Bug 1728781 Comment 1 Edit History

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Original comment by
on 
Almost certainly this:
```
#0  0x00007ffff2bea207 in js::jit::CodePosition::operator<=(js::jit::CodePosition) const (this=0x7ffde21c3a20, other=...) at js/src/jit/RegisterAllocator.h:169
#1  js::jit::BacktrackingAllocator::tryMergeReusedRegister(js::jit::VirtualRegister&, js::jit::VirtualRegister&) (this=this@entry=0x7fffd87e5510, def=..., input=...) at js/src/jit/BacktrackingAllocator.cpp:1138
#2  0x00007ffff2be809a in js::jit::BacktrackingAllocator::mergeAndQueueRegisters() (this=this@entry=0x7fffd87e5510) at js/src/jit/BacktrackingAllocator.cpp:1273
#3  0x00007ffff2be7c0b in js::jit::BacktrackingAllocator::go() (this=0x7fffd87e5510) at js/src/jit/BacktrackingAllocator.cpp:885
#4  0x00007ffff2dce563 in js::jit::GenerateLIR(js::jit::MIRGenerator*) (mir=0x7fffd87e6090) at js/src/jit/Ion.cpp:1518
#5  0x00007ffff2f90484 in js::wasm::IonCompileFunctions(js::wasm::ModuleEnvironment const&, js::wasm::CompilerEnvironment const&, js::LifoAlloc&, mozilla::Vector<js::wasm::FuncCompileInput, 8ul, js::SystemAllocPolicy> const&, js::wasm::CompiledCode*, mozilla::UniquePtr<char [], JS::FreePolicy>*) (moduleEnv=..., compilerEnv=<optimized out>, lifo=..., inputs=..., code=code@entry=0x7fffc318f278, error=0x7fffd87e7b18) at js/src/wasm/WasmIonCompile.cpp:5826
#6  0x00007ffff2f796a7 in ExecuteCompileTask(js::wasm::CompileTask*, mozilla::UniquePtr<char [], JS::FreePolicy>*) (task=task@entry=0x7fffc318ef60, error=0x7ffdf2f80068, error@entry=0x7fffd87e7b18) at js/src/wasm/WasmGenerator.cpp:715
#7  0x00007ffff2f79504 in js::wasm::CompileTask::runHelperThreadTask(js::AutoLockHelperThreadState&) (this=0x7fffc318ef60, lock=...) at js/src/wasm/WasmGenerator.cpp:747
#8  0x00007ffff277e77d in js::GlobalHelperThreadState::runTaskLocked(js::HelperThreadTask*, js::AutoLockHelperThreadState&) (this=this@entry=0x7fffda707000, task=0x7fffc318ef60, locked=...) at js/src/vm/HelperThreads.cpp:2840
#9  0x00007ffff277e3b9 in js::GlobalHelperThreadState::runOneTask(js::AutoLockHelperThreadState&) (this=0x7fffda707000, lock=...) at js/src/vm/HelperThreads.cpp:2809
...
```
Revision 1 by
on 
Almost certainly this:
```
#0  0x00007ffff2bea207 in js::jit::CodePosition::operator<=(js::jit::CodePosition) const (this=0x7ffde21c3a20, other=...) at js/src/jit/RegisterAllocator.h:169
#1  js::jit::BacktrackingAllocator::tryMergeReusedRegister(js::jit::VirtualRegister&, js::jit::VirtualRegister&) (this=this@entry=0x7fffd87e5510, def=..., input=...) at js/src/jit/BacktrackingAllocator.cpp:1138
#2  0x00007ffff2be809a in js::jit::BacktrackingAllocator::mergeAndQueueRegisters() (this=this@entry=0x7fffd87e5510) at js/src/jit/BacktrackingAllocator.cpp:1273
#3  0x00007ffff2be7c0b in js::jit::BacktrackingAllocator::go() (this=0x7fffd87e5510) at js/src/jit/BacktrackingAllocator.cpp:885
#4  0x00007ffff2dce563 in js::jit::GenerateLIR(js::jit::MIRGenerator*) (mir=0x7fffd87e6090) at js/src/jit/Ion.cpp:1518
#5  0x00007ffff2f90484 in js::wasm::IonCompileFunctions(js::wasm::ModuleEnvironment const&, js::wasm::CompilerEnvironment const&, js::LifoAlloc&, mozilla::Vector<js::wasm::FuncCompileInput, 8ul, js::SystemAllocPolicy> const&, js::wasm::CompiledCode*, mozilla::UniquePtr<char [], JS::FreePolicy>*) (moduleEnv=..., compilerEnv=<optimized out>, lifo=..., inputs=..., code=code@entry=0x7fffc318f278, error=0x7fffd87e7b18) at js/src/wasm/WasmIonCompile.cpp:5826
