Undo removal of the runtime libraries. While this may have been a bit

premature, these libraries will be going away for the 2.0 release. Other
arrangements for profiling, gc, etc. should be made in the next few months.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31807 91177308-0d34-0410-b5e6-96231b3b80d8

53 files changed, 3282 insertions, 36 deletions

diff --git a/Makefile b/Makefile
index 97a738805d..c45ac976dd 100644
--- a/Makefile
+++ b/Makefile
@@ -15,23 +15,28 @@ LEVEL := .
 #   3. Build VMCore, which builds the Intrinsics.inc file used by libs.
 #   4. Build libs, which are needed by llvm-config.
 #   5. Build llvm-config, which determines inter-lib dependencies for tools.
-#   6. Build tools, docs.
+#   6. Build tools, runtime, docs.
 #
 DIRS := lib/System lib/Support utils lib/VMCore lib tools/llvm-config \
-        tools docs
+        tools runtime docs
         
 OPTIONAL_DIRS := examples projects
 EXTRA_DIST := test llvm.spec include win32 Xcode
 
 include $(LEVEL)/Makefile.config 
 
+# llvm-gcc4 doesn't need runtime libs.
+ifeq ($(LLVMGCC_MAJVERS),4)
+  DIRS := $(filter-out runtime, $(DIRS))
+endif
+
 ifeq ($(MAKECMDGOALS),libs-only)
-  DIRS := $(filter-out tools docs, $(DIRS))
+  DIRS := $(filter-out tools runtime docs, $(DIRS))
   OPTIONAL_DIRS :=
 endif
 
 ifeq ($(MAKECMDGOALS),tools-only)
-  DIRS := $(filter-out docs, $(DIRS))
+  DIRS := $(filter-out runtime docs, $(DIRS))
   OPTIONAL_DIRS :=
 endif
 
diff --git a/Makefile.config.in b/Makefile.config.in
index f005c69412..2652db3bb9 100644
--- a/Makefile.config.in
+++ b/Makefile.config.in
@@ -207,6 +207,11 @@ OBJ_ROOT := .
 #DISABLE_ASSERTIONS = 1
 @DISABLE_ASSERTIONS@
 
+# When DEBUG_RUNTIME is enabled, the runtime libraries will retain debug
+# symbols.
+#DEBUG_RUNTIME = 1
+@DEBUG_RUNTIME@
+
 # When ENABLE_PROFILING is enabled, the llvm source base is built with profile
 # information to allow gprof to be used to get execution frequencies.
 #ENABLE_PROFILING = 1
diff --git a/Makefile.rules b/Makefile.rules
index a8b1b8056d..f80cc25489 100644
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -1099,10 +1099,18 @@ $(ObjDir)/%.s: %.c $(ObjDir)/.dir $(BUILT_SOURCES)
 	$(Echo) "Compiling $*.c to asm for $(BuildMode) build" $(PIC_FLAG)
 	$(MAYBE_PIC_Compile.C) $< -o $@ -S
 
+
 # make the C and C++ compilers strip debug info out of bytecode libraries.
+ifdef DEBUG_RUNTIME
+$(ObjectsBC): $(ObjDir)/%.bc: $(ObjDir)/%.ll $(GCCAS)
+	$(Echo) "Compiling $*.ll to $*.bc for $(BuildMode) build (bytecode)"
+	$(Verb) $(GCCAS) $< -o $@
+else
 $(ObjectsBC): $(ObjDir)/%.bc: $(ObjDir)/%.ll $(GCCAS)
 	$(Echo) "Compiling $*.ll to $*.bc for $(BuildMode) build (bytecode)"
 	$(Verb) $(GCCAS) -strip-debug $< -o $@
+endif
+
 
 #---------------------------------------------------------
 # Provide rule to build .bc files from .ll sources,
diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index 445e1ba911..4b9e0c31fd 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -268,6 +268,15 @@ else
   AC_SUBST(DISABLE_ASSERTIONS,[[DISABLE_ASSERTIONS=1]])
 fi
 
