https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81687
Bug ID: 81687
Summary: Compiler drops label in OpenMP region
Product: gcc
Version: 7.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: protze at itc dot rwth-aachen.de
Target Milestone: ---
Created attachment 41911
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41911&action=edit
stripped down reproducer
The issue was reproduced on these systems / compilers:
- CENTOS 7.3 / x86_64:
- gcc-Version 4.8.5 20150623 (Red Hat 4.8.5-11) (GCC)
- gcc-Version 5.3.0 (GCC)
- gcc-Version 6.2.0 (GCC)
- gcc-Version 7.1.0 (GCC)
- Ubuntu 17.04 / x86_64:
- gcc version 6.3.0 20170406 (Ubuntu 6.3.0-12ubuntu2)
Compiling attached code with OpenMP flag, the compiler drops the label and
therefore the linker cannot reference the label:
$ gcc -fopenmp label-test.c
/tmp/pj416018/cluster-hpc_5730/cc0vHR78.o: In function `main._omp_fn.0':
test.c:(.text+0x31): undefined reference to `.L4'
Looking into the pre-assembly (-S), the label .L4 is missing when compiling
with OpenMP flag, while $.L4 is used in a movl instruction. The label is there
when compiling without OpenMP flag.
Introducing more instructions before/after the label or referencing the label
using goto does not change the situation. Optimization only changes the name of
the label, but the label is missing in all cases.
