llvm-project/clang/lib/CodeGen/CGStmt.cpp

//===--- CGStmt.cpp - Emit LLVM Code from Statements ----------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This contains code to emit Stmt nodes as LLVM code.
//
//===----------------------------------------------------------------------===//

#include "CGDebugInfo.h"
#include "CGOpenMPRuntime.h"
#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "TargetInfo.h"
#include "clang/AST/Attr.h"
#include "clang/AST/Expr.h"
#include "clang/AST/Stmt.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/Basic/Builtins.h"
#include "clang/Basic/DiagnosticSema.h"
#include "clang/Basic/PrettyStackTrace.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/IR/Assumptions.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/InlineAsm.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/Support/SaveAndRestore.h"

using namespace clang;
using namespace CodeGen;

//===----------------------------------------------------------------------===//
//                              Statement Emission
//===----------------------------------------------------------------------===//

void CodeGenFunction::EmitStopPoint(const Stmt *S) {
  if (CGDebugInfo *DI = getDebugInfo()) {
    SourceLocation Loc;
    Loc = S->getBeginLoc();
    DI->EmitLocation(Builder, Loc);

    LastStopPoint = Loc;
  }
}

void CodeGenFunction::EmitStmt(const Stmt *S, ArrayRef<const Attr *> Attrs) {
  assert(S && "Null statement?");
  PGO.setCurrentStmt(S);

  // These statements have their own debug info handling.
  if (EmitSimpleStmt(S, Attrs))
    return;

  // Check if we are generating unreachable code.
  if (!HaveInsertPoint()) {
    // If so, and the statement doesn't contain a label, then we do not need to
    // generate actual code. This is safe because (1) the current point is
    // unreachable, so we don't need to execute the code, and (2) we've already
    // handled the statements which update internal data structures (like the
    // local variable map) which could be used by subsequent statements.
    if (!ContainsLabel(S)) {
      // Verify that any decl statements were handled as simple, they may be in
      // scope of subsequent reachable statements.
      assert(!isa<DeclStmt>(*S) && "Unexpected DeclStmt!");
      return;
    }

    // Otherwise, make a new block to hold the code.
    EnsureInsertPoint();
  }

  // Generate a stoppoint if we are emitting debug info.
  EmitStopPoint(S);

  // Ignore all OpenMP directives except for simd if OpenMP with Simd is
  // enabled.
  if (getLangOpts().OpenMP && getLangOpts().OpenMPSimd) {
    if (const auto *D = dyn_cast<OMPExecutableDirective>(S)) {
      EmitSimpleOMPExecutableDirective(*D);
      return;
    }
  }

  switch (S->getStmtClass()) {
  case Stmt::NoStmtClass:
  case Stmt::CXXCatchStmtClass:
  case Stmt::SEHExceptStmtClass:
  case Stmt::SEHFinallyStmtClass:
  case Stmt::MSDependentExistsStmtClass:
    llvm_unreachable("invalid statement class to emit generically");
  case Stmt::NullStmtClass:
  case Stmt::CompoundStmtClass:
  case Stmt::DeclStmtClass:
  case Stmt::LabelStmtClass:
  case Stmt::AttributedStmtClass:
  case Stmt::GotoStmtClass:
  case Stmt::BreakStmtClass:
  case Stmt::ContinueStmtClass:
  case Stmt::DefaultStmtClass:
  case Stmt::CaseStmtClass:
  case Stmt::SEHLeaveStmtClass:
    llvm_unreachable("should have emitted these statements as simple");

#define STMT(Type, Base)
#define ABSTRACT_STMT(Op)
#define EXPR(Type, Base) \
  case Stmt::Type##Class:
#include "clang/AST/StmtNodes.inc"
  {
    // Remember the block we came in on.
    llvm::BasicBlock *incoming = Builder.GetInsertBlock();
    assert(incoming && "expression emission must have an insertion point");

    EmitIgnoredExpr(cast<Expr>(S));

    llvm::BasicBlock *outgoing = Builder.GetInsertBlock();
    assert(outgoing && "expression emission cleared block!");

    // The expression emitters assume (reasonably!) that the insertion
    // point is always set.  To maintain that, the call-emission code
    // for noreturn functions has to enter a new block with no
    // predecessors.  We want to kill that block and mark the current
    // insertion point unreachable in the common case of a call like
    // "exit();".  Since expression emission doesn't otherwise create
    // blocks with no predecessors, we can just test for that.
    // However, we must be careful not to do this to our incoming
    // block, because *statement* emission does sometimes create
    // reachable blocks which will have no predecessors until later in
    // the function.  This occurs with, e.g., labels that are not
    // reachable by fallthrough.
    if (incoming != outgoing && outgoing->use_empty()) {
      outgoing->eraseFromParent();
      Builder.ClearInsertionPoint();
    }
    break;
  }

  case Stmt::IndirectGotoStmtClass:
    EmitIndirectGotoStmt(cast<IndirectGotoStmt>(*S)); break;

  case Stmt::IfStmtClass:      EmitIfStmt(cast<IfStmt>(*S));              break;
  case Stmt::WhileStmtClass:   EmitWhileStmt(cast<WhileStmt>(*S), Attrs); break;
  case Stmt::DoStmtClass:      EmitDoStmt(cast<DoStmt>(*S), Attrs);       break;
  case Stmt::ForStmtClass:     EmitForStmt(cast<ForStmt>(*S), Attrs);     break;

  case Stmt::ReturnStmtClass:  EmitReturnStmt(cast<ReturnStmt>(*S));      break;

  case Stmt::SwitchStmtClass:  EmitSwitchStmt(cast<SwitchStmt>(*S));      break;
  case Stmt::GCCAsmStmtClass:  // Intentional fall-through.
  case Stmt::MSAsmStmtClass:   EmitAsmStmt(cast<AsmStmt>(*S));            break;
  case Stmt::CoroutineBodyStmtClass:
    EmitCoroutineBody(cast<CoroutineBodyStmt>(*S));
    break;
  case Stmt::CoreturnStmtClass:
    EmitCoreturnStmt(cast<CoreturnStmt>(*S));
    break;
  case Stmt::CapturedStmtClass: {
    const CapturedStmt *CS = cast<CapturedStmt>(S);
    EmitCapturedStmt(*CS, CS->getCapturedRegionKind());
    }
    break;
  case Stmt::ObjCAtTryStmtClass:
    EmitObjCAtTryStmt(cast<ObjCAtTryStmt>(*S));
    break;
  case Stmt::ObjCAtCatchStmtClass:
    llvm_unreachable(
                    "@catch statements should be handled by EmitObjCAtTryStmt");
  case Stmt::ObjCAtFinallyStmtClass:
    llvm_unreachable(
                  "@finally statements should be handled by EmitObjCAtTryStmt");
  case Stmt::ObjCAtThrowStmtClass:
    EmitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(*S));
    break;
  case Stmt::ObjCAtSynchronizedStmtClass:
    EmitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(*S));
    break;
  case Stmt::ObjCForCollectionStmtClass:
    EmitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(*S));
    break;
  case Stmt::ObjCAutoreleasePoolStmtClass:
    EmitObjCAutoreleasePoolStmt(cast<ObjCAutoreleasePoolStmt>(*S));
    break;

  case Stmt::CXXTryStmtClass:
    EmitCXXTryStmt(cast<CXXTryStmt>(*S));
    break;
  case Stmt::CXXForRangeStmtClass:
    EmitCXXForRangeStmt(cast<CXXForRangeStmt>(*S), Attrs);
    break;
  case Stmt::SEHTryStmtClass:
    EmitSEHTryStmt(cast<SEHTryStmt>(*S));
    break;
  case Stmt::OMPMetaDirectiveClass:
    EmitOMPMetaDirective(cast<OMPMetaDirective>(*S));
    break;
  case Stmt::OMPCanonicalLoopClass:
    EmitOMPCanonicalLoop(cast<OMPCanonicalLoop>(S));
    break;
  case Stmt::OMPParallelDirectiveClass:
    EmitOMPParallelDirective(cast<OMPParallelDirective>(*S));
    break;
  case Stmt::OMPSimdDirectiveClass:
    EmitOMPSimdDirective(cast<OMPSimdDirective>(*S));
    break;
  case Stmt::OMPTileDirectiveClass:
    EmitOMPTileDirective(cast<OMPTileDirective>(*S));
    break;
  case Stmt::OMPUnrollDirectiveClass:
    EmitOMPUnrollDirective(cast<OMPUnrollDirective>(*S));
    break;
  case Stmt::OMPForDirectiveClass:
    EmitOMPForDirective(cast<OMPForDirective>(*S));
    break;
  case Stmt::OMPForSimdDirectiveClass:
    EmitOMPForSimdDirective(cast<OMPForSimdDirective>(*S));
    break;
  case Stmt::OMPSectionsDirectiveClass:
    EmitOMPSectionsDirective(cast<OMPSectionsDirective>(*S));
    break;
  case Stmt::OMPSectionDirectiveClass:
    EmitOMPSectionDirective(cast<OMPSectionDirective>(*S));
    break;
  case Stmt::OMPSingleDirectiveClass:
    EmitOMPSingleDirective(cast<OMPSingleDirective>(*S));
    break;
  case Stmt::OMPMasterDirectiveClass:
    EmitOMPMasterDirective(cast<OMPMasterDirective>(*S));
    break;
  case Stmt::OMPCriticalDirectiveClass:
    EmitOMPCriticalDirective(cast<OMPCriticalDirective>(*S));
    break;
  case Stmt::OMPParallelForDirectiveClass:
    EmitOMPParallelForDirective(cast<OMPParallelForDirective>(*S));
    break;
  case Stmt::OMPParallelForSimdDirectiveClass:
    EmitOMPParallelForSimdDirective(cast<OMPParallelForSimdDirective>(*S));
    break;
  case Stmt::OMPParallelMasterDirectiveClass:
    EmitOMPParallelMasterDirective(cast<OMPParallelMasterDirective>(*S));
    break;
  case Stmt::OMPParallelSectionsDirectiveClass:
    EmitOMPParallelSectionsDirective(cast<OMPParallelSectionsDirective>(*S));
    break;
  case Stmt::OMPTaskDirectiveClass:
    EmitOMPTaskDirective(cast<OMPTaskDirective>(*S));
    break;
  case Stmt::OMPTaskyieldDirectiveClass:
    EmitOMPTaskyieldDirective(cast<OMPTaskyieldDirective>(*S));
    break;
  case Stmt::OMPBarrierDirectiveClass:
    EmitOMPBarrierDirective(cast<OMPBarrierDirective>(*S));
    break;
  case Stmt::OMPTaskwaitDirectiveClass:
    EmitOMPTaskwaitDirective(cast<OMPTaskwaitDirective>(*S));
    break;
  case Stmt::OMPTaskgroupDirectiveClass:
    EmitOMPTaskgroupDirective(cast<OMPTaskgroupDirective>(*S));
    break;
  case Stmt::OMPFlushDirectiveClass:
    EmitOMPFlushDirective(cast<OMPFlushDirective>(*S));
    break;
  case Stmt::OMPDepobjDirectiveClass:
    EmitOMPDepobjDirective(cast<OMPDepobjDirective>(*S));
    break;
  case Stmt::OMPScanDirectiveClass:
    EmitOMPScanDirective(cast<OMPScanDirective>(*S));
    break;
  case Stmt::OMPOrderedDirectiveClass:
    EmitOMPOrderedDirective(cast<OMPOrderedDirective>(*S));
    break;
  case Stmt::OMPAtomicDirectiveClass:
    EmitOMPAtomicDirective(cast<OMPAtomicDirective>(*S));
    break;
  case Stmt::OMPTargetDirectiveClass:
    EmitOMPTargetDirective(cast<OMPTargetDirective>(*S));
    break;
  case Stmt::OMPTeamsDirectiveClass:
    EmitOMPTeamsDirective(cast<OMPTeamsDirective>(*S));
    break;
  case Stmt::OMPCancellationPointDirectiveClass:
    EmitOMPCancellationPointDirective(cast<OMPCancellationPointDirective>(*S));
    break;
  case Stmt::OMPCancelDirectiveClass:
    EmitOMPCancelDirective(cast<OMPCancelDirective>(*S));
    break;
  case Stmt::OMPTargetDataDirectiveClass:
    EmitOMPTargetDataDirective(cast<OMPTargetDataDirective>(*S));
    break;
  case Stmt::OMPTargetEnterDataDirectiveClass:
    EmitOMPTargetEnterDataDirective(cast<OMPTargetEnterDataDirective>(*S));
    break;
  case Stmt::OMPTargetExitDataDirectiveClass:
    EmitOMPTargetExitDataDirective(cast<OMPTargetExitDataDirective>(*S));
    break;
  case Stmt::OMPTargetParallelDirectiveClass:
    EmitOMPTargetParallelDirective(cast<OMPTargetParallelDirective>(*S));
    break;
  case Stmt::OMPTargetParallelForDirectiveClass:
    EmitOMPTargetParallelForDirective(cast<OMPTargetParallelForDirective>(*S));
    break;
  case Stmt::OMPTaskLoopDirectiveClass:
    EmitOMPTaskLoopDirective(cast<OMPTaskLoopDirective>(*S));
    break;
  case Stmt::OMPTaskLoopSimdDirectiveClass:
    EmitOMPTaskLoopSimdDirective(cast<OMPTaskLoopSimdDirective>(*S));
    break;
  case Stmt::OMPMasterTaskLoopDirectiveClass:
    EmitOMPMasterTaskLoopDirective(cast<OMPMasterTaskLoopDirective>(*S));
    break;
  case Stmt::OMPMasterTaskLoopSimdDirectiveClass:
    EmitOMPMasterTaskLoopSimdDirective(
        cast<OMPMasterTaskLoopSimdDirective>(*S));
    break;
  case Stmt::OMPParallelMasterTaskLoopDirectiveClass:
    EmitOMPParallelMasterTaskLoopDirective(
        cast<OMPParallelMasterTaskLoopDirective>(*S));
    break;
  case Stmt::OMPParallelMasterTaskLoopSimdDirectiveClass:
    EmitOMPParallelMasterTaskLoopSimdDirective(
        cast<OMPParallelMasterTaskLoopSimdDirective>(*S));
    break;
  case Stmt::OMPDistributeDirectiveClass:
    EmitOMPDistributeDirective(cast<OMPDistributeDirective>(*S));
    break;
  case Stmt::OMPTargetUpdateDirectiveClass:
    EmitOMPTargetUpdateDirective(cast<OMPTargetUpdateDirective>(*S));
    break;
  case Stmt::OMPDistributeParallelForDirectiveClass:
    EmitOMPDistributeParallelForDirective(
        cast<OMPDistributeParallelForDirective>(*S));
    break;
  case Stmt::OMPDistributeParallelForSimdDirectiveClass:
    EmitOMPDistributeParallelForSimdDirective(
        cast<OMPDistributeParallelForSimdDirective>(*S));
    break;
  case Stmt::OMPDistributeSimdDirectiveClass:
    EmitOMPDistributeSimdDirective(cast<OMPDistributeSimdDirective>(*S));
    break;
  case Stmt::OMPTargetParallelForSimdDirectiveClass:
    EmitOMPTargetParallelForSimdDirective(
        cast<OMPTargetParallelForSimdDirective>(*S));
    break;
  case Stmt::OMPTargetSimdDirectiveClass:
    EmitOMPTargetSimdDirective(cast<OMPTargetSimdDirective>(*S));
    break;
  case Stmt::OMPTeamsDistributeDirectiveClass:
    EmitOMPTeamsDistributeDirective(cast<OMPTeamsDistributeDirective>(*S));
    break;
  case Stmt::OMPTeamsDistributeSimdDirectiveClass:
    EmitOMPTeamsDistributeSimdDirective(
        cast<OMPTeamsDistributeSimdDirective>(*S));
    break;
  case Stmt::OMPTeamsDistributeParallelForSimdDirectiveClass:
    EmitOMPTeamsDistributeParallelForSimdDirective(
        cast<OMPTeamsDistributeParallelForSimdDirective>(*S));
    break;
  case Stmt::OMPTeamsDistributeParallelForDirectiveClass:
    EmitOMPTeamsDistributeParallelForDirective(
        cast<OMPTeamsDistributeParallelForDirective>(*S));
    break;
  case Stmt::OMPTargetTeamsDirectiveClass:
    EmitOMPTargetTeamsDirective(cast<OMPTargetTeamsDirective>(*S));
    break;
  case Stmt::OMPTargetTeamsDistributeDirectiveClass:
    EmitOMPTargetTeamsDistributeDirective(
        cast<OMPTargetTeamsDistributeDirective>(*S));
    break;
  case Stmt::OMPTargetTeamsDistributeParallelForDirectiveClass:
    EmitOMPTargetTeamsDistributeParallelForDirective(
        cast<OMPTargetTeamsDistributeParallelForDirective>(*S));
    break;
  case Stmt::OMPTargetTeamsDistributeParallelForSimdDirectiveClass:
    EmitOMPTargetTeamsDistributeParallelForSimdDirective(
        cast<OMPTargetTeamsDistributeParallelForSimdDirective>(*S));
    break;
  case Stmt::OMPTargetTeamsDistributeSimdDirectiveClass:
    EmitOMPTargetTeamsDistributeSimdDirective(
        cast<OMPTargetTeamsDistributeSimdDirective>(*S));
    break;
  case Stmt::OMPInteropDirectiveClass:
    EmitOMPInteropDirective(cast<OMPInteropDirective>(*S));
    break;
  case Stmt::OMPDispatchDirectiveClass:
    llvm_unreachable("Dispatch directive not supported yet.");
    break;
  case Stmt::OMPMaskedDirectiveClass:
    EmitOMPMaskedDirective(cast<OMPMaskedDirective>(*S));
    break;
  case Stmt::OMPGenericLoopDirectiveClass:
    EmitOMPGenericLoopDirective(cast<OMPGenericLoopDirective>(*S));
    break;
  case Stmt::OMPTeamsGenericLoopDirectiveClass:
    llvm_unreachable("teams loop directive not supported yet.");
    break;
  case Stmt::OMPTargetTeamsGenericLoopDirectiveClass:
    llvm_unreachable("target teams loop directive not supported yet.");
    break;
  case Stmt::OMPParallelGenericLoopDirectiveClass:
    llvm_unreachable("parallel loop directive not supported yet.");
    break;
  case Stmt::OMPTargetParallelGenericLoopDirectiveClass:
    llvm_unreachable("target parallel loop directive not supported yet.");
    break;
  }
}

