583 lines
25 KiB
C++
583 lines
25 KiB
C++
//===- LowerInvoke.cpp - Eliminate Invoke & Unwind instructions -----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This transformation is designed for use by code generators which do not yet
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// support stack unwinding. This pass supports two models of exception handling
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// lowering, the 'cheap' support and the 'expensive' support.
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//
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// 'Cheap' exception handling support gives the program the ability to execute
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// any program which does not "throw an exception", by turning 'invoke'
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// instructions into calls and by turning 'unwind' instructions into calls to
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// abort(). If the program does dynamically use the unwind instruction, the
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// program will print a message then abort.
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//
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// 'Expensive' exception handling support gives the full exception handling
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// support to the program at the cost of making the 'invoke' instruction
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// really expensive. It basically inserts setjmp/longjmp calls to emulate the
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// exception handling as necessary.
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//
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// Because the 'expensive' support slows down programs a lot, and EH is only
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// used for a subset of the programs, it must be specifically enabled by an
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// option.
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//
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// Note that after this pass runs the CFG is not entirely accurate (exceptional
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// control flow edges are not correct anymore) so only very simple things should
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// be done after the lowerinvoke pass has run (like generation of native code).
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// This should not be used as a general purpose "my LLVM-to-LLVM pass doesn't
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// support the invoke instruction yet" lowering pass.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "lowerinvoke"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Constants.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Instructions.h"
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#include "llvm/Intrinsics.h"
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#include "llvm/LLVMContext.h"
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#include "llvm/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Target/TargetLowering.h"
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#include <csetjmp>
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#include <set>
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using namespace llvm;
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STATISTIC(NumInvokes, "Number of invokes replaced");
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STATISTIC(NumSpilled, "Number of registers live across unwind edges");
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static cl::opt<bool> ExpensiveEHSupport("enable-correct-eh-support",
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cl::desc("Make the -lowerinvoke pass insert expensive, but correct, EH code"));
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namespace {
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class LowerInvoke : public FunctionPass {
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// Used for both models.
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Constant *AbortFn;
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// Used for expensive EH support.
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StructType *JBLinkTy;
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GlobalVariable *JBListHead;
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Constant *SetJmpFn, *LongJmpFn, *StackSaveFn, *StackRestoreFn;
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bool useExpensiveEHSupport;
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// We peek in TLI to grab the target's jmp_buf size and alignment
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const TargetLowering *TLI;
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public:
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static char ID; // Pass identification, replacement for typeid
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explicit LowerInvoke(const TargetLowering *tli = NULL,
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bool useExpensiveEHSupport = ExpensiveEHSupport)
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: FunctionPass(ID), useExpensiveEHSupport(useExpensiveEHSupport),
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TLI(tli) {
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initializeLowerInvokePass(*PassRegistry::getPassRegistry());
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}
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bool doInitialization(Module &M);
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bool runOnFunction(Function &F);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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// This is a cluster of orthogonal Transforms
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AU.addPreserved("mem2reg");
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AU.addPreservedID(LowerSwitchID);
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}
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private:
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bool insertCheapEHSupport(Function &F);
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void splitLiveRangesLiveAcrossInvokes(SmallVectorImpl<InvokeInst*>&Invokes);
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void rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
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AllocaInst *InvokeNum, AllocaInst *StackPtr,
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SwitchInst *CatchSwitch);
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bool insertExpensiveEHSupport(Function &F);
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};
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}
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char LowerInvoke::ID = 0;
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INITIALIZE_PASS(LowerInvoke, "lowerinvoke",
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"Lower invoke and unwind, for unwindless code generators",
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false, false)
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char &llvm::LowerInvokePassID = LowerInvoke::ID;
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// Public Interface To the LowerInvoke pass.
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FunctionPass *llvm::createLowerInvokePass(const TargetLowering *TLI) {
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return new LowerInvoke(TLI, ExpensiveEHSupport);
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}
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FunctionPass *llvm::createLowerInvokePass(const TargetLowering *TLI,
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bool useExpensiveEHSupport) {
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return new LowerInvoke(TLI, useExpensiveEHSupport);
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}
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// doInitialization - Make sure that there is a prototype for abort in the
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// current module.