+dnl --enable-debug-runtime : should runtime libraries have debug symbols?
+AC_ARG_ENABLE(debug-runtime,
+   AS_HELP_STRING([--enable-debug-runtime,Build runtime libs with debug symbols (default is NO)]),,enableval=no)
+if test ${enableval} = "no" ; then
+  AC_SUBST(DEBUG_RUNTIME,[[]])
+else
+  AC_SUBST(DEBUG_RUNTIME,[[DEBUG_RUNTIME=1]])
+fi
+
 dnl --enable-jit: check whether they want to enable the jit
 AC_ARG_ENABLE(jit,
   AS_HELP_STRING(--enable-jit,
@@ -811,6 +820,7 @@ AC_CONFIG_MAKEFILE(Makefile)
 AC_CONFIG_MAKEFILE(Makefile.common)
 AC_CONFIG_MAKEFILE(examples/Makefile)
 AC_CONFIG_MAKEFILE(lib/Makefile)
+AC_CONFIG_MAKEFILE(runtime/Makefile)
 AC_CONFIG_MAKEFILE(test/Makefile)
 AC_CONFIG_MAKEFILE(test/Makefile.tests)
 AC_CONFIG_MAKEFILE(tools/Makefile)
@@ -823,6 +833,8 @@ AC_OUTPUT
 dnl Warn loudly if llvm-gcc was not obviously working
 if test "$llvm_cv_llvmgcc_sanity" = "no" ; then
  AC_MSG_WARN([***** llvm-gcc/llvm-g++ was not found, or does not appear to be ])
- AC_MSG_WARN([***** working. Please make sure you have llvm-gcc and llvm-g++ ])
- AC_MSG_WARN([***** in your path before configuring LLVM.])
+ AC_MSG_WARN([***** working. Please make sure you have llvm-gcc and llvm-g++ in])
+ AC_MSG_WARN([***** your path before configuring LLVM. The runtime libraries])
+ AC_MSG_WARN([***** (llvm/runtime) will not be built but you should be able to])
+ AC_MSG_WARN([***** build the llvm tools.])
 fi
diff --git a/configure b/configure
index 7de451773d..7ae686b76d 100755
--- a/configure
+++ b/configure
@@ -830,6 +830,7 @@ BUILD_EXEEXT
 CVSBUILD
 ENABLE_OPTIMIZED
 DISABLE_ASSERTIONS
+DEBUG_RUNTIME
 JIT
 TARGET_HAS_JIT
 ENABLE_DOXYGEN
@@ -1519,6 +1520,7 @@ Optional Features:
   --enable-FEATURE[=ARG]  include FEATURE [ARG=yes]
   --enable-optimized
   --enable-assertions
+  --enable-debug-runtime
   --enable-jit            Enable Just In Time Compiling (default is YES)
   --enable-doxygen        Build doxygen documentation (default is NO)
   --enable-threads        Use threads if available (default is YES)
@@ -4561,6 +4563,21 @@ else
 