#6  0x00007ffff2f796a7 in ExecuteCompileTask(js::wasm::CompileTask*, mozilla::UniquePtr<char [], JS::FreePolicy>*) (task=task@entry=0x7fffc318ef60, error=0x7ffdf2f80068, error@entry=0x7fffd87e7b18) at js/src/wasm/WasmGenerator.cpp:715
#7  0x00007ffff2f79504 in js::wasm::CompileTask::runHelperThreadTask(js::AutoLockHelperThreadState&) (this=0x7fffc318ef60, lock=...) at js/src/wasm/WasmGenerator.cpp:747
#8  0x00007ffff277e77d in js::GlobalHelperThreadState::runTaskLocked(js::HelperThreadTask*, js::AutoLockHelperThreadState&) (this=this@entry=0x7fffda707000, task=0x7fffc318ef60, locked=...) at js/src/vm/HelperThreads.cpp:2840
#9  0x00007ffff277e3b9 in js::GlobalHelperThreadState::runOneTask(js::AutoLockHelperThreadState&) (this=0x7fffda707000, lock=...) at js/src/vm/HelperThreads.cpp:2809
...
```
The program never returns from mergeAndQueueRegisters.
Revision 2 by
on 
Almost certainly this:
```
#0  0x00007ffff2bea207 in js::jit::CodePosition::operator<=(js::jit::CodePosition) const (this=0x7ffde21c3a20, other=...) at js/src/jit/RegisterAllocator.h:169
#1  js::jit::BacktrackingAllocator::tryMergeReusedRegister(js::jit::VirtualRegister&, js::jit::VirtualRegister&) (this=this@entry=0x7fffd87e5510, def=..., input=...) at js/src/jit/BacktrackingAllocator.cpp:1138
#2  0x00007ffff2be809a in js::jit::BacktrackingAllocator::mergeAndQueueRegisters() (this=this@entry=0x7fffd87e5510) at js/src/jit/BacktrackingAllocator.cpp:1273
#3  0x00007ffff2be7c0b in js::jit::BacktrackingAllocator::go() (this=0x7fffd87e5510) at js/src/jit/BacktrackingAllocator.cpp:885
#4  0x00007ffff2dce563 in js::jit::GenerateLIR(js::jit::MIRGenerator*) (mir=0x7fffd87e6090) at js/src/jit/Ion.cpp:1518
#5  0x00007ffff2f90484 in js::wasm::IonCompileFunctions(js::wasm::ModuleEnvironment const&, js::wasm::CompilerEnvironment const&, js::LifoAlloc&, mozilla::Vector<js::wasm::FuncCompileInput, 8ul, js::SystemAllocPolicy> const&, js::wasm::CompiledCode*, mozilla::UniquePtr<char [], JS::FreePolicy>*) (moduleEnv=..., compilerEnv=<optimized out>, lifo=..., inputs=..., code=code@entry=0x7fffc318f278, error=0x7fffd87e7b18) at js/src/wasm/WasmIonCompile.cpp:5826
#6  0x00007ffff2f796a7 in ExecuteCompileTask(js::wasm::CompileTask*, mozilla::UniquePtr<char [], JS::FreePolicy>*) (task=task@entry=0x7fffc318ef60, error=0x7ffdf2f80068, error@entry=0x7fffd87e7b18) at js/src/wasm/WasmGenerator.cpp:715
#7  0x00007ffff2f79504 in js::wasm::CompileTask::runHelperThreadTask(js::AutoLockHelperThreadState&) (this=0x7fffc318ef60, lock=...) at js/src/wasm/WasmGenerator.cpp:747
#8  0x00007ffff277e77d in js::GlobalHelperThreadState::runTaskLocked(js::HelperThreadTask*, js::AutoLockHelperThreadState&) (this=this@entry=0x7fffda707000, task=0x7fffc318ef60, locked=...) at js/src/vm/HelperThreads.cpp:2840
#9  0x00007ffff277e3b9 in js::GlobalHelperThreadState::runOneTask(js::AutoLockHelperThreadState&) (this=0x7fffda707000, lock=...) at js/src/vm/HelperThreads.cpp:2809
...
```
The program appears never to return from mergeAndQueueRegisters.  Number of virtual registers = 332053...  This could just be deadly slow.

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