auto merge of #12027 : vadimcn/rust/compiler-rt, r=alexcrichton

This is an attempt to remove some more of Rust's dependencies on libgcc and replace it with LLVM's compiler-rt lib.  I've added compiler-rt as a submodule and changed libstd to link with it.  
As far as I could verify, after this change, the only symbols still imported by std from libgcc are the stack unwinding functions.   Other crates, however, still picked up symbols from libgcc, not from libstd, as I had hoped.  So linking definitely requires some work. 

I've only tested this on windows, 32-bit linux and android and fully expect it to fail on other platforms. Patches are welcome.

10 files changed, 63 insertions, 5 deletions

diff --git a/.gitmodules b/.gitmodules
index 8663757f5e2..597086229b8 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -9,3 +9,6 @@
 [submodule "src/gyp"]
 	path = src/gyp
 	url = https://github.com/rust-lang/gyp.git
+[submodule "src/compiler-rt"]
+	path = src/compiler-rt
+	url = https://github.com/rust-lang/compiler-rt.git
diff --git a/Makefile.in b/Makefile.in
index d0a7c5402e8..1130ab53d5d 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -355,7 +355,8 @@ endif
 # Prerequisites for using the stageN compiler to build target artifacts
 TSREQ$(1)_T_$(2)_H_$(3) = \
 	$$(HSREQ$(1)_H_$(3)) \
-	$$(TLIB$(1)_T_$(2)_H_$(3))/libmorestack.a
+	$$(TLIB$(1)_T_$(2)_H_$(3))/libmorestack.a \
+	$$(TLIB$(1)_T_$(2)_H_$(3))/libcompiler-rt.a
 
 # Prerequisites for a working stageN compiler and libraries, for a specific
 # target
diff --git a/mk/clean.mk b/mk/clean.mk
index edd0554195b..002db59ad38 100644
--- a/mk/clean.mk
+++ b/mk/clean.mk
@@ -54,6 +54,7 @@ clean-generic-$(2)-$(1):
 	         $(1)/rt \
 		 $(1)/test \
 		 $(1)/stage* \
+		 -type f \(           \
          -name '*.[odasS]' -o \
          -name '*.so' -o      \
          -name '*.dylib' -o   \
@@ -62,6 +63,7 @@ clean-generic-$(2)-$(1):
          -name '*.dll' -o     \
          -name '*.def' -o     \
          -name '*.bc'         \
+         \)                   \
          | xargs rm -f
 	$(Q)find $(1)\
          -name '*.dSYM'       \
@@ -96,6 +98,7 @@ clean$(1)_T_$(2)_H_$(3):						       \
 	    $$(foreach crate,$$(CRATES),clean$(1)_T_$(2)_H_$(3)-lib-$$(crate))  \
 	    $$(foreach tool,$$(TOOLS),clean$(1)_T_$(2)_H_$(3)-tool-$$(tool))
 	$$(Q)rm -f $$(TLIB$(1)_T_$(2)_H_$(3))/libmorestack.a
+	$$(Q)rm -f $$(TLIB$(1)_T_$(2)_H_$(3))/libcompiler-rt.a
 	$(Q)rm -f $$(TLIB$(1)_T_$(2)_H_$(3))/librun_pass_stage* # For unix
 	$(Q)rm -f $$(TLIB$(1)_T_$(2)_H_$(3))/run_pass_stage* # For windows
 
diff --git a/mk/crates.mk b/mk/crates.mk
index d137e5e7775..d7365a827b7 100644
--- a/mk/crates.mk
+++ b/mk/crates.mk
@@ -55,7 +55,7 @@ HOST_CRATES := syntax rustc rustdoc fourcc
 CRATES := $(TARGET_CRATES) $(HOST_CRATES)
 TOOLS := compiletest rustdoc rustc
 
-DEPS_std := native:rustrt
+DEPS_std := native:rustrt native:compiler-rt
 DEPS_extra := std term sync serialize getopts collections
 DEPS_green := std
 DEPS_rustuv := std native:uv native:uv_support
diff --git a/mk/install.mk b/mk/install.mk
index 73c8f2cf8c3..156a545e1ad 100644
--- a/mk/install.mk
+++ b/mk/install.mk
@@ -96,6 +96,7 @@ install-target-$(1)-host-$(2):						\
 		$$(call INSTALL_LIB,$$(call CFG_LIB_GLOB_$(1),$$(crate)));\
 		$$(call INSTALL_LIB,$$(call CFG_RLIB_GLOB,$$(crate)));)
 	$$(Q)$$(call INSTALL_LIB,libmorestack.a)
+	$$(Q)$$(call INSTALL_LIB,libcompiler-rt.a)
 
 endef
 
@@ -110,6 +111,7 @@ install-target-$(1)-host-$(2): $$(CSREQ$$(ISTAGE)_T_$(1)_H_$(2))
 	$$(Q)$$(foreach crate,$$(TARGET_CRATES),\
 	    $$(call INSTALL_LIB,$$(call CFG_RLIB_GLOB,$$(crate)));)
 	$$(Q)$$(call INSTALL_LIB,libmorestack.a)
+	$$(Q)$$(call INSTALL_LIB,libcompiler-rt.a)
 endef
 
