ -505,9 +505,9 @@ clean-local::
 	-$(Q) $(RMDIRS) $(MJIT_HEADER_INSTALL_DIR) $(MJIT_HEADER_BUILD_DIR) $(TIMESTAMPDIR) 2> $(NULL) || $(NULLCMD)
 
 main: $(srcdir)/lib/mjit/instruction.rb
-$(srcdir)/lib/mjit/instruction.rb: $(tooldir)/ruby_vm/views/instruction.rb.erb $(srcdir)/insns.def
+$(srcdir)/lib/mjit/instruction.rb: $(tooldir)/ruby_vm/views/lib/mjit/instruction.rb.erb $(srcdir)/insns.def
 	$(ECHO) generating $@
-	$(Q) $(BASERUBY) -Ku $(tooldir)/insns2vm.rb $(INSNS2VMOPT) $@
+	$(Q) $(BASERUBY) -Ku $(tooldir)/insns2vm.rb --basedir="$(srcdir)" $(INSNS2VMOPT) $@
 
 # DTrace static library hacks described here:
 # https://marc.info/?l=opensolaris-dtrace-discuss&m=114761203110734&w=4

tool/ruby_vm/controllers/application_controller.rb

@@ -16,10 +16,11 @@ require_relative '../models/typemap'
 require_relative '../loaders/vm_opts_h'
 
 class ApplicationController
-  def generate i, destdir
+  def generate i, destdir, basedir
     path = Pathname.new i
     dst = destdir ? Pathname.new(destdir).join(i) : Pathname.new(i)
-    dumper = RubyVM::Dumper.new dst
+    base = basedir ? Pathname.new(basedir) : Pathname.pwd
+    dumper = RubyVM::Dumper.new dst, base.expand_path
     return [path, dumper]
   end
 end

tool/ruby_vm/helpers/dumper.rb

@@ -28,7 +28,7 @@ class RubyVM::Dumper
     path  = Pathname.new(__FILE__)
     path  = (path.relative_path_from(Pathname.pwd) rescue path).dirname
     path += '../views'
-    path += File.basename(spec)
+    path += Pathname.pwd.join(spec).to_s.sub("#{@base}/", '')
     src   = path.read mode: 'rt:utf-8:utf-8'
   rescue Errno::ENOENT
     raise "don't know how to generate #{path}"
@@ -85,10 +85,11 @@ class RubyVM::Dumper
       . join
   end
 
-  def initialize dst
+  def initialize dst, base
     @erb   = {}
     @empty = new_binding
     @file  = cstr dst.to_path
+    @base  = base
   end
 
   def render partial, opts = { :locals => {} }

tool/ruby_vm/scripts/insns2vm.rb

@@ -15,10 +15,10 @@ require_relative '../controllers/application_controller.rb'
 
 module RubyVM::Insns2VM
   def self.router argv
-    options = { destdir: nil }
+    options = { destdir: nil, basedir: nil }
     targets = generate_parser(options).parse argv
     return targets.map do |i|
-      next ApplicationController.new.generate i, options[:destdir]
+      next ApplicationController.new.generate i, options[:destdir], options[:basedir]
     end
   end
 
@@ -84,6 +84,14 @@ module RubyVM::Insns2VM
         options[:destdir] = dir
       end
 
+      this.on "--basedir=DIR", <<-'begin' do |dir|
+        Change the base directory from the current working directory
+        to the given path. Used for searching the source template.
+      begin
+        raise "directory was not found in '#{dir}'" unless Dir.exist?(dir)
+        options[:basedir] = dir
+      end
+
       this.on "-V", "--[no-]verbose", <<-'end'
         Please let us ignore this and be modest.
       end