build: Use clang to compile the runtime if available

8 files changed, 74 insertions, 49 deletions

diff --git a/configure b/configure
index 897209a3878..f24de59c1d1 100755
--- a/configure
+++ b/configure
@@ -194,12 +194,13 @@ putvar CFG_CPUTYPE
 putvar CFG_CONFIGURE_ARGS
 
 step_msg "looking for build programs"
-probe_need CFG_GCC          gcc
 probe_need CFG_GIT          git
 probe_need CFG_PERL         perl
 probe_need CFG_PYTHON       python
 probe_need CFG_CURL         curl
 
+probe CFG_CLANG            clang
+probe CFG_GCC              gcc
 probe CFG_LLVM_CONFIG      llvm-config
 probe CFG_VALGRIND         valgrind
 probe CFG_OCAMLC           ocamlc
@@ -211,6 +212,11 @@ probe CFG_MAKEINFO         makeinfo
 probe CFG_TEXI2PDF         texi2pdf
 probe CFG_TEX              tex
 
+if [ -z "$CFG_CLANG" -a -z "$CFG_GCC" ]
+then
+    err "either clang or gcc is required"
+fi
+
 # Valgrind is only reliable on Linux. On Windows it doesn't work at all, and
 # on the Mac the dynamic linker causes Valgrind to emit a huge stream of
 # errors.
diff --git a/mk/platform.mk b/mk/platform.mk
index c4016c42444..0b01f17a8c4 100644
--- a/mk/platform.mk
+++ b/mk/platform.mk
@@ -1,6 +1,6 @@
 
-CFG_GCC_CFLAGS := -fno-strict-aliasing
-CFG_GCC_LINK_FLAGS :=
+CFG_GCCISH_CFLAGS := -fno-strict-aliasing
+CFG_GCCISH_LINK_FLAGS :=
 
 # On Darwin, we need to run dsymutil so the debugging information ends
 # up in the right place.  On other platforms, it automatically gets
@@ -9,11 +9,11 @@ CFG_DSYMUTIL := true
 
 ifeq ($(CFG_OSTYPE), FreeBSD)
   CFG_LIB_NAME=lib$(1).so
-  CFG_GCC_CFLAGS += -fPIC -march=i686 -I/usr/local/include -O2
-  CFG_GCC_LINK_FLAGS += -shared -fPIC -lpthread -lrt
+  CFG_GCCISH_CFLAGS += -fPIC -march=i686 -I/usr/local/include -O2
+  CFG_GCCISH_LINK_FLAGS += -shared -fPIC -lpthread -lrt
   ifeq ($(CFG_CPUTYPE), x86_64)
-    CFG_GCC_CFLAGS += -m32
-    CFG_GCC_LINK_FLAGS += -m32
+    CFG_GCCISH_CFLAGS += -m32
+    CFG_GCCISH_LINK_FLAGS += -m32
   endif
   CFG_UNIXY := 1
   CFG_LDENV := LD_LIBRARY_PATH
@@ -22,14 +22,14 @@ endif
 
