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view ir/irlandingpad.cpp @ 1117:4c20fcc4252b
Fun with parameter attributes: For several of the "synthetic" parameters added
to D functions, we can apply noalias and nocapture. They are sret parameters,
'nest' pointers passed to nested functions, and _argptr:
Nocapture:
- Sret and nest are nocapture because they don't represent D-level variables,
and thus the callee can't (validly) obtain a pointer to them, let alone keep
it around after it returns.
- _argptr is nocapture because although the callee has access to it as a
pointer, that pointer is invalidated when it returns.
All three are noalias because they're function-local variables
- Sret and _argptr are noalias because they're freshly alloca'd memory only
used for a single function call that's not allowed to keep an aliasing
pointer to it around (since the parameter is nocapture).
- 'Nest' is noalias because the callee only ever has access to one such pointer
per parent function, and every parent function has a different one.
This commit also ensures attributes set on sret, _arguments and _argptr are
propagated to calls to such functions.
It also adds one exception to the general rule that attributes on function types
should propagate to calls: the type of a delegate's function pointer has a
'nest' parameter, but this can either be a true 'nest' (for delegates to nested
functions) or a 'this' (for delegates to member functions). Since 'this' is
neither noalias nor nocapture, and there's generally no way to tell which one it
is, we remove these attributes at the call site if the callee is a delegate.
author | Frits van Bommel <fvbommel wxs.nl> |
---|---|
date | Sat, 14 Mar 2009 22:15:31 +0100 |
parents | f04dde6e882c |
children | 3d1b16dabd25 |
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#include "gen/llvm.h" #include "gen/tollvm.h" #include "gen/irstate.h" #include "gen/runtime.h" #include "gen/logger.h" #include "gen/classes.h" #include "gen/llvmhelpers.h" #include "ir/irlandingpad.h" IRLandingPadInfo::IRLandingPadInfo(Catch* catchstmt, llvm::BasicBlock* end) : finallyBody(NULL) { target = llvm::BasicBlock::Create("catch", gIR->topfunc(), end); gIR->scope() = IRScope(target,end); // assign storage to catch var if(catchstmt->var) { // use the same storage for all exceptions that are not accessed in // nested functions #if DMDV2 if(!catchstmt->var->nestedrefs.dim) { #else if(!catchstmt->var->nestedref) { #endif assert(!catchstmt->var->ir.irLocal); catchstmt->var->ir.irLocal = new IrLocal(catchstmt->var); LLValue* catch_var = gIR->func()->landingPad.getExceptionStorage(); catchstmt->var->ir.irLocal->value = gIR->ir->CreateBitCast(catch_var, getPtrToType(DtoType(catchstmt->var->type))); } // this will alloca if we haven't already and take care of nested refs DtoDeclarationExp(catchstmt->var); // the exception will only be stored in catch_var. copy it over if necessary if(catchstmt->var->ir.irLocal->value != gIR->func()->landingPad.getExceptionStorage()) { LLValue* exc = gIR->ir->CreateBitCast(DtoLoad(gIR->func()->landingPad.getExceptionStorage()), DtoType(catchstmt->var->type)); DtoStore(exc, catchstmt->var->ir.irLocal->value); } } // emit handler, if there is one // handler is zero for instance for 'catch { debug foo(); }' if(catchstmt->handler) catchstmt->handler->toIR(gIR); if (!gIR->scopereturned()) gIR->ir->CreateBr(end); assert(catchstmt->type); catchType = catchstmt->type->toBasetype()->isClassHandle(); assert(catchType); DtoForceDeclareDsymbol(catchType); } IRLandingPadInfo::IRLandingPadInfo(Statement* finallystmt) : target(NULL), finallyBody(finallystmt), catchType(NULL) { } void IRLandingPad::addCatch(Catch* catchstmt, llvm::BasicBlock* end) { unpushed_infos.push_front(IRLandingPadInfo(catchstmt, end)); } void IRLandingPad::addFinally(Statement* finallystmt) { unpushed_infos.push_front(IRLandingPadInfo(finallystmt)); } void IRLandingPad::push(llvm::BasicBlock* inBB) { // store infos such that matches are right to left