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  • #13724

Closed
Open
Opened May 19, 2017 by Moritz Angermann@angermanDeveloper

Clamping of llvm llc to -O1 and -O2

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.

Trac metadata
Trac field Value
Version 8.3
Type Bug
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler (LLVM)
Test case
Differential revisions
BlockedBy
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CC bgamari
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Architecture
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Reference: ghc/ghc#13724