 ifeq ($(CFG_OSTYPE), Linux)
   CFG_LIB_NAME=lib$(1).so
-  CFG_GCC_CFLAGS += -fPIC -march=i686 -O2
-  CFG_GCC_LINK_FLAGS += -shared -fPIC -ldl -lpthread -lrt
-  CFG_GCC_DEF_FLAG := -Wl,--export-dynamic,--dynamic-list=
-  CFG_GCC_PRE_LIB_FLAGS := -Wl,-whole-archive
-  CFG_GCC_POST_LIB_FLAGS := -Wl,-no-whole-archive
+  CFG_GCCISH_CFLAGS += -fPIC -march=i686 -O2
+  CFG_GCCISH_LINK_FLAGS += -shared -fPIC -ldl -lpthread -lrt
+  CFG_GCCISH_DEF_FLAG := -Wl,--export-dynamic,--dynamic-list=
+  CFG_GCCISH_PRE_LIB_FLAGS := -Wl,-whole-archive
+  CFG_GCCISH_POST_LIB_FLAGS := -Wl,-no-whole-archive
   ifeq ($(CFG_CPUTYPE), x86_64)
-    CFG_GCC_CFLAGS += -m32
-    CFG_GCC_LINK_FLAGS += -m32
+    CFG_GCCISH_CFLAGS += -m32
+    CFG_GCCISH_LINK_FLAGS += -m32
   endif
   CFG_UNIXY := 1
   CFG_LDENV := LD_LIBRARY_PATH
@@ -40,8 +40,8 @@ ifeq ($(CFG_OSTYPE), Darwin)
   CFG_LIB_NAME=lib$(1).dylib
   CFG_UNIXY := 1
   CFG_LDENV := DYLD_LIBRARY_PATH
-  CFG_GCC_LINK_FLAGS += -dynamiclib -lpthread
-  CFG_GCC_DEF_FLAG := -Wl,-exported_symbols_list,
+  CFG_GCCISH_LINK_FLAGS += -dynamiclib -lpthread
+  CFG_GCCISH_DEF_FLAG := -Wl,-exported_symbols_list,
   # Darwin has a very blurry notion of "64 bit", and claims it's running
   # "on an i386" when the whole userspace is 64-bit and the compiler
   # emits 64-bit binaries by default. So we just force -m32 here. Smarter
@@ -49,7 +49,12 @@ ifeq ($(CFG_OSTYPE), Darwin)
   #
   # NB: Currently GCC's optimizer breaks rustrt (task-comm-1 hangs) on Darwin.
   CFG_GCC_CFLAGS += -m32 -O0
-  CFG_GCC_LINK_FLAGS += -m32
+  CFG_CLANG_CFLAGS += -m32 -O2
+  ifeq ($(CFG_CPUTYPE), x86_64)
+    CFG_GCCISH_CFLAGS += -arch i386
+    CFG_GCCISH_LINK_FLAGS += -arch i386
+  endif
+  CFG_GCCISH_LINK_FLAGS += -m32
   CFG_DSYMUTIL := dsymutil
   CFG_DEF_SUFFIX := .darwin.def
 endif
@@ -85,8 +90,8 @@ ifdef CFG_WINDOWSY
   ifdef CFG_FLEXLINK
     CFG_BOOT_NATIVE := 1
   endif
-  CFG_GCC_CFLAGS += -march=i686 -O2
-  CFG_GCC_LINK_FLAGS += -shared -fPIC
+  CFG_GCCISH_CFLAGS += -march=i686 -O2
+  CFG_GCCISH_LINK_FLAGS += -shared -fPIC
   CFG_DEF_SUFFIX := .def
 endif
 
@@ -112,16 +117,16 @@ ifdef CFG_UNIXY
     CFG_RUN_TEST=PATH=$(CFG_LDPATH):$(call CFG_TESTLIB,$(1)) $(1)
 
     CFG_INFO := $(info cfg: mingw-cross)
-    CFG_GCC_CROSS := i586-mingw32msvc-
+    CFG_GCCISH_CROSS := i586-mingw32msvc-
     CFG_BOOT_FLAGS += -t win32-x86-pe
     ifdef CFG_VALGRIND
       CFG_VALGRIND += wine
     endif
-    CFG_GCC_CFLAGS := -march=i686
-    CFG_GCC_LINK_FLAGS := -shared
+    CFG_GCCISH_CFLAGS := -march=i686
+    CFG_GCCISH_LINK_FLAGS := -shared
     ifeq ($(CFG_CPUTYPE), x86_64)
-      CFG_GCC_CFLAGS += -m32
-      CFG_GCC_LINK_FLAGS += -m32
+      CFG_GCCISH_CFLAGS += -m32
+      CFG_GCCISH_LINK_FLAGS += -m32
     endif
   endif
   ifdef CFG_VALGRIND
@@ -132,14 +137,28 @@ ifdef CFG_UNIXY
   endif
 endif
 
