LLVM 3.0 segfault compiling std.net.curl with -O3 -g

[redstar]

I tried to build Phobos with optimization level 3 (-O3). I got the following segmentation fault:

[ 52%] Generating std/net/curl.o, std/net/curl.bc
cd /xtra/ldc && /xtra/ldc2_build/bin/ldc2 --output-o --output-bc -c -I/xtra/ldc/runtime/druntime/src -I/xtra/ldc/runtime/druntime/src/gc /xtra/ldc/runtime/phobos/std/net/curl.d -of/xtra/ldc2_build/runtime/std/net/curl.o -g -w -d -O3 -I/xtra/ldc/runtime/phobos

0  ldc2            0x000000000127ee0f
1  ldc2            0x000000000127f169
2  libpthread.so.0 0x00007f099d441b00
3  ldc2            0x000000000104089e llvm::DIDescriptor::getDescriptorField(unsigned int) const + 30
4  ldc2            0x0000000001041318 llvm::DIVariable::Verify() const + 24
5  ldc2            0x0000000000c948f3 llvm::DwarfDebug::beginFunction(llvm::MachineFunction const*) + 3347
6  ldc2            0x0000000000c82693 llvm::AsmPrinter::EmitFunctionHeader() + 611
7  ldc2            0x0000000000a6a1e8
8  ldc2            0x0000000001228d3f llvm::FPPassManager::runOnFunction(llvm::Function&) + 623
9  ldc2            0x0000000001228e2b llvm::FunctionPassManagerImpl::run(llvm::Function&) + 123
10 ldc2            0x0000000001228f96 llvm::FunctionPassManager::run(llvm::Function&) + 102
11 ldc2            0x00000000006440c2 emit_file(llvm::TargetMachine&, llvm::Module&, llvm::raw_fd_ostream&, llvm::TargetMachine::CodeGenFileType) + 546
12 ldc2            0x00000000006447ec writeModule(llvm::Module*, std::string) + 1292
13 ldc2            0x0000000000622fd3 main + 6707
14 libc.so.6       0x00007f099c6936c5 __libc_start_main + 245
15 ldc2            0x000000000063b03d
Stack dump:
0.  Running pass 'X86 AT&T-Style Assembly Printer' on function '@_D3std5regex23__T15ThompsonMatcherTaZ15ThompsonMatcher16__T8evalBackVb1Z8evalBackMFNePS3std5regex13__T6ThreadTmZ6ThreadAS3std5regex12__T5GroupTmZ5GroupZv'
/bin/sh: line 1: 20573 Segmentation fault      /xtra/ldc2_build/bin/ldc2 --output-o --output-bc -c -I/xtra/ldc/runtime/druntime/src -I/xtra/ldc/runtime/druntime/src/gc /xtra/ldc/runtime/phobos/std/net/curl.d -of/xtra/ldc2_build/runtime/std/net/curl.o -g -w -d -O3 -I/xtra/ldc/runtime/phobos
make[2]: *** [runtime/std/net/curl.o] Error 139
make[1]: *** [runtime/CMakeFiles/phobos-ldc.dir/all] Error 2
make: *** [all] Error 2

This happens only if I compiled LDC with LLVM 3.0. Maybe it's a LLVM 3.0 bug...

[dnadlinger]

Either that, or we are emitting invalid debug metadata in a way that isn't caught by the verifier (judging solely from the backtrace, that is).

[redstar]

BTW: This is independent of my commit 34d595d. The error occured before that.

[redstar]

You are right: The segmentation fault does not occur without the -g switch.

[dnadlinger]

Could also be that it's in fact an optimization pass misbehaving – I wouldn't expect -O3 -g to be a well tested combination for Clang, etc. either.

[dnadlinger]

Closing, as it is likely an LLVM 3.0 bug.