[SR-967] SIL verification failed when calling noreturn function before forEach on a NSDictionary

[tjw]

Previous ID	SR-967
Radar	rdar://problem/25882880
Original Reporter	@tjw
Type	Bug
Status	Resolved
Resolution	Done

Environment

Mac OS X 10.11.3
Xcode 7.3 beta 5

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, NotOptimizedOnly, SILOptimizer
Assignee	@tjw
Priority	Medium

md5: 0da401085b42a5ab06d529bfc8dad047

Issue Description:

With the current swift-2.2-branch build, this sample crashes:

import Foundation
extension NSDictionary {
    func x() {
        exit(0)
        forEach { key, value in }
    }
}

Note that this version does not hit the problem:

func x(values:[String:String]) {
    exit(0)
    value.forEach { key, value in
    }
}

~/Source/Swift/build/Ninja-DebugAssert/swift-macosx-x86_64/bin/swift -sdk /Applications/Xcode-7.3-b5.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk abort-before-foreach.swift
abort-before-foreach.swift:5:9: warning: will never be executed
        forEach { key, value in }
        ^
abort-before-foreach.swift:4:9: note: a call to a noreturn function
        exit(0)
        ^
SIL verification failed: Operand of dealloc_stack must be an alloc_stack: isa<AllocStackInst>(DI->getOperand())
Verifying instruction:
     undef = undef<$*NSDictionary>                // user: %10
->   dealloc_stack undef : $*NSDictionary         // id: %10
In function:
// (extension in main):__ObjC.NSDictionary.x () -> ()
sil hidden @_TFE4mainCSo12NSDictionary1xfT_T_ : $@convention(method) (@guaranteed NSDictionary) -> () {
// %0                                             // user: %1
bb0(%0 : $NSDictionary):
  debug_value %0 : $NSDictionary, let, name "self", argno 1 // id: %1
  // function_ref exit
  %2 = function_ref @exit : $@convention(c) @noreturn (Int32) -> () // user: %7
  // function_ref Swift.Int32.init (_builtinIntegerLiteral : Builtin.Int2048) -> Swift.Int32
  %3 = function_ref @_TFVs5Int32CfT22_builtinIntegerLiteralBi2048__S_ : $@convention(thin) (Builtin.Int2048, @thin Int32.Type) -> Int32 // user: %6
  %4 = metatype $@thin Int32.Type                 // user: %6
  %5 = integer_literal $Builtin.Int2048, 0        // user: %6
  %6 = apply %3(%5, %4) : $@convention(thin) (Builtin.Int2048, @thin Int32.Type) -> Int32 // user: %7
  %7 = apply %2(%6) : $@convention(c) @noreturn (Int32) -> ()
  unreachable                                     // id: %8

bb1(%9 : $()):
  dealloc_stack undef : $*NSDictionary            // id: %10
  %11 = tuple ()                                  // user: %12
  return %11 : $()                                // id: %12

bb2(%13 : $ErrorType):
  unreachable                                     // id: %14
}