bool CodeGenFunction::EmitSimpleStmt(const Stmt *S,
                                     ArrayRef<const Attr *> Attrs) {
  switch (S->getStmtClass()) {
  default:
    return false;
  case Stmt::NullStmtClass:
    break;
  case Stmt::CompoundStmtClass:
    EmitCompoundStmt(cast<CompoundStmt>(*S));
    break;
  case Stmt::DeclStmtClass:
    EmitDeclStmt(cast<DeclStmt>(*S));
    break;
  case Stmt::LabelStmtClass:
    EmitLabelStmt(cast<LabelStmt>(*S));
    break;
  case Stmt::AttributedStmtClass:
    EmitAttributedStmt(cast<AttributedStmt>(*S));
    break;
  case Stmt::GotoStmtClass:
    EmitGotoStmt(cast<GotoStmt>(*S));
    break;
  case Stmt::BreakStmtClass:
    EmitBreakStmt(cast<BreakStmt>(*S));
    break;
  case Stmt::ContinueStmtClass:
    EmitContinueStmt(cast<ContinueStmt>(*S));
    break;
  case Stmt::DefaultStmtClass:
    EmitDefaultStmt(cast<DefaultStmt>(*S), Attrs);
    break;
  case Stmt::CaseStmtClass:
    EmitCaseStmt(cast<CaseStmt>(*S), Attrs);
    break;
  case Stmt::SEHLeaveStmtClass:
    EmitSEHLeaveStmt(cast<SEHLeaveStmt>(*S));
    break;
  }
  return true;
}

/// EmitCompoundStmt - Emit a compound statement {..} node.  If GetLast is true,
/// this captures the expression result of the last sub-statement and returns it
/// (for use by the statement expression extension).
Address CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S, bool GetLast,
                                          AggValueSlot AggSlot) {
  PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),S.getLBracLoc(),
                             "LLVM IR generation of compound statement ('{}')");

  // Keep track of the current cleanup stack depth, including debug scopes.
  LexicalScope Scope(*this, S.getSourceRange());

  return EmitCompoundStmtWithoutScope(S, GetLast, AggSlot);
}

Address
CodeGenFunction::EmitCompoundStmtWithoutScope(const CompoundStmt &S,
                                              bool GetLast,
                                              AggValueSlot AggSlot) {

  const Stmt *ExprResult = S.getStmtExprResult();
  assert((!GetLast || (GetLast && ExprResult)) &&
         "If GetLast is true then the CompoundStmt must have a StmtExprResult");

  Address RetAlloca = Address::invalid();

  for (auto *CurStmt : S.body()) {
    if (GetLast && ExprResult == CurStmt) {
      // We have to special case labels here.  They are statements, but when put
      // at the end of a statement expression, they yield the value of their
      // subexpression.  Handle this by walking through all labels we encounter,
      // emitting them before we evaluate the subexpr.
      // Similar issues arise for attributed statements.
      while (!isa<Expr>(ExprResult)) {
        if (const auto *LS = dyn_cast<LabelStmt>(ExprResult)) {
          EmitLabel(LS->getDecl());
          ExprResult = LS->getSubStmt();
        } else if (const auto *AS = dyn_cast<AttributedStmt>(ExprResult)) {
          // FIXME: Update this if we ever have attributes that affect the
          // semantics of an expression.
          ExprResult = AS->getSubStmt();
        } else {
          llvm_unreachable("unknown value statement");
        }
      }

      EnsureInsertPoint();

      const Expr *E = cast<Expr>(ExprResult);
      QualType ExprTy = E->getType();
      if (hasAggregateEvaluationKind(ExprTy)) {
        EmitAggExpr(E, AggSlot);
      } else {
        // We can't return an RValue here because there might be cleanups at
        // the end of the StmtExpr.  Because of that, we have to emit the result
        // here into a temporary alloca.
        RetAlloca = CreateMemTemp(ExprTy);
        EmitAnyExprToMem(E, RetAlloca, Qualifiers(),
                         /*IsInit*/ false);
      }
    } else {
      EmitStmt(CurStmt);
    }
  }

  return RetAlloca;
}

void CodeGenFunction::SimplifyForwardingBlocks(llvm::BasicBlock *BB) {
  llvm::BranchInst *BI = dyn_cast<llvm::BranchInst>(BB->getTerminator());

  // If there is a cleanup stack, then we it isn't worth trying to
  // simplify this block (we would need to remove it from the scope map
  // and cleanup entry).
  if (!EHStack.empty())
    return;

  // Can only simplify direct branches.
  if (!BI || !BI->isUnconditional())
    return;

  // Can only simplify empty blocks.
  if (BI->getIterator() != BB->begin())
    return;

  BB->replaceAllUsesWith(BI->getSuccessor(0));
  BI->eraseFromParent();
  BB->eraseFromParent();
}

void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB, bool IsFinished) {
  llvm::BasicBlock *CurBB = Builder.GetInsertBlock();

  // Fall out of the current block (if necessary).
  EmitBranch(BB);

  if (IsFinished && BB->use_empty()) {
    delete BB;
    return;
  }

  // Place the block after the current block, if possible, or else at
  // the end of the function.
  if (CurBB && CurBB->getParent())
    CurFn->getBasicBlockList().insertAfter(CurBB->getIterator(), BB);
  else
    CurFn->getBasicBlockList().push_back(BB);
  Builder.SetInsertPoint(BB);
}

void CodeGenFunction::EmitBranch(llvm::BasicBlock *Target) {
  // Emit a branch from the current block to the target one if this
  // was a real block.  If this was just a fall-through block after a
  // terminator, don't emit it.
  llvm::BasicBlock *CurBB = Builder.GetInsertBlock();

  if (!CurBB || CurBB->getTerminator()) {
    // If there is no insert point or the previous block is already
    // terminated, don't touch it.
  } else {
    // Otherwise, create a fall-through branch.
    Builder.CreateBr(Target);
  }

  Builder.ClearInsertionPoint();
}

void CodeGenFunction::EmitBlockAfterUses(llvm::BasicBlock *block) {
  bool inserted = false;
  for (llvm::User *u : block->users()) {
    if (llvm::Instruction *insn = dyn_cast<llvm::Instruction>(u)) {
      CurFn->getBasicBlockList().insertAfter(insn->getParent()->getIterator(),
                                             block);
      inserted = true;
      break;
    }
  }

  if (!inserted)
    CurFn->getBasicBlockList().push_back(block);

  Builder.SetInsertPoint(block);
}

CodeGenFunction::JumpDest
CodeGenFunction::getJumpDestForLabel(const LabelDecl *D) {
  JumpDest &Dest = LabelMap[D];
  if (Dest.isValid()) return Dest;

  // Create, but don't insert, the new block.
  Dest = JumpDest(createBasicBlock(D->getName()),
                  EHScopeStack::stable_iterator::invalid(),
                  NextCleanupDestIndex++);
  return Dest;
}

void CodeGenFunction::EmitLabel(const LabelDecl *D) {
  // Add this label to the current lexical scope if we're within any
  // normal cleanups.  Jumps "in" to this label --- when permitted by
  // the language --- may need to be routed around such cleanups.
  if (EHStack.hasNormalCleanups() && CurLexicalScope)
    CurLexicalScope->addLabel(D);

  JumpDest &Dest = LabelMap[D];

  // If we didn't need a forward reference to this label, just go
  // ahead and create a destination at the current scope.
  if (!Dest.isValid()) {
    Dest = getJumpDestInCurrentScope(D->getName());

  // Otherwise, we need to give this label a target depth and remove
  // it from the branch-fixups list.
  } else {
    assert(!Dest.getScopeDepth().isValid() && "already emitted label!");
    Dest.setScopeDepth(EHStack.stable_begin());
    ResolveBranchFixups(Dest.getBlock());
  }

  EmitBlock(Dest.getBlock());

  // Emit debug info for labels.
  if (CGDebugInfo *DI = getDebugInfo()) {
    if (CGM.getCodeGenOpts().hasReducedDebugInfo()) {
      DI->setLocation(D->getLocation());
      DI->EmitLabel(D, Builder);
    }
  }

  incrementProfileCounter(D->getStmt());
}

/// Change the cleanup scope of the labels in this lexical scope to
/// match the scope of the enclosing context.
void CodeGenFunction::LexicalScope::rescopeLabels() {
  assert(!Labels.empty());
  EHScopeStack::stable_iterator innermostScope
    = CGF.EHStack.getInnermostNormalCleanup();

  // Change the scope depth of all the labels.
  for (SmallVectorImpl<const LabelDecl*>::const_iterator
         i = Labels.begin(), e = Labels.end(); i != e; ++i) {
    assert(CGF.LabelMap.count(*i));
    JumpDest &dest = CGF.LabelMap.find(*i)->second;
    assert(dest.getScopeDepth().isValid());
    assert(innermostScope.encloses(dest.getScopeDepth()));
    dest.setScopeDepth(innermostScope);
  }

  // Reparent the labels if the new scope also has cleanups.
  if (innermostScope != EHScopeStack::stable_end() && ParentScope) {
    ParentScope->Labels.append(Labels.begin(), Labels.end());
  }
}


void CodeGenFunction::EmitLabelStmt(const LabelStmt &S) {
  EmitLabel(S.getDecl());

  // IsEHa - emit eha.scope.begin if it's a side entry of a scope
  if (getLangOpts().EHAsynch && S.isSideEntry())
    EmitSehCppScopeBegin();

  EmitStmt(S.getSubStmt());
}

void CodeGenFunction::EmitAttributedStmt(const AttributedStmt &S) {
  bool nomerge = false;
  bool noinline = false;
  bool alwaysinline = false;
  const CallExpr *musttail = nullptr;

  for (const auto *A : S.getAttrs()) {
    switch (A->getKind()) {
    default:
      break;
    case attr::NoMerge:
      nomerge = true;
      break;
    case attr::NoInline:
      noinline = true;
      break;
    case attr::AlwaysInline:
      alwaysinline = true;
      break;
    case attr::MustTail:
      const Stmt *Sub = S.getSubStmt();
      const ReturnStmt *R = cast<ReturnStmt>(Sub);
      musttail = cast<CallExpr>(R->getRetValue()->IgnoreParens());
      break;
    }
  }
  SaveAndRestore<bool> save_nomerge(InNoMergeAttributedStmt, nomerge);
  SaveAndRestore<bool> save_noinline(InNoInlineAttributedStmt, noinline);
  SaveAndRestore<bool> save_alwaysinline(InAlwaysInlineAttributedStmt,
                                         alwaysinline);
  SaveAndRestore<const CallExpr *> save_musttail(MustTailCall, musttail);
  EmitStmt(S.getSubStmt(), S.getAttrs());
}

void CodeGenFunction::EmitGotoStmt(const GotoStmt &S) {
  // If this code is reachable then emit a stop point (if generating
  // debug info). We have to do this ourselves because we are on the
  // "simple" statement path.
  if (HaveInsertPoint())
    EmitStopPoint(&S);

