Add an autoconf option for turning on -gsplit-dwarf by default

when building llvm. This saves quite a bit of time and space when
linking. Please report any problems via bugzilla.

Caveats:

a) This will only work on linux
b) This requires a fairly new binutils
c) This requires a fairly new gdb

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184808 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 47 insertions, 4 deletions

diff --git a/Makefile.config.in b/Makefile.config.in
index fd4f6ef..dcca45f 100644
--- a/Makefile.config.in
+++ b/Makefile.config.in
@@ -235,6 +235,9 @@ ENABLE_LIBCPP = @ENABLE_LIBCPP@
 # When ENABLE_CXX11 is enabled, LLVM uses c++11 mode by default to build.
 ENABLE_CXX11 = @ENABLE_CXX11@
 
+# When ENABLE_SPLIT_DWARF is enabled, LLVM uses -gfission to build in debug mode.
+ENABLE_SPLIT_DWARF = @ENABLE_SPLIT_DWARF@
+
 # When ENABLE_CLANG_ARCMT is enabled, clang will have ARCMigrationTool.
 ENABLE_CLANG_ARCMT = @ENABLE_CLANG_ARCMT@
 
diff --git a/Makefile.rules b/Makefile.rules
index 79ee0e8..ade5f1a 100644
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -297,8 +297,13 @@ else
     KEEP_SYMBOLS := 1
   else
     BuildMode := Debug
+    ifeq ($(ENABLE_SPLIT_DWARF), 1)
+    CXX.Flags += -gsplit-dwarf
+    C.Flags   += -gsplit-dwarf
+    else
     CXX.Flags += -g
     C.Flags   += -g
+    endif
     KEEP_SYMBOLS := 1
   endif
 endif
diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index ad1fd1c..393bd6a 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -510,6 +510,19 @@ case "$enableval" in
   *) AC_MSG_ERROR([Invalid setting for --enable-cxx11. Use "yes" or "no"]) ;;
 esac
 
+dnl --enable-fission : check whether or not to use -gsplit-dwarf on the command
+dnl line
+AC_ARG_ENABLE(split-dwarf,
+              AS_HELP_STRING([--enable-split-dwarf],
+                             [Use split-dwarf if available (default is NO)]),,
+                             enableval=default)
+case "$enableval" in
+  yes) AC_SUBST(ENABLE_SPLIT_DWARF,[1]) ;;
+  no)  AC_SUBST(ENABLE_SPLIT_DWARF,[0]) ;;
+  default) AC_SUBST(ENABLE_SPLIT_DWARF,[0]);;
+  *) AC_MSG_ERROR([Invalid setting for --enable-split-dwarf. Use "yes" or "no"]) ;;
+esac
+
 dnl --enable-clang-arcmt: check whether to enable clang arcmt
 clang_arcmt="yes"
 AC_ARG_ENABLE(clang-arcmt,
diff --git a/configure b/configure
index ef6d92f..48ff01d 100755
--- a/configure
+++ b/configure
@@ -685,6 +685,7 @@ BUILD_CXX
 CVSBUILD
 ENABLE_LIBCPP
 ENABLE_CXX11
+ENABLE_SPLIT_DWARF
 ENABLE_CLANG_ARCMT
 ENABLE_CLANG_STATIC_ANALYZER
 ENABLE_CLANG_REWRITER
@@ -1406,6 +1407,7 @@ Optional Features:
   --enable-polly          Use polly if available (default is YES)
   --enable-libcpp         Use libc++ if available (default is NO)
   --enable-cxx11          Use c++11 if available (default is NO)
+  --enable-split-dwarf    Use split-dwarf if available (default is NO)
   --enable-clang-arcmt    Enable building of clang ARCMT (default is YES)
   --enable-clang-static-analyzer
                           Enable building of clang Static Analyzer (default is
@@ -5165,6 +5167,25 @@ echo "$as_me: error: Invalid setting for --enable-cxx11. Use \"yes\" or \"no\""
    { (exit 1); exit 1; }; } ;;
 esac
 
