From 3d467a890e35edd913f8dee394da00744a1b58ce Mon Sep 17 00:00:00 2001
From: Alexander Kornienko <alexfh@google.com>
Date: Wed, 6 Mar 2019 15:23:50 +0000
Subject: Revert "[CodeGen] Omit range checks from jump tables when lowering
 switches with unreachable default"

This reverts commit 2a0f2c5ef3330846149598220467d9f3c6e8b99c (r355490).

The commit causes an assertion failure when compiling LLVM code:
$ cat repro.cpp
class QQQ {
public:
  bool x() const;
  bool y() const;
  unsigned getSizeInBits() const {
    if (y() || x())
      return getScalarSizeInBits();
    return getScalarSizeInBits() * 2;
  }
  unsigned getScalarSizeInBits() const;
};
int f(const QQQ &Ty) {
  switch (Ty.getSizeInBits()) {
    case 1:
    case 8:
      return 0;
    case 16:
      return 1;
    case 32:
      return 2;
    case 64:
      return 3;
    default:
      __builtin_unreachable();
  }
}
$ clang -O2 -o repro.o repro.cpp
assert.h assertion failed at llvm/include/llvm/ADT/ilist_iterator.h:139 in llvm::ilist_iterator::reference llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::MachineInstr, true, true, void>, true, false>::operator*() const [OptionsT = llvm::ilist_detail::node_options<llvm::MachineInstr, true, true, void>, IsReverse = true, IsConst = false]: !NodePtr->isKnownSentinel()
*** Check failure stack trace: ***
    @     0x558aab4afc10  __assert_fail
    @     0x558aa885479b  llvm::ilist_iterator<>::operator*()
    @     0x558aa8854715  llvm::MachineInstrBundleIterator<>::operator*()
    @     0x558aa92c33c3  llvm::X86InstrInfo::optimizeCompareInstr()
    @     0x558aa9a9c251  (anonymous namespace)::PeepholeOptimizer::optimizeCmpInstr()
    @     0x558aa9a9b371  (anonymous namespace)::PeepholeOptimizer::runOnMachineFunction()
    @     0x558aa99a4fc8  llvm::MachineFunctionPass::runOnFunction()
    @     0x558aab019fc4  llvm::FPPassManager::runOnFunction()
    @     0x558aab01a3a5  llvm::FPPassManager::runOnModule()
    @     0x558aab01aa9b  (anonymous namespace)::MPPassManager::runOnModule()
    @     0x558aab01a635  llvm::legacy::PassManagerImpl::run()
    @     0x558aab01afe1  llvm::legacy::PassManager::run()
    @     0x558aa5914769  (anonymous namespace)::EmitAssemblyHelper::EmitAssembly()
    @     0x558aa5910f44  clang::EmitBackendOutput()
    @     0x558aa5906135  clang::BackendConsumer::HandleTranslationUnit()
    @     0x558aa6d165ad  clang::ParseAST()
    @     0x558aa6a94e22  clang::ASTFrontendAction::ExecuteAction()
    @     0x558aa590255d  clang::CodeGenAction::ExecuteAction()
    @     0x558aa6a94840  clang::FrontendAction::Execute()
    @     0x558aa6a38cca  clang::CompilerInstance::ExecuteAction()
    @     0x558aa4e2294b  clang::ExecuteCompilerInvocation()
    @     0x558aa4df6200  cc1_main()
    @     0x558aa4e1b37f  ExecuteCC1Tool()
    @     0x558aa4e1a725  main
    @     0x7ff20d56abbd  __libc_start_main
    @     0x558aa4df51c9  _start

llvm-svn: 355515
---
 .../CodeGen/AArch64/switch-unreachable-default.ll  | 63 ----------------------
 1 file changed, 63 deletions(-)
 delete mode 100644 llvm/test/CodeGen/AArch64/switch-unreachable-default.ll

(limited to 'llvm/test/CodeGen/AArch64/switch-unreachable-default.ll')

diff --git a/llvm/test/CodeGen/AArch64/switch-unreachable-default.ll b/llvm/test/CodeGen/AArch64/switch-unreachable-default.ll
deleted file mode 100644
index ce11c14d1ca..00000000000
--- a/llvm/test/CodeGen/AArch64/switch-unreachable-default.ll
+++ /dev/null
@@ -1,63 +0,0 @@
-; RUN: llc -O3 -o - %s | FileCheck %s
-
-; Test that the output in the presence of an unreachable default does not have
-; a compare and branch at the top of the switch to handle the default case.
-
-target triple = "aarch64-unknown-linux-gnu"
-
-; Function Attrs: nounwind
-define void @fn(i4) {
-  switch i4 %0, label %default [
-    i4 0, label %case_0
-    i4 1, label %case_1
-    i4 2, label %case_2
-    i4 3, label %case_3
-    i4 4, label %case_4
-    i4 5, label %case_5
-  ]
-
-; CHECK-LABEL: fn:
-; CHECK-NOT:    sub
-; CHECK-NOT:    cmp
-; CHECK-NOT:    b.hi
-; CHECK:        ldrb {{w[0-9]+}}, [{{x[0-9]+}}, {{x[0-9]+}}]
-; CHECK:        add {{x[0-9]+}}, {{x[0-9]+}}, {{x[0-9]+}}, lsl #2
-; CHECK:        br {{x[0-9]+}}
-
-default:
-  unreachable
-
-case_0:
-  tail call void @handle_case_00(i4 %0) #2
-  br label %return_label
-
-case_1:
-  tail call void @handle_case_01(i4 %0) #2
-  br label %return_label
-
-case_2:
-  tail call void @handle_case_02(i4 %0) #2
-  br label %return_label
-
-case_3:
-  tail call void @handle_case_03(i4 %0) #2
-  br label %return_label
-
-case_4:
-  tail call void @handle_case_04(i4 %0) #2
-  br label %return_label
-
-case_5:
-  tail call void @handle_case_05(i4 %0) #2
-  br label %return_label
-
-return_label:
-  ret void
-}
-
-declare  void @handle_case_00(i4)
-declare  void @handle_case_01(i4)
-declare  void @handle_case_02(i4)
-declare  void @handle_case_03(i4)
-declare  void @handle_case_04(i4)
-declare  void @handle_case_05(i4)
-- 
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