Disable -Wuninitialized for gcc

If the compiler is gcc, disable variants of -Wuninitialized depending
on the gcc version.  This gets a lot of false positive warnings out of
the build.

Generate a new configure for the gcc -Wno-uninitialized fix.

Pick up -Wno-uninitialized from configure

Add the option -Wno[-maybe]-uninitialized as determined by configure.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172006 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 53 insertions, 8 deletions

diff --git a/Makefile.config.in b/Makefile.config.in
index 3c4f7b7a32..5cb3c58673 100644
--- a/Makefile.config.in
+++ b/Makefile.config.in
@@ -358,6 +358,10 @@ NO_MISSING_FIELD_INITIALIZERS = @NO_MISSING_FIELD_INITIALIZERS@
 NO_VARIADIC_MACROS = @NO_VARIADIC_MACROS@
 # -Wcovered-switch-default
 COVERED_SWITCH_DEFAULT = @COVERED_SWITCH_DEFAULT@
+# -Wno-uninitialized
+NO_UNINITIALIZED = @NO_UNINITIALIZED@
+# -Wno-maybe-uninitialized
+NO_MAYBE_UNINITIALIZED = @NO_MAYBE_UNINITIALIZED@
 
 # Was polly found in tools/polly?
 LLVM_HAS_POLLY = @LLVM_HAS_POLLY@
diff --git a/Makefile.rules b/Makefile.rules
index c64275f11e..59bab8fcff 100644
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -668,7 +668,8 @@ ifndef NO_PEDANTIC
 CompileCommonOpts += -pedantic -Wno-long-long
 endif
 CompileCommonOpts += -Wall -W -Wno-unused-parameter -Wwrite-strings \
-                     $(EXTRA_OPTIONS) $(COVERED_SWITCH_DEFAULT)
+                     $(EXTRA_OPTIONS) $(COVERED_SWITCH_DEFAULT) \
+                     $(NO_UNINITIALIZED) $(NO_MAYBE_UNINITIALIZED)
 # Enable cast-qual for C++; the workaround is to use const_cast.
 CXX.Flags += -Wcast-qual
 
diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index a1426c1832..c186ed5574 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -1257,7 +1257,27 @@ AC_MSG_CHECKING([optional compiler flags])
 CXX_FLAG_CHECK(NO_VARIADIC_MACROS, [-Wno-variadic-macros])
 CXX_FLAG_CHECK(NO_MISSING_FIELD_INITIALIZERS, [-Wno-missing-field-initializers])
 CXX_FLAG_CHECK(COVERED_SWITCH_DEFAULT, [-Wcovered-switch-default])
-AC_MSG_RESULT([$NO_VARIADIC_MACROS $NO_MISSING_FIELD_INITIALIZERS $COVERED_SWITCH_DEFAULT])
+dnl GCC's potential uninitialized use analysis is weak and presents lots of
+dnl false positives, so disable it.
+if test "$GXX" = "yes"
+then
+  CXX_FLAG_CHECK(NO_MAYBE_UNINITIALIZED, [-Wno-maybe-uninitialized])
+  dnl gcc 4.7 introduced -Wmaybe-uninitialized to distinguish cases which are
+  dnl known to be uninitialized from cases which might be uninitialized.  We 
+  dnl still want to catch the first kind of errors.
+  if test "$NO_MAYBE_UNINITIALIZED" != "-Wno-maybe-uninitialized"
+  then
+    CXX_FLAG_CHECK(NO_UNINITIALIZED, [-Wno-uninitialized])
+  else
+    dnl AC_SUBST doesn't work with empty strings.
+    NO_UNINITIALIZED=
+  fi
+else
+  NO_UNINITIALIZED=
+  NO_MAYBE_UNINITIALIZED=
+fi
+AC_MSG_RESULT([$NO_VARIADIC_MACROS $NO_MISSING_FIELD_INITIALIZERS $COVERED_SWITCH_DEFAULT $NO_UNINITIALIZED $NO_MAYBE_UNINITIALIZED])
+
 
 dnl===-----------------------------------------------------------------------===
 dnl===
diff --git a/configure b/configure
index 3ca2df90ab..95bf6107e3 100755
--- a/configure
+++ b/configure
@@ -767,6 +767,8 @@ LIBADD_DL
 NO_VARIADIC_MACROS
 NO_MISSING_FIELD_INITIALIZERS
 COVERED_SWITCH_DEFAULT
+NO_MAYBE_UNINITIALIZED
+NO_UNINITIALIZED
 USE_UDIS86
 USE_OPROFILE
 USE_INTEL_JITEVENTS
@@ -10485,7 +10487,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<EOF
-#line 10488 "configure"
+#line 10490 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12246,8 +12248,24 @@ NO_MISSING_FIELD_INITIALIZERS=`$CXX -Werror -Wno-missing-field-initializers -fsy
 