 fi
 
+# Check whether --enable-debug-runtime was given.
+if test "${enable_debug_runtime+set}" = set; then
+  enableval=$enable_debug_runtime;
+else
+  enableval=no
+fi
+
+if test ${enableval} = "no" ; then
+  DEBUG_RUNTIME=
+
+else
+  DEBUG_RUNTIME=DEBUG_RUNTIME=1
+
+fi
+
 # Check whether --enable-jit was given.
 if test "${enable_jit+set}" = set; then
   enableval=$enable_jit;
@@ -10281,7 +10298,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<EOF
-#line 10284 "configure"
+#line 10301 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12425,7 +12442,7 @@ ia64-*-hpux*)
   ;;
 *-*-irix6*)
   # Find out which ABI we are using.
-  echo '#line 12428 "configure"' > conftest.$ac_ext
+  echo '#line 12445 "configure"' > conftest.$ac_ext
   if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
   (eval $ac_compile) 2>&5
   ac_status=$?
@@ -14143,11 +14160,11 @@ else
    -e 's:.*FLAGS}\{0,1\} :&$lt_compiler_flag :; t' \
    -e 's: [^ ]*conftest\.: $lt_compiler_flag&:; t' \
    -e 's:$: $lt_compiler_flag:'`
-   (eval echo "\"\$as_me:14146: $lt_compile\"" >&5)
+   (eval echo "\"\$as_me:14163: $lt_compile\"" >&5)
    (eval "$lt_compile" 2>conftest.err)
    ac_status=$?
    cat conftest.err >&5
-   echo "$as_me:14150: \$? = $ac_status" >&5
+   echo "$as_me:14167: \$? = $ac_status" >&5
    if (exit $ac_status) && test -s "$ac_outfile"; then
      # The compiler can only warn and ignore the option if not recognized
      # So say no if there are warnings other than the usual output.
@@ -14411,11 +14428,11 @@ else
    -e 's:.*FLAGS}\{0,1\} :&$lt_compiler_flag :; t' \
    -e 's: [^ ]*conftest\.: $lt_compiler_flag&:; t' \
    -e 's:$: $lt_compiler_flag:'`
-   (eval echo "\"\$as_me:14414: $lt_compile\"" >&5)
+   (eval echo "\"\$as_me:14431: $lt_compile\"" >&5)
    (eval "$lt_compile" 2>conftest.err)
    ac_status=$?
    cat conftest.err >&5
-   echo "$as_me:14418: \$? = $ac_status" >&5
+   echo "$as_me:14435: \$? = $ac_status" >&5
    if (exit $ac_status) && test -s "$ac_outfile"; then
      # The compiler can only warn and ignore the option if not recognized
      # So say no if there are warnings other than the usual output.
@@ -14515,11 +14532,11 @@ else
    -e 's:.*FLAGS}\{0,1\} :&$lt_compiler_flag :; t' \
    -e 's: [^ ]*conftest\.: $lt_compiler_flag&:; t' \
    -e 's:$: $lt_compiler_flag:'`
-   (eval echo "\"\$as_me:14518: $lt_compile\"" >&5)
+   (eval echo "\"\$as_me:14535: $lt_compile\"" >&5)
    (eval "$lt_compile" 2>out/conftest.err)
    ac_status=$?
    cat out/conftest.err >&5
-   echo "$as_me:14522: \$? = $ac_status" >&5
+   echo "$as_me:14539: \$? = $ac_status" >&5
    if (exit $ac_status) && test -s out/conftest2.$ac_objext
    then
      # The compiler can only warn and ignore the option if not recognized
@@ -16967,7 +16984,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<EOF
-#line 16970 "configure"
+#line 16987 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -17067,7 +17084,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<EOF
-#line 17070 "configure"
+#line 17087 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -19435,11 +19452,11 @@ else
    -e 's:.*FLAGS}\{0,1\} :&$lt_compiler_flag :; t' \
    -e 's: [^ ]*conftest\.: $lt_compiler_flag&:; t' \
    -e 's:$: $lt_compiler_flag:'`
-   (eval echo "\"\$as_me:19438: $lt_compile\"" >&5)
+   (eval echo "\"\$as_me:19455: $lt_compile\"" >&5)
    (eval "$lt_compile" 2>conftest.err)
    ac_status=$?
    cat conftest.err >&5
-   echo "$as_me:19442: \$? = $ac_status" >&5
+   echo "$as_me:19459: \$? = $ac_status" >&5
    if (exit $ac_status) && test -s "$ac_outfile"; then
      # The compiler can only warn and ignore the option if not recognized
      # So say no if there are warnings other than the usual output.
@@ -19539,11 +19556,11 @@ else
    -e 's:.*FLAGS}\{0,1\} :&$lt_compiler_flag :; t' \
