From 8de5d46c530ceca9f4add46d5cae3cd52c38eba3 Mon Sep 17 00:00:00 2001
From: Ariadne Conill <ariadne@dereferenced.org>
Date: Fri, 21 Aug 2020 06:46:56 +0000
Subject: [PATCH] On linux targets pass --as-needed by default to the linker,
 but always link the sanitizer libraries with --no-as-needed.

---
 gcc/config/aarch64/aarch64-linux.h |  1 +
 gcc/config/alpha/linux-elf.h       |  2 +-
 gcc/config/arm/linux-elf.h         |  1 +
 gcc/config/gnu-user.h              |  6 +++---
 gcc/config/i386/gnu-user.h         |  2 +-
 gcc/config/i386/gnu-user64.h       |  1 +
 gcc/config/ia64/linux.h            |  2 +-
 gcc/config/mips/gnu-user.h         |  1 +
 gcc/config/riscv/linux.h           |  1 +
 gcc/config/rs6000/linux64.h        |  4 ++--
 gcc/config/rs6000/sysv4.h          |  2 +-
 gcc/config/s390/linux.h            |  2 +-
 gcc/config/sparc/linux.h           |  2 +-
 gcc/gcc.c                          | 28 ++++++++++++++++++++--------
 14 files changed, 36 insertions(+), 19 deletions(-)

diff --git a/gcc/config/aarch64/aarch64-linux.h b/gcc/config/aarch64/aarch64-linux.h
index 7f2529a2a1d..b097e1688aa 100644
--- a/gcc/config/aarch64/aarch64-linux.h
+++ b/gcc/config/aarch64/aarch64-linux.h
@@ -35,6 +35,7 @@
 #define CPP_SPEC "%{pthread:-D_REENTRANT}"
 
 #define LINUX_TARGET_LINK_SPEC  "%{h*}		\
+   --as-needed					\
    %{static:-Bstatic}				\
    %{shared:-shared}				\
    %{symbolic:-Bsymbolic}			\
diff --git a/gcc/config/alpha/linux-elf.h b/gcc/config/alpha/linux-elf.h
index c1dae8ca2cf..a87dc740171 100644
--- a/gcc/config/alpha/linux-elf.h
+++ b/gcc/config/alpha/linux-elf.h
@@ -37,7 +37,7 @@ along with GCC; see the file COPYING3.  If not see
 
 #define ELF_DYNAMIC_LINKER	GNU_USER_DYNAMIC_LINKER
 
-#define LINK_SPEC "-m elf64alpha %{G*} %{relax:-relax}		\
+#define LINK_SPEC "-m elf64alpha --as-needed %{G*} %{relax:-relax}		\
   %{O*:-O3} %{!O*:-O1}						\
   %{shared:-shared}						\
   %{!shared:							\
diff --git a/gcc/config/arm/linux-elf.h b/gcc/config/arm/linux-elf.h
index 0c1c4e70b6b..8b581afacdd 100644
--- a/gcc/config/arm/linux-elf.h
+++ b/gcc/config/arm/linux-elf.h
@@ -70,6 +70,7 @@
      %{rdynamic:-export-dynamic} \
      %{!shared:-dynamic-linker " GNU_USER_DYNAMIC_LINKER "}} \
    -X \
+   --as-needed \
    %{mbig-endian:-EB} %{mlittle-endian:-EL}" \
    SUBTARGET_EXTRA_LINK_SPEC
 