  EmitBranchThroughCleanup(getJumpDestForLabel(S.getLabel()));
}


void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) {
  if (const LabelDecl *Target = S.getConstantTarget()) {
    EmitBranchThroughCleanup(getJumpDestForLabel(Target));
    return;
  }

  // Ensure that we have an i8* for our PHI node.
  llvm::Value *V = Builder.CreateBitCast(EmitScalarExpr(S.getTarget()),
                                         Int8PtrTy, "addr");
  llvm::BasicBlock *CurBB = Builder.GetInsertBlock();

  // Get the basic block for the indirect goto.
  llvm::BasicBlock *IndGotoBB = GetIndirectGotoBlock();

  // The first instruction in the block has to be the PHI for the switch dest,
  // add an entry for this branch.
  cast<llvm::PHINode>(IndGotoBB->begin())->addIncoming(V, CurBB);

  EmitBranch(IndGotoBB);
}

void CodeGenFunction::EmitIfStmt(const IfStmt &S) {
  // The else branch of a consteval if statement is always the only branch that
  // can be runtime evaluated.
  if (S.isConsteval()) {
    const Stmt *Executed = S.isNegatedConsteval() ? S.getThen() : S.getElse();
    if (Executed) {
      RunCleanupsScope ExecutedScope(*this);
      EmitStmt(Executed);
    }
    return;
  }

  // C99 6.8.4.1: The first substatement is executed if the expression compares
  // unequal to 0.  The condition must be a scalar type.
  LexicalScope ConditionScope(*this, S.getCond()->getSourceRange());

  if (S.getInit())
    EmitStmt(S.getInit());

  if (S.getConditionVariable())
    EmitDecl(*S.getConditionVariable());

  // If the condition constant folds and can be elided, try to avoid emitting
  // the condition and the dead arm of the if/else.
  bool CondConstant;
  if (ConstantFoldsToSimpleInteger(S.getCond(), CondConstant,
                                   S.isConstexpr())) {
    // Figure out which block (then or else) is executed.
    const Stmt *Executed = S.getThen();
    const Stmt *Skipped  = S.getElse();
    if (!CondConstant)  // Condition false?
      std::swap(Executed, Skipped);

    // If the skipped block has no labels in it, just emit the executed block.
    // This avoids emitting dead code and simplifies the CFG substantially.
    if (S.isConstexpr() || !ContainsLabel(Skipped)) {
      if (CondConstant)
        incrementProfileCounter(&S);
      if (Executed) {
        RunCleanupsScope ExecutedScope(*this);
        EmitStmt(Executed);
      }
      return;
    }
  }

  // Otherwise, the condition did not fold, or we couldn't elide it.  Just emit
  // the conditional branch.
  llvm::BasicBlock *ThenBlock = createBasicBlock("if.then");
  llvm::BasicBlock *ContBlock = createBasicBlock("if.end");
  llvm::BasicBlock *ElseBlock = ContBlock;
  if (S.getElse())
    ElseBlock = createBasicBlock("if.else");

  // Prefer the PGO based weights over the likelihood attribute.
  // When the build isn't optimized the metadata isn't used, so don't generate
  // it.
  Stmt::Likelihood LH = Stmt::LH_None;
  uint64_t Count = getProfileCount(S.getThen());
  if (!Count && CGM.getCodeGenOpts().OptimizationLevel)
    LH = Stmt::getLikelihood(S.getThen(), S.getElse());
  EmitBranchOnBoolExpr(S.getCond(), ThenBlock, ElseBlock, Count, LH);

  // Emit the 'then' code.
  EmitBlock(ThenBlock);
  incrementProfileCounter(&S);
  {
    RunCleanupsScope ThenScope(*this);
    EmitStmt(S.getThen());
  }
  EmitBranch(ContBlock);

  // Emit the 'else' code if present.
  if (const Stmt *Else = S.getElse()) {
    {
      // There is no need to emit line number for an unconditional branch.
      auto NL = ApplyDebugLocation::CreateEmpty(*this);
      EmitBlock(ElseBlock);
    }
    {
      RunCleanupsScope ElseScope(*this);
      EmitStmt(Else);
    }
    {
      // There is no need to emit line number for an unconditional branch.
      auto NL = ApplyDebugLocation::CreateEmpty(*this);
      EmitBranch(ContBlock);
    }
  }

  // Emit the continuation block for code after the if.
  EmitBlock(ContBlock, true);
}

void CodeGenFunction::EmitWhileStmt(const WhileStmt &S,
                                    ArrayRef<const Attr *> WhileAttrs) {
  // Emit the header for the loop, which will also become
  // the continue target.
  JumpDest LoopHeader = getJumpDestInCurrentScope("while.cond");
  EmitBlock(LoopHeader.getBlock());

  // Create an exit block for when the condition fails, which will
  // also become the break target.
  JumpDest LoopExit = getJumpDestInCurrentScope("while.end");

  // Store the blocks to use for break and continue.
  BreakContinueStack.push_back(BreakContinue(LoopExit, LoopHeader));

  // C++ [stmt.while]p2:
  //   When the condition of a while statement is a declaration, the
  //   scope of the variable that is declared extends from its point
  //   of declaration (3.3.2) to the end of the while statement.
  //   [...]
  //   The object created in a condition is destroyed and created
  //   with each iteration of the loop.
  RunCleanupsScope ConditionScope(*this);

  if (S.getConditionVariable())
    EmitDecl(*S.getConditionVariable());

  // Evaluate the conditional in the while header.  C99 6.8.5.1: The
  // evaluation of the controlling expression takes place before each
  // execution of the loop body.
  llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());

  // while(1) is common, avoid extra exit blocks.  Be sure
  // to correctly handle break/continue though.
  llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal);
  bool CondIsConstInt = C != nullptr;
  bool EmitBoolCondBranch = !CondIsConstInt || !C->isOne();
  const SourceRange &R = S.getSourceRange();
  LoopStack.push(LoopHeader.getBlock(), CGM.getContext(), CGM.getCodeGenOpts(),
                 WhileAttrs, SourceLocToDebugLoc(R.getBegin()),
                 SourceLocToDebugLoc(R.getEnd()),
                 checkIfLoopMustProgress(CondIsConstInt));

  // As long as the condition is true, go to the loop body.
  llvm::BasicBlock *LoopBody = createBasicBlock("while.body");
  if (EmitBoolCondBranch) {
    llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
    if (ConditionScope.requiresCleanups())
      ExitBlock = createBasicBlock("while.exit");
    llvm::MDNode *Weights =
        createProfileWeightsForLoop(S.getCond(), getProfileCount(S.getBody()));
    if (!Weights && CGM.getCodeGenOpts().OptimizationLevel)
      BoolCondVal = emitCondLikelihoodViaExpectIntrinsic(
          BoolCondVal, Stmt::getLikelihood(S.getBody()));
    Builder.CreateCondBr(BoolCondVal, LoopBody, ExitBlock, Weights);

    if (ExitBlock != LoopExit.getBlock()) {
      EmitBlock(ExitBlock);
      EmitBranchThroughCleanup(LoopExit);
    }
  } else if (const Attr *A = Stmt::getLikelihoodAttr(S.getBody())) {
    CGM.getDiags().Report(A->getLocation(),
                          diag::warn_attribute_has_no_effect_on_infinite_loop)
        << A << A->getRange();
    CGM.getDiags().Report(
        S.getWhileLoc(),
        diag::note_attribute_has_no_effect_on_infinite_loop_here)
        << SourceRange(S.getWhileLoc(), S.getRParenLoc());
  }

  // Emit the loop body.  We have to emit this in a cleanup scope
  // because it might be a singleton DeclStmt.
  {
    RunCleanupsScope BodyScope(*this);
    EmitBlock(LoopBody);
    incrementProfileCounter(&S);
    EmitStmt(S.getBody());
  }

  BreakContinueStack.pop_back();

  // Immediately force cleanup.
  ConditionScope.ForceCleanup();

  EmitStopPoint(&S);
  // Branch to the loop header again.
  EmitBranch(LoopHeader.getBlock());

  LoopStack.pop();

  // Emit the exit block.
  EmitBlock(LoopExit.getBlock(), true);

  // The LoopHeader typically is just a branch if we skipped emitting
  // a branch, try to erase it.
  if (!EmitBoolCondBranch)
    SimplifyForwardingBlocks(LoopHeader.getBlock());
}

void CodeGenFunction::EmitDoStmt(const DoStmt &S,
                                 ArrayRef<const Attr *> DoAttrs) {
  JumpDest LoopExit = getJumpDestInCurrentScope("do.end");
  JumpDest LoopCond = getJumpDestInCurrentScope("do.cond");

  uint64_t ParentCount = getCurrentProfileCount();

  // Store the blocks to use for break and continue.
  BreakContinueStack.push_back(BreakContinue(LoopExit, LoopCond));

  // Emit the body of the loop.
  llvm::BasicBlock *LoopBody = createBasicBlock("do.body");

  EmitBlockWithFallThrough(LoopBody, &S);
  {
    RunCleanupsScope BodyScope(*this);
    EmitStmt(S.getBody());
  }

  EmitBlock(LoopCond.getBlock());

  // C99 6.8.5.2: "The evaluation of the controlling expression takes place
  // after each execution of the loop body."

  // Evaluate the conditional in the while header.
  // C99 6.8.5p2/p4: The first substatement is executed if the expression
  // compares unequal to 0.  The condition must be a scalar type.
  llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());

  BreakContinueStack.pop_back();

  // "do {} while (0)" is common in macros, avoid extra blocks.  Be sure
  // to correctly handle break/continue though.
  llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal);
  bool CondIsConstInt = C;
  bool EmitBoolCondBranch = !C || !C->isZero();

  const SourceRange &R = S.getSourceRange();
  LoopStack.push(LoopBody, CGM.getContext(), CGM.getCodeGenOpts(), DoAttrs,
                 SourceLocToDebugLoc(R.getBegin()),
                 SourceLocToDebugLoc(R.getEnd()),
                 checkIfLoopMustProgress(CondIsConstInt));

  // As long as the condition is true, iterate the loop.
  if (EmitBoolCondBranch) {
    uint64_t BackedgeCount = getProfileCount(S.getBody()) - ParentCount;
    Builder.CreateCondBr(
        BoolCondVal, LoopBody, LoopExit.getBlock(),
        createProfileWeightsForLoop(S.getCond(), BackedgeCount));
  }

  LoopStack.pop();

  // Emit the exit block.
  EmitBlock(LoopExit.getBlock());

  // The DoCond block typically is just a branch if we skipped
  // emitting a branch, try to erase it.
  if (!EmitBoolCondBranch)
    SimplifyForwardingBlocks(LoopCond.getBlock());
}

void CodeGenFunction::EmitForStmt(const ForStmt &S,
                                  ArrayRef<const Attr *> ForAttrs) {
  JumpDest LoopExit = getJumpDestInCurrentScope("for.end");

  LexicalScope ForScope(*this, S.getSourceRange());

  // Evaluate the first part before the loop.
  if (S.getInit())
    EmitStmt(S.getInit());

  // Start the loop with a block that tests the condition.
  // If there's an increment, the continue scope will be overwritten
  // later.
  JumpDest CondDest = getJumpDestInCurrentScope("for.cond");
  llvm::BasicBlock *CondBlock = CondDest.getBlock();
  EmitBlock(CondBlock);

  Expr::EvalResult Result;
  bool CondIsConstInt =
      !S.getCond() || S.getCond()->EvaluateAsInt(Result, getContext());

  const SourceRange &R = S.getSourceRange();
  LoopStack.push(CondBlock, CGM.getContext(), CGM.getCodeGenOpts(), ForAttrs,
                 SourceLocToDebugLoc(R.getBegin()),
                 SourceLocToDebugLoc(R.getEnd()),
                 checkIfLoopMustProgress(CondIsConstInt));

  // Create a cleanup scope for the condition variable cleanups.
  LexicalScope ConditionScope(*this, S.getSourceRange());

  // If the for loop doesn't have an increment we can just use the condition as
  // the continue block. Otherwise, if there is no condition variable, we can
  // form the continue block now. If there is a condition variable, we can't
  // form the continue block until after we've emitted the condition, because
  // the condition is in scope in the increment, but Sema's jump diagnostics
  // ensure that there are no continues from the condition variable that jump
  // to the loop increment.
  JumpDest Continue;
  if (!S.getInc())
    Continue = CondDest;
  else if (!S.getConditionVariable())
    Continue = getJumpDestInCurrentScope("for.inc");
  BreakContinueStack.push_back(BreakContinue(LoopExit, Continue));

  if (S.getCond()) {
    // If the for statement has a condition scope, emit the local variable
    // declaration.
    if (S.getConditionVariable()) {
      EmitDecl(*S.getConditionVariable());

      // We have entered the condition variable's scope, so we're now able to
      // jump to the continue block.
      Continue = S.getInc() ? getJumpDestInCurrentScope("for.inc") : CondDest;
      BreakContinueStack.back().ContinueBlock = Continue;
    }

    llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
    // If there are any cleanups between here and the loop-exit scope,
    // create a block to stage a loop exit along.
    if (ForScope.requiresCleanups())
      ExitBlock = createBasicBlock("for.cond.cleanup");

    // As long as the condition is true, iterate the loop.
    llvm::BasicBlock *ForBody = createBasicBlock("for.body");

    // C99 6.8.5p2/p4: The first substatement is executed if the expression
    // compares unequal to 0.  The condition must be a scalar type.
    llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
    llvm::MDNode *Weights =
        createProfileWeightsForLoop(S.getCond(), getProfileCount(S.getBody()));
    if (!Weights && CGM.getCodeGenOpts().OptimizationLevel)
      BoolCondVal = emitCondLikelihoodViaExpectIntrinsic(
          BoolCondVal, Stmt::getLikelihood(S.getBody()));

    Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock, Weights);

    if (ExitBlock != LoopExit.getBlock()) {
      EmitBlock(ExitBlock);
      EmitBranchThroughCleanup(LoopExit);
    }

    EmitBlock(ForBody);
  } else {
    // Treat it as a non-zero constant.  Don't even create a new block for the
    // body, just fall into it.
  }
  incrementProfileCounter(&S);

  {
    // Create a separate cleanup scope for the body, in case it is not
    // a compound statement.
    RunCleanupsScope BodyScope(*this);
    EmitStmt(S.getBody());
  }