+ifdef CFG_CLANG
+  CFG_INFO := $(info cfg: using clang)
+  CFG_GCCISH_CFLAGS += -Wall -Werror -fno-rtti -fno-exceptions -g
+  CFG_GCCISH_LINK_FLAGS += -g
+  CFG_COMPILE_C = $(CFG_GCCISH_CROSS)clang++ $(CFG_GCCISH_CFLAGS) \
+    $(CFG_CLANG_CFLAGS) -c -o $(1) $(2)
+  CFG_DEPEND_C = $(CFG_GCCISH_CROSS)clang++ $(CFG_GCCISH_CFLAGS) -MT "$(1)" \
+    -MM $(2)
+  CFG_LINK_C = $(CFG_GCCISH_CROSS)clang++ $(CFG_GCCISH_LINK_FLAGS) -o $(1) \
+    $(CFG_GCCISH_DEF_FLAG)$(3) $(2)
+else
 ifdef CFG_GCC
   CFG_INFO := $(info cfg: using gcc)
-  CFG_GCC_CFLAGS += -Wall -Werror -fno-rtti -fno-exceptions -g
-  CFG_GCC_LINK_FLAGS += -g
-  CFG_COMPILE_C = $(CFG_GCC_CROSS)g++ $(CFG_GCC_CFLAGS) -c -o $(1) $(2)
-  CFG_DEPEND_C = $(CFG_GCC_CROSS)g++ $(CFG_GCC_CFLAGS) -MT "$(1)" -MM $(2)
-  CFG_LINK_C = $(CFG_GCC_CROSS)g++ $(CFG_GCC_LINK_FLAGS) -o $(1) \
-               $(CFG_GCC_DEF_FLAG)$(3) $(2)
+  CFG_GCCISH_CFLAGS += -Wall -Werror -fno-rtti -fno-exceptions -g
+  CFG_GCCISH_LINK_FLAGS += -g
+  CFG_COMPILE_C = $(CFG_GCCISH_CROSS)g++ $(CFG_GCCISH_CFLAGS) \
+    $(CFG_GCC_CFLAGS) -c -o $(1) $(2)
+  CFG_DEPEND_C = $(CFG_GCCISH_CROSS)g++ $(CFG_GCCISH_CFLAGS) -MT "$(1)" \
+    -MM $(2)
+  CFG_LINK_C = $(CFG_GCCISH_CROSS)g++ $(CFG_GCCISH_LINK_FLAGS) -o $(1) \
+               $(CFG_GCCISH_DEF_FLAG)$(3) $(2)
 else
-  CFG_ERR := $(error please try on a system with gcc)
+  CFG_ERR := $(error please try on a system with gcc or clang)
+endif
 endif
diff --git a/mk/rt.mk b/mk/rt.mk
index ad43b616583..173d811e8c5 100644
--- a/mk/rt.mk
+++ b/mk/rt.mk
@@ -64,7 +64,7 @@ RUNTIME_HDR := rt/globals.h \
 RUNTIME_DEF := rt/rustrt$(CFG_DEF_SUFFIX)
 RUNTIME_INCS := -I $(S)src/rt/isaac -I $(S)src/rt/uthash
 RUNTIME_OBJS := $(RUNTIME_CS:.cpp=.o)
-RUNTIME_LIBS := $(CFG_GCC_POST_LIB_FLAGS)
+RUNTIME_LIBS := $(CFG_GCCISH_POST_LIB_FLAGS)
 
 
 rt/%.o: rt/%.cpp $(MKFILES)
diff --git a/mk/rustllvm.mk b/mk/rustllvm.mk
index df728ffd844..7d09bf16723 100644
--- a/mk/rustllvm.mk
+++ b/mk/rustllvm.mk
@@ -29,8 +29,8 @@ rustllvm/$(CFG_RUSTLLVM): rustllvm/rustllvmbits.a $(RUSTLLVM_OBJS_OBJS) \
                           $(MKFILES) $(RUSTLLVM_HDR) $(RUSTLLVM_DEF)
 	@$(call E, link: $@)
 	$(Q)$(call CFG_LINK_C,$@,$(RUSTLLVM_OBJS_OBJS) \
-	  $(CFG_GCC_PRE_LIB_FLAGS) $(CFG_LLVM_LIBS) \
-          $(CFG_GCC_POST_LIB_FLAGS) rustllvm/rustllvmbits.a \
+	  $(CFG_GCCISH_PRE_LIB_FLAGS) $(CFG_LLVM_LIBS) \
+          $(CFG_GCCISH_POST_LIB_FLAGS) rustllvm/rustllvmbits.a \
 	  $(CFG_LLVM_LIBS) \
           $(CFG_LLVM_LDFLAGS),$(RUSTLLVM_DEF))
 