diff --git a/gcc/config/gnu-user.h b/gcc/config/gnu-user.h
index 5ebbf42a13d..902378e1bad 100644
--- a/gcc/config/gnu-user.h
+++ b/gcc/config/gnu-user.h
@@ -136,7 +136,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define LIBASAN_EARLY_SPEC "%{!shared:libasan_preinit%O%s} " \
   "%{static-libasan:%{!shared:" \
   LD_STATIC_OPTION " --whole-archive -lasan --no-whole-archive " \
-  LD_DYNAMIC_OPTION "}}%{!static-libasan:-lasan}"
+  LD_DYNAMIC_OPTION "}}%{!static-libasan:%{!fuse-ld=gold:--push-state} --no-as-needed -lasan %{fuse-ld=gold:--as-needed;:--pop-state}}"
 #undef LIBHWASAN_EARLY_SPEC
 #define LIBHWASAN_EARLY_SPEC "%{static-libhwasan:%{!shared:" \
   LD_STATIC_OPTION " --whole-archive -lhwasan --no-whole-archive " \
@@ -145,12 +145,12 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define LIBTSAN_EARLY_SPEC "%{!shared:libtsan_preinit%O%s} " \
   "%{static-libtsan:%{!shared:" \
   LD_STATIC_OPTION " --whole-archive -ltsan --no-whole-archive " \
-  LD_DYNAMIC_OPTION "}}%{!static-libtsan:-ltsan}"
+  LD_DYNAMIC_OPTION "}}%{!static-libtsan:%{!fuse-ld=gold:--push-state} --no-as-needed -ltsan %{fuse-ld=gold:--as-needed;:--pop-state}}"
 #undef LIBLSAN_EARLY_SPEC
 #define LIBLSAN_EARLY_SPEC "%{!shared:liblsan_preinit%O%s} " \
   "%{static-liblsan:%{!shared:" \
   LD_STATIC_OPTION " --whole-archive -llsan --no-whole-archive " \
-  LD_DYNAMIC_OPTION "}}%{!static-liblsan:-llsan}"
+  LD_DYNAMIC_OPTION "}}%{!static-liblsan:%{!fuse-ld=gold:--push-state} --no-as-needed -llsan %{fuse-ld=gold:--as-needed;:--pop-state}}"
 #endif
 
 #undef TARGET_F951_OPTIONS
diff --git a/gcc/config/i386/gnu-user.h b/gcc/config/i386/gnu-user.h
index a23e7ab3eb7..12ac8cb93a9 100644
--- a/gcc/config/i386/gnu-user.h
+++ b/gcc/config/i386/gnu-user.h
@@ -68,7 +68,7 @@ along with GCC; see the file COPYING3.  If not see
   { "link_emulation", GNU_USER_LINK_EMULATION },\
   { "dynamic_linker", GNU_USER_DYNAMIC_LINKER }
 
-#define GNU_USER_TARGET_LINK_SPEC "-m %(link_emulation) %{shared:-shared} \
+#define GNU_USER_TARGET_LINK_SPEC "-m %(link_emulation) --as-needed %{shared:-shared} \
   %{!shared: \
     %{!static: \
       %{!static-pie: \
diff --git a/gcc/config/i386/gnu-user64.h b/gcc/config/i386/gnu-user64.h
index f3e25b1412a..712b0f1c30e 100644
--- a/gcc/config/i386/gnu-user64.h
+++ b/gcc/config/i386/gnu-user64.h
@@ -56,6 +56,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
                   "%{" SPEC_64 ":-m " GNU_USER_LINK_EMULATION64 "} \
                    %{" SPEC_32 ":-m " GNU_USER_LINK_EMULATION32 "} \
                    %{" SPEC_X32 ":-m " GNU_USER_LINK_EMULATIONX32 "} \
+  --as-needed \
   %{shared:-shared} \
   %{!shared: \
     %{!static: \
diff --git a/gcc/config/ia64/linux.h b/gcc/config/ia64/linux.h
index ac40c3dfd3f..6e19e25c35a 100644
--- a/gcc/config/ia64/linux.h
+++ b/gcc/config/ia64/linux.h
@@ -58,7 +58,7 @@ do {						\
 #define GLIBC_DYNAMIC_LINKER "/lib/ld-linux-ia64.so.2"
 
 #undef LINK_SPEC
-#define LINK_SPEC "\
+#define LINK_SPEC " --as-needed \
   %{shared:-shared} \
   %{!shared: \
     %{!static: \
diff --git a/gcc/config/mips/gnu-user.h b/gcc/config/mips/gnu-user.h
index a390bcece83..be0ee289367 100644
--- a/gcc/config/mips/gnu-user.h
+++ b/gcc/config/mips/gnu-user.h
@@ -55,6 +55,7 @@ along with GCC; see the file COPYING3.  If not see
 #undef GNU_USER_TARGET_LINK_SPEC
 #define GNU_USER_TARGET_LINK_SPEC "\
   %{G*} %{EB} %{EL} %{mips*} %{shared} \
+ -as-needed \
   %{!shared: \
     %{!static: \
       %{rdynamic:-export-dynamic} \
diff --git a/gcc/config/riscv/linux.h b/gcc/config/riscv/linux.h
index fce5b896e6e..ee29979dd34 100644
--- a/gcc/config/riscv/linux.h
+++ b/gcc/config/riscv/linux.h
@@ -58,6 +58,7 @@ along with GCC; see the file COPYING3.  If not see
   "%{mabi=ilp32:_ilp32}"
 
