It's not necessary to do rounding for alloca operations when the requested
alignment is equal to the stack alignment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40004 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/LowerSetJmp.cpp b/lib/Transforms/IPO/LowerSetJmp.cpp
new file mode 100644
index 0000000..0243980
--- /dev/null
+++ b/lib/Transforms/IPO/LowerSetJmp.cpp
@@ -0,0 +1,534 @@
+//===- LowerSetJmp.cpp - Code pertaining to lowering set/long jumps -------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the lowering of setjmp and longjmp to use the
+// LLVM invoke and unwind instructions as necessary.
+//
+// Lowering of longjmp is fairly trivial. We replace the call with a
+// call to the LLVM library function "__llvm_sjljeh_throw_longjmp()".
+// This unwinds the stack for us calling all of the destructors for
+// objects allocated on the stack.
+//
+// At a setjmp call, the basic block is split and the setjmp removed.
+// The calls in a function that have a setjmp are converted to invoke
+// where the except part checks to see if it's a longjmp exception and,
+// if so, if it's handled in the function. If it is, then it gets the
+// value returned by the longjmp and goes to where the basic block was
+// split. Invoke instructions are handled in a similar fashion with the
+// original except block being executed if it isn't a longjmp except
+// that is handled by that function.
+//
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+// FIXME: This pass doesn't deal with PHI statements just yet. That is,
+// we expect this to occur before SSAification is done. This would seem
+// to make sense, but in general, it might be a good idea to make this
+// pass invokable via the "opt" command at will.
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "lowersetjmp"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Instructions.h"
+#include "llvm/Intrinsics.h"
+#include "llvm/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/InstVisitor.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/VectorExtras.h"
+using namespace llvm;
+
+STATISTIC(LongJmpsTransformed, "Number of longjmps transformed");
+STATISTIC(SetJmpsTransformed , "Number of setjmps transformed");
+STATISTIC(CallsTransformed , "Number of calls invokified");
+STATISTIC(InvokesTransformed , "Number of invokes modified");
+
+namespace {
+ //===--------------------------------------------------------------------===//
+ // LowerSetJmp pass implementation.
+ class VISIBILITY_HIDDEN LowerSetJmp : public ModulePass,
+ public InstVisitor<LowerSetJmp> {
+ // LLVM library functions...
+ Constant *InitSJMap; // __llvm_sjljeh_init_setjmpmap
+ Constant *DestroySJMap; // __llvm_sjljeh_destroy_setjmpmap
+ Constant *AddSJToMap; // __llvm_sjljeh_add_setjmp_to_map
+ Constant *ThrowLongJmp; // __llvm_sjljeh_throw_longjmp
+ Constant *TryCatchLJ; // __llvm_sjljeh_try_catching_longjmp_exception
+ Constant *IsLJException; // __llvm_sjljeh_is_longjmp_exception
+ Constant *GetLJValue; // __llvm_sjljeh_get_longjmp_value
+
+ typedef std::pair<SwitchInst*, CallInst*> SwitchValuePair;
+
+ // Keep track of those basic blocks reachable via a depth-first search of
+ // the CFG from a setjmp call. We only need to transform those "call" and
+ // "invoke" instructions that are reachable from the setjmp call site.
+ std::set<BasicBlock*> DFSBlocks;
+
+ // The setjmp map is going to hold information about which setjmps
+ // were called (each setjmp gets its own number) and with which
+ // buffer it was called.
+ std::map<Function*, AllocaInst*> SJMap;
+
+ // The rethrow basic block map holds the basic block to branch to if
+ // the exception isn't handled in the current function and needs to
+ // be rethrown.
+ std::map<const Function*, BasicBlock*> RethrowBBMap;
+
+ // The preliminary basic block map holds a basic block that grabs the
+ // exception and determines if it's handled by the current function.
+ std::map<const Function*, BasicBlock*> PrelimBBMap;
+
+ // The switch/value map holds a switch inst/call inst pair. The
+ // switch inst controls which handler (if any) gets called and the
+ // value is the value returned to that handler by the call to
+ // __llvm_sjljeh_get_longjmp_value.
