llvm dev - Nov 2018 - libFuzzer on s390x architecture (compiler-rt)

Hello experts,

I am trying to get libFuzzer work on s390x architecture on Ubuntu 16.04.
In doing so I built clang/compiler-rt master branch as per
http://compiler-rt.llvm.org/.

By making following changes I was able to generate
libclang_rt.fuzzer-s390x.a and libclang_rt.fuzzer_no_main-s390x.a

/================================/
/home/llvm/llvm/projects/compiler-rt# git diff
diff --git a/cmake/config-ix.cmake b/cmake/config-ix.cmake
index 7e9ad63..61b3eff 100644
--- a/cmake/config-ix.cmake
+++ b/cmake/config-ix.cmake
@@ -227,7 +227,7 @@ set(ALL_SANITIZER_COMMON_SUPPORTED_ARCH ${X86}
${X86_64} ${PPC64}
 set(ALL_ASAN_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64}
     ${MIPS32} ${MIPS64} ${PPC64} ${S390X})
 set(ALL_DFSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64})
-set(ALL_FUZZER_SUPPORTED_ARCH ${X86_64} ${ARM64})
+set(ALL_FUZZER_SUPPORTED_ARCH ${X86_64} ${ARM64} ${S390X})
/================================/

However, lot of test cases are failing due to following error:

/=================================/
FAIL: libFuzzer :: bad-strcmp.test (4 of 103)
******************** TEST 'libFuzzer :: bad-strcmp.test' FAILED
********************
Script:
--
: 'RUN: at line 1';     /home/llvm/llvm/build/./bin/clang
--driver-mode=g++ -std=c++11 -lstdc++ -O2 -gline-tables-only
-fsanitize=address,fuzzer
-I/home/llvm/llvm/projects/compiler-rt/lib/fuzzer
/home/llvm/llvm/projects/compiler-rt/test/fuzzer/BadStrcmpTest.cpp -o
/home/llvm/llvm/build/projects/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/bad-strcmp.test.tmp-BadStrcmpTest
: 'RUN: at line 2';
/home/llvm/llvm/build/projects/compiler-rt/test/fuzzer/S390XDefaultLinuxConfig/Output/bad-strcmp.test.tmp-BadStrcmpTest
-runs=100000
--
Exit Code: 1

Command Output (stderr):
--
INFO: Seed: 4127689547
INFO: Loaded 1 modules   (2 inline 8-bit counters): 2 [0x801b9ab0,
0x801b9ab2),
INFO: Loaded 1 PC tables (3 PCs): 3 [0x80189908,0x80189938),
*ERROR: The size of coverage PC tables does not match the*
*number of instrumented PCs. This might be a compiler bug,*
*please contact the libFuzzer developers.*
Also check https://bugs.llvm.org/show_bug.cgi?id=34636
for possible workarounds (tl;dr: don't use the old GNU ld)

--
/=================================/

I already tried using Gold linker to no avail.  Here are some details of my
environment:

root at 1b1607e24d3f:/home/llvm/llvm/build# clang -v
clang version 8.0.0 (https://git.llvm.org/git/clang.git/
33b30eb6d622918dcdc0425730a712f0460db522) (https://git.llvm.org/git/llvm.git
fb147dee9d54c7905df5a61539112edc1d5d3a90)
Target: s390x-ibm-linux
Thread model: posix

root at 1b1607e24d3f:/home/llvm/llvm/build# ld -v
GNU ld (GNU Binutils) 2.27

Please let me know if there is something I can look at to get it working on
this arch.

Thanks.
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