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bool LowerInvoke::doInitialization(Module &M) {
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Type *VoidPtrTy = Type::getInt8PtrTy(M.getContext());
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if (useExpensiveEHSupport) {
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// Insert a type for the linked list of jump buffers.
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unsigned JBSize = TLI ? TLI->getJumpBufSize() : 0;
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JBSize = JBSize ? JBSize : 200;
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Type *JmpBufTy = ArrayType::get(VoidPtrTy, JBSize);
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JBLinkTy = StructType::create(M.getContext(), "llvm.sjljeh.jmpbufty");
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Type *Elts[] = { JmpBufTy, PointerType::getUnqual(JBLinkTy) };
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JBLinkTy->setBody(Elts);
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Type *PtrJBList = PointerType::getUnqual(JBLinkTy);
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// Now that we've done that, insert the jmpbuf list head global, unless it
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// already exists.
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if (!(JBListHead = M.getGlobalVariable("llvm.sjljeh.jblist", PtrJBList))) {
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JBListHead = new GlobalVariable(M, PtrJBList, false,
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GlobalValue::LinkOnceAnyLinkage,
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Constant::getNullValue(PtrJBList),
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"llvm.sjljeh.jblist");
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}
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// VisualStudio defines setjmp as _setjmp
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#if defined(_MSC_VER) && defined(setjmp) && \
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!defined(setjmp_undefined_for_msvc)
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# pragma push_macro("setjmp")
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# undef setjmp
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# define setjmp_undefined_for_msvc
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#endif
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SetJmpFn = Intrinsic::getDeclaration(&M, Intrinsic::setjmp);
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#if defined(_MSC_VER) && defined(setjmp_undefined_for_msvc)
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// let's return it to _setjmp state
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# pragma pop_macro("setjmp")
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# undef setjmp_undefined_for_msvc
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#endif
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LongJmpFn = Intrinsic::getDeclaration(&M, Intrinsic::longjmp);
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StackSaveFn = Intrinsic::getDeclaration(&M, Intrinsic::stacksave);
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StackRestoreFn = Intrinsic::getDeclaration(&M, Intrinsic::stackrestore);
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}
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// We need the 'write' and 'abort' functions for both models.
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AbortFn = M.getOrInsertFunction("abort", Type::getVoidTy(M.getContext()),
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(Type *)0);
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return true;
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}
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bool LowerInvoke::insertCheapEHSupport(Function &F) {
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bool Changed = false;
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for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
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if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
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SmallVector<Value*,16> CallArgs(II->op_begin(), II->op_end() - 3);
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// Insert a normal call instruction...
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CallInst *NewCall = CallInst::Create(II->getCalledValue(),
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CallArgs, "", II);
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NewCall->takeName(II);
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NewCall->setCallingConv(II->getCallingConv());
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NewCall->setAttributes(II->getAttributes());
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NewCall->setDebugLoc(II->getDebugLoc());
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II->replaceAllUsesWith(NewCall);
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// Insert an unconditional branch to the normal destination.
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BranchInst::Create(II->getNormalDest(), II);
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// Remove any PHI node entries from the exception destination.
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II->getUnwindDest()->removePredecessor(BB);
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// Remove the invoke instruction now.
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BB->getInstList().erase(II);
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++NumInvokes; Changed = true;
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}
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return Changed;
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}
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/// rewriteExpensiveInvoke - Insert code and hack the function to replace the
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/// specified invoke instruction with a call.
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void LowerInvoke::rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
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AllocaInst *InvokeNum,
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AllocaInst *StackPtr,
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SwitchInst *CatchSwitch) {
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ConstantInt *InvokeNoC = ConstantInt::get(Type::getInt32Ty(II->getContext()),
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InvokeNo);
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// If the unwind edge has phi nodes, split the edge.
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if (isa<PHINode>(II->getUnwindDest()->begin())) {
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SplitCriticalEdge(II, 1, this);
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// If there are any phi nodes left, they must have a single predecessor.
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while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) {
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PN->replaceAllUsesWith(PN->getIncomingValue(0));
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PN->eraseFromParent();
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}
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}
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// Insert a store of the invoke num before the invoke and store zero into the
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// location afterward.
