void CodeGenFunction::EmitWhileStmt(const WhileStmt &S) {
// Emit the header for the loop, insert it, which will create an uncond br to
// it.
llvm::BasicBlock *LoopHeader = createBasicBlock("while.cond");
EmitBlock(LoopHeader);
// Create an exit block for when the condition fails, create a block for the
// body of the loop.
llvm::BasicBlock *ExitBlock = createBasicBlock("while.end");
llvm::BasicBlock *LoopBody = createBasicBlock("while.body");
// Store the blocks to use for break and continue.
BreakContinueStack.push_back(BreakContinue(ExitBlock, LoopHeader));
// 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.
bool EmitBoolCondBranch = true;
if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal))
if (C->isOne())
EmitBoolCondBranch = false;
// As long as the condition is true, go to the loop body.
if (EmitBoolCondBranch)
Builder.CreateCondBr(BoolCondVal, LoopBody, ExitBlock);
// Emit the loop body.
EmitBlock(LoopBody);
EmitStmt(S.getBody());
BreakContinueStack.pop_back();
// Cycle to the condition.
EmitBranch(LoopHeader);
// Emit the exit block.
EmitBlock(ExitBlock, true);
// The LoopHeader typically is just a branch if we skipped emitting
// a branch, try to erase it.
if (!EmitBoolCondBranch)
SimplifyForwardingBlocks(LoopHeader);
}
