Teach the makefile to generate .ll files,

which are helpful in debugging the llvm backend.  Also tell git to ignore
LLVM's intermediate files.

Author: jyasskin

.gitignore

@@ -13,6 +13,8 @@
 *.dSYM
 *.d
 *.o
+*.ll
+*.bc
 *.aux
 *.cp
 *.fn

src/Makefile

@@ -189,6 +189,7 @@ ifdef CFG_LLVM_CONFIG
     lltrans.ml llemit.ml)
   LLC := "$(shell $(CFG_LLVM_CONFIG) --bindir)/llc"
   CFG_LLC_CFLAGS := -march=x86
+  LLVM-DIS := "$(shell $(CFG_LLVM_CONFIG) --bindir)/llvm-dis"
   $(info cfg: found llvm-config at $(CFG_LLVM_CONFIG))
 else
   VARIANT=x86
@@ -664,6 +665,11 @@ test/bench/shootout/%.x86$(CFG_EXE_SUFFIX): test/bench/shootout/%.rs $(REQ)
 	@$(call CFG_ECHO, compile [x86]: $<)
 	$(BOOT) -o $@ $<
 
+%.ll: %.bc
+	@$(call CFG_ECHO, dis [llvm]: $<)
+	$(CFG_QUIET)$(LLVM-DIS) -o $@ $<
+
+
 %.s: %.bc
 	@$(call CFG_ECHO, compile [llvm]: $<)
 	$(CFG_QUIET)$(LLC) $(CFG_LLC_CFLAGS) -o $@ $<