+ std::map<const Function*, SwitchValuePair> SwitchValMap;
+
+ // A map of which setjmps we've seen so far in a function.
+ std::map<const Function*, unsigned> SetJmpIDMap;
+
+ AllocaInst* GetSetJmpMap(Function* Func);
+ BasicBlock* GetRethrowBB(Function* Func);
+ SwitchValuePair GetSJSwitch(Function* Func, BasicBlock* Rethrow);
+
+ void TransformLongJmpCall(CallInst* Inst);
+ void TransformSetJmpCall(CallInst* Inst);
+
+ bool IsTransformableFunction(const std::string& Name);
+ public:
+ static char ID; // Pass identification, replacement for typeid
+ LowerSetJmp() : ModulePass((intptr_t)&ID) {}
+
+ void visitCallInst(CallInst& CI);
+ void visitInvokeInst(InvokeInst& II);
+ void visitReturnInst(ReturnInst& RI);
+ void visitUnwindInst(UnwindInst& UI);
+
+ bool runOnModule(Module& M);
+ bool doInitialization(Module& M);
+ };
+
+ char LowerSetJmp::ID = 0;
+ RegisterPass<LowerSetJmp> X("lowersetjmp", "Lower Set Jump");
+} // end anonymous namespace
+
+// run - Run the transformation on the program. We grab the function
+// prototypes for longjmp and setjmp. If they are used in the program,
+// then we can go directly to the places they're at and transform them.
+bool LowerSetJmp::runOnModule(Module& M) {
+ bool Changed = false;
+
+ // These are what the functions are called.
+ Function* SetJmp = M.getFunction("llvm.setjmp");
+ Function* LongJmp = M.getFunction("llvm.longjmp");
+
+ // This program doesn't have longjmp and setjmp calls.
+ if ((!LongJmp || LongJmp->use_empty()) &&
+ (!SetJmp || SetJmp->use_empty())) return false;
+
+ // Initialize some values and functions we'll need to transform the
+ // setjmp/longjmp functions.
+ doInitialization(M);
+
+ if (SetJmp) {
+ for (Value::use_iterator B = SetJmp->use_begin(), E = SetJmp->use_end();
+ B != E; ++B) {
+ BasicBlock* BB = cast<Instruction>(*B)->getParent();
+ for (df_ext_iterator<BasicBlock*> I = df_ext_begin(BB, DFSBlocks),
+ E = df_ext_end(BB, DFSBlocks); I != E; ++I)
+ /* empty */;
+ }
+
+ while (!SetJmp->use_empty()) {
+ assert(isa<CallInst>(SetJmp->use_back()) &&
+ "User of setjmp intrinsic not a call?");
+ TransformSetJmpCall(cast<CallInst>(SetJmp->use_back()));
+ Changed = true;
+ }
+ }
+
+ if (LongJmp)
+ while (!LongJmp->use_empty()) {
+ assert(isa<CallInst>(LongJmp->use_back()) &&
+ "User of longjmp intrinsic not a call?");
+ TransformLongJmpCall(cast<CallInst>(LongJmp->use_back()));
+ Changed = true;
+ }
+
+ // Now go through the affected functions and convert calls and invokes
+ // to new invokes...
+ for (std::map<Function*, AllocaInst*>::iterator
+ B = SJMap.begin(), E = SJMap.end(); B != E; ++B) {
+ Function* F = B->first;
+ for (Function::iterator BB = F->begin(), BE = F->end(); BB != BE; ++BB)
+ for (BasicBlock::iterator IB = BB->begin(), IE = BB->end(); IB != IE; ) {
+ visit(*IB++);
+ if (IB != BB->end() && IB->getParent() != BB)
+ break; // The next instruction got moved to a different block!
+ }
+ }
+
+ DFSBlocks.clear();
+ SJMap.clear();
+ RethrowBBMap.clear();
+ PrelimBBMap.clear();
+ SwitchValMap.clear();
+ SetJmpIDMap.clear();
+
+ return Changed;
+}
+
+// doInitialization - For the lower long/setjmp pass, this ensures that a
+// module contains a declaration for the intrisic functions we are going
+// to call to convert longjmp and setjmp calls.