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new StoreInst(InvokeNoC, InvokeNum, true, II); // volatile
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// Insert a store of the stack ptr before the invoke, so we can restore it
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// later in the exception case.
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CallInst* StackSaveRet = CallInst::Create(StackSaveFn, "ssret", II);
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new StoreInst(StackSaveRet, StackPtr, true, II); // volatile
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BasicBlock::iterator NI = II->getNormalDest()->getFirstInsertionPt();
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// nonvolatile.
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new StoreInst(Constant::getNullValue(Type::getInt32Ty(II->getContext())),
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InvokeNum, false, NI);
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Instruction* StackPtrLoad =
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new LoadInst(StackPtr, "stackptr.restore", true,
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II->getUnwindDest()->getFirstInsertionPt());
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CallInst::Create(StackRestoreFn, StackPtrLoad, "")->insertAfter(StackPtrLoad);
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// Add a switch case to our unwind block.
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CatchSwitch->addCase(InvokeNoC, II->getUnwindDest());
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// Insert a normal call instruction.
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SmallVector<Value*,16> CallArgs(II->op_begin(), II->op_end() - 3);
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CallInst *NewCall = CallInst::Create(II->getCalledValue(),
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CallArgs, "", II);
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NewCall->takeName(II);
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NewCall->setCallingConv(II->getCallingConv());
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NewCall->setAttributes(II->getAttributes());
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NewCall->setDebugLoc(II->getDebugLoc());
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II->replaceAllUsesWith(NewCall);
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// Replace the invoke with an uncond branch.
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BranchInst::Create(II->getNormalDest(), NewCall->getParent());
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II->eraseFromParent();
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}
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/// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until
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/// we reach blocks we've already seen.
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static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) {
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if (!LiveBBs.insert(BB).second) return; // already been here.
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for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
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MarkBlocksLiveIn(*PI, LiveBBs);
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}
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// First thing we need to do is scan the whole function for values that are
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// live across unwind edges. Each value that is live across an unwind edge
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// we spill into a stack location, guaranteeing that there is nothing live
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// across the unwind edge. This process also splits all critical edges
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// coming out of invoke's.
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void LowerInvoke::
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splitLiveRangesLiveAcrossInvokes(SmallVectorImpl<InvokeInst*> &Invokes) {
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// First step, split all critical edges from invoke instructions.
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for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
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InvokeInst *II = Invokes[i];
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SplitCriticalEdge(II, 0, this);
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SplitCriticalEdge(II, 1, this);
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assert(!isa<PHINode>(II->getNormalDest()) &&
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!isa<PHINode>(II->getUnwindDest()) &&
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"critical edge splitting left single entry phi nodes?");
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}
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Function *F = Invokes.back()->getParent()->getParent();
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// To avoid having to handle incoming arguments specially, we lower each arg
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// to a copy instruction in the entry block. This ensures that the argument
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// value itself cannot be live across the entry block.
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BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin();
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while (isa<AllocaInst>(AfterAllocaInsertPt) &&
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isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize()))
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++AfterAllocaInsertPt;
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for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
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AI != E; ++AI) {
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Type *Ty = AI->getType();
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// Aggregate types can't be cast, but are legal argument types, so we have
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// to handle them differently. We use an extract/insert pair as a
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// lightweight method to achieve the same goal.
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if (isa<StructType>(Ty) || isa<ArrayType>(Ty) || isa<VectorType>(Ty)) {
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Instruction *EI = ExtractValueInst::Create(AI, 0, "",AfterAllocaInsertPt);
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Instruction *NI = InsertValueInst::Create(AI, EI, 0);
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NI->insertAfter(EI);
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AI->replaceAllUsesWith(NI);
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// Set the operand of the instructions back to the AllocaInst.
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EI->setOperand(0, AI);
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NI->setOperand(0, AI);
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} else {
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// This is always a no-op cast because we're casting AI to AI->getType()
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// so src and destination types are identical. BitCast is the only
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// possibility.
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CastInst *NC = new BitCastInst(
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AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt);
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AI->replaceAllUsesWith(NC);
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// Set the operand of the cast instruction back to the AllocaInst.