nInfos.push(infos.size()); infos.insert(infos.end(), unpushed_infos.begin(), unpushed_infos.end()); unpushed_infos.clear(); constructLandingPad(inBB); // store as invoke target padBBs.push(inBB); } void IRLandingPad::pop() { padBBs.pop(); size_t n = nInfos.top(); infos.resize(n); nInfos.pop(); } llvm::BasicBlock* IRLandingPad::get() { if(padBBs.size() == 0) return NULL; else return padBBs.top(); } void IRLandingPad::constructLandingPad(llvm::BasicBlock* inBB) { // save and rewrite scope IRScope savedscope = gIR->scope(); gIR->scope() = IRScope(inBB,savedscope.end); // eh_ptr = llvm.eh.exception(); llvm::Function* eh_exception_fn = GET_INTRINSIC_DECL(eh_exception); LLValue* eh_ptr = gIR->ir->CreateCall(eh_exception_fn); // build selector arguments LLSmallVector<LLValue*, 6> selectorargs; // put in classinfos in the right order bool hasFinally = false; std::deque<IRLandingPadInfo>::iterator it = infos.begin(), end = infos.end(); for(; it != end; ++it) { if(it->finallyBody) hasFinally = true; else { if(catchToInt.find(it->catchType) == catchToInt.end()) { int newval = 1 + catchToInt.size(); catchToInt[it->catchType] = newval; } assert(it->catchType); assert(it->catchType->ir.irStruct); selectorargs.insert(selectorargs.begin(), it->catchType->ir.irStruct->classInfo); } } // if there's a finally, the eh table has to have a 0 action if(hasFinally) selectorargs.push_back(llvm::ConstantInt::get(LLType::Int32Ty, 0)); // personality fn llvm::Function* personality_fn = LLVM_D_GetRuntimeFunction(gIR->module, "_d_eh_personality"); LLValue* personality_fn_arg = gIR->ir->CreateBitCast(personality_fn, getPtrToType(LLType::Int8Ty)); selectorargs.insert(selectorargs.begin(), personality_fn_arg); // eh storage target selectorargs.insert(selectorargs.begin(), eh_ptr); // if there is a catch and some catch allocated storage, store exception object if(catchToInt.size() && catch_var) { const LLType* objectTy = DtoType(ClassDeclaration::object->type); gIR->ir->CreateStore(gIR->ir->CreateBitCast(eh_ptr, objectTy), catch_var); } // eh_sel = llvm.eh.selector(eh_ptr, cast(byte*)&_d_eh_personality, <selectorargs>); llvm::Function* eh_selector_fn; if (global.params.is64bit) eh_selector_fn = GET_INTRINSIC_DECL(eh_selector_i64); else eh_selector_fn = GET_INTRINSIC_DECL(eh_selector_i32); LLValue* eh_sel = gIR->ir->CreateCall(eh_selector_fn, selectorargs.begin(), selectorargs.end()); // emit finallys and switches that branch to catches until there are no more catches // then simply branch to the finally chain llvm::SwitchInst* switchinst = NULL; std::deque<IRLandingPadInfo>::reverse_iterator rit, rend = infos.rend(); for(rit = infos.rbegin(); rit != rend; ++rit) { // if it's a finally, emit its code if(rit->finallyBody) { if(switchinst) switchinst = NULL; // since this may be emitted multiple times // give the labels a new scope gIR->func()->pushUniqueLabelScope("finally"); rit->finallyBody->toIR(gIR); gIR->func()->popLabelScope(); } // otherwise it's a catch and we'll add a switch case else { if(!switchinst) { switchinst = gIR->ir->CreateSwitch(eh_sel, llvm::BasicBlock::Create("switchdefault", gIR->topfunc(), gIR->scopeend()), infos.size()); gIR->scope() = IRScope(switchinst->getDefaultDest(), gIR->scopeend()); } // dubious comment // catches matched first get the largest switchval, so do size - unique int llvm::ConstantInt* switchval = llvm::ConstantInt::get(DtoSize_t(), catchToInt[rit->catchType]); // and make sure we don't add the same switchval twice, may happen with nested trys if(!switchinst->findCaseValue(switchval)) switchinst->addCase(switchval, rit->target); } } // no catch matched and all finallys executed - resume unwind llvm::Function* unwind_resume_fn = LLVM_D_GetRuntimeFunction(gIR->module, "_d_eh_resume_unwind"); gIR->ir->CreateCall(unwind_resume_fn, eh_ptr); gIR->ir->CreateUnreachable(); gIR->scope() = savedscope; } LLValue* IRLandingPad::getExceptionStorage() { if(!catch_var) { Logger::println("Making new catch var"); const LLType* objectTy = DtoType(ClassDeclaration::object->type); catch_var = DtoAlloca(objectTy,"catchvar"); } return catch_var; }