0  swift                    0x00000001080b35fe llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 46
1  swift                    0x00000001080b3a39 PrintStackTraceSignalHandler(void*) + 25
2  swift                    0x00000001080b02d9 llvm::sys::RunSignalHandlers() + 425
3  swift                    0x00000001080b3d62 SignalHandler(int) + 354
4  libsystem_platform.dylib 0x00007fff8eb7feaa _sigtramp + 26
5  swift                    0x0000000108b2bd1d cmark_strbuf__initbuf + 97548
6  swift                    0x00000001080b3a5b raise + 27
7  swift                    0x00000001080b3b02 abort + 18
8  swift                    0x00000001030e00a7 (anonymous namespace)::SILVerifier::_require(bool, llvm::Twine const&, std::__1::function<void ()> const&) + 327
9  swift                    0x00000001030ec89c (anonymous namespace)::SILVerifier::checkDeallocStackInst(swift::DeallocStackInst*) + 172
10 swift                    0x00000001030e4977 (anonymous namespace)::SILVerifierBase<(anonymous namespace)::SILVerifier>::visitDeallocStackInst(swift::DeallocStackInst*) + 55
11 swift                    0x00000001030e324a swift::SILVisitor<(anonymous namespace)::SILVerifier, void>::visit(swift::ValueBase*) + 378
12 swift                    0x00000001030e2fd2 swift::SILVisitor<(anonymous namespace)::SILVerifier, void>::visitSILBasicBlock(swift::SILBasicBlock*) + 146
13 swift                    0x00000001030e2f14 (anonymous namespace)::SILVerifier::visitSILBasicBlock(swift::SILBasicBlock*) + 932
14 swift                    0x00000001030e2589 swift::SILVisitor<(anonymous namespace)::SILVerifier, void>::visitSILFunction(swift::SILFunction*) + 121
15 swift                    0x00000001030e049a (anonymous namespace)::SILVerifier::visitSILFunction(swift::SILFunction*) + 1002
16 swift                    0x00000001030de299 (anonymous namespace)::SILVerifier::verify() + 25
17 swift                    0x00000001030de235 swift::SILFunction::verify() const + 37
18 swift                    0x00000001030df542 swift::SILModule::verify() const + 386
19 swift                    0x00000001037dd042 swift::SerializedSILLoader::SerializedSILLoader(swift::ASTContext&, swift::SILModule*, swift::SerializedSILLoader::Callback*) + 658
20 swift                    0x00000001037dd31d swift::SerializedSILLoader::SerializedSILLoader(swift::ASTContext&, swift::SILModule*, swift::SerializedSILLoader::Callback*) + 45
21 swift                    0x0000000103067544 swift::SerializedSILLoader::create(swift::ASTContext&, swift::SILModule*, swift::SerializedSILLoader::Callback*) + 84
22 swift                    0x000000010305b9be swift::SILModule::getSILLoader() + 206
23 swift                    0x00000001030642f3 swift::SILModule::linkFunction(swift::SILFunction*, swift::SILOptions::LinkingMode) + 67
24 swift                    0x00000001034ea2b3 getCalleeFunction(swift::FullApplySite, bool&, llvm::SmallVectorImpl<swift::SILValue>&, llvm::SmallVectorImpl<swift::SILValue>&, swift::PartialApplyInst*&, swift::SILOptions::LinkingMode) + 2003
25 swift                    0x00000001034e90d3 runOnFunctionRecursively(swift::SILFunction*, swift::FullApplySite, swift::SILOptions::LinkingMode, llvm::DenseSet<swift::SILFunction*, llvm::DenseMapInfo<swift::SILFunction*> >&, llvm::ImmutableSet<swift::SILFunction*, llvm::ImutContainerInfo<swift::SILFunction*> >::Factory&, llvm::ImmutableSet<swift::SILFunction*, llvm::ImutContainerInfo<swift::SILFunction*> >, swift::ClassHierarchyAnalysis*) + 1283
26 swift                    0x00000001034e8a06 (anonymous namespace)::MandatoryInlining::run() + 406
27 swift                    0x0000000103458278 swift::SILPassManager::runModulePass(swift::SILModuleTransform*) + 600
28 swift                    0x00000001034596bd swift::SILPassManager::runOneIteration() + 1261
29 swift                    0x000000010345a503 swift::SILPassManager::run() + 3555
30 swift                    0x000000010346e89d swift::runSILDiagnosticPasses(swift::SILModule&) + 477
31 swift                    0x0000000102c4e527 performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, llvm::ArrayRef<char const*>, int&) + 9607
32 swift                    0x0000000102c4b6f4 frontend_main(llvm::ArrayRef<char const*>, char const*, void*) + 12596
33 swift                    0x0000000102c33477 main + 4231
34 libdyld.dylib            0x00007fff901fa5ad start + 1
35 libdyld.dylib            0x000000000000000c start + 1876974176
Stack dump:
0.  Program arguments: /Users/bungi/Source/Swift/build/Ninja-DebugAssert/swift-macosx-x86_64/bin/swift -frontend -interpret abort-before-foreach.swift -target x86_64-apple-macosx10.9 -enable-objc-interop -sdk /Applications/Xcode-7.3-b5.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk -color-diagnostics -module-name main 
1.  While running SILModuleTransform "Mandatory Inlining".
2.  While verifying SIL function @_TFE4mainCSo12NSDictionary1xfT_T_ for 'x' at abort-before-foreach.swift:3:5
zsh: illegal hardware instruction  ~/Source/Swift/build/Ninja-DebugAssert/swift-macosx-x86_64/bin/swift -sdk  

[gottesmm]

Mandatory inlining is in the culprit. So it is in the optimizer, but not with optimization enabled.

[rudkx]

NoReturnFolding is making the dealloc_stack with an undef operand.

I think we should just loosen the verification and allow this, since this is unreachable code that we will eliminate in another mandatory pass.

[rudkx]

Fixed in e2cbc5b.