auto merge of #8220 : luqmana/rust/arm-linux, r=cmr

Update the arm linux support some more. We had a previous patch for the RasberryPi. This adds a new target `arm-unknown-linux-gnueabi` for more general arm linux support.

Build/Host machine: x86_64 Debian testing (jessie) with the `gcc-4.4-arm-linux-gnueabi` package

Tested on targets:

- TS-7800 Feroceon (ARMv5TEJ) running Debian 7.0 wheezy
- Beaglebone black (ARMv7) running Angstrom GNU/Linux v2012.12
   - rustc flags:  `--target=arm-unknown-linux-gnueabi --linker=arm-linux-gnueabi-gcc`

- Samsung Galaxy S II (to make sure android still works)
   - rustc flags:  `--target=arm-linux-androideabi --android-cross-path=[path to standalone toolchain]`

Since not all arm devices (i.e. afaik anything older than armv6 like the ts-7800 i tested on) supported getting the tls address via the `mrc` instruction, I made it also try via the magic address the kernel maps into the address space (0xFFFF0FF0). One or the other should work (and on android it seems like both work).

Also fixes a bug where rustc would always try to invoke the android assembler for any kind of arm target.

mk/platform.mk

@@ -241,7 +241,7 @@ CFG_RUN_TARG_i686-apple-darwin=$(call CFG_RUN_i686-apple-darwin,,$(2))
 # arm-linux-androideabi configuration
 CC_arm-linux-androideabi=$(CFG_ANDROID_CROSS_PATH)/bin/arm-linux-androideabi-gcc
 CXX_arm-linux-androideabi=$(CFG_ANDROID_CROSS_PATH)/bin/arm-linux-androideabi-g++
-CPP_arm-linux-androideabi=$(CFG_ANDROID_CROSS_PATH)/bin/arm-linux-androideabi-gcc
+CPP_arm-linux-androideabi=$(CFG_ANDROID_CROSS_PATH)/bin/arm-linux-androideabi-gcc -E
 AR_arm-linux-androideabi=$(CFG_ANDROID_CROSS_PATH)/bin/arm-linux-androideabi-ar
 CFG_LIB_NAME_arm-linux-androideabi=lib$(1).so
 CFG_LIB_GLOB_arm-linux-androideabi=lib$(1)-*.so
@@ -272,7 +272,7 @@ AR_arm-unknown-linux-gnueabihf=arm-linux-gnueabihf-ar
 CFG_LIB_NAME_arm-unknown-linux-gnueabihf=lib$(1).so
 CFG_LIB_GLOB_arm-unknown-linux-gnueabihf=lib$(1)-*.so
 CFG_LIB_DSYM_GLOB_arm-unknown-linux-gnueabihf=lib$(1)-*.dylib.dSYM
-CFG_GCCISH_CFLAGS_arm-unknown-linux-gnueabihf := -Wall -g -fPIC
+CFG_GCCISH_CFLAGS_arm-unknown-linux-gnueabihf := -Wall -g -fPIC -D__arm__
 CFG_GCCISH_CXXFLAGS_arm-unknown-linux-gnueabihf := -fno-rtti
 CFG_GCCISH_LINK_FLAGS_arm-unknown-linux-gnueabihf := -shared -fPIC -g
 CFG_GCCISH_DEF_FLAG_arm-unknown-linux-gnueabihf := -Wl,--export-dynamic,--dynamic-list=
@@ -290,6 +290,32 @@ CFG_RUN_arm-unknown-linux-gnueabihf=
 CFG_RUN_TARG_arm-unknown-linux-gnueabihf=
 RUSTC_FLAGS_arm-unknown-linux-gnueabihf := --linker=$(CC_arm-unknown-linux-gnueabihf)
 