+//
+// This function is always successful, unless it isn't.
+bool LowerSetJmp::doInitialization(Module& M)
+{
+ const Type *SBPTy = PointerType::get(Type::Int8Ty);
+ const Type *SBPPTy = PointerType::get(SBPTy);
+
+ // N.B. See llvm/runtime/GCCLibraries/libexception/SJLJ-Exception.h for
+ // a description of the following library functions.
+
+ // void __llvm_sjljeh_init_setjmpmap(void**)
+ InitSJMap = M.getOrInsertFunction("__llvm_sjljeh_init_setjmpmap",
+ Type::VoidTy, SBPPTy, (Type *)0);
+ // void __llvm_sjljeh_destroy_setjmpmap(void**)
+ DestroySJMap = M.getOrInsertFunction("__llvm_sjljeh_destroy_setjmpmap",
+ Type::VoidTy, SBPPTy, (Type *)0);
+
+ // void __llvm_sjljeh_add_setjmp_to_map(void**, void*, unsigned)
+ AddSJToMap = M.getOrInsertFunction("__llvm_sjljeh_add_setjmp_to_map",
+ Type::VoidTy, SBPPTy, SBPTy,
+ Type::Int32Ty, (Type *)0);
+
+ // void __llvm_sjljeh_throw_longjmp(int*, int)
+ ThrowLongJmp = M.getOrInsertFunction("__llvm_sjljeh_throw_longjmp",
+ Type::VoidTy, SBPTy, Type::Int32Ty,
+ (Type *)0);
+
+ // unsigned __llvm_sjljeh_try_catching_longjmp_exception(void **)
+ TryCatchLJ =
+ M.getOrInsertFunction("__llvm_sjljeh_try_catching_longjmp_exception",
+ Type::Int32Ty, SBPPTy, (Type *)0);
+
+ // bool __llvm_sjljeh_is_longjmp_exception()
+ IsLJException = M.getOrInsertFunction("__llvm_sjljeh_is_longjmp_exception",
+ Type::Int1Ty, (Type *)0);
+
+ // int __llvm_sjljeh_get_longjmp_value()
+ GetLJValue = M.getOrInsertFunction("__llvm_sjljeh_get_longjmp_value",
+ Type::Int32Ty, (Type *)0);
+ return true;
+}
+
+// IsTransformableFunction - Return true if the function name isn't one
+// of the ones we don't want transformed. Currently, don't transform any
+// "llvm.{setjmp,longjmp}" functions and none of the setjmp/longjmp error
+// handling functions (beginning with __llvm_sjljeh_...they don't throw
+// exceptions).
+bool LowerSetJmp::IsTransformableFunction(const std::string& Name) {
+ std::string SJLJEh("__llvm_sjljeh");
+
+ if (Name.size() > SJLJEh.size())
+ return std::string(Name.begin(), Name.begin() + SJLJEh.size()) != SJLJEh;
+
+ return true;
+}
+
+// TransformLongJmpCall - Transform a longjmp call into a call to the
+// internal __llvm_sjljeh_throw_longjmp function. It then takes care of
+// throwing the exception for us.
+void LowerSetJmp::TransformLongJmpCall(CallInst* Inst)
+{
+ const Type* SBPTy = PointerType::get(Type::Int8Ty);
+
+ // Create the call to "__llvm_sjljeh_throw_longjmp". This takes the
+ // same parameters as "longjmp", except that the buffer is cast to a
+ // char*. It returns "void", so it doesn't need to replace any of
+ // Inst's uses and doesn't get a name.
+ CastInst* CI =
+ new BitCastInst(Inst->getOperand(1), SBPTy, "LJBuf", Inst);
+ new CallInst(ThrowLongJmp, CI, Inst->getOperand(2), "", Inst);
+
+ SwitchValuePair& SVP = SwitchValMap[Inst->getParent()->getParent()];
+
+ // If the function has a setjmp call in it (they are transformed first)
+ // we should branch to the basic block that determines if this longjmp
+ // is applicable here. Otherwise, issue an unwind.