    -e 's: [^ ]*conftest\.: $lt_compiler_flag&:; t' \
    -e 's:$: $lt_compiler_flag:'`
-   (eval echo "\"\$as_me:19542: $lt_compile\"" >&5)
+   (eval echo "\"\$as_me:19559: $lt_compile\"" >&5)
    (eval "$lt_compile" 2>out/conftest.err)
    ac_status=$?
    cat out/conftest.err >&5
-   echo "$as_me:19546: \$? = $ac_status" >&5
+   echo "$as_me:19563: \$? = $ac_status" >&5
    if (exit $ac_status) && test -s out/conftest2.$ac_objext
    then
      # The compiler can only warn and ignore the option if not recognized
@@ -21109,11 +21126,11 @@ else
    -e 's:.*FLAGS}\{0,1\} :&$lt_compiler_flag :; t' \
    -e 's: [^ ]*conftest\.: $lt_compiler_flag&:; t' \
    -e 's:$: $lt_compiler_flag:'`
-   (eval echo "\"\$as_me:21112: $lt_compile\"" >&5)
+   (eval echo "\"\$as_me:21129: $lt_compile\"" >&5)
    (eval "$lt_compile" 2>conftest.err)
    ac_status=$?
    cat conftest.err >&5
-   echo "$as_me:21116: \$? = $ac_status" >&5
+   echo "$as_me:21133: \$? = $ac_status" >&5
    if (exit $ac_status) && test -s "$ac_outfile"; then
      # The compiler can only warn and ignore the option if not recognized
      # So say no if there are warnings other than the usual output.
@@ -21213,11 +21230,11 @@ else
    -e 's:.*FLAGS}\{0,1\} :&$lt_compiler_flag :; t' \
    -e 's: [^ ]*conftest\.: $lt_compiler_flag&:; t' \
    -e 's:$: $lt_compiler_flag:'`
-   (eval echo "\"\$as_me:21216: $lt_compile\"" >&5)
+   (eval echo "\"\$as_me:21233: $lt_compile\"" >&5)
    (eval "$lt_compile" 2>out/conftest.err)
    ac_status=$?
    cat out/conftest.err >&5
-   echo "$as_me:21220: \$? = $ac_status" >&5
+   echo "$as_me:21237: \$? = $ac_status" >&5
    if (exit $ac_status) && test -s out/conftest2.$ac_objext
    then
      # The compiler can only warn and ignore the option if not recognized
@@ -23448,11 +23465,11 @@ else
    -e 's:.*FLAGS}\{0,1\} :&$lt_compiler_flag :; t' \
    -e 's: [^ ]*conftest\.: $lt_compiler_flag&:; t' \
    -e 's:$: $lt_compiler_flag:'`
-   (eval echo "\"\$as_me:23451: $lt_compile\"" >&5)
+   (eval echo "\"\$as_me:23468: $lt_compile\"" >&5)
    (eval "$lt_compile" 2>conftest.err)
    ac_status=$?
    cat conftest.err >&5
-   echo "$as_me:23455: \$? = $ac_status" >&5
+   echo "$as_me:23472: \$? = $ac_status" >&5
    if (exit $ac_status) && test -s "$ac_outfile"; then
      # The compiler can only warn and ignore the option if not recognized
      # So say no if there are warnings other than the usual output.
@@ -23716,11 +23733,11 @@ else
    -e 's:.*FLAGS}\{0,1\} :&$lt_compiler_flag :; t' \
    -e 's: [^ ]*conftest\.: $lt_compiler_flag&:; t' \
    -e 's:$: $lt_compiler_flag:'`
-   (eval echo "\"\$as_me:23719: $lt_compile\"" >&5)
+   (eval echo "\"\$as_me:23736: $lt_compile\"" >&5)
    (eval "$lt_compile" 2>conftest.err)
    ac_status=$?
    cat conftest.err >&5
-   echo "$as_me:23723: \$? = $ac_status" >&5
+   echo "$as_me:23740: \$? = $ac_status" >&5
    if (exit $ac_status) && test -s "$ac_outfile"; then
      # The compiler can only warn and ignore the option if not recognized
      # So say no if there are warnings other than the usual output.
@@ -23820,11 +23837,11 @@ else
    -e 's:.*FLAGS}\{0,1\} :&$lt_compiler_flag :; t' \
    -e 's: [^ ]*conftest\.: $lt_compiler_flag&:; t' \
    -e 's:$: $lt_compiler_flag:'`
-   (eval echo "\"\$as_me:23823: $lt_compile\"" >&5)
+   (eval echo "\"\$as_me:23840: $lt_compile\"" >&5)
    (eval "$lt_compile" 2>out/conftest.err)
    ac_status=$?
    cat out/conftest.err >&5
-   echo "$as_me:23827: \$? = $ac_status" >&5
+   echo "$as_me:23844: \$? = $ac_status" >&5
    if (exit $ac_status) && test -s out/conftest2.$ac_objext
    then
      # The compiler can only warn and ignore the option if not recognized
@@ -33414,6 +33431,9 @@ ac_config_commands="$ac_config_commands examples/Makefile"
 ac_config_commands="$ac_config_commands lib/Makefile"
 