  // If there is an increment, emit it next.
  if (S.getInc()) {
    EmitBlock(Continue.getBlock());
    EmitStmt(S.getInc());
  }

  BreakContinueStack.pop_back();

  ConditionScope.ForceCleanup();

  EmitStopPoint(&S);
  EmitBranch(CondBlock);

  ForScope.ForceCleanup();

  LoopStack.pop();

  // Emit the fall-through block.
  EmitBlock(LoopExit.getBlock(), true);
}

void
CodeGenFunction::EmitCXXForRangeStmt(const CXXForRangeStmt &S,
                                     ArrayRef<const Attr *> ForAttrs) {
  JumpDest LoopExit = getJumpDestInCurrentScope("for.end");

  LexicalScope ForScope(*this, S.getSourceRange());

  // Evaluate the first pieces before the loop.
  if (S.getInit())
    EmitStmt(S.getInit());
  EmitStmt(S.getRangeStmt());
  EmitStmt(S.getBeginStmt());
  EmitStmt(S.getEndStmt());

  // Start the loop with a block that tests the condition.
  // If there's an increment, the continue scope will be overwritten
  // later.
  llvm::BasicBlock *CondBlock = createBasicBlock("for.cond");
  EmitBlock(CondBlock);

  const SourceRange &R = S.getSourceRange();
  LoopStack.push(CondBlock, CGM.getContext(), CGM.getCodeGenOpts(), ForAttrs,
                 SourceLocToDebugLoc(R.getBegin()),
                 SourceLocToDebugLoc(R.getEnd()));

  // If there are any cleanups between here and the loop-exit scope,
  // create a block to stage a loop exit along.
  llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
  if (ForScope.requiresCleanups())
    ExitBlock = createBasicBlock("for.cond.cleanup");

  // The loop body, consisting of the specified body and the loop variable.
  llvm::BasicBlock *ForBody = createBasicBlock("for.body");

  // The body is executed if the expression, contextually converted
  // to bool, is true.
  llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
  llvm::MDNode *Weights =
      createProfileWeightsForLoop(S.getCond(), getProfileCount(S.getBody()));
  if (!Weights && CGM.getCodeGenOpts().OptimizationLevel)
    BoolCondVal = emitCondLikelihoodViaExpectIntrinsic(
        BoolCondVal, Stmt::getLikelihood(S.getBody()));
  Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock, Weights);

  if (ExitBlock != LoopExit.getBlock()) {
    EmitBlock(ExitBlock);
    EmitBranchThroughCleanup(LoopExit);
  }

  EmitBlock(ForBody);
  incrementProfileCounter(&S);

  // Create a block for the increment. In case of a 'continue', we jump there.
  JumpDest Continue = getJumpDestInCurrentScope("for.inc");

  // Store the blocks to use for break and continue.
  BreakContinueStack.push_back(BreakContinue(LoopExit, Continue));

  {
    // Create a separate cleanup scope for the loop variable and body.
    LexicalScope BodyScope(*this, S.getSourceRange());
    EmitStmt(S.getLoopVarStmt());
    EmitStmt(S.getBody());
  }

  EmitStopPoint(&S);
  // If there is an increment, emit it next.
  EmitBlock(Continue.getBlock());
  EmitStmt(S.getInc());

  BreakContinueStack.pop_back();

  EmitBranch(CondBlock);

  ForScope.ForceCleanup();

  LoopStack.pop();

  // Emit the fall-through block.
  EmitBlock(LoopExit.getBlock(), true);
}

void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) {
  if (RV.isScalar()) {
    Builder.CreateStore(RV.getScalarVal(), ReturnValue);
  } else if (RV.isAggregate()) {
    LValue Dest = MakeAddrLValue(ReturnValue, Ty);
    LValue Src = MakeAddrLValue(RV.getAggregateAddress(), Ty);
    EmitAggregateCopy(Dest, Src, Ty, getOverlapForReturnValue());
  } else {
    EmitStoreOfComplex(RV.getComplexVal(), MakeAddrLValue(ReturnValue, Ty),
                       /*init*/ true);
  }
  EmitBranchThroughCleanup(ReturnBlock);
}

namespace {
// RAII struct used to save and restore a return statment's result expression.
struct SaveRetExprRAII {
  SaveRetExprRAII(const Expr *RetExpr, CodeGenFunction &CGF)
      : OldRetExpr(CGF.RetExpr), CGF(CGF) {
    CGF.RetExpr = RetExpr;
  }
  ~SaveRetExprRAII() { CGF.RetExpr = OldRetExpr; }
  const Expr *OldRetExpr;
  CodeGenFunction &CGF;
};
} // namespace

/// If we have 'return f(...);', where both caller and callee are SwiftAsync,
/// codegen it as 'tail call ...; ret void;'.
static void makeTailCallIfSwiftAsync(const CallExpr *CE, CGBuilderTy &Builder,
                                     const CGFunctionInfo *CurFnInfo) {
  auto calleeQualType = CE->getCallee()->getType();
  const FunctionType *calleeType = nullptr;
  if (calleeQualType->isFunctionPointerType() ||
      calleeQualType->isFunctionReferenceType() ||
      calleeQualType->isBlockPointerType() ||
      calleeQualType->isMemberFunctionPointerType()) {
    calleeType = calleeQualType->getPointeeType()->castAs<FunctionType>();
  } else if (auto *ty = dyn_cast<FunctionType>(calleeQualType)) {
    calleeType = ty;
  } else if (auto CMCE = dyn_cast<CXXMemberCallExpr>(CE)) {
    if (auto methodDecl = CMCE->getMethodDecl()) {
      // getMethodDecl() doesn't handle member pointers at the moment.
      calleeType = methodDecl->getType()->castAs<FunctionType>();
    } else {
      return;
    }
  } else {
    return;
  }
  if (calleeType->getCallConv() == CallingConv::CC_SwiftAsync &&
      (CurFnInfo->getASTCallingConvention() == CallingConv::CC_SwiftAsync)) {
    auto CI = cast<llvm::CallInst>(&Builder.GetInsertBlock()->back());
    CI->setTailCallKind(llvm::CallInst::TCK_MustTail);
    Builder.CreateRetVoid();
    Builder.ClearInsertionPoint();
  }
}

/// EmitReturnStmt - Note that due to GCC extensions, this can have an operand
/// if the function returns void, or may be missing one if the function returns
/// non-void.  Fun stuff :).
void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) {
  if (requiresReturnValueCheck()) {
    llvm::Constant *SLoc = EmitCheckSourceLocation(S.getBeginLoc());
    auto *SLocPtr =
        new llvm::GlobalVariable(CGM.getModule(), SLoc->getType(), false,
                                 llvm::GlobalVariable::PrivateLinkage, SLoc);
    SLocPtr->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
    CGM.getSanitizerMetadata()->disableSanitizerForGlobal(SLocPtr);
    assert(ReturnLocation.isValid() && "No valid return location");
    Builder.CreateStore(Builder.CreateBitCast(SLocPtr, Int8PtrTy),
                        ReturnLocation);
  }

  // Returning from an outlined SEH helper is UB, and we already warn on it.
  if (IsOutlinedSEHHelper) {
    Builder.CreateUnreachable();
    Builder.ClearInsertionPoint();
  }

  // Emit the result value, even if unused, to evaluate the side effects.
  const Expr *RV = S.getRetValue();

  // Record the result expression of the return statement. The recorded
  // expression is used to determine whether a block capture's lifetime should
  // end at the end of the full expression as opposed to the end of the scope
  // enclosing the block expression.
  //
  // This permits a small, easily-implemented exception to our over-conservative
  // rules about not jumping to statements following block literals with
  // non-trivial cleanups.
  SaveRetExprRAII SaveRetExpr(RV, *this);

  RunCleanupsScope cleanupScope(*this);
  if (const auto *EWC = dyn_cast_or_null<ExprWithCleanups>(RV))
    RV = EWC->getSubExpr();
  // FIXME: Clean this up by using an LValue for ReturnTemp,
  // EmitStoreThroughLValue, and EmitAnyExpr.
  // Check if the NRVO candidate was not globalized in OpenMP mode.
  if (getLangOpts().ElideConstructors && S.getNRVOCandidate() &&
      S.getNRVOCandidate()->isNRVOVariable() &&
      (!getLangOpts().OpenMP ||
       !CGM.getOpenMPRuntime()
            .getAddressOfLocalVariable(*this, S.getNRVOCandidate())
            .isValid())) {
    // Apply the named return value optimization for this return statement,
    // which means doing nothing: the appropriate result has already been
    // constructed into the NRVO variable.

    // If there is an NRVO flag for this variable, set it to 1 into indicate
    // that the cleanup code should not destroy the variable.
    if (llvm::Value *NRVOFlag = NRVOFlags[S.getNRVOCandidate()])
      Builder.CreateFlagStore(Builder.getTrue(), NRVOFlag);
  } else if (!ReturnValue.isValid() || (RV && RV->getType()->isVoidType())) {
    // Make sure not to return anything, but evaluate the expression
    // for side effects.
    if (RV) {
      EmitAnyExpr(RV);
      if (auto *CE = dyn_cast<CallExpr>(RV))
        makeTailCallIfSwiftAsync(CE, Builder, CurFnInfo);
    }
  } else if (!RV) {
    // Do nothing (return value is left uninitialized)
  } else if (FnRetTy->isReferenceType()) {
    // If this function returns a reference, take the address of the expression
    // rather than the value.
    RValue Result = EmitReferenceBindingToExpr(RV);
    Builder.CreateStore(Result.getScalarVal(), ReturnValue);
  } else {
    switch (getEvaluationKind(RV->getType())) {
    case TEK_Scalar:
      Builder.CreateStore(EmitScalarExpr(RV), ReturnValue);
      break;
    case TEK_Complex:
      EmitComplexExprIntoLValue(RV, MakeAddrLValue(ReturnValue, RV->getType()),
                                /*isInit*/ true);
      break;
    case TEK_Aggregate:
      EmitAggExpr(RV, AggValueSlot::forAddr(
                          ReturnValue, Qualifiers(),
                          AggValueSlot::IsDestructed,
                          AggValueSlot::DoesNotNeedGCBarriers,
                          AggValueSlot::IsNotAliased,
                          getOverlapForReturnValue()));
      break;
    }
  }

  ++NumReturnExprs;
  if (!RV || RV->isEvaluatable(getContext()))
    ++NumSimpleReturnExprs;

  cleanupScope.ForceCleanup();
  EmitBranchThroughCleanup(ReturnBlock);
}

void CodeGenFunction::EmitDeclStmt(const DeclStmt &S) {
  // As long as debug info is modeled with instructions, we have to ensure we
  // have a place to insert here and write the stop point here.
  if (HaveInsertPoint())
    EmitStopPoint(&S);

  for (const auto *I : S.decls())
    EmitDecl(*I);
}

void CodeGenFunction::EmitBreakStmt(const BreakStmt &S) {
  assert(!BreakContinueStack.empty() && "break stmt not in a loop or switch!");

  // If this code is reachable then emit a stop point (if generating
  // debug info). We have to do this ourselves because we are on the
  // "simple" statement path.
  if (HaveInsertPoint())
    EmitStopPoint(&S);

  EmitBranchThroughCleanup(BreakContinueStack.back().BreakBlock);
}

void CodeGenFunction::EmitContinueStmt(const ContinueStmt &S) {
  assert(!BreakContinueStack.empty() && "continue stmt not in a loop!");

  // If this code is reachable then emit a stop point (if generating
  // debug info). We have to do this ourselves because we are on the
  // "simple" statement path.
  if (HaveInsertPoint())
    EmitStopPoint(&S);

  EmitBranchThroughCleanup(BreakContinueStack.back().ContinueBlock);
}

/// EmitCaseStmtRange - If case statement range is not too big then
/// add multiple cases to switch instruction, one for each value within
/// the range. If range is too big then emit "if" condition check.
void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S,
                                        ArrayRef<const Attr *> Attrs) {
  assert(S.getRHS() && "Expected RHS value in CaseStmt");

  llvm::APSInt LHS = S.getLHS()->EvaluateKnownConstInt(getContext());
  llvm::APSInt RHS = S.getRHS()->EvaluateKnownConstInt(getContext());

  // Emit the code for this case. We do this first to make sure it is
  // properly chained from our predecessor before generating the
  // switch machinery to enter this block.
  llvm::BasicBlock *CaseDest = createBasicBlock("sw.bb");
  EmitBlockWithFallThrough(CaseDest, &S);
  EmitStmt(S.getSubStmt());

  // If range is empty, do nothing.
  if (LHS.isSigned() ? RHS.slt(LHS) : RHS.ult(LHS))
    return;

  Stmt::Likelihood LH = Stmt::getLikelihood(Attrs);
  llvm::APInt Range = RHS - LHS;
  // FIXME: parameters such as this should not be hardcoded.
  if (Range.ult(llvm::APInt(Range.getBitWidth(), 64))) {
    // Range is small enough to add multiple switch instruction cases.
    uint64_t Total = getProfileCount(&S);
    unsigned NCases = Range.getZExtValue() + 1;
    // We only have one region counter for the entire set of cases here, so we
    // need to divide the weights evenly between the generated cases, ensuring
    // that the total weight is preserved. E.g., a weight of 5 over three cases
    // will be distributed as weights of 2, 2, and 1.
    uint64_t Weight = Total / NCases, Rem = Total % NCases;
    for (unsigned I = 0; I != NCases; ++I) {
      if (SwitchWeights)
        SwitchWeights->push_back(Weight + (Rem ? 1 : 0));
      else if (SwitchLikelihood)
        SwitchLikelihood->push_back(LH);

      if (Rem)
        Rem--;
      SwitchInsn->addCase(Builder.getInt(LHS), CaseDest);
      ++LHS;
    }
    return;
  }

  // The range is too big. Emit "if" condition into a new block,
  // making sure to save and restore the current insertion point.
  llvm::BasicBlock *RestoreBB = Builder.GetInsertBlock();

  // Push this test onto the chain of range checks (which terminates
  // in the default basic block). The switch's default will be changed
  // to the top of this chain after switch emission is complete.
  llvm::BasicBlock *FalseDest = CaseRangeBlock;
  CaseRangeBlock = createBasicBlock("sw.caserange");

  CurFn->getBasicBlockList().push_back(CaseRangeBlock);
  Builder.SetInsertPoint(CaseRangeBlock);

