Make nmake benchmark work on mswin

The `benchmark` recipe collected files with `$(find ... | sort)`,
which cmd.exe cannot interpret, so `nmake benchmark` failed with
`'sort)' is not recognized`.  Select the files with Ruby instead so
the recipe works regardless of the shell, and pass the executables
with forward slashes for benchmark-driver's Shellwords splitting.

benchmark/README.md

@@ -62,8 +62,7 @@ make benchmark ITEM=vm
 # Run some limited benchmarks in ITEM-matched files
 make benchmark ITEM=vm OPTS=--filter=block
 
-# You can specify the benchmark by an exact filename instead of using the default argument:
-# ARGS = $$(find $(srcdir)/benchmark -maxdepth 1 -name '*$(ITEM)*.yml' -o -name '*$(ITEM)*.rb')
+# You can specify the benchmark by exact filenames instead of matching ITEM:
 make benchmark ARGS=benchmark/erb_render.yml
 
 # You can specify any option via $OPTS

common.mk

@@ -1440,15 +1440,24 @@ COMPARE_RUBY = $(BASERUBY)
 BENCH_RUBY = $(RUNRUBY)
 BENCH_OPTS = --output=markdown --output-compare -v
 ITEM =
-ARGS = $$(find $(srcdir)/benchmark -maxdepth 1 -name '$(ITEM)' -o -name '*$(ITEM)*.yml' -o -name '*$(ITEM)*.rb' | sort)
+ARGS =
 OPTS =
 
-# See benchmark/README.md for details.
+# Select the benchmark files with Ruby instead of `find | sort`, so the
+# recipe runs on any platform regardless of the shell.  When ARGS is
+# empty, collect the files matching ITEM under benchmark/.  Executables
+# are passed with forward slashes because benchmark-driver splits them
+# with Shellwords, which eats backslashes.  See benchmark/README.md.
 benchmark: miniruby$(EXEEXT) update-benchmark-driver PHONY
-	$(BASERUBY) -rrubygems -I$(srcdir)/benchmark/lib $(srcdir)/benchmark/benchmark-driver/exe/benchmark-driver \
-	            --executables="compare-ruby::$(COMPARE_RUBY) -I$(EXTOUT)/common --disable-gem" \
-	            --executables="built-ruby::$(BENCH_RUBY) --disable-gem" \
-	            $(BENCH_OPTS) $(ARGS) $(OPTS)
+	$(BASERUBY) -rrubygems -I$(srcdir)/benchmark/lib \
+	    -e "files = %w[$(ARGS)]" \
+	    -e "files = Dir.glob(['$(ITEM)', '*$(ITEM)*.yml', '*$(ITEM)*.rb'], base: '$(srcdir)/benchmark').reject(&:empty?).sort.uniq.map {|f| '$(srcdir)/benchmark/' + f} if files.empty?" \
+	    -e "ARGV.map! {|a| a.start_with?('--executables') ? a.gsub(92.chr, '/') : a}" \
+	    -e "ARGV.concat(files)" \
+	    -e "load '$(srcdir)/benchmark/benchmark-driver/exe/benchmark-driver'" -- \
+	    --executables="compare-ruby::$(COMPARE_RUBY) -I$(EXTOUT)/common --disable-gem" \
+	    --executables="built-ruby::$(BENCH_RUBY) --disable-gem" \
+	    $(BENCH_OPTS) $(OPTS)
 
 run.gdb:
 	echo set breakpoint pending on         > run.gdb