 
+ac_config_commands="$ac_config_commands runtime/Makefile"
+
+
 ac_config_commands="$ac_config_commands test/Makefile"
 
 
@@ -34007,6 +34027,7 @@ do
     "Makefile.common") CONFIG_COMMANDS="$CONFIG_COMMANDS Makefile.common" ;;
     "examples/Makefile") CONFIG_COMMANDS="$CONFIG_COMMANDS examples/Makefile" ;;
     "lib/Makefile") CONFIG_COMMANDS="$CONFIG_COMMANDS lib/Makefile" ;;
+    "runtime/Makefile") CONFIG_COMMANDS="$CONFIG_COMMANDS runtime/Makefile" ;;
     "test/Makefile") CONFIG_COMMANDS="$CONFIG_COMMANDS test/Makefile" ;;
     "test/Makefile.tests") CONFIG_COMMANDS="$CONFIG_COMMANDS test/Makefile.tests" ;;
     "tools/Makefile") CONFIG_COMMANDS="$CONFIG_COMMANDS tools/Makefile" ;;
@@ -34148,6 +34169,7 @@ BUILD_EXEEXT!$BUILD_EXEEXT$ac_delim
 CVSBUILD!$CVSBUILD$ac_delim
 ENABLE_OPTIMIZED!$ENABLE_OPTIMIZED$ac_delim
 DISABLE_ASSERTIONS!$DISABLE_ASSERTIONS$ac_delim
+DEBUG_RUNTIME!$DEBUG_RUNTIME$ac_delim
 JIT!$JIT$ac_delim
 TARGET_HAS_JIT!$TARGET_HAS_JIT$ac_delim
 ENABLE_DOXYGEN!$ENABLE_DOXYGEN$ac_delim
@@ -34170,7 +34192,6 @@ ifGNUmake!$ifGNUmake$ac_delim
 LN_S!$LN_S$ac_delim
 CMP!$CMP$ac_delim
 CP!$CP$ac_delim
-DATE!$DATE$ac_delim
 _ACEOF
 
   if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 97; then
@@ -34212,6 +34233,7 @@ _ACEOF
 ac_delim='%!_!# '
 for ac_last_try in false false false false false :; do
   cat >conf$$subs.sed <<_ACEOF
+DATE!$DATE$ac_delim
 FIND!$FIND$ac_delim
 MKDIR!$MKDIR$ac_delim
 MV!$MV$ac_delim
@@ -34277,7 +34299,7 @@ LIBOBJS!$LIBOBJS$ac_delim
 LTLIBOBJS!$LTLIBOBJS$ac_delim
 _ACEOF
 