 $(foreach target,$(CFG_TARGET), \
diff --git a/mk/rt.mk b/mk/rt.mk
index f2226b1ae3e..ebb1f83398e 100644
--- a/mk/rt.mk
+++ b/mk/rt.mk
@@ -217,6 +217,37 @@ $$(LIBUV_DIR_$(1))/Release/libuv.a: $$(LIBUV_DEPS) $$(LIBUV_MAKEFILE_$(1)) \
 
 endif
 
+################################################################################
+# compiler-rt
+################################################################################
+
+ifdef CFG_ENABLE_FAST_MAKE
+COMPRT_DEPS := $(S)/.gitmodules
+else
+COMPRT_DEPS := $(wildcard \
+              $(S)src/compiler-rt/* \
+              $(S)src/compiler-rt/*/* \
+              $(S)src/compiler-rt/*/*/* \
+              $(S)src/compiler-rt/*/*/*/*)
+endif
+
+COMPRT_NAME_$(1) := $$(call CFG_STATIC_LIB_NAME_$(1),compiler-rt)
+COMPRT_LIB_$(1) := $$(RT_OUTPUT_DIR_$(1))/$$(COMPRT_NAME_$(1))
+COMPRT_BUILD_DIR_$(1) := $$(RT_OUTPUT_DIR_$(1))/compiler-rt
+
+$$(COMPRT_LIB_$(1)): $$(COMPRT_DEPS)
+	@$$(call E, make: compiler-rt)
+	$$(Q)$$(MAKE) -C "$(S)src/compiler-rt" \
+		ProjSrcRoot="$(S)src/compiler-rt" \
+		ProjObjRoot="$$(abspath $$(COMPRT_BUILD_DIR_$(1)))" \
+		CC="$$(CC_$(1))" \
+		AR="$$(AR_$(1))" \
+		RANLIB="$$(AR_$(1)) s" \
+		CFLAGS="$$(CFG_GCCISH_CFLAGS_$(1))" \
+		TargetTriple=$(1) \
+		triple-runtime
+	$$(Q)cp $$(COMPRT_BUILD_DIR_$(1))/triple/runtime/libcompiler_rt.a $$(COMPRT_LIB_$(1))
+
 endef
 
 # Instantiate template for all stages/targets
diff --git a/mk/target.mk b/mk/target.mk
index 461e09da625..03569cb8b67 100644
--- a/mk/target.mk
+++ b/mk/target.mk
@@ -138,6 +138,12 @@ $$(TBIN$(1)_T_$(2)_H_$(3))/:
 $$(TLIB$(1)_T_$(2)_H_$(3))/:
 	mkdir -p $$@
 
+$$(TLIB$(1)_T_$(2)_H_$(3))/libcompiler-rt.a: \
+	    $$(RT_OUTPUT_DIR_$(2))/$$(call CFG_STATIC_LIB_NAME_$(2),compiler-rt) \
+	    | $$(TLIB$(1)_T_$(2)_H_$(3))/ $$(SNAPSHOT_RUSTC_POST_CLEANUP)
+	@$$(call E, cp: $$@)
+	$$(Q)cp $$< $$@
+
 $$(TLIB$(1)_T_$(2)_H_$(3))/libmorestack.a: \
 	    $$(RT_OUTPUT_DIR_$(2))/$$(call CFG_STATIC_LIB_NAME_$(2),morestack) \
 	    | $$(TLIB$(1)_T_$(2)_H_$(3))/ $$(SNAPSHOT_RUSTC_POST_CLEANUP)
diff --git a/mk/tests.mk b/mk/tests.mk
index 5f7566ef6d5..c2b298dbb9c 100644
--- a/mk/tests.mk
+++ b/mk/tests.mk
@@ -262,6 +262,7 @@ tidy:
 		| grep '^$(S)src/gyp' -v \
 		| grep '^$(S)src/etc' -v \
 		| grep '^$(S)src/doc' -v \
+		| grep '^$(S)src/compiler-rt' -v \
 		| xargs $(CFG_PYTHON) $(S)src/etc/check-binaries.py
 
 endif
diff --git a/src/compiler-rt b/src/compiler-rt
new file mode 160000
+Subproject d4606f1818dd8dfeaa3e509cd1cbac4482c3513
diff --git a/src/librustc/back/link.rs b/src/librustc/back/link.rs
index 099f376aded..72ae70565a7 100644
--- a/src/librustc/back/link.rs
+++ b/src/librustc/back/link.rs
@@ -1005,6 +1005,7 @@ fn link_rlib(sess: Session,
 fn link_staticlib(sess: Session, obj_filename: &Path, out_filename: &Path) {
     let mut a = link_rlib(sess, None, obj_filename, out_filename);
     a.add_native_library("morestack").unwrap();
+    a.add_native_library("compiler-rt").unwrap();
 
     let crates = sess.cstore.get_used_crates(cstore::RequireStatic);
     for &(cnum, ref path) in crates.iter() {
@@ -1132,6 +1133,19 @@ fn link_args(sess: Session,
         args.push(~"-shared-libgcc");
     }
 
+    if sess.targ_cfg.os == abi::OsAndroid {
+        // Many of the symbols defined in compiler-rt are also defined in libgcc.
+        // Android linker doesn't like that by default.
+        args.push(~"-Wl,--allow-multiple-definition");
+    }
+
+    // Stack growth requires statically linking a __morestack function
+    args.push(~"-lmorestack");
+    // compiler-rt contains implementations of low-level LLVM helpers
+    // It should go before platform and user libraries, so it has first dibs
+    // at resolving symbols that also appear in libgcc.
+    args.push(~"-lcompiler-rt");
+
     add_local_native_libraries(&mut args, sess);
     add_upstream_rust_crates(&mut args, sess, dylib, tmpdir);
     add_upstream_native_libraries(&mut args, sess);
@@ -1159,9 +1173,6 @@ fn link_args(sess: Session,
                        ~"-L/usr/local/lib/gcc44"]);
     }
 
-    // Stack growth requires statically linking a __morestack function
-    args.push(~"-lmorestack");
-
     // FIXME (#2397): At some point we want to rpath our guesses as to
     // where extern libraries might live, based on the
     // addl_lib_search_paths