diff --git a/mk/stage1.mk b/mk/stage1.mk
index eb30e782511..ab63b181f08 100644
--- a/mk/stage1.mk
+++ b/mk/stage1.mk
@@ -6,8 +6,8 @@ stage1/std.o: $(STDLIB_CRATE) $(STDLIB_INPUTS) \
 
 stage1/$(CFG_STDLIB): stage1/std.o stage1/glue.o
 	@$(call E, link: $@)
-	$(Q)gcc $(CFG_GCC_CFLAGS) stage1/glue.o $(CFG_GCC_LINK_FLAGS) -o $@ $< \
-		-Lstage1 -Lrt -lrustrt
+	$(Q)gcc $(CFG_GCCISH_CFLAGS) stage1/glue.o $(CFG_GCCISH_LINK_FLAGS) \
+        -o $@ $< -Lstage1 -Lrt -lrustrt
 
 stage1/rustc.o: $(COMPILER_CRATE) $(COMPILER_INPUTS) $(SREQ0)
 	@$(call E, compile: $@)
@@ -30,11 +30,11 @@ stage1/intrinsics.bc:	$(INTRINSICS_BC)
 
 stage1/%.o: stage1/%.s
 	@$(call E, assemble [gcc]: $@)
-	$(Q)gcc $(CFG_GCC_CFLAGS) -o $@ -c $<
+	$(Q)gcc $(CFG_GCCISH_CFLAGS) -o $@ -c $<
 
 stage1/%$(X): stage1/%.o  $(SREQ0)
 	@$(call E, link [gcc]: $@)
-	$(Q)gcc $(CFG_GCC_CFLAGS) stage1/glue.o -o $@ $< \
+	$(Q)gcc $(CFG_GCCISH_CFLAGS) stage1/glue.o -o $@ $< \
       -Lstage1 -Lrustllvm -Lrt -lrustrt -lrustllvm -lstd -lm
 	@# dsymutil sometimes fails or prints a warning, but the
 	@# program still runs.  Since it simplifies debugging other
diff --git a/mk/stage2.mk b/mk/stage2.mk
index 5e7a7885195..f2eba3b0f14 100644
--- a/mk/stage2.mk
+++ b/mk/stage2.mk
@@ -6,8 +6,8 @@ stage2/std.o: $(STDLIB_CRATE) $(STDLIB_INPUTS) \
 
 stage2/$(CFG_STDLIB): stage2/std.o stage2/glue.o
 	@$(call E, link: $@)
-	$(Q)gcc $(CFG_GCC_CFLAGS) stage2/glue.o $(CFG_GCC_LINK_FLAGS) -o $@ $< \
-		-Lstage2 -Lrt -lrustrt
+	$(Q)gcc $(CFG_GCCISH_CFLAGS) stage2/glue.o $(CFG_GCCISH_LINK_FLAGS) -o \
+        $@ $< -Lstage2 -Lrt -lrustrt
 
 stage2/rustc.o: $(COMPILER_CRATE) $(COMPILER_INPUTS) $(SREQ1)
 	@$(call E, compile: $@)
@@ -30,11 +30,11 @@ stage2/intrinsics.bc:	$(INTRINSICS_BC)
 
 stage2/%.o: stage2/%.s
 	@$(call E, assemble [gcc]: $@)
-	$(Q)gcc $(CFG_GCC_CFLAGS) -o $@ -c $<
+	$(Q)gcc $(CFG_GCCISH_CFLAGS) -o $@ -c $<
 