+ if (SVP.first)
+ new BranchInst(SVP.first->getParent(), Inst);
+ else
+ new UnwindInst(Inst);
+
+ // Remove all insts after the branch/unwind inst. Go from back to front to
+ // avoid replaceAllUsesWith if possible.
+ BasicBlock *BB = Inst->getParent();
+ Instruction *Removed;
+ do {
+ Removed = &BB->back();
+ // If the removed instructions have any users, replace them now.
+ if (!Removed->use_empty())
+ Removed->replaceAllUsesWith(UndefValue::get(Removed->getType()));
+ Removed->eraseFromParent();
+ } while (Removed != Inst);
+
+ ++LongJmpsTransformed;
+}
+
+// GetSetJmpMap - Retrieve (create and initialize, if necessary) the
+// setjmp map. This map is going to hold information about which setjmps
+// were called (each setjmp gets its own number) and with which buffer it
+// was called. There can be only one!
+AllocaInst* LowerSetJmp::GetSetJmpMap(Function* Func)
+{
+ if (SJMap[Func]) return SJMap[Func];
+
+ // Insert the setjmp map initialization before the first instruction in
+ // the function.
+ Instruction* Inst = Func->getEntryBlock().begin();
+ assert(Inst && "Couldn't find even ONE instruction in entry block!");
+
+ // Fill in the alloca and call to initialize the SJ map.
+ const Type *SBPTy = PointerType::get(Type::Int8Ty);
+ AllocaInst* Map = new AllocaInst(SBPTy, 0, "SJMap", Inst);
+ new CallInst(InitSJMap, Map, "", Inst);
+ return SJMap[Func] = Map;
+}
+
+// GetRethrowBB - Only one rethrow basic block is needed per function.
+// If this is a longjmp exception but not handled in this block, this BB
+// performs the rethrow.
+BasicBlock* LowerSetJmp::GetRethrowBB(Function* Func)
+{
+ if (RethrowBBMap[Func]) return RethrowBBMap[Func];
+
+ // The basic block we're going to jump to if we need to rethrow the
+ // exception.
+ BasicBlock* Rethrow = new BasicBlock("RethrowExcept", Func);
+
+ // Fill in the "Rethrow" BB with a call to rethrow the exception. This
+ // is the last instruction in the BB since at this point the runtime
+ // should exit this function and go to the next function.
+ new UnwindInst(Rethrow);
+ return RethrowBBMap[Func] = Rethrow;
+}
+
+// GetSJSwitch - Return the switch statement that controls which handler
+// (if any) gets called and the value returned to that handler.
+LowerSetJmp::SwitchValuePair LowerSetJmp::GetSJSwitch(Function* Func,
+ BasicBlock* Rethrow)
+{
+ if (SwitchValMap[Func].first) return SwitchValMap[Func];
+
+ BasicBlock* LongJmpPre = new BasicBlock("LongJmpBlkPre", Func);
+ BasicBlock::InstListType& LongJmpPreIL = LongJmpPre->getInstList();
+
+ // Keep track of the preliminary basic block for some of the other
+ // transformations.
+ PrelimBBMap[Func] = LongJmpPre;
+
+ // Grab the exception.
+ CallInst* Cond = new CallInst(IsLJException, "IsLJExcept");
+ LongJmpPreIL.push_back(Cond);
+
+ // The "decision basic block" gets the number associated with the
+ // setjmp call returning to switch on and the value returned by
+ // longjmp.
+ BasicBlock* DecisionBB = new BasicBlock("LJDecisionBB", Func);
+ BasicBlock::InstListType& DecisionBBIL = DecisionBB->getInstList();
+
+ new BranchInst(DecisionBB, Rethrow, Cond, LongJmpPre);
+
+ // Fill in the "decision" basic block.