  // Emit range check.
  llvm::Value *Diff =
    Builder.CreateSub(SwitchInsn->getCondition(), Builder.getInt(LHS));
  llvm::Value *Cond =
    Builder.CreateICmpULE(Diff, Builder.getInt(Range), "inbounds");

  llvm::MDNode *Weights = nullptr;
  if (SwitchWeights) {
    uint64_t ThisCount = getProfileCount(&S);
    uint64_t DefaultCount = (*SwitchWeights)[0];
    Weights = createProfileWeights(ThisCount, DefaultCount);

    // Since we're chaining the switch default through each large case range, we
    // need to update the weight for the default, ie, the first case, to include
    // this case.
    (*SwitchWeights)[0] += ThisCount;
  } else if (SwitchLikelihood)
    Cond = emitCondLikelihoodViaExpectIntrinsic(Cond, LH);

  Builder.CreateCondBr(Cond, CaseDest, FalseDest, Weights);

  // Restore the appropriate insertion point.
  if (RestoreBB)
    Builder.SetInsertPoint(RestoreBB);
  else
    Builder.ClearInsertionPoint();
}

void CodeGenFunction::EmitCaseStmt(const CaseStmt &S,
                                   ArrayRef<const Attr *> Attrs) {
  // If there is no enclosing switch instance that we're aware of, then this
  // case statement and its block can be elided.  This situation only happens
  // when we've constant-folded the switch, are emitting the constant case,
  // and part of the constant case includes another case statement.  For
  // instance: switch (4) { case 4: do { case 5: } while (1); }
  if (!SwitchInsn) {
    EmitStmt(S.getSubStmt());
    return;
  }

  // Handle case ranges.
  if (S.getRHS()) {
    EmitCaseStmtRange(S, Attrs);
    return;
  }

  llvm::ConstantInt *CaseVal =
    Builder.getInt(S.getLHS()->EvaluateKnownConstInt(getContext()));
  if (SwitchLikelihood)
    SwitchLikelihood->push_back(Stmt::getLikelihood(Attrs));

  // If the body of the case is just a 'break', try to not emit an empty block.
  // If we're profiling or we're not optimizing, leave the block in for better
  // debug and coverage analysis.
  if (!CGM.getCodeGenOpts().hasProfileClangInstr() &&
      CGM.getCodeGenOpts().OptimizationLevel > 0 &&
      isa<BreakStmt>(S.getSubStmt())) {
    JumpDest Block = BreakContinueStack.back().BreakBlock;

    // Only do this optimization if there are no cleanups that need emitting.
    if (isObviouslyBranchWithoutCleanups(Block)) {
      if (SwitchWeights)
        SwitchWeights->push_back(getProfileCount(&S));
      SwitchInsn->addCase(CaseVal, Block.getBlock());

      // If there was a fallthrough into this case, make sure to redirect it to
      // the end of the switch as well.
      if (Builder.GetInsertBlock()) {
        Builder.CreateBr(Block.getBlock());
        Builder.ClearInsertionPoint();
      }
      return;
    }
  }

  llvm::BasicBlock *CaseDest = createBasicBlock("sw.bb");
  EmitBlockWithFallThrough(CaseDest, &S);
  if (SwitchWeights)
    SwitchWeights->push_back(getProfileCount(&S));
  SwitchInsn->addCase(CaseVal, CaseDest);

  // Recursively emitting the statement is acceptable, but is not wonderful for
  // code where we have many case statements nested together, i.e.:
  //  case 1:
  //    case 2:
  //      case 3: etc.
  // Handling this recursively will create a new block for each case statement
  // that falls through to the next case which is IR intensive.  It also causes
  // deep recursion which can run into stack depth limitations.  Handle
  // sequential non-range case statements specially.
  //
  // TODO When the next case has a likelihood attribute the code returns to the
  // recursive algorithm. Maybe improve this case if it becomes common practice
  // to use a lot of attributes.
  const CaseStmt *CurCase = &S;
  const CaseStmt *NextCase = dyn_cast<CaseStmt>(S.getSubStmt());

  // Otherwise, iteratively add consecutive cases to this switch stmt.
  while (NextCase && NextCase->getRHS() == nullptr) {
    CurCase = NextCase;
    llvm::ConstantInt *CaseVal =
      Builder.getInt(CurCase->getLHS()->EvaluateKnownConstInt(getContext()));

    if (SwitchWeights)
      SwitchWeights->push_back(getProfileCount(NextCase));
    if (CGM.getCodeGenOpts().hasProfileClangInstr()) {
      CaseDest = createBasicBlock("sw.bb");
      EmitBlockWithFallThrough(CaseDest, CurCase);
    }
    // Since this loop is only executed when the CaseStmt has no attributes
    // use a hard-coded value.
    if (SwitchLikelihood)
      SwitchLikelihood->push_back(Stmt::LH_None);

    SwitchInsn->addCase(CaseVal, CaseDest);
    NextCase = dyn_cast<CaseStmt>(CurCase->getSubStmt());
  }

  // Generate a stop point for debug info if the case statement is
  // followed by a default statement. A fallthrough case before a
  // default case gets its own branch target.
  if (CurCase->getSubStmt()->getStmtClass() == Stmt::DefaultStmtClass)
    EmitStopPoint(CurCase);

  // Normal default recursion for non-cases.
  EmitStmt(CurCase->getSubStmt());
}

void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S,
                                      ArrayRef<const Attr *> Attrs) {
  // If there is no enclosing switch instance that we're aware of, then this
  // default statement can be elided. This situation only happens when we've
  // constant-folded the switch.
  if (!SwitchInsn) {
    EmitStmt(S.getSubStmt());
    return;
  }

  llvm::BasicBlock *DefaultBlock = SwitchInsn->getDefaultDest();
  assert(DefaultBlock->empty() &&
         "EmitDefaultStmt: Default block already defined?");

  if (SwitchLikelihood)
    SwitchLikelihood->front() = Stmt::getLikelihood(Attrs);

  EmitBlockWithFallThrough(DefaultBlock, &S);

  EmitStmt(S.getSubStmt());
}

/// CollectStatementsForCase - Given the body of a 'switch' statement and a
/// constant value that is being switched on, see if we can dead code eliminate
/// the body of the switch to a simple series of statements to emit.  Basically,
/// on a switch (5) we want to find these statements:
///    case 5:
///      printf(...);    <--
///      ++i;            <--
///      break;
///
/// and add them to the ResultStmts vector.  If it is unsafe to do this
/// transformation (for example, one of the elided statements contains a label
/// that might be jumped to), return CSFC_Failure.  If we handled it and 'S'
/// should include statements after it (e.g. the printf() line is a substmt of
/// the case) then return CSFC_FallThrough.  If we handled it and found a break
/// statement, then return CSFC_Success.
///
/// If Case is non-null, then we are looking for the specified case, checking
/// that nothing we jump over contains labels.  If Case is null, then we found
/// the case and are looking for the break.
///
/// If the recursive walk actually finds our Case, then we set FoundCase to
/// true.
///
enum CSFC_Result { CSFC_Failure, CSFC_FallThrough, CSFC_Success };
static CSFC_Result CollectStatementsForCase(const Stmt *S,
                                            const SwitchCase *Case,
                                            bool &FoundCase,
                              SmallVectorImpl<const Stmt*> &ResultStmts) {
  // If this is a null statement, just succeed.
  if (!S)
    return Case ? CSFC_Success : CSFC_FallThrough;

  // If this is the switchcase (case 4: or default) that we're looking for, then
  // we're in business.  Just add the substatement.
  if (const SwitchCase *SC = dyn_cast<SwitchCase>(S)) {
    if (S == Case) {
      FoundCase = true;
      return CollectStatementsForCase(SC->getSubStmt(), nullptr, FoundCase,
                                      ResultStmts);
    }

    // Otherwise, this is some other case or default statement, just ignore it.
    return CollectStatementsForCase(SC->getSubStmt(), Case, FoundCase,
                                    ResultStmts);
  }

  // If we are in the live part of the code and we found our break statement,
  // return a success!
  if (!Case && isa<BreakStmt>(S))
    return CSFC_Success;

  // If this is a switch statement, then it might contain the SwitchCase, the
  // break, or neither.
  if (const CompoundStmt *CS = dyn_cast<CompoundStmt>(S)) {
    // Handle this as two cases: we might be looking for the SwitchCase (if so
    // the skipped statements must be skippable) or we might already have it.
    CompoundStmt::const_body_iterator I = CS->body_begin(), E = CS->body_end();
    bool StartedInLiveCode = FoundCase;
    unsigned StartSize = ResultStmts.size();

    // If we've not found the case yet, scan through looking for it.
    if (Case) {
      // Keep track of whether we see a skipped declaration.  The code could be
      // using the declaration even if it is skipped, so we can't optimize out
      // the decl if the kept statements might refer to it.
      bool HadSkippedDecl = false;

      // If we're looking for the case, just see if we can skip each of the
      // substatements.
      for (; Case && I != E; ++I) {
        HadSkippedDecl |= CodeGenFunction::mightAddDeclToScope(*I);

        switch (CollectStatementsForCase(*I, Case, FoundCase, ResultStmts)) {
        case CSFC_Failure: return CSFC_Failure;
        case CSFC_Success:
          // A successful result means that either 1) that the statement doesn't
          // have the case and is skippable, or 2) does contain the case value
          // and also contains the break to exit the switch.  In the later case,
          // we just verify the rest of the statements are elidable.
          if (FoundCase) {
            // If we found the case and skipped declarations, we can't do the
            // optimization.
            if (HadSkippedDecl)
              return CSFC_Failure;

            for (++I; I != E; ++I)
              if (CodeGenFunction::ContainsLabel(*I, true))
                return CSFC_Failure;
            return CSFC_Success;
          }
          break;
        case CSFC_FallThrough:
          // If we have a fallthrough condition, then we must have found the
          // case started to include statements.  Consider the rest of the
          // statements in the compound statement as candidates for inclusion.
          assert(FoundCase && "Didn't find case but returned fallthrough?");
          // We recursively found Case, so we're not looking for it anymore.
          Case = nullptr;

          // If we found the case and skipped declarations, we can't do the
          // optimization.
          if (HadSkippedDecl)
            return CSFC_Failure;
          break;
        }
      }

      if (!FoundCase)
        return CSFC_Success;

      assert(!HadSkippedDecl && "fallthrough after skipping decl");
    }

    // If we have statements in our range, then we know that the statements are
    // live and need to be added to the set of statements we're tracking.
    bool AnyDecls = false;
    for (; I != E; ++I) {
      AnyDecls |= CodeGenFunction::mightAddDeclToScope(*I);

      switch (CollectStatementsForCase(*I, nullptr, FoundCase, ResultStmts)) {
      case CSFC_Failure: return CSFC_Failure;
      case CSFC_FallThrough:
        // A fallthrough result means that the statement was simple and just
        // included in ResultStmt, keep adding them afterwards.
        break;
      case CSFC_Success:
        // A successful result means that we found the break statement and
        // stopped statement inclusion.  We just ensure that any leftover stmts
        // are skippable and return success ourselves.
        for (++I; I != E; ++I)
          if (CodeGenFunction::ContainsLabel(*I, true))
            return CSFC_Failure;
        return CSFC_Success;
      }
    }

    // If we're about to fall out of a scope without hitting a 'break;', we
    // can't perform the optimization if there were any decls in that scope
    // (we'd lose their end-of-lifetime).
    if (AnyDecls) {
      // If the entire compound statement was live, there's one more thing we
      // can try before giving up: emit the whole thing as a single statement.
      // We can do that unless the statement contains a 'break;'.
      // FIXME: Such a break must be at the end of a construct within this one.
      // We could emit this by just ignoring the BreakStmts entirely.
      if (StartedInLiveCode && !CodeGenFunction::containsBreak(S)) {
        ResultStmts.resize(StartSize);
        ResultStmts.push_back(S);
      } else {
        return CSFC_Failure;
      }
    }

    return CSFC_FallThrough;
  }

  // Okay, this is some other statement that we don't handle explicitly, like a
  // for statement or increment etc.  If we are skipping over this statement,
  // just verify it doesn't have labels, which would make it invalid to elide.
  if (Case) {
    if (CodeGenFunction::ContainsLabel(S, true))
      return CSFC_Failure;
    return CSFC_Success;
  }

  // Otherwise, we want to include this statement.  Everything is cool with that
  // so long as it doesn't contain a break out of the switch we're in.
  if (CodeGenFunction::containsBreak(S)) return CSFC_Failure;

  // Otherwise, everything is great.  Include the statement and tell the caller
  // that we fall through and include the next statement as well.
  ResultStmts.push_back(S);
  return CSFC_FallThrough;
}

/// FindCaseStatementsForValue - Find the case statement being jumped to and
/// then invoke CollectStatementsForCase to find the list of statements to emit
/// for a switch on constant.  See the comment above CollectStatementsForCase
/// for more details.
static bool FindCaseStatementsForValue(const SwitchStmt &S,
                                       const llvm::APSInt &ConstantCondValue,
                                SmallVectorImpl<const Stmt*> &ResultStmts,
                                       ASTContext &C,
                                       const SwitchCase *&ResultCase) {
  // First step, find the switch case that is being branched to.  We can do this
  // efficiently by scanning the SwitchCase list.
  const SwitchCase *Case = S.getSwitchCaseList();
  const DefaultStmt *DefaultCase = nullptr;

  for (; Case; Case = Case->getNextSwitchCase()) {
    // It's either a default or case.  Just remember the default statement in
    // case we're not jumping to any numbered cases.
    if (const DefaultStmt *DS = dyn_cast<DefaultStmt>(Case)) {
      DefaultCase = DS;
      continue;
    }

    // Check to see if this case is the one we're looking for.
    const CaseStmt *CS = cast<CaseStmt>(Case);
    // Don't handle case ranges yet.
    if (CS->getRHS()) return false;

    // If we found our case, remember it as 'case'.
    if (CS->getLHS()->EvaluateKnownConstInt(C) == ConstantCondValue)
      break;
  }

  // If we didn't find a matching case, we use a default if it exists, or we
  // elide the whole switch body!
  if (!Case) {
    // It is safe to elide the body of the switch if it doesn't contain labels
    // etc.  If it is safe, return successfully with an empty ResultStmts list.
    if (!DefaultCase)
      return !CodeGenFunction::ContainsLabel(&S);
    Case = DefaultCase;
  }