+# Check whether --enable-split-dwarf was given.
+if test "${enable_split_dwarf+set}" = set; then
+  enableval=$enable_split_dwarf;
+else
+  enableval=default
+fi
+
+case "$enableval" in
+  yes) ENABLE_SPLIT_DWARF=1
+ ;;
+  no)  ENABLE_SPLIT_DWARF=0
+ ;;
+  default) ENABLE_SPLIT_DWARF=0
+;;
+  *) { { echo "$as_me:$LINENO: error: Invalid setting for --enable-split-dwarf. Use \"yes\" or \"no\"" >&5
+echo "$as_me: error: Invalid setting for --enable-split-dwarf. Use \"yes\" or \"no\"" >&2;}
+   { (exit 1); exit 1; }; } ;;
+esac
+
 clang_arcmt="yes"
 # Check whether --enable-clang-arcmt was given.
 if test "${enable_clang_arcmt+set}" = set; then
@@ -10518,7 +10539,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<EOF
-#line 10521 "configure"
+#line 10542 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -23349,6 +23370,7 @@ BUILD_CXX!$BUILD_CXX$ac_delim
 CVSBUILD!$CVSBUILD$ac_delim
 ENABLE_LIBCPP!$ENABLE_LIBCPP$ac_delim
 ENABLE_CXX11!$ENABLE_CXX11$ac_delim
+ENABLE_SPLIT_DWARF!$ENABLE_SPLIT_DWARF$ac_delim
 ENABLE_CLANG_ARCMT!$ENABLE_CLANG_ARCMT$ac_delim
 ENABLE_CLANG_STATIC_ANALYZER!$ENABLE_CLANG_STATIC_ANALYZER$ac_delim
 ENABLE_CLANG_REWRITER!$ENABLE_CLANG_REWRITER$ac_delim
@@ -23362,7 +23384,6 @@ DEBUG_RUNTIME!$DEBUG_RUNTIME$ac_delim
 DEBUG_SYMBOLS!$DEBUG_SYMBOLS$ac_delim
 KEEP_SYMBOLS!$KEEP_SYMBOLS$ac_delim
 JIT!$JIT$ac_delim
-TARGET_HAS_JIT!$TARGET_HAS_JIT$ac_delim
 _ACEOF
 
   if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 97; then
@@ -23404,6 +23425,7 @@ _ACEOF
 ac_delim='%!_!# '
 for ac_last_try in false false false false false :; do
   cat >conf$$subs.sed <<_ACEOF
+TARGET_HAS_JIT!$TARGET_HAS_JIT$ac_delim
 ENABLE_DOCS!$ENABLE_DOCS$ac_delim
 ENABLE_DOXYGEN!$ENABLE_DOXYGEN$ac_delim
 LLVM_ENABLE_THREADS!$LLVM_ENABLE_THREADS$ac_delim
@@ -23500,7 +23522,6 @@ LLVM_MANDIR!$LLVM_MANDIR$ac_delim
 LLVM_CONFIGTIME!$LLVM_CONFIGTIME$ac_delim
 BINDINGS_TO_BUILD!$BINDINGS_TO_BUILD$ac_delim
 ALL_BINDINGS!$ALL_BINDINGS$ac_delim
-OCAML_LIBDIR!$OCAML_LIBDIR$ac_delim
 _ACEOF
 
   if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 97; then
@@ -23542,6 +23563,7 @@ _ACEOF
 ac_delim='%!_!# '
 for ac_last_try in false false false false false :; do
   cat >conf$$subs.sed <<_ACEOF
+OCAML_LIBDIR!$OCAML_LIBDIR$ac_delim
 ENABLE_VISIBILITY_INLINES_HIDDEN!$ENABLE_VISIBILITY_INLINES_HIDDEN$ac_delim
 RPATH!$RPATH$ac_delim
 RDYNAMIC!$RDYNAMIC$ac_delim
@@ -23550,7 +23572,7 @@ LIBOBJS!$LIBOBJS$ac_delim
 LTLIBOBJS!$LTLIBOBJS$ac_delim
 _ACEOF
 
-  if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 6; then
+  if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 7; then
     break
   elif $ac_last_try; then
     { { echo "$as_me:$LINENO: error: could not make $CONFIG_STATUS" >&5