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// Normally it's forbidden to replace a CastInst's operand because it
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// could cause the opcode to reflect an illegal conversion. However,
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// we're replacing it here with the same value it was constructed with.
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// We do this because the above replaceAllUsesWith() clobbered the
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// operand, but we want this one to remain.
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NC->setOperand(0, AI);
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}
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}
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// Finally, scan the code looking for instructions with bad live ranges.
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for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
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for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) {
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// Ignore obvious cases we don't have to handle. In particular, most
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// instructions either have no uses or only have a single use inside the
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// current block. Ignore them quickly.
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Instruction *Inst = II;
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if (Inst->use_empty()) continue;
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if (Inst->hasOneUse() &&
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cast<Instruction>(Inst->use_back())->getParent() == BB &&
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!isa<PHINode>(Inst->use_back())) continue;
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// If this is an alloca in the entry block, it's not a real register
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// value.
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if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst))
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if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin())
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continue;
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// Avoid iterator invalidation by copying users to a temporary vector.
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SmallVector<Instruction*,16> Users;
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for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end();
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UI != E; ++UI) {
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Instruction *User = cast<Instruction>(*UI);
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if (User->getParent() != BB || isa<PHINode>(User))
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Users.push_back(User);
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}
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// Scan all of the uses and see if the live range is live across an unwind
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// edge. If we find a use live across an invoke edge, create an alloca
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// and spill the value.
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std::set<InvokeInst*> InvokesWithStoreInserted;
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// Find all of the blocks that this value is live in.
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std::set<BasicBlock*> LiveBBs;
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LiveBBs.insert(Inst->getParent());
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while (!Users.empty()) {
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Instruction *U = Users.back();
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Users.pop_back();
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if (!isa<PHINode>(U)) {
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MarkBlocksLiveIn(U->getParent(), LiveBBs);
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} else {
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// Uses for a PHI node occur in their predecessor block.
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PHINode *PN = cast<PHINode>(U);
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for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
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if (PN->getIncomingValue(i) == Inst)
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MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs);
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}
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}
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// Now that we know all of the blocks that this thing is live in, see if
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// it includes any of the unwind locations.
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bool NeedsSpill = false;
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for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
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BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest();
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if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) {
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NeedsSpill = true;
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}
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}
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// If we decided we need a spill, do it.
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if (NeedsSpill) {
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++NumSpilled;
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DemoteRegToStack(*Inst, true);
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}
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}
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}
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bool LowerInvoke::insertExpensiveEHSupport(Function &F) {
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SmallVector<ReturnInst*,16> Returns;
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SmallVector<InvokeInst*,16> Invokes;
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UnreachableInst* UnreachablePlaceholder = 0;
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for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
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if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
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// Remember all return instructions in case we insert an invoke into this
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// function.
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Returns.push_back(RI);
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} else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
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Invokes.push_back(II);
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}
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if (Invokes.empty()) return false;
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NumInvokes += Invokes.size();
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// TODO: This is not an optimal way to do this. In particular, this always
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// inserts setjmp calls into the entries of functions with invoke instructions
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// even though there are possibly paths through the function that do not
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// execute any invokes. In particular, for functions with early exits, e.g.
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// the 'addMove' method in hexxagon, it would be nice to not have to do the
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// setjmp stuff on the early exit path. This requires a bit of dataflow, but
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// would not be too hard to do.
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// If we have an invoke instruction, insert a setjmp that dominates all
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// invokes. After the setjmp, use a cond branch that goes to the original
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// code path on zero, and to a designated 'catch' block of nonzero.
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Value *OldJmpBufPtr = 0;
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if (!Invokes.empty()) {
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// First thing we need to do is scan the whole function for values that are
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// live across unwind edges. Each value that is live across an unwind edge
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// we spill into a stack location, guaranteeing that there is nothing live
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// across the unwind edge. This process also splits all critical edges
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// coming out of invoke's.
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splitLiveRangesLiveAcrossInvokes(Invokes);
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BasicBlock *EntryBB = F.begin();
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// Create an alloca for the incoming jump buffer ptr and the new jump buffer
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// that needs to be restored on all exits from the function. This is an
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// alloca because the value needs to be live across invokes.
