> Am 23.10.2019 um 03:35 schrieb Prabhakar Kushwaha <prabhakar.pkin@xxxxxxxxx>: > > > Adding other mailing list, folks... > > Hi All, > > I am trying to build kselftest on Linux-5.4 on ubuntu 18.04. I installed > LLVM-9.0.0 and Clang-9.0.0 from below links after following steps from > [1] because of discussion [2] > > https://releases.llvm.org/9.0.0/llvm-9.0.0.src.tar.xz > https://releases.llvm.org/9.0.0/clang-tools-extra-9.0.0.src.tar.xz > https://releases.llvm.org/9.0.0/cfe-9.0.0.src.tar.xz > > Now, i am trying with llc -march=bpf, with this segmentation fault is > coming as below: > > gcc -g -Wall -O2 -I../../../include/uapi -I../../../lib > -I../../../lib/bpf -I../../../../include/generated -DHAVE_GENHDR > -I../../../include -Dbpf_prog_load=bpf_prog_test_load > -Dbpf_load_program=bpf_test_load_program test_flow_dissector.c > /usr/src/tovards/linux/tools/testing/selftests/bpf/test_stub.o > /usr/src/tovards/linux/tools/testing/selftests/bpf/libbpf.a -lcap -lelf > -lrt -lpthread -o > /usr/src/tovards/linux/tools/testing/selftests/bpf/test_flow_dissector > gcc -g -Wall -O2 -I../../../include/uapi -I../../../lib > -I../../../lib/bpf -I../../../../include/generated -DHAVE_GENHDR > -I../../../include -Dbpf_prog_load=bpf_prog_test_load > -Dbpf_load_program=bpf_test_load_program > test_tcp_check_syncookie_user.c > /usr/src/tovards/linux/tools/testing/selftests/bpf/test_stub.o > /usr/src/tovards/linux/tools/testing/selftests/bpf/libbpf.a -lcap -lelf > -lrt -lpthread -o > /usr/src/tovards/linux/tools/testing/selftests/bpf/test_tcp_check_syncookie_user > gcc -g -Wall -O2 -I../../../include/uapi -I../../../lib > -I../../../lib/bpf -I../../../../include/generated -DHAVE_GENHDR > -I../../../include -Dbpf_prog_load=bpf_prog_test_load > -Dbpf_load_program=bpf_test_load_program test_lirc_mode2_user.c > /usr/src/tovards/linux/tools/testing/selftests/bpf/test_stub.o > /usr/src/tovards/linux/tools/testing/selftests/bpf/libbpf.a -lcap -lelf > -lrt -lpthread -o > /usr/src/tovards/linux/tools/testing/selftests/bpf/test_lirc_mode2_user > (clang -I. -I./include/uapi -I../../../include/uapi > -I/usr/src/tovards/linux/tools/testing/selftests/bpf/../usr/include > -D__TARGET_ARCH_arm64 -g -idirafter /usr/local/include -idirafter > /usr/local/lib/clang/9.0.0/include -idirafter > /usr/include/aarch64-linux-gnu -idirafter /usr/include > -Wno-compare-distinct-pointer-types -O2 -target bpf -emit-llvm \ > -c progs/test_core_reloc_arrays.c -o - || echo "clang failed") | \ > llc -march=bpf -mcpu=probe -filetype=obj -o > /usr/src/tovards/linux/tools/testing/selftests/bpf/test_core_reloc_arrays.o > Stack dump: > 0. Program arguments: llc -march=bpf -mcpu=probe -filetype=obj -o > /usr/src/tovards/linux/tools/testing/selftests/bpf/test_core_reloc_arrays.o > 1. Running pass 'Function Pass Manager' on module '<stdin>'. > 2. Running pass 'BPF Assembly Printer' on function '@test_core_arrays' > #0 0x0000aaaac618db08 llvm::sys::PrintStackTrace(llvm::raw_ostream&) > (/usr/local/bin/llc+0x152eb08) > Segmentation fault Hi, FWIW I can confirm that this is happening on s390 too with llvm-project commit 950b800c451f. Here is the reduced sample that triggers this (with -march=bpf -mattr=+alu32): struct b { int e; } c; int f() { return __builtin_preserve_field_info(c.e, 0); } This is compiled into: 0B bb.0 (%ir-block.0): 16B %0:gpr = LD_imm64 @"b:0:0$0:0" 32B $w0 = COPY %0:gpr, debug-location !17; 1-E.c:5:3 48B RET implicit killed $w0, debug-location !17; 1-E.c:5:3 and then BPFInstrInfo::copyPhysReg chokes on COPY, since $w0 and %0 are in different register classes. I'm currently bisecting, and also checking whether supporting asymmetric copies (like X86 does in CopyToFromAsymmetricReg) would resolve that. Best regards, Ilya
