[llvm-dev] IR Pass Ordering Sensitivity

[John Regehr via llvm-dev]

These are definitely LLVM bugs. It would be best to report reduced test 
cases against top of tree.

We should have some automated infrastructure for finding these too...

John


On 10/13/17 11:06 PM, Kavon Farvardin via llvm-dev wrote:
> Hi,
> 
> I'm trying to autotune a good sequence of IR optimization passes and I 
> seem to run into segfaults in opt (in LLVM5) with certain pass orderings.
> 
> Is this expected behavior? If so, what would be the recommended way of 
> determining pass dependencies so that I can encode them into the tuner?
> 
> 
> The test program can be found here: 
> https://gist.github.com/kavon/92d153cdd54ce9b77162af3af47d4c95
> 
> Here's what happens:
> 
> kavon at cronus:~/m/autotune|master⚡*?
> ➤ /Users/kavon/msr/llvm5/bin/opt  -inline -mem2reg -inferattrs -ipconstprop -gvn -simplifycfg -bdce -sink -dse -adce -instcombine -early-cse-memssa -early-cse-memssa -dse -adce -simplifycfg -sink -ipconstprop -gvn -bdce -instcombine -jump-threading -inline -sroa ./src/apps/raytracer.bc -o ./out/raytracer_opt1043.bc
> 0  opt                      0x000000010ebd4498 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 40
> 1  opt                      0x000000010ebd4a46 SignalHandler(int) + 342
> 2  libsystem_platform.dylib 0x00007fff8ce5352a _sigtramp + 26
> 3  opt                      0x000000010eb8ef4f llvm::StringMapImpl::FindKey(llvm::StringRef) const + 303
> 4  opt                      0x000000010e770235 llvm::PMDataManager::add(llvm::Pass*, bool) + 917
> 5  opt                      0x000000010e76d6ef llvm::PMTopLevelManager::schedulePass(llvm::Pass*) + 2367
> 6  opt                      0x000000010d755c9e main + 8846
> 7  libdyld.dylib            0x00007fff8c0c85ad start + 1
> 8  libdyld.dylib            0x000000000000001c start + 1945336432
> Stack dump:
> 0.	Program arguments: /Users/kavon/msr/llvm5/bin/opt -inline -mem2reg -inferattrs -ipconstprop -gvn -simplifycfg -bdce -sink -dse -adce -instcombine -early-cse-memssa -early-cse-memssa -dse -adce -simplifycfg -sink -ipconstprop -gvn -bdce -instcombine -jump-threading -inline -sroa ./src/apps/raytracer.bc -o ./out/raytracer_opt1043.bc
> fish: “/Users/kavon/msr/llvm5/bin/opt…” terminated by signal SIGSEGV (Address boundary error)
> 
> 
> Thanks,
> Kavon
> 
> 
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