 #define LINK_SPEC "\
+-as-needed \
 -melf" XLEN_SPEC DEFAULT_ENDIAN_SPEC "riscv" LD_EMUL_SUFFIX " \
 %{mno-relax:--no-relax} \
 %{mbig-endian:-EB} \
diff --git a/gcc/config/rs6000/linux64.h b/gcc/config/rs6000/linux64.h
index e3f2cd254f6..43499ed29cf 100644
--- a/gcc/config/rs6000/linux64.h
+++ b/gcc/config/rs6000/linux64.h
@@ -374,13 +374,13 @@ extern int dot_symbols;
 					   " -m elf64ppc")
 #endif
 
-#define LINK_OS_LINUX_SPEC32 LINK_OS_LINUX_EMUL32 " %{!shared: %{!static: \
+#define LINK_OS_LINUX_SPEC32 LINK_OS_LINUX_EMUL32 " --as-needed %{!shared: %{!static: \
   %{!static-pie: \
     %{rdynamic:-export-dynamic} \
     -dynamic-linker " GNU_USER_DYNAMIC_LINKER32 "}}} \
   %(link_os_extra_spec32)"
 
-#define LINK_OS_LINUX_SPEC64 LINK_OS_LINUX_EMUL64 " %{!shared: %{!static: \
+#define LINK_OS_LINUX_SPEC64 LINK_OS_LINUX_EMUL64 " --as-needed %{!shared: %{!static: \
   %{!static-pie: \
     %{rdynamic:-export-dynamic} \
     -dynamic-linker " GNU_USER_DYNAMIC_LINKER64 "}}} \
diff --git a/gcc/config/rs6000/sysv4.h b/gcc/config/rs6000/sysv4.h
index 510abe169c5..3c1f3a8ec5d 100644
--- a/gcc/config/rs6000/sysv4.h
+++ b/gcc/config/rs6000/sysv4.h
@@ -789,7 +789,7 @@ GNU_USER_TARGET_CC1_SPEC
 #define GNU_USER_DYNAMIC_LINKER GLIBC_DYNAMIC_LINKER
 #endif
 
-#define LINK_OS_LINUX_SPEC "-m elf32ppclinux %{!shared: %{!static: \
+#define LINK_OS_LINUX_SPEC "-m elf32ppclinux --as-needed %{!shared: %{!static: \
   %{rdynamic:-export-dynamic} \
   -dynamic-linker " GNU_USER_DYNAMIC_LINKER "}}"
 
diff --git a/gcc/config/s390/linux.h b/gcc/config/s390/linux.h
index daa48fdfc2b..2fcfc5d770f 100644
--- a/gcc/config/s390/linux.h
+++ b/gcc/config/s390/linux.h
@@ -82,7 +82,7 @@ along with GCC; see the file COPYING3.  If not see
 
 #undef  LINK_SPEC
 #define LINK_SPEC \
-  "%{m31:-m elf_s390}%{m64:-m elf64_s390} \
+  "%{m31:-m elf_s390}%{m64:-m elf64_s390} --as-needed \
    %{shared:-shared} \
    %{!shared: \
       %{static:-static} \
diff --git a/gcc/config/sparc/linux.h b/gcc/config/sparc/linux.h
index 2550d7ee8f0..7596d0b2757 100644
--- a/gcc/config/sparc/linux.h
+++ b/gcc/config/sparc/linux.h
@@ -81,7 +81,7 @@ extern const char *host_detect_local_cpu (int argc, const char **argv);
 #define GLIBC_DYNAMIC_LINKER "/lib/ld-linux.so.2"
 