-  if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 63; then
+  if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 64; then
     break
   elif $ac_last_try; then
     { { echo "$as_me:$LINENO: error: could not make $CONFIG_STATUS" >&5
@@ -34688,6 +34710,8 @@ echo "$as_me: executing $ac_file commands" >&6;}
    ${SHELL} ${llvm_src}/autoconf/install-sh -c ${srcdir}/examples/Makefile examples/Makefile ;;
     "lib/Makefile":C) ${llvm_src}/autoconf/mkinstalldirs `dirname lib/Makefile`
    ${SHELL} ${llvm_src}/autoconf/install-sh -c ${srcdir}/lib/Makefile lib/Makefile ;;
+    "runtime/Makefile":C) ${llvm_src}/autoconf/mkinstalldirs `dirname runtime/Makefile`
+   ${SHELL} ${llvm_src}/autoconf/install-sh -c ${srcdir}/runtime/Makefile runtime/Makefile ;;
     "test/Makefile":C) ${llvm_src}/autoconf/mkinstalldirs `dirname test/Makefile`
    ${SHELL} ${llvm_src}/autoconf/install-sh -c ${srcdir}/test/Makefile test/Makefile ;;
     "test/Makefile.tests":C) ${llvm_src}/autoconf/mkinstalldirs `dirname test/Makefile.tests`
@@ -34909,8 +34933,12 @@ fi
 if test "$llvm_cv_llvmgcc_sanity" = "no" ; then
  { echo "$as_me:$LINENO: WARNING: ***** llvm-gcc/llvm-g++ was not found, or does not appear to be " >&5
 echo "$as_me: WARNING: ***** llvm-gcc/llvm-g++ was not found, or does not appear to be " >&2;}
- { echo "$as_me:$LINENO: WARNING: ***** working. Please make sure you have llvm-gcc and llvm-g++ " >&5
-echo "$as_me: WARNING: ***** working. Please make sure you have llvm-gcc and llvm-g++ " >&2;}
- { echo "$as_me:$LINENO: WARNING: ***** in your path before configuring LLVM." >&5
-echo "$as_me: WARNING: ***** in your path before configuring LLVM." >&2;}
+ { echo "$as_me:$LINENO: WARNING: ***** working. Please make sure you have llvm-gcc and llvm-g++ in" >&5
+echo "$as_me: WARNING: ***** working. Please make sure you have llvm-gcc and llvm-g++ in" >&2;}
+ { echo "$as_me:$LINENO: WARNING: ***** your path before configuring LLVM. The runtime libraries" >&5
+echo "$as_me: WARNING: ***** your path before configuring LLVM. The runtime libraries" >&2;}
+ { echo "$as_me:$LINENO: WARNING: ***** (llvm/runtime) will not be built but you should be able to" >&5
+echo "$as_me: WARNING: ***** (llvm/runtime) will not be built but you should be able to" >&2;}
+ { echo "$as_me:$LINENO: WARNING: ***** build the llvm tools." >&5
+echo "$as_me: WARNING: ***** build the llvm tools." >&2;}
 fi
diff --git a/runtime/GC/GCInterface.h b/runtime/GC/GCInterface.h
new file mode 100644
index 0000000000..4eb48183bc
--- /dev/null
+++ b/runtime/GC/GCInterface.h
@@ -0,0 +1,48 @@
+/*===-- GCInterface.h - Public interface exposed by garbage collectors ----===*\
+|*
+|*                     The LLVM Compiler Infrastructure
+|*
+|* This file was developed by the LLVM research group and is distributed under
+|* the University of Illinois Open Source License. See LICENSE.TXT for details.
+|*
+|*===----------------------------------------------------------------------===*|
+|*
+|* This file defines the common public interface that must be exposed by all
+|* LLVM garbage collectors.
+|*
+\*===----------------------------------------------------------------------===*/
+
+#ifndef GCINTERFACE_H
+#define GCINTERFACE_H
+
+/* llvm_cg_walk_gcroots - This function is exposed by the LLVM code generator,
+ * and allows us to traverse the roots on the stack.
+ */
+void llvm_cg_walk_gcroots(void (*FP)(void **Root, void *Meta));
+
+
+/* llvm_gc_initialize - This function is called to initalize the garbage
+ * collector.
+ */
+void llvm_gc_initialize(unsigned InitialHeapSize);
+
+/* llvm_gc_allocate - This function allocates Size bytes from the heap and
+ * returns a pointer to it.
+ */
+void *llvm_gc_allocate(unsigned Size);
+
+/* llvm_gc_collect - This function forces a garbage collection cycle.
+ */
+void llvm_gc_collect();
+
+/* llvm_gc_read - This function should be implemented to include any read
+ * barrier code that is needed by the garbage collector.
+ */
+void *llvm_gc_read(void *ObjPtr, void **FieldPtr);