+# arm-unknown-linux-gnueabi configuration
+CC_arm-unknown-linux-gnueabi=arm-linux-gnueabi-gcc
+CXX_arm-unknown-linux-gnueabi=arm-linux-gnueabi-g++
+CPP_arm-unknown-linux-gnueabi=arm-linux-gnueabi-gcc -E
+AR_arm-unknown-linux-gnueabi=arm-linux-gnueabi-ar
+CFG_LIB_NAME_arm-unknown-linux-gnueabi=lib$(1).so
+CFG_LIB_GLOB_arm-unknown-linux-gnueabi=lib$(1)-*.so
+CFG_LIB_DSYM_GLOB_arm-unknown-linux-gnueabi=lib$(1)-*.dylib.dSYM
+CFG_GCCISH_CFLAGS_arm-unknown-linux-gnueabi := -Wall -g -fPIC -D__arm__
+CFG_GCCISH_CXXFLAGS_arm-unknown-linux-gnueabi := -fno-rtti
+CFG_GCCISH_LINK_FLAGS_arm-unknown-linux-gnueabi := -shared -fPIC -g
+CFG_GCCISH_DEF_FLAG_arm-unknown-linux-gnueabi := -Wl,--export-dynamic,--dynamic-list=
+CFG_GCCISH_PRE_LIB_FLAGS_arm-unknown-linux-gnueabi := -Wl,-whole-archive
+CFG_GCCISH_POST_LIB_FLAGS_arm-unknown-linux-gnueabi := -Wl,-no-whole-archive
+CFG_DEF_SUFFIX_arm-unknown-linux-gnueabi := .linux.def
+CFG_INSTALL_NAME_ar,-unknown-linux-gnueabi =
+CFG_LIBUV_LINK_FLAGS_arm-unknown-linux-gnueabi =
+CFG_EXE_SUFFIX_arm-unknown-linux-gnueabi :=
+CFG_WINDOWSY_arm-unknown-linux-gnueabi :=
+CFG_UNIXY_arm-unknown-linux-gnueabi := 1
+CFG_PATH_MUNGE_arm-unknown-linux-gnueabi := true
+CFG_LDPATH_arm-unknown-linux-gnueabi :=
+CFG_RUN_arm-unknown-linux-gnueabi=
+CFG_RUN_TARG_arm-unknown-linux-gnueabi=
+RUSTC_FLAGS_arm-unknown-linux-gnueabi := --linker=$(CC_arm-unknown-linux-gnueabi)
+
 # mips-unknown-linux-gnu configuration
 CC_mips-unknown-linux-gnu=mips-linux-gnu-gcc
 CXX_mips-unknown-linux-gnu=mips-linux-gnu-g++
@@ -450,7 +476,7 @@ define CFG_MAKE_TOOLCHAIN
         $$(CFG_GCCISH_DEF_FLAG_$(1))$$(3) $$(2)        \
         $$(call CFG_INSTALL_NAME_$(1),$$(4))
 
-  ifneq ($(1),arm-linux-androideabi)
+  ifneq ($(HOST_$(1)),arm)
 
   # We're using llvm-mc as our assembler because it supports
   # .cfi pseudo-ops on mac
@@ -462,9 +488,9 @@ define CFG_MAKE_TOOLCHAIN
                     -o=$$(1)
   else
 
-  # For the Android cross, use the Android assembler
+  # For the ARM crosses, use the toolchain assembler
   # XXX: We should be able to use the LLVM assembler
-  CFG_ASSEMBLE_$(1)=$$(CPP_$(1)) $$(CFG_DEPEND_FLAGS) $$(2) -c -o $$(1)
+  CFG_ASSEMBLE_$(1)=$$(CC_$(1)) $$(CFG_DEPEND_FLAGS) $$(2) -c -o $$(1)
 
   endif
 

src/librustc/driver/driver.rs

@@ -335,7 +335,7 @@ pub fn phase_5_run_llvm_passes(sess: Session,
                                outputs: &OutputFilenames) {
 
     // NB: Android hack
-    if sess.targ_cfg.arch == abi::Arm &&
+    if sess.targ_cfg.os == session::os_android &&
         (sess.opts.output_type == link::output_type_object ||
          sess.opts.output_type == link::output_type_exe) {
         let output_type = link::output_type_assembly;

src/rt/arch/arm/record_sp.S

@@ -14,22 +14,36 @@
 .globl get_sp
 
 record_sp_limit:
+	// First, try to read TLS address from coprocessor
 	mrc p15, #0, r3, c13, c0, #3
+	cmp r3, #0
+	// Otherwise, try to read from magic address 0xFFFF0FF0
+	mvneq r3, #0xF000
+	ldreq r3, [r3, #-15]
+
 #if __ANDROID__
 	add r3, r3, #252
 #elif __linux__
 	add r3, r3, #4
 #endif
+
 	str r0, [r3]
 	mov pc, lr
 
 get_sp_limit:
+	// First, try to read TLS address from coprocessor
 	mrc p15, #0, r3, c13, c0, #3
+	cmp r3, #0
+	// Otherwise, try to read from magic address 0xFFFF0FF0
+	mvneq r3, #0xF000
+	ldreq r3, [r3, #-15]
+
 #if __ANDROID__
 	add r3, r3, #252
 #elif __linux__
 	add r3, r3, #4
 #endif
+
 	ldr r0, [r3]
 	mov pc, lr