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unsigned Align = TLI ? TLI->getJumpBufAlignment() : 0;
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AllocaInst *JmpBuf =
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new AllocaInst(JBLinkTy, 0, Align,
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"jblink", F.begin()->begin());
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Value *Idx[] = { Constant::getNullValue(Type::getInt32Ty(F.getContext())),
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ConstantInt::get(Type::getInt32Ty(F.getContext()), 1) };
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OldJmpBufPtr = GetElementPtrInst::Create(JmpBuf, Idx, "OldBuf",
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EntryBB->getTerminator());
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// Copy the JBListHead to the alloca.
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Value *OldBuf = new LoadInst(JBListHead, "oldjmpbufptr", true,
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EntryBB->getTerminator());
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new StoreInst(OldBuf, OldJmpBufPtr, true, EntryBB->getTerminator());
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// Add the new jumpbuf to the list.
|
|
new StoreInst(JmpBuf, JBListHead, true, EntryBB->getTerminator());
|
|
|
|
// Create the catch block. The catch block is basically a big switch
|
|
// statement that goes to all of the invoke catch blocks.
|
|
BasicBlock *CatchBB =
|
|
BasicBlock::Create(F.getContext(), "setjmp.catch", &F);
|
|
|
|
// Create an alloca which keeps track of the stack pointer before every
|
|
// invoke, this allows us to properly restore the stack pointer after
|
|
// long jumping.
|
|
AllocaInst *StackPtr = new AllocaInst(Type::getInt8PtrTy(F.getContext()), 0,
|
|
"stackptr", EntryBB->begin());
|
|
|
|
// Create an alloca which keeps track of which invoke is currently
|
|
// executing. For normal calls it contains zero.
|
|
AllocaInst *InvokeNum = new AllocaInst(Type::getInt32Ty(F.getContext()), 0,
|
|
"invokenum",EntryBB->begin());
|
|
new StoreInst(ConstantInt::get(Type::getInt32Ty(F.getContext()), 0),
|
|
InvokeNum, true, EntryBB->getTerminator());
|
|
|
|
// Insert a load in the Catch block, and a switch on its value. By default,
|
|
// we go to a block that just does an unwind (which is the correct action
|
|
// for a standard call). We insert an unreachable instruction here and
|
|
// modify the block to jump to the correct unwinding pad later.
|
|
BasicBlock *UnwindBB = BasicBlock::Create(F.getContext(), "unwindbb", &F);
|
|
UnreachablePlaceholder = new UnreachableInst(F.getContext(), UnwindBB);
|
|
|
|
Value *CatchLoad = new LoadInst(InvokeNum, "invoke.num", true, CatchBB);
|
|
SwitchInst *CatchSwitch =
|
|
SwitchInst::Create(CatchLoad, UnwindBB, Invokes.size(), CatchBB);
|
|
|
|
// Now that things are set up, insert the setjmp call itself.
|
|
|
|
// Split the entry block to insert the conditional branch for the setjmp.
|
|
BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(),
|
|
"setjmp.cont");
|
|
|
|
Idx[1] = ConstantInt::get(Type::getInt32Ty(F.getContext()), 0);
|
|
Value *JmpBufPtr = GetElementPtrInst::Create(JmpBuf, Idx, "TheJmpBuf",
|
|
EntryBB->getTerminator());
|
|
JmpBufPtr = new BitCastInst(JmpBufPtr,
|
|
Type::getInt8PtrTy(F.getContext()),
|
|
"tmp", EntryBB->getTerminator());
|
|
Value *SJRet = CallInst::Create(SetJmpFn, JmpBufPtr, "sjret",
|
|
EntryBB->getTerminator());
|
|
|
|
// Compare the return value to zero.
|
|
Value *IsNormal = new ICmpInst(EntryBB->getTerminator(),
|
|
ICmpInst::ICMP_EQ, SJRet,
|
|
Constant::getNullValue(SJRet->getType()),
|
|
"notunwind");
|
|
// Nuke the uncond branch.
|
|
EntryBB->getTerminator()->eraseFromParent();
|
|
|
|
// Put in a new condbranch in its place.