  // Ok, we know which case is being jumped to, try to collect all the
  // statements that follow it.  This can fail for a variety of reasons.  Also,
  // check to see that the recursive walk actually found our case statement.
  // Insane cases like this can fail to find it in the recursive walk since we
  // don't handle every stmt kind:
  // switch (4) {
  //   while (1) {
  //     case 4: ...
  bool FoundCase = false;
  ResultCase = Case;
  return CollectStatementsForCase(S.getBody(), Case, FoundCase,
                                  ResultStmts) != CSFC_Failure &&
         FoundCase;
}

static Optional<SmallVector<uint64_t, 16>>
getLikelihoodWeights(ArrayRef<Stmt::Likelihood> Likelihoods) {
  // Are there enough branches to weight them?
  if (Likelihoods.size() <= 1)
    return None;

  uint64_t NumUnlikely = 0;
  uint64_t NumNone = 0;
  uint64_t NumLikely = 0;
  for (const auto LH : Likelihoods) {
    switch (LH) {
    case Stmt::LH_Unlikely:
      ++NumUnlikely;
      break;
    case Stmt::LH_None:
      ++NumNone;
      break;
    case Stmt::LH_Likely:
      ++NumLikely;
      break;
    }
  }

  // Is there a likelihood attribute used?
  if (NumUnlikely == 0 && NumLikely == 0)
    return None;

  // When multiple cases share the same code they can be combined during
  // optimization. In that case the weights of the branch will be the sum of
  // the individual weights. Make sure the combined sum of all neutral cases
  // doesn't exceed the value of a single likely attribute.
  // The additions both avoid divisions by 0 and make sure the weights of None
  // don't exceed the weight of Likely.
  const uint64_t Likely = INT32_MAX / (NumLikely + 2);
  const uint64_t None = Likely / (NumNone + 1);
  const uint64_t Unlikely = 0;

  SmallVector<uint64_t, 16> Result;
  Result.reserve(Likelihoods.size());
  for (const auto LH : Likelihoods) {
    switch (LH) {
    case Stmt::LH_Unlikely:
      Result.push_back(Unlikely);
      break;
    case Stmt::LH_None:
      Result.push_back(None);
      break;
    case Stmt::LH_Likely:
      Result.push_back(Likely);
      break;
    }
  }

  return Result;
}

void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) {
  // Handle nested switch statements.
  llvm::SwitchInst *SavedSwitchInsn = SwitchInsn;
  SmallVector<uint64_t, 16> *SavedSwitchWeights = SwitchWeights;
  SmallVector<Stmt::Likelihood, 16> *SavedSwitchLikelihood = SwitchLikelihood;
  llvm::BasicBlock *SavedCRBlock = CaseRangeBlock;

  // See if we can constant fold the condition of the switch and therefore only
  // emit the live case statement (if any) of the switch.
  llvm::APSInt ConstantCondValue;
  if (ConstantFoldsToSimpleInteger(S.getCond(), ConstantCondValue)) {
    SmallVector<const Stmt*, 4> CaseStmts;
    const SwitchCase *Case = nullptr;
    if (FindCaseStatementsForValue(S, ConstantCondValue, CaseStmts,
                                   getContext(), Case)) {
      if (Case)
        incrementProfileCounter(Case);
      RunCleanupsScope ExecutedScope(*this);

      if (S.getInit())
        EmitStmt(S.getInit());

      // Emit the condition variable if needed inside the entire cleanup scope
      // used by this special case for constant folded switches.
      if (S.getConditionVariable())
        EmitDecl(*S.getConditionVariable());

      // At this point, we are no longer "within" a switch instance, so
      // we can temporarily enforce this to ensure that any embedded case
      // statements are not emitted.
      SwitchInsn = nullptr;

      // Okay, we can dead code eliminate everything except this case.  Emit the
      // specified series of statements and we're good.
      for (unsigned i = 0, e = CaseStmts.size(); i != e; ++i)
        EmitStmt(CaseStmts[i]);
      incrementProfileCounter(&S);

      // Now we want to restore the saved switch instance so that nested
      // switches continue to function properly
      SwitchInsn = SavedSwitchInsn;

      return;
    }
  }

  JumpDest SwitchExit = getJumpDestInCurrentScope("sw.epilog");

  RunCleanupsScope ConditionScope(*this);

  if (S.getInit())
    EmitStmt(S.getInit());

  if (S.getConditionVariable())
    EmitDecl(*S.getConditionVariable());
  llvm::Value *CondV = EmitScalarExpr(S.getCond());

  // Create basic block to hold stuff that comes after switch
  // statement. We also need to create a default block now so that
  // explicit case ranges tests can have a place to jump to on
  // failure.
  llvm::BasicBlock *DefaultBlock = createBasicBlock("sw.default");
  SwitchInsn = Builder.CreateSwitch(CondV, DefaultBlock);
  if (PGO.haveRegionCounts()) {
    // Walk the SwitchCase list to find how many there are.
    uint64_t DefaultCount = 0;
    unsigned NumCases = 0;
    for (const SwitchCase *Case = S.getSwitchCaseList();
         Case;
         Case = Case->getNextSwitchCase()) {
      if (isa<DefaultStmt>(Case))
        DefaultCount = getProfileCount(Case);
      NumCases += 1;
    }
    SwitchWeights = new SmallVector<uint64_t, 16>();
    SwitchWeights->reserve(NumCases);
    // The default needs to be first. We store the edge count, so we already
    // know the right weight.
    SwitchWeights->push_back(DefaultCount);
  } else if (CGM.getCodeGenOpts().OptimizationLevel) {
    SwitchLikelihood = new SmallVector<Stmt::Likelihood, 16>();
    // Initialize the default case.
    SwitchLikelihood->push_back(Stmt::LH_None);
  }

  CaseRangeBlock = DefaultBlock;

  // Clear the insertion point to indicate we are in unreachable code.
  Builder.ClearInsertionPoint();

  // All break statements jump to NextBlock. If BreakContinueStack is non-empty
  // then reuse last ContinueBlock.
  JumpDest OuterContinue;
  if (!BreakContinueStack.empty())
    OuterContinue = BreakContinueStack.back().ContinueBlock;

  BreakContinueStack.push_back(BreakContinue(SwitchExit, OuterContinue));

  // Emit switch body.
  EmitStmt(S.getBody());

  BreakContinueStack.pop_back();

  // Update the default block in case explicit case range tests have
  // been chained on top.
  SwitchInsn->setDefaultDest(CaseRangeBlock);

  // If a default was never emitted:
  if (!DefaultBlock->getParent()) {
    // If we have cleanups, emit the default block so that there's a
    // place to jump through the cleanups from.
    if (ConditionScope.requiresCleanups()) {
      EmitBlock(DefaultBlock);

    // Otherwise, just forward the default block to the switch end.
    } else {
      DefaultBlock->replaceAllUsesWith(SwitchExit.getBlock());
      delete DefaultBlock;
    }
  }

  ConditionScope.ForceCleanup();

  // Emit continuation.
  EmitBlock(SwitchExit.getBlock(), true);
  incrementProfileCounter(&S);

  // If the switch has a condition wrapped by __builtin_unpredictable,
  // create metadata that specifies that the switch is unpredictable.
  // Don't bother if not optimizing because that metadata would not be used.
  auto *Call = dyn_cast<CallExpr>(S.getCond());
  if (Call && CGM.getCodeGenOpts().OptimizationLevel != 0) {
    auto *FD = dyn_cast_or_null<FunctionDecl>(Call->getCalleeDecl());
    if (FD && FD->getBuiltinID() == Builtin::BI__builtin_unpredictable) {
      llvm::MDBuilder MDHelper(getLLVMContext());
      SwitchInsn->setMetadata(llvm::LLVMContext::MD_unpredictable,
                              MDHelper.createUnpredictable());
    }
  }

  if (SwitchWeights) {
    assert(SwitchWeights->size() == 1 + SwitchInsn->getNumCases() &&
           "switch weights do not match switch cases");
    // If there's only one jump destination there's no sense weighting it.
    if (SwitchWeights->size() > 1)
      SwitchInsn->setMetadata(llvm::LLVMContext::MD_prof,
                              createProfileWeights(*SwitchWeights));
    delete SwitchWeights;
  } else if (SwitchLikelihood) {
    assert(SwitchLikelihood->size() == 1 + SwitchInsn->getNumCases() &&
           "switch likelihoods do not match switch cases");
    Optional<SmallVector<uint64_t, 16>> LHW =
        getLikelihoodWeights(*SwitchLikelihood);
    if (LHW) {
      llvm::MDBuilder MDHelper(CGM.getLLVMContext());
      SwitchInsn->setMetadata(llvm::LLVMContext::MD_prof,
                              createProfileWeights(*LHW));
    }
    delete SwitchLikelihood;
  }
  SwitchInsn = SavedSwitchInsn;
  SwitchWeights = SavedSwitchWeights;
  SwitchLikelihood = SavedSwitchLikelihood;
  CaseRangeBlock = SavedCRBlock;
}

static std::string
SimplifyConstraint(const char *Constraint, const TargetInfo &Target,
                 SmallVectorImpl<TargetInfo::ConstraintInfo> *OutCons=nullptr) {
  std::string Result;

  while (*Constraint) {
    switch (*Constraint) {
    default:
      Result += Target.convertConstraint(Constraint);
      break;
    // Ignore these
    case '*':
    case '?':
    case '!':
    case '=': // Will see this and the following in mult-alt constraints.
    case '+':
      break;
    case '#': // Ignore the rest of the constraint alternative.
      while (Constraint[1] && Constraint[1] != ',')
        Constraint++;
      break;
    case '&':
    case '%':
      Result += *Constraint;
      while (Constraint[1] && Constraint[1] == *Constraint)
        Constraint++;
      break;
    case ',':
      Result += "|";
      break;
    case 'g':
      Result += "imr";
      break;
    case '[': {
      assert(OutCons &&
             "Must pass output names to constraints with a symbolic name");
      unsigned Index;
      bool result = Target.resolveSymbolicName(Constraint, *OutCons, Index);
      assert(result && "Could not resolve symbolic name"); (void)result;
      Result += llvm::utostr(Index);
      break;
    }
    }

    Constraint++;
  }

  return Result;
}

/// AddVariableConstraints - Look at AsmExpr and if it is a variable declared
/// as using a particular register add that as a constraint that will be used
/// in this asm stmt.
static std::string
AddVariableConstraints(const std::string &Constraint, const Expr &AsmExpr,
                       const TargetInfo &Target, CodeGenModule &CGM,
                       const AsmStmt &Stmt, const bool EarlyClobber,
                       std::string *GCCReg = nullptr) {
  const DeclRefExpr *AsmDeclRef = dyn_cast<DeclRefExpr>(&AsmExpr);
  if (!AsmDeclRef)
    return Constraint;
  const ValueDecl &Value = *AsmDeclRef->getDecl();
  const VarDecl *Variable = dyn_cast<VarDecl>(&Value);
  if (!Variable)
    return Constraint;
  if (Variable->getStorageClass() != SC_Register)
    return Constraint;
  AsmLabelAttr *Attr = Variable->getAttr<AsmLabelAttr>();
  if (!Attr)
    return Constraint;
  StringRef Register = Attr->getLabel();
  assert(Target.isValidGCCRegisterName(Register));
  // We're using validateOutputConstraint here because we only care if
  // this is a register constraint.
  TargetInfo::ConstraintInfo Info(Constraint, "");
  if (Target.validateOutputConstraint(Info) &&
      !Info.allowsRegister()) {
    CGM.ErrorUnsupported(&Stmt, "__asm__");
    return Constraint;
  }
  // Canonicalize the register here before returning it.
  Register = Target.getNormalizedGCCRegisterName(Register);
  if (GCCReg != nullptr)
    *GCCReg = Register.str();
  return (EarlyClobber ? "&{" : "{") + Register.str() + "}";
}

std::pair<llvm::Value*, llvm::Type *> CodeGenFunction::EmitAsmInputLValue(
    const TargetInfo::ConstraintInfo &Info, LValue InputValue,
    QualType InputType, std::string &ConstraintStr, SourceLocation Loc) {
  if (Info.allowsRegister() || !Info.allowsMemory()) {
    if (CodeGenFunction::hasScalarEvaluationKind(InputType))
      return {EmitLoadOfLValue(InputValue, Loc).getScalarVal(), nullptr};

    llvm::Type *Ty = ConvertType(InputType);
    uint64_t Size = CGM.getDataLayout().getTypeSizeInBits(Ty);
    if ((Size <= 64 && llvm::isPowerOf2_64(Size)) ||
        getTargetHooks().isScalarizableAsmOperand(*this, Ty)) {
      Ty = llvm::IntegerType::get(getLLVMContext(), Size);

      return {Builder.CreateLoad(Builder.CreateElementBitCast(
                  InputValue.getAddress(*this), Ty)),
              nullptr};
    }
  }

  Address Addr = InputValue.getAddress(*this);
  ConstraintStr += '*';
  return {Addr.getPointer(), Addr.getElementType()};
}

std::pair<llvm::Value *, llvm::Type *>
CodeGenFunction::EmitAsmInput(const TargetInfo::ConstraintInfo &Info,
                              const Expr *InputExpr,
                              std::string &ConstraintStr) {
  // If this can't be a register or memory, i.e., has to be a constant
  // (immediate or symbolic), try to emit it as such.
  if (!Info.allowsRegister() && !Info.allowsMemory()) {
    if (Info.requiresImmediateConstant()) {
      Expr::EvalResult EVResult;
      InputExpr->EvaluateAsRValue(EVResult, getContext(), true);

      llvm::APSInt IntResult;
      if (EVResult.Val.toIntegralConstant(IntResult, InputExpr->getType(),
                                          getContext()))
        return {llvm::ConstantInt::get(getLLVMContext(), IntResult), nullptr};
    }

    Expr::EvalResult Result;
    if (InputExpr->EvaluateAsInt(Result, getContext()))
      return {llvm::ConstantInt::get(getLLVMContext(), Result.Val.getInt()),
              nullptr};
  }

  if (Info.allowsRegister() || !Info.allowsMemory())
    if (CodeGenFunction::hasScalarEvaluationKind(InputExpr->getType()))
      return {EmitScalarExpr(InputExpr), nullptr};
  if (InputExpr->getStmtClass() == Expr::CXXThisExprClass)
    return {EmitScalarExpr(InputExpr), nullptr};
  InputExpr = InputExpr->IgnoreParenNoopCasts(getContext());
  LValue Dest = EmitLValue(InputExpr);
  return EmitAsmInputLValue(Info, Dest, InputExpr->getType(), ConstraintStr,
                            InputExpr->getExprLoc());
}