 stage2/%$(X): stage2/%.o  $(SREQ1)
 	@$(call E, link [gcc]: $@)
-	$(Q)gcc $(CFG_GCC_CFLAGS) stage2/glue.o -o $@ $< \
+	$(Q)gcc $(CFG_GCCISH_CFLAGS) stage2/glue.o -o $@ $< \
       -Lstage2 -Lrustllvm -Lrt -lrustrt -lrustllvm -lstd -lm
 	@# dsymutil sometimes fails or prints a warning, but the
 	@# program still runs.  Since it simplifies debugging other
diff --git a/mk/stage3.mk b/mk/stage3.mk
index feba49727ca..0c119d1d42a 100644
--- a/mk/stage3.mk
+++ b/mk/stage3.mk
@@ -6,8 +6,8 @@ stage3/std.o: $(STDLIB_CRATE) $(STDLIB_INPUTS) \
 
 stage3/$(CFG_STDLIB): stage3/std.o stage3/glue.o
 	@$(call E, link: $@)
-	$(Q)gcc $(CFG_GCC_CFLAGS) stage3/glue.o $(CFG_GCC_LINK_FLAGS) -o $@ $< \
-		-Lstage3 -Lrt -lrustrt
+	$(Q)gcc $(CFG_GCCISH_CFLAGS) stage3/glue.o $(CFG_GCCISH_LINK_FLAGS) -o \
+        $@ $< -Lstage3 -Lrt -lrustrt
 
 stage3/rustc.o: $(COMPILER_CRATE) $(COMPILER_INPUTS) $(SREQ2)
 	@$(call E, compile: $@)
@@ -30,11 +30,11 @@ stage3/intrinsics.bc:	$(INTRINSICS_BC)
 
 stage3/%.o: stage3/%.s
 	@$(call E, assemble [gcc]: $@)
-	$(Q)gcc $(CFG_GCC_CFLAGS) -o $@ -c $<
+	$(Q)gcc $(CFG_GCCISH_CFLAGS) -o $@ -c $<
 
 stage3/%$(X): stage3/%.o  $(SREQ2)
 	@$(call E, link [gcc]: $@)
-	$(Q)gcc $(CFG_GCC_CFLAGS) stage3/glue.o -o $@ $< \
+	$(Q)gcc $(CFG_GCCISH_CFLAGS) stage3/glue.o -o $@ $< \
       -Lstage3 -Lrustllvm -Lrt -lrustrt -lrustllvm -lstd -lm
 	@# dsymutil sometimes fails or prints a warning, but the
 	@# program still runs.  Since it simplifies debugging other
diff --git a/mk/tests.mk b/mk/tests.mk
index 42eb05944df..48af58c1754 100644
--- a/mk/tests.mk
+++ b/mk/tests.mk
@@ -185,7 +185,7 @@ compile-check: tidy \
 
 %.stage0$(X): %.stage0.o  $(SREQ0)
 	@$(call E, link [gcc]: $@)
-	$(Q)gcc $(CFG_GCC_CFLAGS) stage1/glue.o -o $@ $< \
+	$(Q)gcc $(CFG_GCCISH_CFLAGS) stage1/glue.o -o $@ $< \
       -Lstage1 -Lrt -lrustrt -lstd -lm
 	@# dsymutil sometimes fails or prints a warning, but the
 	@# program still runs.  Since it simplifies debugging other
@@ -194,7 +194,7 @@ compile-check: tidy \
 
 %.stage1$(X): %.stage1.o $(SREQ1)
 	@$(call E, link [gcc]: $@)
-	$(Q)gcc $(CFG_GCC_CFLAGS) stage2/glue.o -o $@ $< \
+	$(Q)gcc $(CFG_GCCISH_CFLAGS) stage2/glue.o -o $@ $< \
       -Lstage2 -Lrt -lrustrt -lstd -lm
 	@# dsymutil sometimes fails or prints a warning, but the
 	@# program still runs.  Since it simplifies debugging other
@@ -203,7 +203,7 @@ compile-check: tidy \
 
 %.stage2$(X): %.stage2.o $(SREQ2)
 	@$(call E, link [gcc]: $@)
-	$(Q)gcc $(CFG_GCC_CFLAGS) stage3/glue.o -o $@ $< \
+	$(Q)gcc $(CFG_GCCISH_CFLAGS) stage3/glue.o -o $@ $< \
       -Lstage3 -Lrt -lrustrt -lstd -lm
 	@# dsymutil sometimes fails or prints a warning, but the
 	@# program still runs.  Since it simplifies debugging other