 COVERED_SWITCH_DEFAULT=`$CXX -Werror -Wcovered-switch-default -fsyntax-only -xc /dev/null 2>/dev/null && echo -Wcovered-switch-default`
 
-{ echo "$as_me:$LINENO: result: $NO_VARIADIC_MACROS $NO_MISSING_FIELD_INITIALIZERS $COVERED_SWITCH_DEFAULT" >&5
-echo "${ECHO_T}$NO_VARIADIC_MACROS $NO_MISSING_FIELD_INITIALIZERS $COVERED_SWITCH_DEFAULT" >&6; }
+if test "$GXX" = "yes"
+then
+  NO_MAYBE_UNINITIALIZED=`$CXX -Werror -Wno-maybe-uninitialized -fsyntax-only -xc /dev/null 2>/dev/null && echo -Wno-maybe-uninitialized`
+
+        if test "$NO_MAYBE_UNINITIALIZED" != "-Wno-maybe-uninitialized"
+  then
+    NO_UNINITIALIZED=`$CXX -Werror -Wno-uninitialized -fsyntax-only -xc /dev/null 2>/dev/null && echo -Wno-uninitialized`
+
+  else
+        NO_UNINITIALIZED=
+  fi
+else
+  NO_UNINITIALIZED=
+  NO_MAYBE_UNINITIALIZED=
+fi
+{ echo "$as_me:$LINENO: result: $NO_VARIADIC_MACROS $NO_MISSING_FIELD_INITIALIZERS $COVERED_SWITCH_DEFAULT $NO_UNINITIALIZED $NO_MAYBE_UNINITIALIZED" >&5
+echo "${ECHO_T}$NO_VARIADIC_MACROS $NO_MISSING_FIELD_INITIALIZERS $COVERED_SWITCH_DEFAULT $NO_UNINITIALIZED $NO_MAYBE_UNINITIALIZED" >&6; }
+
 
 
 
@@ -22303,6 +22321,8 @@ LIBADD_DL!$LIBADD_DL$ac_delim
 NO_VARIADIC_MACROS!$NO_VARIADIC_MACROS$ac_delim
 NO_MISSING_FIELD_INITIALIZERS!$NO_MISSING_FIELD_INITIALIZERS$ac_delim
 COVERED_SWITCH_DEFAULT!$COVERED_SWITCH_DEFAULT$ac_delim
+NO_MAYBE_UNINITIALIZED!$NO_MAYBE_UNINITIALIZED$ac_delim
+NO_UNINITIALIZED!$NO_UNINITIALIZED$ac_delim
 USE_UDIS86!$USE_UDIS86$ac_delim
 USE_OPROFILE!$USE_OPROFILE$ac_delim
 USE_INTEL_JITEVENTS!$USE_INTEL_JITEVENTS$ac_delim
@@ -22330,8 +22350,6 @@ OCAML_LIBDIR!$OCAML_LIBDIR$ac_delim
 ENABLE_VISIBILITY_INLINES_HIDDEN!$ENABLE_VISIBILITY_INLINES_HIDDEN$ac_delim
 RPATH!$RPATH$ac_delim
 RDYNAMIC!$RDYNAMIC$ac_delim
-program_prefix!$program_prefix$ac_delim
-LIBOBJS!$LIBOBJS$ac_delim
 _ACEOF
 
   if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 97; then
@@ -22373,10 +22391,12 @@ _ACEOF
 ac_delim='%!_!# '
 for ac_last_try in false false false false false :; do
   cat >conf$$subs.sed <<_ACEOF
+program_prefix!$program_prefix$ac_delim
+LIBOBJS!$LIBOBJS$ac_delim
 LTLIBOBJS!$LTLIBOBJS$ac_delim
 _ACEOF
 
-  if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 1; then
+  if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 3; then
     break
   elif $ac_last_try; then
     { { echo "$as_me:$LINENO: error: could not make $CONFIG_STATUS" >&5