Use snap runtime, and the old main.o, for stage1

This is intended to be reverted again after I register the next
snapshot.

Author: marijnh

mk/rt.mk

@@ -106,10 +106,16 @@ ifdef CFG_WINDOWSY
 rt/main.ll: rt/main.ll.in
 	@$(call E, sed: $@)
 	$(Q)sed 's/MAIN/WinMain@16/' < $^ > $@
+rt/main0.ll: rt/main0.ll.in
+	@$(call E, sed: $@)
+	$(Q)sed 's/MAIN/WinMain@16/' < $^ > $@
 else
 rt/main.ll: rt/main.ll.in
 	@$(call E, sed: $@)
 	$(Q)sed 's/MAIN/main/' < $^ > $@
+rt/main0.ll: rt/main0.ll.in
+	@$(call E, sed: $@)
+	$(Q)sed 's/MAIN/main/' < $^ > $@
 endif
 
 rt/%.o: rt/%.ll $(MKFILES)

mk/target.mk

@@ -11,10 +11,6 @@ $$(TARGET_LIB$(1)$(2))/intrinsics.bc: $$(INTRINSICS_BC)
 	@$$(call E, cp: $$@)
 	$$(Q)cp $$< $$@
 
-$$(TARGET_LIB$(1)$(2))/main.o: rt/main.o
-	@$$(call E, cp: $$@)
-	$$(Q)cp $$< $$@
-
 $$(TARGET_LIB$(1)$(2))/$$(CFG_STDLIB): \
 	$$(STDLIB_CRATE) $$(STDLIB_INPUTS) \
         $$(TARGET_SREQ$(1)$(2))
@@ -27,9 +23,23 @@ $$(TARGET_LIB$(1)$(2))/libstd.rlib: \
 	@$$(call E, compile_and_link: $$@)
 	$$(STAGE$(1)) --lib --static -o $$@ $$<
 
+ifeq ($(1), 0)
+$$(TARGET_LIB$(1)$(2))/main.o: rt/main0.o
+	@$$(call E, cp: $$@)
+	$$(Q)cp $$< $$@
+
+$$(TARGET_LIB$(1)$(2))/$$(CFG_RUNTIME): stage0/lib/$$(CFG_RUNTIME)
+	@$$(call E, cp: $$@)
+	$$(Q)cp $$< $$@
+else
+$$(TARGET_LIB$(1)$(2))/main.o: rt/main.o
+	@$$(call E, cp: $$@)
+	$$(Q)cp $$< $$@
+
 $$(TARGET_LIB$(1)$(2))/$$(CFG_RUNTIME): rt/$$(CFG_RUNTIME)
 	@$$(call E, cp: $$@)
 	$$(Q)cp $$< $$@
+endif
 
 $$(TARGET_LIB$(1)$(2))/$$(CFG_RUSTLLVM): rustllvm/$$(CFG_RUSTLLVM)
 	@$$(call E, cp: $$@)

src/rt/main0.ll.in

@@ -0,0 +1,43 @@
+%0 = type { i32, [1 x i32] }
+%1 = type { i32, i32 }
+%2 = type { i32, %3 }
+%3 = type { %tydesc*, %4, i1, {} }
+%4 = type { i1*, i1* }
+%5 = type { i32, i32, i32, i32, [0 x %6*] }
+%6 = type { i32, i32, i32, i32, [0 x i8] }
+
+%tydesc = type { %tydesc**, i32, i32, void (i1*, %task*, i1*, %tydesc**, i8*)*, void (i1*, %task*, i1*, %tydesc**, i8*)*, void (i1*, %task*, i1*, %tydesc**, i8*)*, void (i1*, %task*, i1*, %tydesc**, i8*)*, void (i1*, %task*, i1*, %tydesc**, i8*)*, void (i1*, %task*, i1*, %tydesc**, i8*)*, void (i1*, %task*, i1*, %tydesc**, i8*)*, void (i1*, %task*, i1*, %tydesc**, i8*, i8*, i8)* }
+
+%task = type { i32, i32, i32, i32, i32, i32, i32, i32 }
+
+%vec = type { i32, i32, [0 x i8] }
+
+@_rust_crate_map_toplevel = external global %0
+
+declare i32 @rust_start(i32, i32, i32, i32)
+
+declare external fastcc void @_rust_main(i1* nocapture, %task*, %2* nocapture, %vec*)
+
+define void @_rust_main_wrap(i1* nocapture, %task *, %2* nocapture, %vec *)
+{
+  tail call fastcc void @_rust_main(i1* %0, %task *%1, %2* nocapture %2, %vec* %3)
+  ret void
+}
+
+%nullary_fn = type void (i1*, %task*, %2*)
+
+define void @_rust_spawn_wrap(
+       i1* nocapture, %task*, %2* nocapture, %nullary_fn* %f)
+{
+  call void %f(i1* %0, %task *%1, %2* nocapture %2)
+  ret void
+}
+
+declare external void @set_spawn_wrapper(void (i1*, %task*, %2*, %nullary_fn*)*);
+
+define i32 @"MAIN"(i32, i32) {
+  call void @set_spawn_wrapper(void (i1*, %task*, %2*, %nullary_fn*)* @_rust_spawn_wrap)
+
+  %result = tail call i32 @rust_start(i32 ptrtoint (void (i1*, %task*, %2*, %vec*)* @_rust_main_wrap to i32), i32 %0, i32 %1, i32 ptrtoint (%0* @_rust_crate_map_toplevel to i32))
+  ret i32 %result
+}