/// getAsmSrcLocInfo - Return the !srcloc metadata node to attach to an inline
/// asm call instruction.  The !srcloc MDNode contains a list of constant
/// integers which are the source locations of the start of each line in the
/// asm.
static llvm::MDNode *getAsmSrcLocInfo(const StringLiteral *Str,
                                      CodeGenFunction &CGF) {
  SmallVector<llvm::Metadata *, 8> Locs;
  // Add the location of the first line to the MDNode.
  Locs.push_back(llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
      CGF.Int64Ty, Str->getBeginLoc().getRawEncoding())));
  StringRef StrVal = Str->getString();
  if (!StrVal.empty()) {
    const SourceManager &SM = CGF.CGM.getContext().getSourceManager();
    const LangOptions &LangOpts = CGF.CGM.getLangOpts();
    unsigned StartToken = 0;
    unsigned ByteOffset = 0;

    // Add the location of the start of each subsequent line of the asm to the
    // MDNode.
    for (unsigned i = 0, e = StrVal.size() - 1; i != e; ++i) {
      if (StrVal[i] != '\n') continue;
      SourceLocation LineLoc = Str->getLocationOfByte(
          i + 1, SM, LangOpts, CGF.getTarget(), &StartToken, &ByteOffset);
      Locs.push_back(llvm::ConstantAsMetadata::get(
          llvm::ConstantInt::get(CGF.Int64Ty, LineLoc.getRawEncoding())));
    }
  }

  return llvm::MDNode::get(CGF.getLLVMContext(), Locs);
}

static void UpdateAsmCallInst(llvm::CallBase &Result, bool HasSideEffect,
                              bool HasUnwindClobber, bool ReadOnly,
                              bool ReadNone, bool NoMerge, const AsmStmt &S,
                              const std::vector<llvm::Type *> &ResultRegTypes,
                              const std::vector<llvm::Type *> &ArgElemTypes,
                              CodeGenFunction &CGF,
                              std::vector<llvm::Value *> &RegResults) {
  if (!HasUnwindClobber)
    Result.addFnAttr(llvm::Attribute::NoUnwind);

  if (NoMerge)
    Result.addFnAttr(llvm::Attribute::NoMerge);
  // Attach readnone and readonly attributes.
  if (!HasSideEffect) {
    if (ReadNone)
      Result.addFnAttr(llvm::Attribute::ReadNone);
    else if (ReadOnly)
      Result.addFnAttr(llvm::Attribute::ReadOnly);
  }

  // Add elementtype attribute for indirect constraints.
  for (auto Pair : llvm::enumerate(ArgElemTypes)) {
    if (Pair.value()) {
      auto Attr = llvm::Attribute::get(
          CGF.getLLVMContext(), llvm::Attribute::ElementType, Pair.value());
      Result.addParamAttr(Pair.index(), Attr);
    }
  }

  // Slap the source location of the inline asm into a !srcloc metadata on the
  // call.
  if (const auto *gccAsmStmt = dyn_cast<GCCAsmStmt>(&S))
    Result.setMetadata("srcloc",
                       getAsmSrcLocInfo(gccAsmStmt->getAsmString(), CGF));
  else {
    // At least put the line number on MS inline asm blobs.
    llvm::Constant *Loc =
        llvm::ConstantInt::get(CGF.Int64Ty, S.getAsmLoc().getRawEncoding());
    Result.setMetadata("srcloc",
                       llvm::MDNode::get(CGF.getLLVMContext(),
                                         llvm::ConstantAsMetadata::get(Loc)));
  }

  if (CGF.getLangOpts().assumeFunctionsAreConvergent())
    // Conservatively, mark all inline asm blocks in CUDA or OpenCL as
    // convergent (meaning, they may call an intrinsically convergent op, such
    // as bar.sync, and so can't have certain optimizations applied around
    // them).
    Result.addFnAttr(llvm::Attribute::Convergent);
  // Extract all of the register value results from the asm.
  if (ResultRegTypes.size() == 1) {
    RegResults.push_back(&Result);
  } else {
    for (unsigned i = 0, e = ResultRegTypes.size(); i != e; ++i) {
      llvm::Value *Tmp = CGF.Builder.CreateExtractValue(&Result, i, "asmresult");
      RegResults.push_back(Tmp);
    }
  }
}

void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) {
  // Assemble the final asm string.
  std::string AsmString = S.generateAsmString(getContext());

  // Get all the output and input constraints together.
  SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
  SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;

  for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) {
    StringRef Name;
    if (const GCCAsmStmt *GAS = dyn_cast<GCCAsmStmt>(&S))
      Name = GAS->getOutputName(i);
    TargetInfo::ConstraintInfo Info(S.getOutputConstraint(i), Name);
    bool IsValid = getTarget().validateOutputConstraint(Info); (void)IsValid;
    assert(IsValid && "Failed to parse output constraint");
    OutputConstraintInfos.push_back(Info);
  }

  for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) {
    StringRef Name;
    if (const GCCAsmStmt *GAS = dyn_cast<GCCAsmStmt>(&S))
      Name = GAS->getInputName(i);
    TargetInfo::ConstraintInfo Info(S.getInputConstraint(i), Name);
    bool IsValid =
      getTarget().validateInputConstraint(OutputConstraintInfos, Info);
    assert(IsValid && "Failed to parse input constraint"); (void)IsValid;
    InputConstraintInfos.push_back(Info);
  }

  std::string Constraints;

  std::vector<LValue> ResultRegDests;
  std::vector<QualType> ResultRegQualTys;
  std::vector<llvm::Type *> ResultRegTypes;
  std::vector<llvm::Type *> ResultTruncRegTypes;
  std::vector<llvm::Type *> ArgTypes;
  std::vector<llvm::Type *> ArgElemTypes;
  std::vector<llvm::Value*> Args;
  llvm::BitVector ResultTypeRequiresCast;

  // Keep track of inout constraints.
  std::string InOutConstraints;
  std::vector<llvm::Value*> InOutArgs;
  std::vector<llvm::Type*> InOutArgTypes;
  std::vector<llvm::Type*> InOutArgElemTypes;

  // Keep track of out constraints for tied input operand.
  std::vector<std::string> OutputConstraints;

  // Keep track of defined physregs.
  llvm::SmallSet<std::string, 8> PhysRegOutputs;

  // An inline asm can be marked readonly if it meets the following conditions:
  //  - it doesn't have any sideeffects
  //  - it doesn't clobber memory
  //  - it doesn't return a value by-reference
  // It can be marked readnone if it doesn't have any input memory constraints
  // in addition to meeting the conditions listed above.
  bool ReadOnly = true, ReadNone = true;

  for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) {
    TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i];

    // Simplify the output constraint.
    std::string OutputConstraint(S.getOutputConstraint(i));
    OutputConstraint = SimplifyConstraint(OutputConstraint.c_str() + 1,
                                          getTarget(), &OutputConstraintInfos);

    const Expr *OutExpr = S.getOutputExpr(i);
    OutExpr = OutExpr->IgnoreParenNoopCasts(getContext());

    std::string GCCReg;
    OutputConstraint = AddVariableConstraints(OutputConstraint, *OutExpr,
                                              getTarget(), CGM, S,
                                              Info.earlyClobber(),
                                              &GCCReg);
    // Give an error on multiple outputs to same physreg.
    if (!GCCReg.empty() && !PhysRegOutputs.insert(GCCReg).second)
      CGM.Error(S.getAsmLoc(), "multiple outputs to hard register: " + GCCReg);

    OutputConstraints.push_back(OutputConstraint);
    LValue Dest = EmitLValue(OutExpr);
    if (!Constraints.empty())
      Constraints += ',';

    // If this is a register output, then make the inline asm return it
    // by-value.  If this is a memory result, return the value by-reference.
    QualType QTy = OutExpr->getType();
    const bool IsScalarOrAggregate = hasScalarEvaluationKind(QTy) ||
                                     hasAggregateEvaluationKind(QTy);
    if (!Info.allowsMemory() && IsScalarOrAggregate) {

      Constraints += "=" + OutputConstraint;
      ResultRegQualTys.push_back(QTy);
      ResultRegDests.push_back(Dest);

      llvm::Type *Ty = ConvertTypeForMem(QTy);
      const bool RequiresCast = Info.allowsRegister() &&
          (getTargetHooks().isScalarizableAsmOperand(*this, Ty) ||
           Ty->isAggregateType());

      ResultTruncRegTypes.push_back(Ty);
      ResultTypeRequiresCast.push_back(RequiresCast);

      if (RequiresCast) {
        unsigned Size = getContext().getTypeSize(QTy);
        Ty = llvm::IntegerType::get(getLLVMContext(), Size);
      }
      ResultRegTypes.push_back(Ty);
      // If this output is tied to an input, and if the input is larger, then
      // we need to set the actual result type of the inline asm node to be the
      // same as the input type.
      if (Info.hasMatchingInput()) {
        unsigned InputNo;
        for (InputNo = 0; InputNo != S.getNumInputs(); ++InputNo) {
          TargetInfo::ConstraintInfo &Input = InputConstraintInfos[InputNo];
          if (Input.hasTiedOperand() && Input.getTiedOperand() == i)
            break;
        }
        assert(InputNo != S.getNumInputs() && "Didn't find matching input!");

        QualType InputTy = S.getInputExpr(InputNo)->getType();
        QualType OutputType = OutExpr->getType();

        uint64_t InputSize = getContext().getTypeSize(InputTy);
        if (getContext().getTypeSize(OutputType) < InputSize) {
          // Form the asm to return the value as a larger integer or fp type.
          ResultRegTypes.back() = ConvertType(InputTy);
        }
      }
      if (llvm::Type* AdjTy =
            getTargetHooks().adjustInlineAsmType(*this, OutputConstraint,
                                                 ResultRegTypes.back()))
        ResultRegTypes.back() = AdjTy;
      else {
        CGM.getDiags().Report(S.getAsmLoc(),
                              diag::err_asm_invalid_type_in_input)
            << OutExpr->getType() << OutputConstraint;
      }

      // Update largest vector width for any vector types.
      if (auto *VT = dyn_cast<llvm::VectorType>(ResultRegTypes.back()))
        LargestVectorWidth =
            std::max((uint64_t)LargestVectorWidth,
                     VT->getPrimitiveSizeInBits().getKnownMinSize());
    } else {
      Address DestAddr = Dest.getAddress(*this);
      // Matrix types in memory are represented by arrays, but accessed through
      // vector pointers, with the alignment specified on the access operation.
      // For inline assembly, update pointer arguments to use vector pointers.
      // Otherwise there will be a mis-match if the matrix is also an
      // input-argument which is represented as vector.
      if (isa<MatrixType>(OutExpr->getType().getCanonicalType()))
        DestAddr = Builder.CreateElementBitCast(
            DestAddr, ConvertType(OutExpr->getType()));

      ArgTypes.push_back(DestAddr.getType());
      ArgElemTypes.push_back(DestAddr.getElementType());
      Args.push_back(DestAddr.getPointer());
      Constraints += "=*";
      Constraints += OutputConstraint;
      ReadOnly = ReadNone = false;
    }

    if (Info.isReadWrite()) {
      InOutConstraints += ',';

      const Expr *InputExpr = S.getOutputExpr(i);
      llvm::Value *Arg;
      llvm::Type *ArgElemType;
      std::tie(Arg, ArgElemType) = EmitAsmInputLValue(
          Info, Dest, InputExpr->getType(), InOutConstraints,
          InputExpr->getExprLoc());

      if (llvm::Type* AdjTy =
          getTargetHooks().adjustInlineAsmType(*this, OutputConstraint,
                                               Arg->getType()))
        Arg = Builder.CreateBitCast(Arg, AdjTy);

      // Update largest vector width for any vector types.
      if (auto *VT = dyn_cast<llvm::VectorType>(Arg->getType()))
        LargestVectorWidth =
            std::max((uint64_t)LargestVectorWidth,
                     VT->getPrimitiveSizeInBits().getKnownMinSize());
      // Only tie earlyclobber physregs.
      if (Info.allowsRegister() && (GCCReg.empty() || Info.earlyClobber()))
        InOutConstraints += llvm::utostr(i);
      else
        InOutConstraints += OutputConstraint;

      InOutArgTypes.push_back(Arg->getType());
      InOutArgElemTypes.push_back(ArgElemType);
      InOutArgs.push_back(Arg);
    }
  }

  // If this is a Microsoft-style asm blob, store the return registers (EAX:EDX)
  // to the return value slot. Only do this when returning in registers.
  if (isa<MSAsmStmt>(&S)) {
    const ABIArgInfo &RetAI = CurFnInfo->getReturnInfo();
    if (RetAI.isDirect() || RetAI.isExtend()) {
      // Make a fake lvalue for the return value slot.
      LValue ReturnSlot = MakeAddrLValueWithoutTBAA(ReturnValue, FnRetTy);
      CGM.getTargetCodeGenInfo().addReturnRegisterOutputs(
          *this, ReturnSlot, Constraints, ResultRegTypes, ResultTruncRegTypes,
          ResultRegDests, AsmString, S.getNumOutputs());
      SawAsmBlock = true;
    }
  }

  for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) {
    const Expr *InputExpr = S.getInputExpr(i);

    TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];

    if (Info.allowsMemory())
      ReadNone = false;

    if (!Constraints.empty())
      Constraints += ',';

    // Simplify the input constraint.
    std::string InputConstraint(S.getInputConstraint(i));
    InputConstraint = SimplifyConstraint(InputConstraint.c_str(), getTarget(),
                                         &OutputConstraintInfos);

    InputConstraint = AddVariableConstraints(
        InputConstraint, *InputExpr->IgnoreParenNoopCasts(getContext()),
        getTarget(), CGM, S, false /* No EarlyClobber */);

    std::string ReplaceConstraint (InputConstraint);
    llvm::Value *Arg;
    llvm::Type *ArgElemType;
    std::tie(Arg, ArgElemType) = EmitAsmInput(Info, InputExpr, Constraints);

    // If this input argument is tied to a larger output result, extend the
    // input to be the same size as the output.  The LLVM backend wants to see
    // the input and output of a matching constraint be the same size.  Note
    // that GCC does not define what the top bits are here.  We use zext because
    // that is usually cheaper, but LLVM IR should really get an anyext someday.
    if (Info.hasTiedOperand()) {
      unsigned Output = Info.getTiedOperand();
      QualType OutputType = S.getOutputExpr(Output)->getType();
      QualType InputTy = InputExpr->getType();

      if (getContext().getTypeSize(OutputType) >
          getContext().getTypeSize(InputTy)) {
        // Use ptrtoint as appropriate so that we can do our extension.
        if (isa<llvm::PointerType>(Arg->getType()))
          Arg = Builder.CreatePtrToInt(Arg, IntPtrTy);
        llvm::Type *OutputTy = ConvertType(OutputType);
        if (isa<llvm::IntegerType>(OutputTy))
          Arg = Builder.CreateZExt(Arg, OutputTy);
        else if (isa<llvm::PointerType>(OutputTy))
          Arg = Builder.CreateZExt(Arg, IntPtrTy);
        else if (OutputTy->isFloatingPointTy())
          Arg = Builder.CreateFPExt(Arg, OutputTy);
      }
      // Deal with the tied operands' constraint code in adjustInlineAsmType.
      ReplaceConstraint = OutputConstraints[Output];
    }
    if (llvm::Type* AdjTy =
          getTargetHooks().adjustInlineAsmType(*this, ReplaceConstraint,
                                                   Arg->getType()))
      Arg = Builder.CreateBitCast(Arg, AdjTy);
    else
      CGM.getDiags().Report(S.getAsmLoc(), diag::err_asm_invalid_type_in_input)
          << InputExpr->getType() << InputConstraint;

