https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77702
Bug ID: 77702 Summary: suffix or operands invalid for `movq' Product: gcc Version: 5.4.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: jonhnanthan at gmail dot com Target Milestone: --- Fails to compile at OS X 10.11.6 Homebrew version of GCC. I think it should work. $ /usr/local/bin/gcc-5 main.c -o main /var/folders/7c/sf7771js2lx54wp3hl7hsh1h0000gn/T//cc1dp4ru.s:13:suffix or operands invalid for `movq' $ /usr/local/bin/gcc-5 -O1 main.c -o main $ ./main result: 2.302585 $ /usr/local/bin/gcc-5 -v Using built-in specs. COLLECT_GCC=/usr/local/bin/gcc-5 COLLECT_LTO_WRAPPER=/usr/local/Cellar/gcc5/5.4.0/libexec/gcc/x86_64-apple-darwin15.5.0/5.4.0/lto-wrapper Target: x86_64-apple-darwin15.5.0 Configured with: ../configure --build=x86_64-apple-darwin15.5.0 --prefix=/usr/local/Cellar/gcc5/5.4.0 --libdir=/usr/local/Cellar/gcc5/5.4.0/lib/gcc/5 --enable-languages=c,c++,objc,obj-c++,fortran --program-suffix=-5 --with-gmp=/usr/local/opt/gmp --with-mpfr=/usr/local/opt/mpfr --with-mpc=/usr/local/opt/libmpc --with-isl=/usr/local/opt/isl014 --with-system-zlib --enable-libstdcxx-time=yes --enable-stage1-checking --enable-checking=release --enable-lto --disable-werror --with-pkgversion='Homebrew gcc5 5.4.0' --with-bugurl=https://github.com/Homebrew/homebrew-versions/issues --enable-plugin --disable-nls --enable-multilib Thread model: posix gcc version 5.4.0 (Homebrew gcc5 5.4.0) $ cat main.c #include <stdio.h> #include <math.h> int main() { printf("result: %f\n", log(10)); return 0; } Only works if optimization is turned on.