Hi All,
We are observing a segmentation fault in opt with -x86-codegen switch. This happens with any general llvm-IR. Please find attached a simple testcase. It can be reproduced with the following.
opt -S -o a.out.ll a.ll -x86-codegen
The traces of the error is as follows.
Stack dump:
0. Program arguments: /home/raghesh/code/mirror/llvm-project/build/bin/opt -S -o a.out.ll a.ll -x86-codegen
#0 0x00007ff5339d728a llvm::sys::PrintStackTrace(llvm::raw_ostream&) (/home/raghesh/code/mirror/llvm-project/build/bin/…/lib/libLLVM-10svn.so+0x76528a)
#1 0x00007ff5339d4f64 llvm::sys::RunSignalHandlers() (/home/raghesh/code/mirror/llvm-project/build/bin/…/lib/libLLVM-10svn.so+0x762f64)
#2 0x00007ff5339d50a2 SignalHandler(int) (/home/raghesh/code/mirror/llvm-project/build/bin/…/lib/libLLVM-10svn.so+0x7630a2)
#3 0x00007ff53291ef20 (/lib/x86_64-linux-gnu/libc.so.6+0x3ef20)
#4 0x00007ff533d86080 llvm::MachineModuleInfo::MachineModuleInfo(llvm::LLVMTargetMachine const*) (/home/raghesh/code/mirror/llvm-project/build/bin/…/lib/libLLVM-10svn.so+0xb14080)
#5 0x00007ff533d86178 llvm::Pass* llvm::callDefaultCtorllvm::MachineModuleInfo() (/home/raghesh/code/mirror/llvm-project/build/bin/…/lib/libLLVM-10svn.so+0xb14178)
#6 0x00007ff533b0c83d llvm::PMTopLevelManager::schedulePass(llvm::Pass*) (/home/raghesh/code/mirror/llvm-project/build/bin/…/lib/libLLVM-10svn.so+0x89a83d)
#7 0x00007ff533b0c9a3 llvm::PMTopLevelManager::schedulePass(llvm::Pass*) (/home/raghesh/code/mirror/llvm-project/build/bin/…/lib/libLLVM-10svn.so+0x89a9a3)
#8 0x0000557729456ac4 main (/home/raghesh/code/mirror/llvm-project/build/bin/opt+0x1dac4)
#9 0x00007ff532901b97 __libc_start_main /build/glibc-OTsEL5/glibc-2.27/csu/…/csu/libc-start.c:344:0
#10 0x000055772945795a _start (/home/raghesh/code/mirror/llvm-project/build/bin/opt+0x1e95a)
Segmentation fault (core dumped)
With a preliminary analysis, it can be seen that MachineModuleInfo pass which is a “Required” dependency of MachineFunction pass invoked by -x86-codegen.Here, the MachineModuleInfo is created through the call to llvm::callDefaultCtorllvm::MachineModuleInfo(). However, the default constructor of MachineModuleInfo expects a valid pointer to LLVMTargetMachine, which happens to be nullptr in this case and triggers seg fault when accessed.
It would be great if someone could have a look at it and provide or suggest the proper fix.
Regards,
a.ll (1.65 KB)