 #undef  LINK_SPEC
-#define LINK_SPEC "-m elf32_sparc %{shared:-shared} \
+#define LINK_SPEC "-m elf32_sparc --as-needed %{shared:-shared} \
   %{!mno-relax:%{!r:-relax}} \
   %{!shared: \
     %{!static: \
diff --git a/gcc/gcc.c b/gcc/gcc.c
index faf9ce76b3d..1ad5da6d769 100644
--- a/gcc/gcc.c
+++ b/gcc/gcc.c
@@ -737,8 +737,11 @@ proper position among the other output files.  */
 #ifdef LIBASAN_EARLY_SPEC
 #define LIBASAN_SPEC STATIC_LIBASAN_LIBS
 #elif defined(HAVE_LD_STATIC_DYNAMIC)
-#define LIBASAN_SPEC "%{static-libasan:" LD_STATIC_OPTION \
-		     "} -lasan %{static-libasan:" LD_DYNAMIC_OPTION "}" \
+#define LIBASAN_SPEC "%{static-libasan:" LD_STATIC_OPTION "}" \
+		     " %{!static-libasan:%{!fuse-ld=gold:--push-state }--no-as-needed}" \
+		     " -lasan " \
+		     " %{static-libasan:" LD_DYNAMIC_OPTION "}" \
+		     " %{!static-libasan:%{fuse-ld=gold:--as-needed;:--pop-state}}" \
 		     STATIC_LIBASAN_LIBS
 #else
 #define LIBASAN_SPEC "-lasan" STATIC_LIBASAN_LIBS
@@ -773,8 +776,11 @@ proper position among the other output files.  */
 #ifdef LIBTSAN_EARLY_SPEC
 #define LIBTSAN_SPEC STATIC_LIBTSAN_LIBS
 #elif defined(HAVE_LD_STATIC_DYNAMIC)
-#define LIBTSAN_SPEC "%{static-libtsan:" LD_STATIC_OPTION \
-		     "} -ltsan %{static-libtsan:" LD_DYNAMIC_OPTION "}" \
+#define LIBTSAN_SPEC "%{static-libtsan:" LD_STATIC_OPTION "}" \
+		     " %{!static-libtsan:%{!fuse-ld=gold:--push-state }--no-as-needed}" \
+		     " -ltsan " \
+		     " %{static-libtsan:" LD_DYNAMIC_OPTION "}" \
+		     " %{!static-libtsan:%{fuse-ld=gold:--as-needed;:--pop-state}}" \
 		     STATIC_LIBTSAN_LIBS
 #else
 #define LIBTSAN_SPEC "-ltsan" STATIC_LIBTSAN_LIBS
@@ -791,8 +797,11 @@ proper position among the other output files.  */
 #ifdef LIBLSAN_EARLY_SPEC
 #define LIBLSAN_SPEC STATIC_LIBLSAN_LIBS
 #elif defined(HAVE_LD_STATIC_DYNAMIC)
-#define LIBLSAN_SPEC "%{static-liblsan:" LD_STATIC_OPTION \
-		     "} -llsan %{static-liblsan:" LD_DYNAMIC_OPTION "}" \
+#define LIBLSAN_SPEC "%{static-liblsan:" LD_STATIC_OPTION "}" \
+		     " %{!static-liblsan:%{!fuse-ld=gold:--push-state }--no-as-needed}" \
+		     " -llsan " \
+		     " %{static-liblsan:" LD_DYNAMIC_OPTION "}" \
+		     " %{!static-liblsan:%{fuse-ld=gold:--as-needed;:--pop-state}}" \
 		     STATIC_LIBLSAN_LIBS
 #else
 #define LIBLSAN_SPEC "-llsan" STATIC_LIBLSAN_LIBS
@@ -807,8 +816,11 @@ proper position among the other output files.  */
 #define STATIC_LIBUBSAN_LIBS \
   " %{static-libubsan|static:%:include(libsanitizer.spec)%(link_libubsan)}"
 #ifdef HAVE_LD_STATIC_DYNAMIC
-#define LIBUBSAN_SPEC "%{static-libubsan:" LD_STATIC_OPTION \
-		     "} -lubsan %{static-libubsan:" LD_DYNAMIC_OPTION "}" \
+#define LIBUBSAN_SPEC "%{static-libubsan:" LD_STATIC_OPTION "}" \
+		     " %{!static-libubsan:%{!fuse-ld=gold:--push-state }--no-as-needed}" \
+		     " -lubsan " \
+		     " %{static-libubsan:" LD_DYNAMIC_OPTION "}" \
+		     " %{!static-libubsan:%{fuse-ld=gold:--as-needed;:--pop-state}}" \
 		     STATIC_LIBUBSAN_LIBS
 #else
 #define LIBUBSAN_SPEC "-lubsan" STATIC_LIBUBSAN_LIBS
-- 
2.35.1

