https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68147
Bug ID: 68147
Summary: Potential incorrect code generation for string
self-assignment
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: mar...@mpa-garching.mpg.de
Target Milestone: ---
Host: x86_64-unknown-linux-gnu
Target: x86_64-unknown-linux-gnu
Build: x86_64-unknown-linux-gnu
Created attachment 36616
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36616&action=edit
test case
Current gfortran trunk compiles the following testcase into a binary which
outputs "a.o", where I would naively expect "a.out".
martin@marvin ~ $ gfortran -v -ffree-form test.f
Driving: gfortran -v -ffree-form test.f -l gfortran -l m -shared-libgcc
Using built-in specs.
COLLECT_GCC=gfortran
COLLECT_LTO_WRAPPER=/home/martin/ugcc/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /home/martin/gcc/configure --disable-multilib --enable-gold
--enable-plugins --prefix=/home/martin/ugcc --enable-languages=c++,fortran
--enable-target=all --enable-checking=release --disable-bootstrap
Thread model: posix
gcc version 6.0.0 20150923 (experimental) [trunk revision
3bf38a0:6620841:618c2dcced6864af8a34ed341525c556bb44b375] (GCC)
COLLECT_GCC_OPTIONS='-v' '-ffree-form' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'
/home/martin/ugcc/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/f951 test.f -quiet
-dumpbase test.f -mtune=generic -march=x86-64 -auxbase test -version
-ffree-form -fintrinsic-modules-path
/home/martin/ugcc/lib/gcc/x86_64-pc-linux-gnu/6.0.0/finclude -o /tmp/cco9Tqxj.s
GNU Fortran (GCC) version 6.0.0 20150923 (experimental) [trunk revision
3bf38a0:6620841:618c2dcced6864af8a34ed341525c556bb44b375] (x86_64-pc-linux-gnu)
compiled by GNU C version 4.8.4, GMP version 5.1.3, MPFR version
3.1.2-p3, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU Fortran2008 (GCC) version 6.0.0 20150923 (experimental) [trunk revision
3bf38a0:6620841:618c2dcced6864af8a34ed341525c556bb44b375] (x86_64-pc-linux-gnu)
compiled by GNU C version 4.8.4, GMP version 5.1.3, MPFR version
3.1.2-p3, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
COLLECT_GCC_OPTIONS='-v' '-ffree-form' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'
as -v --64 -o /tmp/ccwxULsf.o /tmp/cco9Tqxj.s
GNU assembler version 2.24 (x86_64-linux-gnu) using BFD version (GNU Binutils
for Ubuntu) 2.24
Reading specs from
/home/martin/ugcc/lib/gcc/x86_64-pc-linux-gnu/6.0.0/../../../../lib64/libgfortran.spec
rename spec lib to liborig
COLLECT_GCC_OPTIONS='-v' '-ffree-form' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'
COMPILER_PATH=/home/martin/ugcc/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/:/home/martin/ugcc/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/:/home/martin/ugcc/libexec/gcc/x86_64-pc-linux-gnu/:/home/martin/ugcc/lib/gcc/x86_64-pc-linux-gnu/6.0.0/:/home/martin/ugcc/lib/gcc/x86_64-pc-linux-gnu/
LIBRARY_PATH=/home/martin/ugcc/lib/gcc/x86_64-pc-linux-gnu/6.0.0/:/home/martin/ugcc/lib/gcc/x86_64-pc-linux-gnu/6.0.0/../../../../lib64/:/lib/x86_64-linux-gnu/:/lib/../lib64/:/usr/lib/x86_64-linux-gnu/:/home/martin/ugcc/lib/gcc/x86_64-pc-linux-gnu/6.0.0/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-ffree-form' '-shared-libgcc' '-mtune=generic'
'-march=x86-64'
/home/martin/ugcc/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/collect2 -plugin
/home/martin/ugcc/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/liblto_plugin.so
-plugin-opt=/home/martin/ugcc/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
-plugin-opt=-fresolution=/tmp/ccCtMKpb.res -plugin-opt=-pass-through=-lgcc_s
-plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lquadmath
-plugin-opt=-pass-through=-lm -plugin-opt=-pass-through=-lgcc_s
-plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lc
-plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc
--eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2
/usr/lib/x86_64-linux-gnu/crt1.o /usr/lib/x86_64-linux-gnu/crti.o
/home/martin/ugcc/lib/gcc/x86_64-pc-linux-gnu/6.0.0/crtbegin.o
-L/home/martin/ugcc/lib/gcc/x86_64-pc-linux-gnu/6.0.0
-L/home/martin/ugcc/lib/gcc/x86_64-pc-linux-gnu/6.0.0/../../../../lib64
-L/lib/x86_64-linux-gnu -L/lib/../lib64 -L/usr/lib/x86_64-linux-gnu
-L/home/martin/ugcc/lib/gcc/x86_64-pc-linux-gnu/6.0.0/../../.. /tmp/ccwxULsf.o
-lgfortran -lm -lgcc_s -lgcc -lquadmath -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc
/home/martin/ugcc/lib/gcc/x86_64-pc-linux-gnu/6.0.0/crtend.o
/usr/lib/x86_64-linux-gnu/crtn.o
martin@marvin ~ $ ./a.out
a.o
If I remove the if-statement, the code works as expected.
Intel ifort 15.0 outputs "a.out".
Am I missing some subtleties regarding self-assignment of allocatable strings?