|
|
BranchInst::Create(ContBlock, CatchBB, IsNormal, EntryBB);
|
|
|
|
// At this point, we are all set up, rewrite each invoke instruction.
|
|
for (unsigned i = 0, e = Invokes.size(); i != e; ++i)
|
|
rewriteExpensiveInvoke(Invokes[i], i+1, InvokeNum, StackPtr, CatchSwitch);
|
|
}
|
|
|
|
// We know that there is at least one unwind.
|
|
|
|
// Create three new blocks, the block to load the jmpbuf ptr and compare
|
|
// against null, the block to do the longjmp, and the error block for if it
|
|
// is null. Add them at the end of the function because they are not hot.
|
|
BasicBlock *UnwindHandler = BasicBlock::Create(F.getContext(),
|
|
"dounwind", &F);
|
|
BasicBlock *UnwindBlock = BasicBlock::Create(F.getContext(), "unwind", &F);
|
|
BasicBlock *TermBlock = BasicBlock::Create(F.getContext(), "unwinderror", &F);
|
|
|
|
// If this function contains an invoke, restore the old jumpbuf ptr.
|
|
Value *BufPtr;
|
|
if (OldJmpBufPtr) {
|
|
// Before the return, insert a copy from the saved value to the new value.
|
|
BufPtr = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", UnwindHandler);
|
|
new StoreInst(BufPtr, JBListHead, UnwindHandler);
|
|
} else {
|
|
BufPtr = new LoadInst(JBListHead, "ehlist", UnwindHandler);
|
|
}
|
|
|
|
// Load the JBList, if it's null, then there was no catch!
|
|
Value *NotNull = new ICmpInst(*UnwindHandler, ICmpInst::ICMP_NE, BufPtr,
|
|
Constant::getNullValue(BufPtr->getType()),
|
|
"notnull");
|
|
BranchInst::Create(UnwindBlock, TermBlock, NotNull, UnwindHandler);
|
|
|
|
// Create the block to do the longjmp.
|
|
// Get a pointer to the jmpbuf and longjmp.
|
|
Value *Idx[] = { Constant::getNullValue(Type::getInt32Ty(F.getContext())),
|
|
ConstantInt::get(Type::getInt32Ty(F.getContext()), 0) };
|
|
Idx[0] = GetElementPtrInst::Create(BufPtr, Idx, "JmpBuf", UnwindBlock);
|
|
Idx[0] = new BitCastInst(Idx[0],
|
|
Type::getInt8PtrTy(F.getContext()),
|
|
"tmp", UnwindBlock);
|
|
Idx[1] = ConstantInt::get(Type::getInt32Ty(F.getContext()), 1);
|
|
CallInst::Create(LongJmpFn, Idx, "", UnwindBlock);
|
|
new UnreachableInst(F.getContext(), UnwindBlock);
|
|
|
|
// Set up the term block ("throw without a catch").
|
|
new UnreachableInst(F.getContext(), TermBlock);
|
|
|
|
// Insert a call to abort()
|
|
CallInst::Create(AbortFn, "",
|
|
TermBlock->getTerminator())->setTailCall();
|
|
|
|
// Replace the inserted unreachable with a branch to the unwind handler.
|
|
if (UnreachablePlaceholder) {
|
|
BranchInst::Create(UnwindHandler, UnreachablePlaceholder);
|
|
UnreachablePlaceholder->eraseFromParent();
|
|
}
|
|
|
|
// Finally, for any returns from this function, if this function contains an
|
|
// invoke, restore the old jmpbuf pointer to its input value.
|
|
if (OldJmpBufPtr) {
|
|
for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
|
|
ReturnInst *R = Returns[i];
|
|
|
|
// Before the return, insert a copy from the saved value to the new value.
|
|
Value *OldBuf = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", true, R);
|
|
new StoreInst(OldBuf, JBListHead, true, R);
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
bool LowerInvoke::runOnFunction(Function &F) {
|
|
if (useExpensiveEHSupport)
|
|
return insertExpensiveEHSupport(F);
|
|
else
|
|
return insertCheapEHSupport(F);
|
|
}
|