+ CallInst* LJVal = new CallInst(GetLJValue, "LJVal");
+ DecisionBBIL.push_back(LJVal);
+ CallInst* SJNum = new CallInst(TryCatchLJ, GetSetJmpMap(Func), "SJNum");
+ DecisionBBIL.push_back(SJNum);
+
+ SwitchInst* SI = new SwitchInst(SJNum, Rethrow, 0, DecisionBB);
+ return SwitchValMap[Func] = SwitchValuePair(SI, LJVal);
+}
+
+// TransformSetJmpCall - The setjmp call is a bit trickier to transform.
+// We're going to convert all setjmp calls to nops. Then all "call" and
+// "invoke" instructions in the function are converted to "invoke" where
+// the "except" branch is used when returning from a longjmp call.
+void LowerSetJmp::TransformSetJmpCall(CallInst* Inst)
+{
+ BasicBlock* ABlock = Inst->getParent();
+ Function* Func = ABlock->getParent();
+
+ // Add this setjmp to the setjmp map.
+ const Type* SBPTy = PointerType::get(Type::Int8Ty);
+ CastInst* BufPtr =
+ new BitCastInst(Inst->getOperand(1), SBPTy, "SBJmpBuf", Inst);
+ std::vector<Value*> Args =
+ make_vector<Value*>(GetSetJmpMap(Func), BufPtr,
+ ConstantInt::get(Type::Int32Ty,
+ SetJmpIDMap[Func]++), 0);
+ new CallInst(AddSJToMap, &Args[0], Args.size(), "", Inst);
+
+ // We are guaranteed that there are no values live across basic blocks
+ // (because we are "not in SSA form" yet), but there can still be values live
+ // in basic blocks. Because of this, splitting the setjmp block can cause
+ // values above the setjmp to not dominate uses which are after the setjmp
+ // call. For all of these occasions, we must spill the value to the stack.
+ //
+ std::set<Instruction*> InstrsAfterCall;
+
+ // The call is probably very close to the end of the basic block, for the
+ // common usage pattern of: 'if (setjmp(...))', so keep track of the
+ // instructions after the call.
+ for (BasicBlock::iterator I = ++BasicBlock::iterator(Inst), E = ABlock->end();
+ I != E; ++I)
+ InstrsAfterCall.insert(I);
+
+ for (BasicBlock::iterator II = ABlock->begin();
+ II != BasicBlock::iterator(Inst); ++II)
+ // Loop over all of the uses of instruction. If any of them are after the
+ // call, "spill" the value to the stack.
+ for (Value::use_iterator UI = II->use_begin(), E = II->use_end();
+ UI != E; ++UI)
+ if (cast<Instruction>(*UI)->getParent() != ABlock ||
+ InstrsAfterCall.count(cast<Instruction>(*UI))) {
+ DemoteRegToStack(*II);
+ break;
+ }
+ InstrsAfterCall.clear();
+
+ // Change the setjmp call into a branch statement. We'll remove the
+ // setjmp call in a little bit. No worries.
+ BasicBlock* SetJmpContBlock = ABlock->splitBasicBlock(Inst);
+ assert(SetJmpContBlock && "Couldn't split setjmp BB!!");
+
+ SetJmpContBlock->setName(ABlock->getName()+"SetJmpCont");
+
+ // Add the SetJmpContBlock to the set of blocks reachable from a setjmp.
+ DFSBlocks.insert(SetJmpContBlock);
+
+ // This PHI node will be in the new block created from the
+ // splitBasicBlock call.
+ PHINode* PHI = new PHINode(Type::Int32Ty, "SetJmpReturn", Inst);
+
+ // Coming from a call to setjmp, the return is 0.
+ PHI->addIncoming(ConstantInt::getNullValue(Type::Int32Ty), ABlock);
+
+ // Add the case for this setjmp's number...
+ SwitchValuePair SVP = GetSJSwitch(Func, GetRethrowBB(Func));
+ SVP.first->addCase(ConstantInt::get(Type::Int32Ty, SetJmpIDMap[Func] - 1),
+ SetJmpContBlock);
+
+ // Value coming from the handling of the exception.
+ PHI->addIncoming(SVP.second, SVP.second->getParent());
+
+ // Replace all uses of this instruction with the PHI node created by
+ // the eradication of setjmp.