+
+/* llvm_gc_write - This function should be implemented to include any write
+ * barrier code that is needed by the garbage collector.
+ */
+void llvm_gc_write(void *V, void *ObjPtr, void **FieldPtr);
+
+#endif
diff --git a/runtime/GC/Makefile b/runtime/GC/Makefile
new file mode 100644
index 0000000000..b57dc85907
--- /dev/null
+++ b/runtime/GC/Makefile
@@ -0,0 +1,19 @@
+##===- runtime/GC/Makefile ---------------------------------*- Makefile -*-===##
+# 
+#                     The LLVM Compiler Infrastructure
+#
+# This file was developed by the LLVM research group and is distributed under
+# the University of Illinois Open Source License. See LICENSE.TXT for details.
+# 
+##===----------------------------------------------------------------------===##
+
+LEVEL = ../..
+PARALLEL_DIRS := SemiSpace
+EXTRA_DIST := gc_exported_symbols.lst
+include $(LEVEL)/Makefile.common
+
+# Install target for libraries: Copy into $LLVMGCCDIR/bytecode-libs
+#
+install::
+
+clean::
diff --git a/runtime/GC/SemiSpace/Makefile b/runtime/GC/SemiSpace/Makefile
new file mode 100644
index 0000000000..6f8e54ce27
--- /dev/null
+++ b/runtime/GC/SemiSpace/Makefile
@@ -0,0 +1,19 @@
+##===- runtime/GC/SemiSpace/Makefile -----------------------*- Makefile -*-===##
+# 
+#                     The LLVM Compiler Infrastructure
+#
+# This file was developed by the LLVM research group and is distributed under
+# the University of Illinois Open Source License. See LICENSE.TXT for details.
+# 
+##===----------------------------------------------------------------------===##
+
+LEVEL = ../../..
+BYTECODE_LIBRARY = 1
+LIBRARYNAME = gcsemispace
+BYTECODE_DESTINATION = $(CFERuntimeLibDir)
+EXPORTED_SYMBOL_FILE = $(PROJ_SRC_DIR)/../gc_exported_symbols.lst
+
+include $(LEVEL)/Makefile.common
+
+CompileCommonOpts := $(filter-out -pedantic,$(CompileCommonOpts))
+CompileCommonOpts := $(filter-out -Wno-long-long,$(CompileCommonOpts))
diff --git a/runtime/GC/SemiSpace/semispace.c b/runtime/GC/SemiSpace/semispace.c
new file mode 100644
index 0000000000..cb5864b0bd
--- /dev/null
+++ b/runtime/GC/SemiSpace/semispace.c
@@ -0,0 +1,122 @@
+/*===-- semispace.c - Simple semi-space copying garbage collector ---------===*\
+|*
+|*                     The LLVM Compiler Infrastructure
+|*
+|* This file was developed by the LLVM research group and is distributed under
+|* the University of Illinois Open Source License. See LICENSE.TXT for details.
+|* 
+|*===----------------------------------------------------------------------===*|
+|* 
+|* This garbage collector is an extremely simple copying collector.  It splits
+|* the managed region of memory into two pieces: the current space to allocate
+|* from, and the copying space.  When the portion being allocated from fills up,
+|* a garbage collection cycle happens, which copies all live blocks to the other
+|* half of the managed space.
+|*
+\*===----------------------------------------------------------------------===*/
+
+#include "../GCInterface.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* AllocPtr - This points to the next byte that is available for allocation.
+ */
+static char *AllocPtr;
+
+/* AllocEnd - This points to the first byte not available for allocation.  When
+ * AllocPtr passes this, we have run out of space.
+ */
+static char *AllocEnd;
+
+/* CurSpace/OtherSpace - These pointers point to the two regions of memory that
+ * we switch between.  The unallocated portion of the CurSpace is known to be
+ * zero'd out, but the OtherSpace contains junk.
+ */
+static void *CurSpace, *OtherSpace;
+
+/* SpaceSize - The size of each space. */
+static unsigned SpaceSize;
+
+/* llvm_gc_initialize - Allocate the two spaces that we plan to switch between.
+ */
+void llvm_gc_initialize(unsigned InitialHeapSize) {
+  SpaceSize = InitialHeapSize/2;
+  CurSpace = AllocPtr = calloc(1, SpaceSize);
+  OtherSpace = malloc(SpaceSize);
+  AllocEnd = AllocPtr + SpaceSize;
+}
+
+/* We always want to inline the fast path, but never want to inline the slow
+ * path.