Open Radar

 
Summary:
The following function crashes the compiler when Whole Module Optimization is enabled:

func crash() {
    let valNodesLarge = 0..<global
    
    _ = { () -> [UnsafeMutablePointer<Int>] in
        let nodes = UnsafeMutablePointer<Int>.alloc(global)
        nodes.initializeFrom(valNodesLarge)
        
        return (0..<global).map { _ in nodes }
    }()
    
    _ = [Int]()
    for val in valNodesLarge {
        print(val)
    }
}

It needs to be in a separate file from the main swift file in which the global variable is defined and the function is called:

let global = 1000000
crash()


I tried to pinpoint the exact problem by further reducing the function but I hit a point where pretty much any change to the code makes it compile successfully.

An example project and crash report are attached.

Steps to Reproduce:
1. Run the attached project


Expected Results:
The code should compile successfully

Actual Results:
Compiler segfaults:

0  swift                    0x0000000102d19edb llvm::sys::PrintStackTrace(__sFILE*) + 43
1  swift                    0x0000000102d1a61b SignalHandler(int) + 379
2  libsystem_platform.dylib 0x00007fff95333eaa _sigtramp + 26
3  libsystem_platform.dylib 000000000000000000 _sigtramp + 1791803760
4  swift                    0x0000000100f26977 swift::irgen::IRGenDebugInfo::getOrCreateScope(swift::SILDebugScope*) + 519
5  swift                    0x0000000100f26b5a swift::irgen::IRGenDebugInfo::setCurrentLoc(swift::irgen::IRBuilder&, swift::SILDebugScope*, llvm::Optional<swift::SILLocation>) + 58
6  swift                    0x0000000100f3b9bb swift::irgen::IRGenModule::emitSILFunction(swift::SILFunction*) + 10619
7  swift                    0x0000000100ea3c93 swift::irgen::IRGenModuleDispatcher::emitLazyDefinitions() + 307
8  swift                    0x0000000100f221c4 swift::performIRGeneration(swift::IRGenOptions&, swift::ModuleDecl*, swift::SILModule*, llvm::StringRef, llvm::LLVMContext&) + 1508
9  swift                    0x0000000100e2a7dd performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&) + 13757
10 swift                    0x0000000100e2700a frontend_main(llvm::ArrayRef<char const*>, char const*, void*) + 2682
11 swift                    0x0000000100e23697 main + 2247
12 libdyld.dylib            0x00007fff8b77f5ad start + 1

Version:
Xcode 7.0b6 (7A192o)
Apple Swift version 2.0 (swiftlang-700.0.57.3 clang-700.0.72)

Notes:
This might be related to some other crashes (with different stack traces) that I encountered while trying to reduce this issue.

I will update this report with the respective radars once I have filed them.