+ Inst->replaceAllUsesWith(PHI);
+ Inst->getParent()->getInstList().erase(Inst);
+
+ ++SetJmpsTransformed;
+}
+
+// visitCallInst - This converts all LLVM call instructions into invoke
+// instructions. The except part of the invoke goes to the "LongJmpBlkPre"
+// that grabs the exception and proceeds to determine if it's a longjmp
+// exception or not.
+void LowerSetJmp::visitCallInst(CallInst& CI)
+{
+ if (CI.getCalledFunction())
+ if (!IsTransformableFunction(CI.getCalledFunction()->getName()) ||
+ CI.getCalledFunction()->isIntrinsic()) return;
+
+ BasicBlock* OldBB = CI.getParent();
+
+ // If not reachable from a setjmp call, don't transform.
+ if (!DFSBlocks.count(OldBB)) return;
+
+ BasicBlock* NewBB = OldBB->splitBasicBlock(CI);
+ assert(NewBB && "Couldn't split BB of \"call\" instruction!!");
+ DFSBlocks.insert(NewBB);
+ NewBB->setName("Call2Invoke");
+
+ Function* Func = OldBB->getParent();
+
+ // Construct the new "invoke" instruction.
+ TerminatorInst* Term = OldBB->getTerminator();
+ std::vector<Value*> Params(CI.op_begin() + 1, CI.op_end());
+ InvokeInst* II = new
+ InvokeInst(CI.getCalledValue(), NewBB, PrelimBBMap[Func],
+ &Params[0], Params.size(), CI.getName(), Term);
+
+ // Replace the old call inst with the invoke inst and remove the call.
+ CI.replaceAllUsesWith(II);
+ CI.getParent()->getInstList().erase(&CI);
+
+ // The old terminator is useless now that we have the invoke inst.
+ Term->getParent()->getInstList().erase(Term);
+ ++CallsTransformed;
+}
+
+// visitInvokeInst - Converting the "invoke" instruction is fairly
+// straight-forward. The old exception part is replaced by a query asking
+// if this is a longjmp exception. If it is, then it goes to the longjmp
+// exception blocks. Otherwise, control is passed the old exception.
+void LowerSetJmp::visitInvokeInst(InvokeInst& II)
+{
+ if (II.getCalledFunction())
+ if (!IsTransformableFunction(II.getCalledFunction()->getName()) ||
+ II.getCalledFunction()->isIntrinsic()) return;
+
+ BasicBlock* BB = II.getParent();
+
+ // If not reachable from a setjmp call, don't transform.
+ if (!DFSBlocks.count(BB)) return;
+
+ BasicBlock* ExceptBB = II.getUnwindDest();
+
+ Function* Func = BB->getParent();
+ BasicBlock* NewExceptBB = new BasicBlock("InvokeExcept", Func);
+ BasicBlock::InstListType& InstList = NewExceptBB->getInstList();
+
+ // If this is a longjmp exception, then branch to the preliminary BB of
+ // the longjmp exception handling. Otherwise, go to the old exception.
+ CallInst* IsLJExcept = new CallInst(IsLJException, "IsLJExcept");
+ InstList.push_back(IsLJExcept);
+
+ new BranchInst(PrelimBBMap[Func], ExceptBB, IsLJExcept, NewExceptBB);
+
+ II.setUnwindDest(NewExceptBB);
+ ++InvokesTransformed;
+}
+
+// visitReturnInst - We want to destroy the setjmp map upon exit from the
+// function.
+void LowerSetJmp::visitReturnInst(ReturnInst &RI) {
+ Function* Func = RI.getParent()->getParent();
+ new CallInst(DestroySJMap, GetSetJmpMap(Func), "", &RI);
+}
+
+// visitUnwindInst - We want to destroy the setjmp map upon exit from the
+// function.
+void LowerSetJmp::visitUnwindInst(UnwindInst &UI) {
+ Function* Func = UI.getParent()->getParent();
+ new CallInst(DestroySJMap, GetSetJmpMap(Func), "", &UI);
+}
+
+ModulePass *llvm::createLowerSetJmpPass() {
+ return new LowerSetJmp();
+}
+