    // Update largest vector width for any vector types.
    if (auto *VT = dyn_cast<llvm::VectorType>(Arg->getType()))
      LargestVectorWidth =
          std::max((uint64_t)LargestVectorWidth,
                   VT->getPrimitiveSizeInBits().getKnownMinSize());

    ArgTypes.push_back(Arg->getType());
    ArgElemTypes.push_back(ArgElemType);
    Args.push_back(Arg);
    Constraints += InputConstraint;
  }

  // Append the "input" part of inout constraints.
  for (unsigned i = 0, e = InOutArgs.size(); i != e; i++) {
    ArgTypes.push_back(InOutArgTypes[i]);
    ArgElemTypes.push_back(InOutArgElemTypes[i]);
    Args.push_back(InOutArgs[i]);
  }
  Constraints += InOutConstraints;

  // Labels
  SmallVector<llvm::BasicBlock *, 16> Transfer;
  llvm::BasicBlock *Fallthrough = nullptr;
  bool IsGCCAsmGoto = false;
  if (const auto *GS =  dyn_cast<GCCAsmStmt>(&S)) {
    IsGCCAsmGoto = GS->isAsmGoto();
    if (IsGCCAsmGoto) {
      for (const auto *E : GS->labels()) {
        JumpDest Dest = getJumpDestForLabel(E->getLabel());
        Transfer.push_back(Dest.getBlock());
        llvm::BlockAddress *BA =
            llvm::BlockAddress::get(CurFn, Dest.getBlock());
        Args.push_back(BA);
        ArgTypes.push_back(BA->getType());
        ArgElemTypes.push_back(nullptr);
        if (!Constraints.empty())
          Constraints += ',';
        Constraints += 'i';
      }
      Fallthrough = createBasicBlock("asm.fallthrough");
    }
  }

  bool HasUnwindClobber = false;

  // Clobbers
  for (unsigned i = 0, e = S.getNumClobbers(); i != e; i++) {
    StringRef Clobber = S.getClobber(i);

    if (Clobber == "memory")
      ReadOnly = ReadNone = false;
    else if (Clobber == "unwind") {
      HasUnwindClobber = true;
      continue;
    } else if (Clobber != "cc") {
      Clobber = getTarget().getNormalizedGCCRegisterName(Clobber);
      if (CGM.getCodeGenOpts().StackClashProtector &&
          getTarget().isSPRegName(Clobber)) {
        CGM.getDiags().Report(S.getAsmLoc(),
                              diag::warn_stack_clash_protection_inline_asm);
      }
    }

    if (isa<MSAsmStmt>(&S)) {
      if (Clobber == "eax" || Clobber == "edx") {
        if (Constraints.find("=&A") != std::string::npos)
          continue;
        std::string::size_type position1 =
            Constraints.find("={" + Clobber.str() + "}");
        if (position1 != std::string::npos) {
          Constraints.insert(position1 + 1, "&");
          continue;
        }
        std::string::size_type position2 = Constraints.find("=A");
        if (position2 != std::string::npos) {
          Constraints.insert(position2 + 1, "&");
          continue;
        }
      }
    }
    if (!Constraints.empty())
      Constraints += ',';

    Constraints += "~{";
    Constraints += Clobber;
    Constraints += '}';
  }

  assert(!(HasUnwindClobber && IsGCCAsmGoto) &&
         "unwind clobber can't be used with asm goto");

  // Add machine specific clobbers
  std::string MachineClobbers = getTarget().getClobbers();
  if (!MachineClobbers.empty()) {
    if (!Constraints.empty())
      Constraints += ',';
    Constraints += MachineClobbers;
  }

  llvm::Type *ResultType;
  if (ResultRegTypes.empty())
    ResultType = VoidTy;
  else if (ResultRegTypes.size() == 1)
    ResultType = ResultRegTypes[0];
  else
    ResultType = llvm::StructType::get(getLLVMContext(), ResultRegTypes);

  llvm::FunctionType *FTy =
    llvm::FunctionType::get(ResultType, ArgTypes, false);

  bool HasSideEffect = S.isVolatile() || S.getNumOutputs() == 0;

  llvm::InlineAsm::AsmDialect GnuAsmDialect =
      CGM.getCodeGenOpts().getInlineAsmDialect() == CodeGenOptions::IAD_ATT
          ? llvm::InlineAsm::AD_ATT
          : llvm::InlineAsm::AD_Intel;
  llvm::InlineAsm::AsmDialect AsmDialect = isa<MSAsmStmt>(&S) ?
    llvm::InlineAsm::AD_Intel : GnuAsmDialect;

  llvm::InlineAsm *IA = llvm::InlineAsm::get(
      FTy, AsmString, Constraints, HasSideEffect,
      /* IsAlignStack */ false, AsmDialect, HasUnwindClobber);
  std::vector<llvm::Value*> RegResults;
  if (IsGCCAsmGoto) {
    llvm::CallBrInst *Result =
        Builder.CreateCallBr(IA, Fallthrough, Transfer, Args);
    EmitBlock(Fallthrough);
    UpdateAsmCallInst(cast<llvm::CallBase>(*Result), HasSideEffect, false,
                      ReadOnly, ReadNone, InNoMergeAttributedStmt, S,
                      ResultRegTypes, ArgElemTypes, *this, RegResults);
  } else if (HasUnwindClobber) {
    llvm::CallBase *Result = EmitCallOrInvoke(IA, Args, "");
    UpdateAsmCallInst(*Result, HasSideEffect, true, ReadOnly, ReadNone,
                      InNoMergeAttributedStmt, S, ResultRegTypes, ArgElemTypes,
                      *this, RegResults);
  } else {
    llvm::CallInst *Result =
        Builder.CreateCall(IA, Args, getBundlesForFunclet(IA));
    UpdateAsmCallInst(cast<llvm::CallBase>(*Result), HasSideEffect, false,
                      ReadOnly, ReadNone, InNoMergeAttributedStmt, S,
                      ResultRegTypes, ArgElemTypes, *this, RegResults);
  }

  assert(RegResults.size() == ResultRegTypes.size());
  assert(RegResults.size() == ResultTruncRegTypes.size());
  assert(RegResults.size() == ResultRegDests.size());
  // ResultRegDests can be also populated by addReturnRegisterOutputs() above,
  // in which case its size may grow.
  assert(ResultTypeRequiresCast.size() <= ResultRegDests.size());
  for (unsigned i = 0, e = RegResults.size(); i != e; ++i) {
    llvm::Value *Tmp = RegResults[i];
    llvm::Type *TruncTy = ResultTruncRegTypes[i];

    // If the result type of the LLVM IR asm doesn't match the result type of
    // the expression, do the conversion.
    if (ResultRegTypes[i] != ResultTruncRegTypes[i]) {

      // Truncate the integer result to the right size, note that TruncTy can be
      // a pointer.
      if (TruncTy->isFloatingPointTy())
        Tmp = Builder.CreateFPTrunc(Tmp, TruncTy);
      else if (TruncTy->isPointerTy() && Tmp->getType()->isIntegerTy()) {
        uint64_t ResSize = CGM.getDataLayout().getTypeSizeInBits(TruncTy);
        Tmp = Builder.CreateTrunc(Tmp,
                   llvm::IntegerType::get(getLLVMContext(), (unsigned)ResSize));
        Tmp = Builder.CreateIntToPtr(Tmp, TruncTy);
      } else if (Tmp->getType()->isPointerTy() && TruncTy->isIntegerTy()) {
        uint64_t TmpSize =CGM.getDataLayout().getTypeSizeInBits(Tmp->getType());
        Tmp = Builder.CreatePtrToInt(Tmp,
                   llvm::IntegerType::get(getLLVMContext(), (unsigned)TmpSize));
        Tmp = Builder.CreateTrunc(Tmp, TruncTy);
      } else if (TruncTy->isIntegerTy()) {
        Tmp = Builder.CreateZExtOrTrunc(Tmp, TruncTy);
      } else if (TruncTy->isVectorTy()) {
        Tmp = Builder.CreateBitCast(Tmp, TruncTy);
      }
    }

    LValue Dest = ResultRegDests[i];
    // ResultTypeRequiresCast elements correspond to the first
    // ResultTypeRequiresCast.size() elements of RegResults.
    if ((i < ResultTypeRequiresCast.size()) && ResultTypeRequiresCast[i]) {
      unsigned Size = getContext().getTypeSize(ResultRegQualTys[i]);
      Address A = Builder.CreateElementBitCast(Dest.getAddress(*this),
                                               ResultRegTypes[i]);
      if (getTargetHooks().isScalarizableAsmOperand(*this, TruncTy)) {
        Builder.CreateStore(Tmp, A);
        continue;
      }

      QualType Ty = getContext().getIntTypeForBitwidth(Size, /*Signed*/ false);
      if (Ty.isNull()) {
        const Expr *OutExpr = S.getOutputExpr(i);
        CGM.getDiags().Report(OutExpr->getExprLoc(),
                              diag::err_store_value_to_reg);
        return;
      }
      Dest = MakeAddrLValue(A, Ty);
    }
    EmitStoreThroughLValue(RValue::get(Tmp), Dest);
  }
}

LValue CodeGenFunction::InitCapturedStruct(const CapturedStmt &S) {
  const RecordDecl *RD = S.getCapturedRecordDecl();
  QualType RecordTy = getContext().getRecordType(RD);

  // Initialize the captured struct.
  LValue SlotLV =
    MakeAddrLValue(CreateMemTemp(RecordTy, "agg.captured"), RecordTy);

  RecordDecl::field_iterator CurField = RD->field_begin();
  for (CapturedStmt::const_capture_init_iterator I = S.capture_init_begin(),
                                                 E = S.capture_init_end();
       I != E; ++I, ++CurField) {
    LValue LV = EmitLValueForFieldInitialization(SlotLV, *CurField);
    if (CurField->hasCapturedVLAType()) {
      EmitLambdaVLACapture(CurField->getCapturedVLAType(), LV);
    } else {
      EmitInitializerForField(*CurField, LV, *I);
    }
  }

  return SlotLV;
}

/// Generate an outlined function for the body of a CapturedStmt, store any
/// captured variables into the captured struct, and call the outlined function.
llvm::Function *
CodeGenFunction::EmitCapturedStmt(const CapturedStmt &S, CapturedRegionKind K) {
  LValue CapStruct = InitCapturedStruct(S);

  // Emit the CapturedDecl
  CodeGenFunction CGF(CGM, true);
  CGCapturedStmtRAII CapInfoRAII(CGF, new CGCapturedStmtInfo(S, K));
  llvm::Function *F = CGF.GenerateCapturedStmtFunction(S);
  delete CGF.CapturedStmtInfo;

  // Emit call to the helper function.
  EmitCallOrInvoke(F, CapStruct.getPointer(*this));

  return F;
}

Address CodeGenFunction::GenerateCapturedStmtArgument(const CapturedStmt &S) {
  LValue CapStruct = InitCapturedStruct(S);
  return CapStruct.getAddress(*this);
}

/// Creates the outlined function for a CapturedStmt.
llvm::Function *
CodeGenFunction::GenerateCapturedStmtFunction(const CapturedStmt &S) {
  assert(CapturedStmtInfo &&
    "CapturedStmtInfo should be set when generating the captured function");
  const CapturedDecl *CD = S.getCapturedDecl();
  const RecordDecl *RD = S.getCapturedRecordDecl();
  SourceLocation Loc = S.getBeginLoc();
  assert(CD->hasBody() && "missing CapturedDecl body");

  // Build the argument list.
  ASTContext &Ctx = CGM.getContext();
  FunctionArgList Args;
  Args.append(CD->param_begin(), CD->param_end());

  // Create the function declaration.
  const CGFunctionInfo &FuncInfo =
    CGM.getTypes().arrangeBuiltinFunctionDeclaration(Ctx.VoidTy, Args);
  llvm::FunctionType *FuncLLVMTy = CGM.getTypes().GetFunctionType(FuncInfo);

  llvm::Function *F =
    llvm::Function::Create(FuncLLVMTy, llvm::GlobalValue::InternalLinkage,
                           CapturedStmtInfo->getHelperName(), &CGM.getModule());
  CGM.SetInternalFunctionAttributes(CD, F, FuncInfo);
  if (CD->isNothrow())
    F->addFnAttr(llvm::Attribute::NoUnwind);

  // Generate the function.
  StartFunction(CD, Ctx.VoidTy, F, FuncInfo, Args, CD->getLocation(),
                CD->getBody()->getBeginLoc());
  // Set the context parameter in CapturedStmtInfo.
  Address DeclPtr = GetAddrOfLocalVar(CD->getContextParam());
  CapturedStmtInfo->setContextValue(Builder.CreateLoad(DeclPtr));

  // Initialize variable-length arrays.
  LValue Base = MakeNaturalAlignAddrLValue(CapturedStmtInfo->getContextValue(),
                                           Ctx.getTagDeclType(RD));
  for (auto *FD : RD->fields()) {
    if (FD->hasCapturedVLAType()) {
      auto *ExprArg =
          EmitLoadOfLValue(EmitLValueForField(Base, FD), S.getBeginLoc())
              .getScalarVal();
      auto VAT = FD->getCapturedVLAType();
      VLASizeMap[VAT->getSizeExpr()] = ExprArg;
    }
  }

  // If 'this' is captured, load it into CXXThisValue.
  if (CapturedStmtInfo->isCXXThisExprCaptured()) {
    FieldDecl *FD = CapturedStmtInfo->getThisFieldDecl();
    LValue ThisLValue = EmitLValueForField(Base, FD);
    CXXThisValue = EmitLoadOfLValue(ThisLValue, Loc).getScalarVal();
  }

  PGO.assignRegionCounters(GlobalDecl(CD), F);
  CapturedStmtInfo->EmitBody(*this, CD->getBody());
  FinishFunction(CD->getBodyRBrace());

  return F;
}