void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) {
llvm::Value *CondV = EmitScalarExpr(S.getCond());
// Handle nested switch statements.
llvm::SwitchInst *SavedSwitchInsn = SwitchInsn;
llvm::BasicBlock *SavedCRBlock = CaseRangeBlock;
// 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 *NextBlock = createBasicBlock("sw.epilog");
llvm::BasicBlock *DefaultBlock = createBasicBlock("sw.default");
SwitchInsn = Builder.CreateSwitch(CondV, DefaultBlock);
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.
llvm::BasicBlock *ContinueBlock = 0;
if (!BreakContinueStack.empty())
ContinueBlock = BreakContinueStack.back().ContinueBlock;
// Ensure any vlas created between there and here, are undone
BreakContinueStack.push_back(BreakContinue(NextBlock, ContinueBlock));
// 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->setSuccessor(0, CaseRangeBlock);
// If a default was never emitted then reroute any jumps to it and
// discard.
if (!DefaultBlock->getParent()) {
DefaultBlock->replaceAllUsesWith(NextBlock);
delete DefaultBlock;
}
// Emit continuation.
EmitBlock(NextBlock, true);
SwitchInsn = SavedSwitchInsn;
CaseRangeBlock = SavedCRBlock;
}
