#13724: Clamping of llvm llc to -O1 and -O2 -------------------------------------+------------------------------------- Reporter: angerman | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.3 (LLVM) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- We currently clamp the optimization level of llvm llc (3.9 and 4.0) within `[1,2]`. The reason is that with `-O0`, the naive register allocator can topple over with {{{ Error while trying to spill R1 from class GPR: Cannot scavenge register without an emergency spill slot! }}} and with `-O3` the `llvm::SelectionDAGISel::LowerArguments` may break, when compiling `rts/HeapStackCheck.cmm` with the stage1 ghc. {{{ 0 llc 0x0000000102ae63e8 llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 40 1 llc 0x0000000102ae69a6 SignalHandler(int) + 358 2 libsystem_platform.dylib 0x00007fffc23f4b3a _sigtramp + 26 3 libsystem_c.dylib 0x00007fffc226498b __vfprintf + 17876 4 llc 0x00000001029d5123 llvm::SelectionDAGISel::LowerArguments(llvm::Function const&) + 5699 5 llc 0x0000000102a21a35 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) + 3381 6 llc 0x0000000102a202b1 llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) + 1457 7 llc 0x0000000101bdc474 (anonymous namespace)::ARMDAGToDAGISel::runOnMachineFunction(llvm::MachineFunction&) + 20 8 llc 0x00000001025573a6 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) + 134 9 llc 0x000000010274fb12 llvm::FPPassManager::runOnFunction(llvm::Function&) + 498 10 llc 0x000000010274fd23 llvm::FPPassManager::runOnModule(llvm::Module&) + 67 11 llc 0x00000001027501b8 llvm::legacy::PassManagerImpl::run(llvm::Module&) + 920 12 llc 0x000000010195f075 compileModule(char**, llvm::LLVMContext&) + 12133 13 llc 0x000000010195bf0b main + 491 14 libdyld.dylib 0x00007fffc21e5235 start + 1 Stack dump: 0. Program arguments: llc -O3 -mtriple=arm-unknown-linux-gnueabihf -enable-tbaa /var/folders/fv/xqjrpfj516n5xq_m_ljpsjx00000gn/T/ghc33674_0/ghc_6.bc -o /var/folders/fv/xqjrpfj516n5xq_m_ljpsjx00000gn/T/ghc33674_0/ghc_7.lm_s 1. Running pass 'Function Pass Manager' on module '/var/folders/fv/xqjrpfj516n5xq_m_ljpsjx00000gn/T/ghc33674_0/ghc_6.bc'. 2. Running pass 'ARM Instruction Selection' on function '@"stg_gc_f1$def"' }}} `opt` and `llc` should respect `-opt_lo` and `-opt_lc`, such that `-opt_lc=-O3` can be used to validate the behaviour. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13724 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler