[FFmpeg-devel] [PATCH] configure: add -fPIE instead of -pie to C flags for ThreadSanitizer

Wan-Teh Chang wtc at google.com
Sat Dec 3 00:04:53 EET 2016

-pie was added to C flags for ThreadSanitizer in commit
19f251a2882a8d0779b432e63bf282e4d9c443bb. Under clang 3.8.0, the -pie
flag causes a compiler warning and a linker error when running configure
--toolchain=clang-tsan. Here is an excerpt from config.log:

clang ... -fsanitize=thread -pie -std=c11 -fomit-frame-pointer -pthread -c -o /tmp/ffconf.hL61stP9.o /tmp/ffconf.YO6ZaSFG.c
clang: warning: argument unused during compilation: '-pie'
clang -fsanitize=thread -pie -Wl,--as-needed -Wl,-z,noexecstack -o /tmp/ffconf.W5c2e41l /tmp/ffconf.hL61stP9.o -lbz2 -pthread
/usr/bin/ld: /tmp/ffconf.hL61stP9.o: relocation R_X86_64_PC32 against undefined symbol `atan2f@@GLIBC_2.2.5' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Bad value
clang: error: linker command failed with exit code 1 (use -v to see invocation)

To be conservative, I changed -pie to -fPIE. But the documentation seems
to imply just -fsanitize=thread is enough:


Signed-off-by: Wan-Teh Chang <wtc at google.com>
 configure | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/configure b/configure
index ee473b9..0e1ae61 100755
--- a/configure
+++ b/configure
@@ -3523,7 +3523,7 @@ case "$toolchain" in
-        add_cflags  -fsanitize=thread -pie
+        add_cflags  -fsanitize=thread -fPIE
         add_ldflags -fsanitize=thread -pie
         case "$toolchain" in

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